Category: Boat Engine

Welcome to part 4 of a series on my Johnson 6hp 1967 Outboard Gear Case (part 1, part 2, part 3…).  The short story is I wasn’t successful at removing the old oil retainer on my own 😛  It’s really stuck in the impeller housing and retainer assembly (382796) and I have to be careful because Evinrude / Johnson no longer produces that housing!  Now you get to learn from my struggles.  In part 5 you’ll see I was sort of doomed because the last person used Red high-strength loctite and really sealed those old oil retainers in the impeller housing and the propeller shaft bearing!

Advice on removing Oil Seals / Retainers

Once I had a mess on my hands and a better sense of what didn’t work, I started looking around the internet to see other people’s techniques and to discover if there’s anything I could have done better (even though I was probably doomed by red loctite).

This fellow has a pretty rough manner with his engines, but I like his straightforward technique for removing an oil seal.  It certainly appeals to someone that doesn’t have a big shop and lots of fancy tools.  But I think it would have damaged the soft zinc / aluminium impeller housing on the Johnson ’67 outboard.  If you look at some of my photos in the other posts you can see the last mechanic was a bit rough and chipped the inside of the impeller housing.  I don’t want to worsen that so I’m trying to avoid pushing on the soft zinc housing.  You want to jump ahead to minute 6:15 in this video:

It makes me feel better that this guy also uses the drill and screw technique to pull his old oil seals:

His taping method is probably better than the straight pull I was putting on mine.  But again there was just too much locktite on mine, or the old oil retainer (300599) that was already in my engine was just a bit too big for the space, or both.  It certainly looked like someone else had chipped the soft zinc impeller housing in the past trying to get an oil retainer out of there.  Or perhaps it’s just the nature of this Johnson 1967 6hp design to have a really tight fit?  But as I mentioned I didn’t really want to chip up the zinc housing any more, so I focused my force on the screws in the oil retainer itself.  Perhaps the previous mechanic used this technique to fit this damn oil retainer in there!  haha

More seriously, this fellow seems to speak from experience and has a very precise technique for installing the new oil retainer to avoid rolling the rubber seal.  I notice that he also uses a jiggle / tap to get the old oil seal out – Something I definitely need to remember for the future.  I also think his advice about using lots of grease to avoid burning / seizing the rubber on the first run is very important.

This guy has a good technique for removing bushings. Given the shape of the impeller housing it wouldn’t work on my oil retainer for the ’67 Johnson 6hp, but I like the logic and simplicity of this technique:

Now, I’ve had to deal with this impeller housing before in the series on the water cooling system in part 3.  And my Dad’s neighbour, who is a mechanical engineer that worked for Johnson briefly in the early 1970s, used a small handheld propane torch to apply some heat to the steel/brass parts that pass through the zinc / aluminium housing in order to loosen them up.  Risky business when there’s no replacement part, but I’m sort of at the end of the road here and it seems less risky than trying to cut through the brass retainer without cutting into the zinc housing.

Car mechanics are lucky they don’t have a soft zinc / aluminium housing to work around!  As an aside, I really like Scotty’s video style here, the monologue is really well edited:

But for my problem I want to think of heat more in an induction sense. I’m not recommending this system for the Johnson ’67 oil retainer, it’s overkill, but I think this example of induction heating gives a better vision of what you want to be thinking about when you’re using the propane torch:

Next steps were to buy a torch and beg Sam and Lloyd Rooke to help a brother out again, and see if they have steadier hands when it comes to this tricky work! Stay tuned for part 5.

This is part 3 of a series on my Johnson 6hp 1967 Outboard Gear Case (part 1, part 2).  Here I’ll illustrate the dis-assembly and the troubleshooting.  All the part numbers refer to the Johnson 1968 6hp CD-25A 1968 Gearcase Group schematic on shop2.evinrude.com.

The propeller was easy to slide off, after removing the cotter pin.  The picture is a little dark here, but if you click into the larger image you can see the Drive Pin (307949).  This is often called the “Shear Pin” because if you hit or tangle something in the water it’s designed to shear off / break and let the propeller spin free so excessive force doesn’t travel along the propeller shaft into the gears and up the driveshaft into the engine.  I’ve been told it’s wise to carry a couple of spare shear pins with you in case you need to replace one in the wild.

