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Re: 1964 Johnson 40hp RD-26S

Posted: Sun Sep 06, 2020 10:06 pm
by haventaclue
Ah the joys of boating :D . I'm sure you'll get it shorted.
When I was building and working on "NO-KIT" doing anything at Downings pier, there was a fella who, as soon as I arrived, left.
I found out years later, he observed my trial and tribulations with water testing "NO-KIT" and the Merc800, and left 'cause he figured something was going to go wrong

Re: 1964 Johnson 40hp RD-26S

Posted: Mon Sep 07, 2020 10:53 am
by Rapier
I've known CMBA members to do that too..if only to avoid being consulted.

Interesting to watch others recovering yesterday..Busted trailer rollers, a Broom Scorpio with no deck and re-inforced with CSM that looked like it had been slopped on with a yard brush and a Wilson flyer in ubiquitous orange / blue with similar treatment. As long as it floats...except the Broom was close to going under due to the removal of the splashwell, the weight of the motor and the acute angle of the trailer on recovery.

Re: 1964 Johnson 40hp RD-26S

Posted: Wed Sep 16, 2020 12:07 pm
by LitchboroughLitchbor
Ah - the joys of boating!

I was so impressed with your work on the '64 Johnson, that when I saw a '65, I decided it needed a good home, and I needed a spare engine. Surprisingly our little day out with the '62 engine at Abingdon in August was pleasantly trouble-free - but I'm not confident about taking this engine on the sea.

I've no idea how the '65 engine will work out. I may just prove to be another list of problems - it hasn't got a starter motor.

After lying un-used for about 10 years, I'm recommissioning my Fletcher 18 and Merc 150. So far it's needed parts for the trailer, and for the engine a new CDI Electronics stator and both switchboxes, a trim solenoid and kill switch and seemed to almost there ...... until I noticed cracks in the gearcase! Surprisingly the gearcase is not leaking, and I think it will be okay on the Thames - but before this boat goes on the sea, it looks like this will be another £500+ to fix.

PS. Do you use fuel proofer on your carb cork floats? I've been giving this a try.

Re: 1964 Johnson 40hp RD-26S

Posted: Tue Sep 29, 2020 1:02 pm
by LitchboroughLitchbor
And 1 more thing to add to the shopping list for the Mercury 150hp - an oil injection warning fault.

I'm not sure whether this is real a problem - like a seized injection pump and sheared drive gear - or a problem with the system that monitors the things that do the work - like a sensor or the warning module. Either way another few hundred pounds to add to the bill.

Still, it works nicely enough on 50:1 pre-mix, so our outing at Abingdon this Sunday was pleasantly uneventful. The only thing to watch out for there is the sudden fall-off at the end of the slipway. Go any further and one trailer wheel fall into the deeps. So to get the boat off I had to thread the winch strap around the first keel roller and winch off. I've never tried this before, but it worked okay.

Met a friendly guy there, Gavin Kerr, who'd lost his trailer over the edge before. He's selling a nice '65 Avenger boat with '70 Merc 150 straight six: ... ct_details

Re: 1964 Johnson 40hp RD-26S

Posted: Thu Oct 08, 2020 10:49 am
by Rapier
We have a public slipway like that next to the RSrnYC at Hamble. I had to recover my Broom Gemini uisng the breakback trailer and winching it over the gravel...

The Avenger was restored thoroughly by one of the regular contributors to the forum, a marine engineer and CMBA member. Is testament to his work that it still looks fabulous; think has gone through a few hands since he did the work.

I haven't done anything re. asking the AOMCi guys about the OMC 40hp powerhead differences - wondered if you'd managed to find out which would be suitable. Having got the '65 model do you still need one?

Re: 1964 Johnson 40hp RD-26S

Posted: Wed Oct 14, 2020 1:04 pm
by Rapier
Decided to investigate the 'jumping out of gear' that was happening at Cardiff last month. There are a number of causes of this, so I didn't assume the worst. Some causes: incorrect adjustment of the remote controller throttle cable, either in the controller, or where the cable 'sits' on the shift lever on the side of the motor, play, or incorrect adjustment of the bellcrank (under the powerhead - this can be shimmed, if worn), worn shift connector (behind the 'window' on the exhaust tube), which consists of s/steel bolts screwed into a brass connector; after lining up the detent in each shift shaft. Often these get cross threaded, so the lower shift shaft can slide past it's hold, preventing the gear engagement. The clutch dog and it's cradle can wear, ditto the faces of the gears - often these are caused by less than positive engagement of the remote controller shift lever.

I tested for all the potential issues and found it was most likely the adjustment of the knurled knob at the end of the shift cable on the engine side. I'd had similar at Fritton soon after joining the CMBA as an OMC rookie and Rod Champkin kindly came to the rescue. Having adjusted that, there was still the nagging doubt...the gearbox was the only part of the motor I hadn't delved into, for good reason..there were no signs of any issue. The gears engaged (I thought), there was no water / milkiness in the (expensive and recently dealer-serviced) gear oil, the propeller shaft was clear of debris / line and the shaft bearings all felt smooth.

So, I dropped the gear box, drained it and noticed tell tale water ingress from the one trip out, either the drain vent screws loose / washers are old, or the shaft seals hardened, perished from age, or cut. A length of spaghetti seal fits in a groove of the lower casing and an O ring in a groove around the propeller shaft seal - these perish with age and the original sealant can degrade.

