1964 Johnson 40hp RD-26S

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1964 Johnson 40hp RD-26S

Post by Rapier »

Have been working on this motor for a few weeks..

It's the typical OMC 40hp twin of the 60s. The Johnsons were a premium product, but I find their styling tame compared to their Evinrude counterparts. This one came from Falmouth and in the 14 years that we'd go to the annual rally there, we'd invariably go into an outboard dealer for Rock Oil and various bits and pieces needed, or not, to continue to run our outboards. The Johnson lover that Mike was (I'd sold him so many parts motors..even I'd lost the will); he'd spotted a motor in the showroom that was as nice as his, and would always ask the owner if he'd sell it. The answer was always that it was belonged to a family member and wasn't for sale.

Over the years we'd see it there on the stand. Mike passed away early in 2019 and it was a few months later that I was doing my usual 'internet finds' searches and recognised a Johnson that had appeared on eBay. According to the seller he'd serviced it and it wasn't pumping ater and after many hours of labout they presumably thought it a dead loss. I can't remember bidding on it, or making an offer...but a few days later I drove to Falmouth and back, spending 6 hours on the return journey; almost stationary on the M5, with the motor and it's controls in the back of my station wagon.

Fast forward a year and in my resolution to clear up the Backyard Boatyard (aka the encampment) and the need to have a backup motor for the '60 Merc 300 on my Pearly Miss; I finally decided to move it indoors and look for the problem.
Attachments
1st Year of the 50:1 ratio motors
1st Year of the 50:1 ratio motors
GRP one-piece cowling  (West Bend were the 1st), a variation on the Mercury wrap and faceplate.
GRP one-piece cowling (West Bend were the 1st), a variation on the Mercury wrap and faceplate.
1964 Johnson 40hp RD-26S
1964 Johnson 40hp RD-26S
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Re: 1964 Johnson 40hp RD-26S

Post by Rapier »

Compression on both cylinders was a respectable no variance 110psi. These twins are not pleasant to pull over by hand and the technique used requires most of the starter cord to be pulled out. I had two old starter motors and their brackets hiding in the parts bin, they're both prestolite but one had a more modern system of brushes, a more stable mounting bracket and as it turned out, less wear, when I serviced them.

Surprisingly this motor had both the toothed flywheel ring gear and the starter motor bracket fitted. I can only assume both were factory fitted as neither showed any sign of past use. To have both is a huge bonus; brackets, starter motors and flyhweels are becoming hard to source and a used 'kit' can set one back £80 to £100.

The OMC 40hp is a useful (period) motor if you want to run a 12ft to 14ft classic. They're simple to maintain, with little specialist tooling required other than a factory flywheel puller (about £80 new). This tool comes with a selection of hardened bolts that fit OMC's range of motors. Some use a standard harmonic balancer puller quite successfully, but I've seen flywheels with shredded threads and broken steel bolts embedded, so I use the proper factory tool. Don't try the prybar / crowbar and mallet option on these motors....

These motors are not huge horsepower, but they have decent torque, a wide range of propellers and are surprisingly quiet when running. The cowls are padded with foam (can be a fire hazard) and the midsections are shrouded, supposedly to keep them quieter, but are just a gimmick to made them look as big as the competition. West Bend and Chrysler did the same thing on their twins. By '69 OMC went back to a one piece midsection, similar to the 1958 modesl, but reinforced. I mention this only as the bolts holding the shrouded sections sieze in situ and mostly require heat and an impact driver to release, which will mess up a nice paint job.

The midsection shroud has a small removable panel to access the internal panel removed when releasing the shift shaft and the bolts / screws seize there too. I have come to dread doing this job, if I haven't worked on it before. As it was it all came apart easily (and went back on with lashings of 24C and 101 grease) and I was able to get the gearbox off within minutes.
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IMG_4698 (Large).JPG
IMG_4697 (Large).JPG
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Re: 1964 Johnson 40hp RD-26S

Post by Rapier »

The professionals had presumably tried just about everything to ascertain why this motor was not cooling, I formed the opinion that the non pumping issue was likely due to a water tube (possibly a squashed grommet) and under-powerhead problem. With the flywheel off (to replace the points and check the coils and condensors..all new) it was looking like I'd have to separate the two and have a good look under the powerhead.

The cause was unlikely to have been an impeller break-up. I wanted to drop the gearbox to look at the water pump, impeller, keyway, pump grommets, water tubes to the powerhead in case someone had something. The driveshaft was clean (is stainless steel, unlike...) properly greased splines (have had to do battle with a stuck driveshaft before) and a fresh 'o' ring installed at the top of the shaft (prevents washing out of the grease and keeps grime out of the splines). The water pump housing unbolted (have sheared many bolts before), the keyway was still in position and the impeller, while sticky, was still pliable and showed no wear. The pump housing was old and pitted, but would have functioned fine and the two nylon grommets were undeformed (they can catch on the angled water pipes (when remounting the gearbox) and collapse cutting off the water supply to the powerhead). The water tubes in the midsection showed no sign of blockage.