In the next image below you can see the Shift Lever Pivot Pin (308376), note that the head has a cross / Phillips head on it.  When you’re doing a basic oil change (like in the video at the beginning of part 1) this is the “screw” that people sometimes mistake for the oil drain plug and washer (307551).  The oil drain plug has a flat / slotted head on it.  If you remove the shift lever pivot pin, and your shifter lever (303340) stays in place, then you should be able to just slide it back in without issue.  You’ll know that it slid in properly if you can shift from neutral into forward or reverse because this is the pin that connects the shift rod (309582) to the cradle (303381) that snugs right onto the clutch dog (377458).  But if you remove it, and that shifter lever moves, then you might have trouble getting the pin through both the hole in the outer housing and the two holes on the top of the shifter lever (see image below).  Anyways, the seal / washer (307853) on this pin was looking pretty rough, and even though I never saw lube leaking out of it I’d say it really needed replacing.

Below is a picture of inside the gearcase where I’m removing the little cotter pin (306376) that holds the shift rod pin (302504) to the shifter lever (303340).  Towards the lower right of the picture you can see the two holes in the shifter lever that the pin (in the picture above) needs to slide through after it’s entered the housing.  I was really relieved that even though I had a fairly serious oil leak and I’m using the outboard in salt water there was no rusting of the gears inside the gearcase.

Once you get that shifter lever disengaged from the shift rod, then the whole propeller shaft and gear assembly lifts out really easily to expose the pinon gear (312108) that’s attached to the driveshaft:

Here’s the whole gearcase group exploded a bit, with the front bearing (303380) and gear and bushing (377152) off the propeller shaft:

This is the main head and bearing (382291) and the reverse gear (305216) sliding off the propeller shaft:

And this is a close up of the front bearing (303380) and gear and bushing (377152) and one of the thrust washers (303361).  You can also see the cradle (303381) and clutch dog shifter (377458) to the right of the image:

This spaghetti string gearcase seal (309044) looked pretty compressed and worn out, but I never saw oil leaking from the housing itself.  So while it probably didn’t help, I don’t think it was the main source of the problem:

When I lifted the impeller housing plate (303376) it was really ugly looking underneath inside the impeller housing and retainer assembly (382796)!  This is what slowly clued me into realizing that there was an oil retainer there (either CD-25A 0-314167 or CD-25C 0-300599), which seals around the drive shaft.  It seems that oil retainer is probably the primary problem!

Below is an image of the same impeller housing and retainer assembly after being cleaned up a little so you can actually tell there’s a separate oil retainer part in the middle.  It’s hard to see, but in this photo the old oil retainer that is currently there in the impeller housing and is not working is stamped “300599” which corresponds to the schematic for CD-25C.  However the driveshaft does wobble in this, either because of wear and tear, or because someone in the past installed the wrong part.  Hard to know.

It is worth noting that the schematic diagrams for both CD-25A and CD-25C show the gearcase head oil retainer on the propeller shaft as part #313282.  However in my engine there’s an old oil retainer there stamped “303345” which seems to be a generic Sierra OMC part based some Google searches… This suggests someone had this engine apart in the past and I’m not looking at factory settings for any of these seals.

Below is an image of the new oil retainer I’m going to use (CD-25A 0-314167).  I picked this part based on my hypothesis in part 2, which matches with Leeroy’s hypothesis. To save you a click, I decided that my 1967 Johnson Seahorse 6hp model and run/version number CD-24D was probably built later in the year 1967.  I also decided that the schematic for the 1968 Johnson Seahorse 6hp model and run/version number CD-25A was probably earlier in the year 1968, and therefore they had a greater likelihood of having similar parts.  In the real working world if you were building engines right before Christmas and then came back after New Years there probably wouldn’t be a lot of change in how you built the engines.  However if you have more information on the run/version numbers please us know in the comments below!  Normally people in the 20th century numbered things 1-2-3 A-B-C, but sometimes people came up with other wacky ID formulas.  Also, I am not a trained mechanic, and I’m accepting the risk that I’ll have to do this all again with different oil retainers if I’m wrong about the impeller housing oil retainer CD-25A 314167 versus CD-25C 300599.