It's a messy job, but after cleaning all parts in solvent, laid the components on the bench (take pics at all stages..) and evaluated their condition. There was a little wear in the forward gear and the clutch dog, but the two gear surfaces were fine and both timken bearings unmarked and without any play. Turning to the seals, the prop shaft one was fine, as was the shift shaft, but the drive shaft seal felt unyielding. Ideally replace all of them. I had a few new on the shelf and fitted that. I'd lost my slide hammer in the house move, so had to get medieval in an attempt drive it out from the top...after 56 years it required some persuasion. When I seal it up, I'll use new drain / fill washers too - they are not expensive. The gear shafts was reassembled and installed. I'd cleaned up the mating surfaces - they're a matched set, fitted a new spaghetti seal and propshaft seal, then ran a bead of permatex around all mating surfaces and threads before bolting it all up again and allowing the sealant to set for 24 hours, before refilling the gearcase. I have no means to pressurise the box and look for leaks, so will keep an eye out for further water ingress...

Having prepared the housings for new seals and sealant, I took another used gear box off the shelf. It had a different water intake to my Johnson which led me to think it was the later prop shaft and clutch dog. I wanted to strip it and put the parts away for later use, but ended up rebuilding it as a spare. Blue paint indicated it was an Evinrude 40hp Bigtwin version...They are also interchangeable as the back of the water pump housing has the twin pipes - it's just the intake / prime setup that differs (there is also another 40hp type that is not interchangeable with the earlier motors...)

Around 1967 the prop shaft was re-designed with a hole below the clutch dog with a spring and two detent balls that run in grooves, in the splined section of the dog clutch (see pics below). I think it's to minimise and smooth the movement of the clutch dog, but don't quote me..Both systems are interchangeable within the gearbox casings and I don't believe there's a noticeable difference in use. The only word of warning is don't slide the clutch dog back off the shaft as the flying bits will go to that special place all lost parts go to (under the workbench that weighs in at about 200kgs). My m.o. is to wrap the shaft in a knotted freezer bag, while knocking the clutch dog back off the prop shaft. Mike took his apart in fading light, on the slipway at Falmouth - cue a bunch of CMBA members doing an finger search while looking for the spring and ball bearings - luckily they were found. The clue (if you don't know the age / source of the gearbox) will always be the resistance of the spring holding the detent balls in. i.e. the clutch dog shouldn't drop off the shaft of it's own volition.

Re: 1964 Johnson 40hp RD-26S

Posted: Tue Oct 20, 2020 2:27 pm
by Rapier
Just when I was starting to suffer from OMC 40hp gearbox rebuild fatigue ('64, post '67 and post '71..), a shopping bag of loose post '67 parts was found on a shelf I was clearing. Kind donations from CMBA members...The garage already stank of used gear oil, so I bit the bullet, stripped, cleaned and put this one together with it's skeg, sprayed with storage seal and bagged it for later- was great as there were no 'issues' with it.

Re: 1964 Johnson 40hp RD-26S

Posted: Fri Nov 27, 2020 1:08 pm
by LitchboroughLitchbor
Hi Rapier

I was wrong about the spare Johnson 40hp engine I've bought. I'm not sure why I bought it? I suppose I just couldn't pass it by. Actually, it's not a '65 model. The serial plate is gone, but it's probably a '62 RD-24 or '63 RD-25 - so exactly the same as my original engine - but without an electric starter.

I'm now understanding why the two previous owners were so keen to move it on! The rewind starter was not working (I've fixed that) and bits of coil insulation were appearing from under the flywheel. On the plus side it does appear to have compression, although I haven't tested this properly yet. I'm sure I'll enjoy fixing it and maybe having a back-up engine is a good idea?

After my trusty home-made flywheel puller finally disintegrated, Bob at South Coast has just sent me the factory flywheel puller and new magneto parts. If this engine proves okay, I might stick with the two I've got, rather than starting to swap or dismantle powerheads. But I haven't really made up my mind on this yet. I've still got some NOS over-size pistons and rings sitting on the shelf.

I'm currently battling with 3 Evinrude Fisherman 6hp, where I've stripped down the powerheads on 2 of them. These were horribly seized and the pistons looked awful, but with new rings, I've surprisingly managed to get all 3 of them running - after a fashion! My idea was to strip them completely, as a learning experience before attempting anything too drastic on the Johnsons. So far the only bits I haven't dismantled are the exhaust port water jackets. I'm presently following the workshop manual's advice and facing up two of cylinder heads, with a sheet of plate glass and 120 and 180 grit paper. Both were warped, and one quite pitted, but they're looking better now. I suspect my oriignal Johnson will need some attention to the cylinder head. It had an intermittent overheating issue. I've found my wife's digital thermometer great for checking the temperature of these cylinder heads, to figure out what is going on with the cooling system.

You've given a very nice account of the strip-down on your gearbox. I did something similar on mine, years ago, and struggled with that spaghetti seal! I found it quite difficult to make that box leak-proof. I was reminded of this last week, when I stumbled across the original drive dog. Back then I replaced this and the selector fork - which was worn on the forward gear face. Since then the gear change has been quite reliable.