It was when I pried the impeller wear plate up that I noticed the typical crusty deposits under the plate and coating all the channels. Worse was to come as the intake tubes from the area above the anti-cavitation plate were completely blocked with salt and crust, which meant no water was finding it's way into the pump in the first place and the priming system (the immersing of the gearbox in water) wasn't working. After removing the intake plate above the cav plate (again with heat / impact driver..) an hour or so of work with a dental pick, scalpel, wire brushes and various pallet knives was enough to clear the channels, so that I could paint some acid over the balance of the deposits and flush it all out with fresh water.

Once removed I separated the pump from the tubes to find that the one of the channels / balances for water flow was blocked too. This needed to be hand drilled eventually..the picks wouldn't reach far enough into the orifice. I guess that at the last service the impeller would have been replaced with a smattering of gear oil, in order to help it into the housing - in the absence of water flow had heated up and then been left there..hence the stickiness of the rubber.
Attachments
Blocked channel
Blocked channel
More deposits
More deposits
Fairly clean after deposit removal.
Fairly clean after deposit removal.
Intake screen removed to access the base of the intake tubes.
Intake screen removed to access the base of the intake tubes.
Worn water pump - the 40s use at least 3 different styles and have different sized impellers..
Worn water pump - the 40s use at least 3 different styles and have different sized impellers..
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Re: 1964 Johnson 40hp RD-26S

Post by Rapier »

Having seen the blockage in the lower unit, I needed to remove the cylinder head to check that the same deposits weren't around the water jacket in the power head. These passages are not particularly wide so can block up a motor run in salt water, if not flushed after use. The head came off easily and whilst there was some sand / grit at the base of the water jacket was otherwise free of debris / deposits.

By this stage the list of parts needed was as follows:
- cylinder head gasket £17.00
- thermostat (the jury is always out on whether to install, or not..I do now) £19.99
- thermostat gasket £2.50
- waterpump housing £25.00
- waterpump housing cap gasket £4.25
- points £14.99
- water pump impeller £15.00
- fuel line and bulb £19.99
- bespoke battery cables £23.00
- universal push button switch £4.50
- OMC starter solenoid £17.50

Parts are becoming hard to find in the UK for these motors..most of the above were unobtainable (NLA) from my regular suppliers (and if they were obtainable were eyewateringly expensive), i.e. a water pump housing is now RRP £100. With a bit of searching for parts compatibility online I was able to find replacements for obsolete bits and used this link to verify the correct parts. The prices varied widely as well, with nearly £8 difference on the head gasket alone.

https://www.marineengine.com/parts/john ... odel=RD-26

Some were stock I had...sourced from jumbles and people who've given me extra bits from their own stock. Either way I make the comment that even a very good project can end up being uneconomical to repair. My labour 'rate' is far less than a professional and I work a lot slower and methodically than I used to, but I reckon I have spent 15-20hours on this. I ordered a piston for my Chrysler from the US recently...the ebay global shipping rip-off meant a $24 piston became £70 by the time everyone had taken their (unearned ) cut - my point is that a project becomes even less viable when the ca. £165 bill above needs to be sourced from there..
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Cylinder head
Cylinder head
Block
Block
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Re: 1964 Johnson 40hp RD-26S

Post by Rapier »

All my parts arrived, with the waterpump being a match for my old one (despite a different part number). I'd tried to fill the pitting in the old, but depsite a nice smooth finish, wondered how long it would last. As the old managed 56 years, I'll be 'late' before the new part corrodes. Fitted new gaskets to the thermostat housing, covering the new thermostat. 'Skimmed' the head and fitted the new gasket and torqued it to initial setting. The pump didn't fit quite right, until I realised I'd twisted the wear plate enought that the bolt holes didn't line up... The easy way to replace an impeller on these is to mount the impeller on it's key, slide the pump housing down the driveshaft, then rotate the driveshaft clockwise (with propshaft facing away from you) while putting some pressure with another hand on the top of the housing. I use padded mole grips to hold and turn the shaft (lightly) as everything gets a bit greasy. The impeller vanes will set in the direction of travel; I'd pre-greased and ran the screws through to clean the threads out, before bolting it up. Greased the splines (not the top of the driveshaft) and fitted the O ring before mating gearbox and mid-section. The lower shift shaft mates up to the upper using a brass connector with two stainless steel bolts - these are easy to cross thread and chew up the brass connector..they were £17 the last time I checked about 8 years ago, so I use a socket on a screwdriver attachment to feel the thread in...
Attachments
New waterpump mounted and screwed in
New waterpump mounted and screwed in
Part numbers 305095 & 381576
Part numbers 305095 & 381576
IMG_4684 (Large).JPG
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Re: 1964 Johnson 40hp RD-26S