The new oil retainer is roughly the diameter of a quarter.  If you click and open the larger image you can see the very cool little spring that synches the rubber seal inwards to seal around the driveshaft as it passes down through the impeller housing into the gear case.  This new part #314167 slid over the driveshaft easily and feels quite snug – so far so good.  Gotta remember to put some grease there so the rubber doesn’t stick, twist or burn on the first use.

More in part 4 on how successful I was at removing those oil retainers and bushings 😛

This is part 2 of a series on my Johnson 6hp 1967 Outboard Gear Case (see part 1 here, part 3).  Before I get into the disassembly, I thought I’d show the seals / gaskets / washers / plugs that I’m replacing.

The first thing to note is that the 1967 CD-24D parts aren’t up on the Evinrude / Johnson website. It only starts at 1968.  I’ve found (so far) for the water system and gear case all the parts from the 1968 schematics are working.  Also for 1968 there’s a 25-A and a 25-C (plus others), and it seems that A and C are the same mostly.  If you know the logic for distinguishing these different schematics please leave a comment below.

So I’ve been using 25-A as my replacement for the CD-24D based on a recommendation from one of the marine supply shops up in Nanaimo that had an old paper manual, but that’s a hazy memory and I don’t have any documentary evidence to prove it.

Update: I got up this morning (Sun) with a fresh brain, took a look at the parts strewn around the living room, and had an aha! moment.  There is also an oil retainer in the bottom of the impeller housing that seals it off the top of the gear case housing (around the driveshaft).  I didn’t order that part yesterday!  It’s so old an cruddy that it just looks like one piece, but George Keats’ video clued me that there’s actually a removable metal housing and rubber seal there!  In this photo I think you can see the Oil Retainer (CD-25A 314167? CD-25C 300599?) in the center of the underneath of the impeller housing, and just off to the right is the smaller and lower Shift Rod Bushing (303332) that hides the Shift Rod “O” Ring (301877):

Unfortunately with the Impeller Driveshaft Oil Retainer I finally found the part of the Gearcase Group diagram (#14) where CD-25A and CD-25C actually differ.  Damn!  So now I really need to be sure of how to translate my 1967 CD-24D to a 1968 schematic number:

I’ll check out Leeroy’s site again, and then maybe email the Evinrude / Johnson corporate archives!  Drat.  I was excited for a second about this link http://shop.evinrude.com/media/document/ModelNumberReference.pdf which I think Leeroy borrowed from, but it doesn’t give any detail about those final model run/version letters for the Johnson CD-24 and CD-25.

I suppose the logic I’ll use is that, assuming the main model number increments by 1 for each year (CD-24 in 1967 to CD-25 in 1968), and assuming that the final letters are the version/run numbers, then CD-24D would probably be later in 1967 and CD-25A would probably be earlier in 1968.  So it seems there would be less variation in parts the closer the version/run.  Perhaps this theory is supported by the fact that there’s actually a CD-25C Oil Retainer (300599) in there now and I’ve been having a hell of a time with clogs in the water system and oil leaks…  I’m about ready to try the CD-25A Oil Retainer (314167).  You’ll know I’m wrong if I’m writing more blog posts about this in 6 months to a year!!  Ok, re-editing again and it looks like Leeroy and I independently came up with the same theory, “& the A could be a model revision, so this motor would probably be made in the very first part of the year”.  That’s good enough for me!

Anyhow, here are the other new seals / washers / gaskets that Sherwood Marine had in stock today (Sat).  The rest is coming from their Vancouver store later this week.

The white plugs / washers (311598) are for the flathead slot oil drain drain screws / plugs (307551) on the lower outside of the gearcase.  The small black ring (307853) is for the phillips crosshead screw / pin (308376) on the lower outside of the gearcase, you can see how the old one on the left is sort of flattened and widened.  But I never saw oil leaking out of that screw so it’s hard to imagine a lot of water getting in that way.  The big black ring (301877) is for the shift rod bushing (303332).

