Kohler 4 cylinder engine.

Stamford24 wrote:

I'd forget the idea of welding it. Looking at it, there is such a small land between crown and top groove, you would be asking for trouble. No matter how hard you try there will be distortion. Look for another, I'd try looking at car pistons with a 2" bore, you might get lucky and fing something close.

My dad's got a friend who rebuilds & restores veteran motorbikes (as well as vintage stuff, he's a bit of a character, but a very good engineer), he's always finding odd pistons for things & machining them to fit. If all else fails he may be able to help.

nutgone wrote:

kevjhnsn wrote:
............is there a part or casting number on the piston ,as i used to sell onan/kolar/jlo 2 stroke and 4 stroke ex mod engine geny parts, and my mate up york way still has some on the shelf but with out some form of id ?????
kev

Kev, the only mark I can find on the pistons is the numbers stamped on the tops. Each one is stamped with it's own cylinder number & each one has the same other mark on it: 2.005 (which is the size in inches, I guess).

They are very distinctive though, & Kohler didn't make many different models of 4 cylinder engine, I think there were only 3 different types (this one & 2 larger side-valve units), although they were each coupled to a bewildering array of different generators.

I've cleaned a few of them up now, got them all off their con rods & removed the 2 compression rings from one of them (that took a very long time! ). I will put some more pics up tomorrow.

Also, the oil scraper rings seem very well stuck on. One is broken (not my fault).

I have also started to play with the broken one, but had to stop as it was getting too late to be hammering in the workshop. Now it's off I can clearly see daylight through the cracks. I was going to see if I could punch the top back up from inside, not sure where I would go from there. metal putty maybe??? (I'm only half joking there, if I could somehow secure it from the bottom a repair may be possible, but it's a massive & very doubtful maybe)

ive sent the email over to colin
so will wait for a response
will get back to you as soon as i get a result good or bad mate
kev

also just remembered
kholer and onan have many parts the same as each other ,most even used to come in onan/kholer original parts boxes
this maybe of help to you also "or not
kev

Cheers Kev.

I will definitely need some rings for this engine, as I already have 2 broken ones & I haven't managed to even budge any of the oil scraper rings yet.

I've been thinking about that broken piston, maybe brazing would be the way to go???

If the cylinder numbers are stamped onto the piston tops it sounds as if it's been stripped in the past.

The snapped piston rings are good to use to clean the carbon out of the piston ring grooves.

Stu.

nutgone wrote:

I've been thinking about that broken piston, maybe brazing would be the way to go???

Please say you are joking here Matt?

Forget the old piston, start looking for a replacement. Get down to that Ardingly Autojumble and have a rummage I'm afraid it wont be that whirlwind resto your used to doing but doing the job proper will be worth it in the end.

I've had a couple of people suggest brazing it, someone even suggested silver solder (& claims it would take the heat).

Trouble is, the last thing I want is to have it break up again while the engine is running, I would rather leave number 4 out & have it run on 3 cylinders.

There's a bloke in Canada who's got a spares engine, he's happy to let me have a piston, but he reckons the postage would be too much, maybe I should get back on to him.

Well, I've been checking out the prices of a full set of rings for this engine, & they're over US$160 plus postage But at least I now have the accurate size of the rings, I will just have to be more careful with the rest of them.

So, Stamford, what would be your main objections to brazing the piston? It would certainly put up with the heat, & the combustion chamber is massive on these engines, loads of clearance for the valves, & the compression ratio is very low, around 5:1 or so.

The thing is, if the piston is scrap anyway, I see no harm in experimenting with it, but like all these things, there's a lot of different ideas flying around, but no actual experience. I must admit, you never hear of anyone repairing a piston.

Well if your prepared to risk it have a go, you can prove me wrong, just think though of what might happen if it does go wrong... and also explaining that in Court if it happens at a rally and causes injury to others! I doubt your insurance would accept it. It might well work but the fact that its not an accepted repair would put me off doing it. If you can get the chap in Canada to list the item as a gift then you may get away with no duty. Post shouldnt be horrendous. I admire your keenness but just think about this one a bit more.