Post by Rapier »

These OMCs are typically manual start here in the UK. I can only imagine the price differential between manual and electric start was such that most purchasers opted for the manual start version. Personally I hate pulling these over by hand - having torn a muscle years ago and waited months for it to heal, every manual OMC 40hp I've had since then has been converted to electric start. This one had the all important flywhweel ring gear and starter motor bracket already there. However, all the paint was undisturbed and the original blanking grommet (for the loom) in place; so, can only assume it had never been converted. This was good, as the bracket, ring gear and starter motors are hard to find here and one can expect to pay around £100 for the lot. To complete the package, I had a starter motor I'd bought years before and while I waited for a starter solenoid (screw holes fit the air filter on the powerhead tray..), cleaned, serviced and ensured it had all the right readings before mounting it to the powerhead. Instead of opting for the full loom and key switch, all wired in via a factory junction box with solenoid in situ, a simple automtive style momentary push button switch is used. Battery cables were bought on eBay, made to measure with terminals per my spec. The whole lot was wired up and works a treat. I don't much like electrical bits sitting under carbs, so will make a simple plastic cap from an aerosol can.
Attachments
IMG_4669 (Large).JPG
IMG_4694 (Large).JPG
IMG_4695 (Large).JPG
IMG_4693 (Large).JPG
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Re: 1964 Johnson 40hp RD-26S

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Today was test day. I normally use a Flushette device on these 40s, but having never run it up I needed to have the l/u properly under water and the water pump fully submerged. The drum was duly filled to overflowing & lacking a 50:1 fuel oil mix I just used 24:1. Odd leak from the fuel filter bowl (tighened up), choke on & pressed the button - it fired instantly and the trick is to manually shut the choke off before the motor dies, which I didn;t manage to do. So, second time lucky. These motors have a exhaust / water bypass system that works from start up, before the thermostat opens and water flows from the exhaust bypass. It's not a great system - lacking the tell tale that is common on all motors now. The cue is when they stop pumping properly, the engine / exhaust note changes. It took ages for water to pump through though and I ended up testing the new (60-62 degree C) thermostat in a cooking pot on the stove with a thermometer attached to the side. Sure enough the old spare thermostats opened at that temperature, with the new following 10 degrees later...

The jury is always out whether to install, or remove thermostats from these 40s. I won't join the debate tho', I run them with...however, in order to check the flow of water I removed it for another test and got a proper gush from the exhaust snout. The video below shows with thermostat in situ, opening around 1:01 and producing steam. The final job was to find and mount my trusty carrying handle for these...they're a bit like marmite, but I find they're useful when asking the Mrs to help lug the motor around, as the unadorned cowlings have little grip.

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OMC 40hp carrying handle.
OMC 40hp carrying handle.
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Re: 1964 Johnson 40hp RD-26S

Post by Rapier »

Off to Cardiff Bay to test the motor in anger. Spare shear and split pins under the hood, and the OMC dash mounted on/off switch I've modified to fit a generic kill switch. Prop is 10 x 13 1/4.
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IMG_4858 (Large).JPG
IMG_4859 (Large).JPG
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Re: 1964 Johnson 40hp RD-26S

Post by haventaclue »

How did it go ?
no matter how bad it is,it can always get worse,I'm an optimist

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Re: 1964 Johnson 40hp RD-26S

Post by Rapier »

Not entirely well..

The carb float needle got stuck leading to flooding (at the pontoon), we recovered the boat as I was worried about dropping screws down the leg (an OMC shrouded midsection trait).

In the process of recovering ithe boat, I slipped on green slime and went a over t, into that water (is fithy with effluent and run-off, but all made worse by a lack of dry clothes), to the great amusement of all (Voyeurs, all of them!). We fixed the float issue (great chewing gum trick to hold float bowl screws!), launched again, pottered about at 5knots, but realised the original prop had spun. Swapped that out (the only thing that I had packed properly..) and off I went.

Opened up and rattled around the bay at 26mph, very successfully. but it partially jumped out of gear a few times. Then heard a ting-ting rattle under the flywheel which I've heard before..is the manual starter shifting over, i.e. the bolts are undone.., found all 5..again is a common trait (needs locktite, or anti-vibration washers). Fired it up again. only to have the motor die, once more. This time realised I'd pulled the fuel pipe to get access and it was pumping fuel into the motor tray. Fixed that, then had the motor die on me once more..this time the glass bowl filter (another 50s OMC thing) had shifted (I'd probably not tightended that up either, and they strip threads too..).

So, was towed in for lunch. We left awhile later when the rain came in. The only safe place was to sit at idle under the carriageway bridge, avoiding the runoff from 40ft above..

The family Ikea shopping brigade came to my rescue however and was able to recover.
Attachments
Some wag, with a sense of humour.
Some wag, with a sense of humour.
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