All in all, I think that Impeller Driveshaft Oil Retainer is the main culprit because I’ve actually seen creamy oil dripping down out of the copper water tube (304317)!

A couple of other parts were also difficult to identify / differentiate.  I was staring at the head and bearing (0382291) on my propeller shaft and wondering where it ended and the oil retainer (0313282) began…  I sort of poked from the inside / backside at the rubber seal inside the oil retainer with a small screwdriver to see if I could slide the entire metal/rubber unit out, but the rubber ring was really mushy and seemed like I should think about it some more before tearing the rubber apart without having a new part in my hand yet 🙂  Luckily George Keats and his son did a similar operation on their 1976 Evinrude and posted a great video!  My oil retainer looks slightly different than their seal, but I think it’s essentially the same design.  Thanks so much for sharing this George!

One other thing I discovered is that my shift rod is held in place by a sort of square detent spring (303466) that interacts with 3 notches in the shift rod:

That detent spring is a little hard to see here because it’s dark on dark, but it’s to the right just above the flathead slot screw that holds it in place:

Thought I’d point out those 3 notches on the shift rod and the corresponding detent spring because when I first took it apart it wasn’t easy to get it back into place and I was like ‘groan, what have I got myself into’ 🙂  But once I got a little screwdriver in there for leverage it wasn’t too tricky.  Now I really get it, and can actually remember when I was using my shifter that feeling of clicking into those 3 notches!

More in part 3 on the diassembly of the gear case and the troubleshooting.

This is part 1 of a series about my Johnson 6hp 1967 Outboard Gear Case / Lower Unit. (part 2, part 3, part 4 …)

Having already addressed the more pressing problem of the water cooling system, I realized the gear case was probably not water tight.  The first sign of this was creamy “oil” leaking out of the motor when it was stowed horizontally in the boat (via the water intake screen) 🙁  In a strange way it was better than seeing nothing at all, which could have meant there was absolutely no oil left.  As mechanic Leeroy Wisner warns:

There should be a dark thick gear oil.   If it is a thick creamy color it has water contamination inside.  If no oil comes out, your unit has a leaky shaft seal, which may have let water in and then over time also drained out if not ran for some time.  If this is the case then you may have a rusty prop shaft or gears.  Either of these will put a lot of excess resistance on the motor when shifted into either forward or reverse, causing it to bog down. <http://www.leeroysramblings.com/OMC_6hp.htm>

To start I followed some clear and simple video instructions from BRP – Marine Propulsion Systems on how to change the gear case oil:

I didn’t have much hope that changing the lube and the oil drain washers would fix the problem but, it seemed worth trying a simple fix first in case those washers were the source of the leak.  And it did get me out on the water a couple times with my new (to me) boat.   Thanks to the gang at Sherwood Marine (especially Chris) for parts, tools and advice.  Here’s the first round of drained creamy oil and the Johnson Gear Case Lube Pump in action:

However after a couple of trips I noticed there always seemed to be a bit of a rainbow around the outboard when it was in the water, and on the last run I saw some strange bubbles once when I shifted from forward, to neutral and into reverse.  Both of these symptoms suggested (to me) there was still a water leak that needed to be fixed.

The second time I drained the gearcase oil I got a little more clever and purchased a cheap $1.75 painting insert to catch the old gear case lubricant.  Sadly it was totally creamy again:

I also realized that it is possible to get things done without a garage, workshop and outboard stand if you really want/need to!  Please note I am lucky to have a very understanding wife, and accept no responsibility if you try something similar in your home 😉  You’ll also see some lumber there because I’m planning to build a Peter Nielsen (from Sail Magazine) outboard stand in the near future.

Right from the beginning of this process I was watching a tour of an old Johnson gear case by James at Highland Outboards.  I watched it a couple of times in preparation and still went back for details when I was disassembling the gear case.  It’s very helpful and I would highly recommend watching it before taking yours apart.  Thanks James!!

To get the housing open on mine I had to stabilize the engine by pushing down on the lower unit / leg above the propeller shaft, so that I could also apply some very firm but gentle downwards pressure on the bottom of the fin, in order to pop open the old watertight adhesive/sealant.  This caused me some concern as I was doing it, but everything worked out fine for me.  I was glad I didn’t have to use a blow torch or chemical sprays to release the sealant (see note above about wife and living room workshop!).

Once inside the gear case, I was particularly slow at realizing that the shift rod and lever was still holding the propeller shaft and gears in the housing.  At first I was wiggling the propeller shaft wondering why it was stuck, looking at one strange screw thinking perhaps I needed to take it out (more on that later), and wondering if some old adhesive / sealant on the main bearing was stuck.  But I watched James’ video again and he didn’t mention releasing that screw, but he did push the shift rod down to create space, and once I did that the prop shaft and gears had space to slide out without any issue.

Thankfully once inside I only saw a tiny bit of normal wear and no real rust:

My metal fuzz seemed to be captured under what James called the main bearing and seal (what the Johnson website calls the head and bearing for the Johnson 1968 6hp CD-25A).  As I worked the main bearing off the propeller shaft there was a gritty feel and I needed to add some oil and really roll it back and forth to slide it off.  The fuzz all got captured in a hole on the propeller shaft:

Luckily the gears in the housing doesn’t seem rusty at all.  There’s just a bit of rust around the old seals, so that seems to be one place where the water is getting in.

Stay tuned for part 2.  I’ve got to run for Sherwood Marine before they close!

This is part 4 in a series on fixing the water cooling system on my Johnson 6hp 1967 outboard (part 1, part 2, part 3).

Recap

So it was time to call in the big guns.  Luckily Sam and his dad Lloyd have been working on outboards their whole lives (& then some) and had some time to help me out.  As a recap, the initial water intake screen, the tube between the propeller and the impeller, and the impeller itself all seemed reasonably fine (but we replaced impeller in part 3 while in there anyways and kept the old one as a backup).  In addition the final bit of tube for exhaust \ water outflow tube was fine.  So the problem was in the middle of the system.

The first step was to grab some Muriatic Acid (watered down hydrochloric acid) from the local hardware store, in case we needed to run it through the water cooling tube (be careful, I wouldn’t use pressure myself).  Lloyd said that, before resorting to acid, he’d try to get a little farther into the engine block (he seemed to be pointing at the Powerhead Group Crankcase area).  But it’s good to have the supplies you need and it was only $6.50 at Home Hardware in Sidney:

Once we got to work the first step was to remove the old broken thermostat and gasket from the top right away.  Not only was the spring broken off the top but the whole unit was encrusted with salt and corrosion:

Next we fired it up to try and get some water down through the tube in the engine block (and partly in the hope that those shoe elves had fixed it for me, but no such luck):

We did see the water drain in slowly and release a couple of slow air bubbles. A good sign! There’s a chance that the block started loosening when we got a bit of fresh water in there the weekend before to work away in the heat all week.  It certainly didn’t hurt.  To try and encourage the movement of water and air, we blocked the exhaust tube with a finger to create a bit of suction, but there were no miracles.

So we went out to get a new thermostat, gasket and seal at Sherwood Marine for $40 (I didn’t get a picture of the part numbers unfortunately):

I also grabbed some 2-stroke Johnson engine oil while we were at Sherwood Marine in Keating Cross Road.  Leeroy Wisner suggested that other 2-strokes used on land (like weed-whackers) tend to run a little hotter than an outboard so the oil is a different grade.  That sounded reasonable enough to me:

To replace the thermostat we first needed to plug up the holes for the water system, and then use a wire brush to clean off the ruined old seal (tip – if you can’t find a seal you can cut up old cereal boxes into the right shape and stack up 2 or 3 layers and maybe add some gasket goo if you like)

Lloyd made us solemnly swear to use grease, grease and more grease.  He said his old man made him use lots of grease, and he’d seen years later that even if the bolt was almost gone/eaten away by salt water corosion the sections that remained would turn in the housing:

Once we got that new thermostat in and fired it up again, there was actually a tiny little trickle of water peeing out the exhaust hole already!  By this point we’d added a good solid squeeze of dish detergent to the garbage pail of water to really start lubricating and loosening up the water cooling system.  But there was still not enough water flow to say it was fixed.

There was still a blockage (slowly getting looser from fresh water) not far up from the bottom/impeller in that copper tube heading towards the engine block.  Lloyd and Sam had a good trick with a stiff ~14 gauge chicken wire hammered flat on the end to make a shovel.  With the motor sitting upright so bits would fall down with gravity Sam pushed the stiff wire up from the bottom and twisted a bit to clear the salt block.  Then we poured in some more fresh water at the top and blew compressed air down through the engine block area, and blew the bits out the bottom!

Then we ran it again in that giant garbage can of water (to totally submerge the impeller housing and lower unit) mixed with a good squirt of dish detergent.  At that point water was flowing out really nicely like in the YouTube videos and the engine block stayed cool!

Finally here’s a video of the Johnson Seahorse 6hp 1967 Outboard Cooling again!

What a great feeling that was.  And here she is back onboard the Islander 21′

This is part 3 in a series on fixing the water cooling system on my Johnson 6hp 1967 outboard (part 1, part 2, part 4).

Workspace

To start my dad and I set up a makeshift outboard stand using a folding workbench, a 2×4, and a large steel clamp.  Not as nice as Peter Nielson’s (link) but it got us rolling very quickly for free on day one when we had more pressing issues.  Don’t forget to weigh down the opposite side, we used jugs of oil found in the garage, but down-rigger cannonballs or dumbbells would’ve been perfect.

We also set up a small bucket of water to cover the water intake.  In retrospect it may have been too small to allow for proper cooling and suction (more in part 4).  I don’t think it was an issue but, if you’re still in the planning stage, plan to use a full (clean) garbage can or a bucket that at least covers the lower unit above the bulge where the impeller housing.

Dis-assembly and Impeller Replacement

To remove the lower unit (as described in detail in the videos by James from Highland Outboards mentioned earlier) you need to release the 4 or 5 exterior bolts surrounding the large bulge (surrounding the impeller housing), then wiggle the lower unit down gently an inch or so until you can see this soft brass screw/bolt.  Magnets won’t work so plan to have a very small diameter socket wrench extension or/and some needle nose pliers to make your life easier.  A headlamp is also helpful so you don’t annoy each other talking about the right angle for lights.

After releasing that shift rod screw it’s easy to slide off what is generally called the “lower unit” and drive shaft, to expose what the Johnson website diagrams calls the “gearcase group”.

We had to clean a goopy mess of oil mixed with salt water, before we could see the impeller housing screws clearly.

This is what it looked like cleaned up, helps understand that bulge in the exterior housing:

Next step was to release the 4 screws holding the impeller housing on.  In our case they were seized.  We applied liberal amounts of WD-40 and waited a few minutes, but the flathead screws were stuck and the heads started stripping!  Luckily one of my parent’s neighbours Peter is a mechanical engineer who actually worked for Johnson in the early 1970s and he had a trick of using a handheld propane torch on low to put focused heat on just the stainless steel screw heads for about 3-5 seconds.  Be extremely careful because the impeller housing is zinc which is soft and will deform if you put direct heat on it.

The combo of the WD-40, waiting 10 minutes, and applying heat did the trick.  Later we bought new screws with squareheads to avoid the stripping problem in the future (Note– I need to replace them again because we didn’t get stainless steel :P).  So finally we were in to see the impeller itself:

I think my dad had shoes on at the beginning of this session, but somehow he’s barefoot again here… Anyhow, it’s a good thing I like taking photos while other people work because the direction that those fins spin in is part of the mechanical design and you must remember which way they turn when you are forcing the new impeller into the housing.  And Peter suggested there isn’t a universal rule so pay attention to whether it’s clockwise or counterclockwise and hope the last person did it right.  By the way, despite what the videos say, when Peter saw this impeller he thought it still looked mechanically sound and suggested keeping it onboard as a backup if I ever needed it in a pinch.

Once we had that part out we were able to run all over Nanaimo B.C. looking for a replacement until Dean at MPS saved the day with his excellent stock.  Note that this Sierra Marine Engine and Drive Parts 18-3001 (replacing the 1968 0-277-181) was only $21.31 including tax at MPS and is $25.29 online from Evinrude / Johnson.  So it pays to check out your local marine supply stores.

Note that when you’re squeezing the new impeller into the housing it’s a very tight fit and you really need to press it in there and get the fins pointing in the right direction.  And pay attention to the little pin that slides into the center hole along the drive shaft.

Re-assembly

Once the impeller housing is back together, putting the lower unit back on can be a big pain.  You need to get the drive shaft into a small hole that leads to the engine block way at the top in the dark, you need to make sure the copper tube slides into the plastic hole on the top of the impeller housing, and then you need to wrestle the gear rod into the right spot to get the screw back in.  When all that aligns it feels smooth and easy, so try to do some deep breathing and just poke around until it clicks.

Impeller Again

We ran it and no water came out – that was disappointing.  So our first thought was that we did something wrong putting the impeller in, so we disassembled everything again.  I’m glad that we did because I actually noticed that the new impeller was such a tight squeeze that shavings came off and went up into the chamber that leads up to the copper tube and then the engine block.  I hope a good water flow would wash that rubber dust out, but it’s something to be aware of I guess.

When reassembling it a second time we followed Leeroy Wisner’s advice and lubricated with a bit of vaseline.  If you click to zoom in you can see how the tips got a little shaved into place:

Unfortunately after a slower reassembly (at the tired end of the day), there was still no water spitting out the exhaust.

Initial Investigation of Thermostat

Since replacing the impeller wasn’t enough, the next step was to try and isolate the location of the issue by pouring some water up from the bottom of the system into the copper tube that leads into the engine block.  The water didn’t get too far which hinted that there was a block somewhere up inside.

We had a bit of time, so we took off the top to try and pour some water down from the top of the system.  Here’s the top of the thermostat housing, the 3 bolts were tight but they actually came out with a bit of coaxing!

Having opened the thermostat we tried to check the short tube heading out to the exhaust exit (the easier part to check), it seemed clear:

We tried a bit of water out the exit and then on top of the thermostat.  It didn’t really get past the thermostat so that seemed to be the next big hurdle:

But that was the end of the day, so the next step was to pack up and call up the big guns and bribe Sam and his dad with some coffee and donuts.  Next steps were to replace the thermostat and try to clear out whatever is blocked up inside the copper tube that winds through the engine block?!

(Spoiler alert- pouring water up from the bottom and down from the top & doing everything back up & leaving the motor in a hot car for a week seemed to loosen up the salt chunk a bit.)

Aside on Clamp Screws

Also, while we were at Parker Marine and Marine Parts Supply they both confirmed that the Johnson Clamp Screw Kit (0-388-346) was $105 Canadian!! I am really glad Evinrude/Johnson still makes parts available, but in this case the default thread for a 5/8″ by 2″ bolt from Home Depot worked just fine (we didn’t need this handy advice http://www.bola.de/en/technical-information/screw-joints/determination-of-thread-types.html) and I couldn’t justify the $100 difference this time.

This is part 2 in a series on my Johnson 6hp 1967 outboard.  Click here for Part 1, Part 3, Part 4.

Bruce Stott and I saw a problem/symptom where no water was spitting out of the outboard, and the engine started getting quite hot and steaming/smoking a little. Never a good sign.  Luckily we only got to the end of the dock before we noticed and decided to turn back for more maintenance, so I’m hoping nothing got seized.

The main theories were:

-Water line is plugged with salt/muck

-Impeller water pump is malfunctioning

To start I found an old service manual on the internet for this Johnson 1967 6hp – Here’s a link 52138772-Johnson-6HP-1965-68.  On p.179 there’s a paragraph on the “Cooling System” which also says check the thermostat, if equipped.  Figure OM4-17 on p.182 gives a sense of the parts (love this old engine because it doesn’t have many parts) and the water tube is specified in Figure OM4-19.

Then I found a short video by 767ambu (https://youtu.be/wmjGFAEiv5k).  I liked the simplicity of it because it helped me start wrapping my head around the work, but obviously it’s not enough.

Luckily James from Highland Outboards gives a great 4 part tutorial on changing the impeller that you’ve got to watch:

Part 1 https://youtu.be/Niri5EgQ6nU

Part 2 https://youtu.be/NtGhCnYN_L4

Part 3 https://youtu.be/pm8mg8W39q8

Part 4 https://youtu.be/xxFp5eXS8Bw

You may need some marine parts and you may not find them at the generalist boat stores you normally go to.  If you’re near Victoria or Sidney B.C. you could try Sherwood Marine where Dustin Campbell really knows his stuff (email parts@sherwoodmarine.com). If you’re near Nanaimo B.C. I’d recommend talking to Dean Rispin at Marine Parts Supply (MPS) of Canada (email drispin@MarinePartsSupply.com).

Evinrude Johnson also has online parts diagrams and codes online if you want to research them before talking to the parts suppliers.

The parts and supplies I was looking for were:

1) A functional impeller that fits.  Dean at MPS in Nanaimo stocks Sierra Marine Engine and Drive Parts Impeller 18-3001, which replaces OMC 0-277-181, 0-434-424.  They come in a pack of 1 for about $20, so I bought 2 while they were there in front of me.

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2) Suitable solvent for washing parts (e.g. mineral spirits, brake cleaner or POR-15 Cleaner Degreaser).  I didn’t actually need this or get any but I’m sure I will one day.  This seems like a great article link for more info http://www.enginebuildermag.com/2007/07/cleaning-engine-parts-in-the-real-world/

3) Proper lubricant for the gears and bearings.  I grabbed a tube of Evinrude Johnson Triple-Guard Grease while I was at Parker Marine in Nanaimo.  I got a tube for $7.50 but looks like it can go for a bit more online.  Not sure if this is exactly the right stuff but it’s waterproof grease and says it can mix with other greases, so I’m hoping the old ’67 won’t be too fussy. By the way it was at Parker Marine’s Johnson museum that I realized my outboard is indeed a Seahorse and started to see some similarities and design improvements in different older models.

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Phew, well that’s it for part 2.  I’ll get into the impeller process photos and tips in part 3. Then the thermostat and line clearing in part 4!

(Spoiler alert- there’s still a blockage in the middle of the tube still, after the impeller replacement.  It seems to be in the line that runs through the engine block, before it gets to the thermostat which is still bone dry and corroded.  So I’ve got to either flush it out, or study the details of Leeroy Wisner’s suggestions for overhauling the water cooling system in preparation for part 4! http://www.leeroysramblings.com/OMC_6hp.htm  A big thank you Leeroy!)

This is part 1 of a few posts on repairs to the cooling system on my Johnson 6hp 1967 outboard (part 2, part 3, part 4). Here it is as I bought it, sitting on the kicker bracket:

I know it’s a 1967 because of the model number CD-24 (D) on the motor.  Note that the Johnson 6hp from 1968 has model number CD-25, and that seems to be the first year in the online supplier databases, but the same service manual covers both (I found it on Scribd):

I bought the boat the last week of April, broke my foot playing floor hockey a few days later the first week of May, and after a few weeks of recovery I was heading out for the first sail with Bruce Stott of Gulf Islands Cruising School Ltd. at the end of June.  I met Bruce Stott doing the Canadian Power and Sail Saanich Peninsula Squadron courses in North Saanich and he’s a great teacher. So anyways, at the end of my dock, on the way to the marina gas dock, we noticed that the outboard wasn’t spitting water and was getting hot.  So I learned about sculling with the tiller / rudder and we turned back to my slip.  This is what the outboard looked like inside the first time we opened it up.  Obviously someone had given it a good overhaul at some point:

This past weekend I worked on the impeller for the first time which I’ll tell you about in part 2!

In advance I’d like to thank James from Highland Outboards (https://www.youtube.com/user/highlandoutboards/about) and also Dean Rispin from Marine Parts Supply (MPS) of Canada at the new location in Nanaimo B.C. (http://www.marinepartssupply.com/contact) for their help with the impeller repairs!