I have to agree with Stanford and say the only way is replacement of the piston. If you did manage to repair it and it failed when running think of the cost to repair, in fact the engine would be scrap as you might damage the head, the bore, the valves, if the piston disintegrates and you end up with just the con rod banging about in the cylinder then you could end up with damage to the crank. The risk is yours but I thought we always tried our best to restore engines not just patch them up, I understand that you don't have a money tree but this could be an engine to put to one side till you save up for the correct parts.

Nuts at the end of the day it's your engine and you can do what you like to it, we're just trying to give advice weather you take it or not that's up to you.

Stu.

This may be a long shot but have you tried Chester Hudson in Heathfield i know he doesnt deal specifically with engines but does have an array of stock and am sure may have some kohler stuff

heres details http://www.mdr.co.uk/tillerparts/tillerparts.html

The piston isn't going to be repairable. I attempted to pop out the bits of crown today & a crack has opened up down the skirt, just at the top. The crown material is very thin as well, extremely thin for a piston, even if it is cast iron, no wonder it went. Just goes to show; never try to move a piston with a thin metal bar, always use a block of wood of a good width.

I've also had some trouble with one of the valves, it was well & truly stuck in the guide, in fact the guide came out with the valve stuck in it. I got it out eventually, just it's in 4 different pieces. Still, all the others are fine, so I've got a good pattern, but the guide will need to be reamed before another valve goes in there (I've never known a valve stuck so hard before).

I also need more rings, so far I haven't managed to get a single oil scraper ring off in one piece. Trouble is they have slits in them, so they are very weak & I honestly can't see any of them coming off whole (still got 2 to try). I might get one or two compression rings off whole though, but even those are well rusted in, not just stuck with carbon, they're actually slightly rusted underneath. I'm soaking each piston in methylated spirit, which definitely seems to work, but as I say, they're well stuck in there.

I think I need to get hold of the guy in Canada & see what the situation is. What I would like (in an ideal world) is a set of 4 pistons, with rings & a spare valve. Weather or not he will let these go is another matter. He said he's going to have a look into postage charges for me.

Since stripping the head I have found that the valves are numbered as well. Not the actual valves themselves, but each number, from 1 to 8, is stamped into the head, just next to each seat. & I'm told the pistons (as well as other parts) were numbered on these engines from new, to aid maintenance personnel. Don't know how true that is though.

There are a few scratches on the face of the head. At first I thought they might be cracks, but thankfully they're only scratches. If it causes me any problems with the seal I will just have to break my own rules & add a smear of Wellseal or something. Fortunately the head gasket is good & should be re-usable, as are the exhaust manifold gaskets, all the others can be made up.

Anyway, there's a long way to go with this one, I haven't even started cleaning it yet, I've still got the mag to finish off, & the carb to do, so plenty to keep me occupied.

I'm off to a classic bike show next weekend, I will put one of the valves & a piston in my pockets, see if I can find anything similar there, it's doubtful but there is an autojumble there, you never know.

I hope you can get something sorted either from the Canadian or the auto jumble. I bet there's lots of the parts you need sitting in parts stores all over the UK. There must have been a few companies that used this type of engine it's just trying to find them. Maybe some wanted adds might help if you can get them into farming/plant magazines for free.

Stu.

That's a good idea Stu. There will be a piston ring specialist company at the Bristol Bike Show next weekend, so I will be sure to take the exact sizes, written down, with me, as well as another piston.

The guy from Canada got in touch last night/this morning, I told him how I was getting on, then I decided to get to the point, so I politely told him what I need & what I want (need:- a piston, some rings & a valve. Want:- 4 pistons, with rings, & a valve) & just asked him if he could help out with any of that.

So I'm just waiting to hear back now. Obviously I'm hopeful, building myself up for a big disappointment no doubt. If he can't help me then I will start looking elsewhere.

I've got plenty to keep me occupied in the meantime, I still haven't started cleaning this one (I did a little cleaning of the cylinder head last night, but that was more looking for cracks & defects). It may well end up even being painted before I get the bits to complete the project, & I've still got a Stuart Turner P6 to sort out as well (which will probably be sold to raise funds once it's done). That still needs a barrel & a magneto to complete. Then there's still a Douglas generating set in my sister's garden which needs restoring (Ian says he's doing that one, but we all know what that means ).

So, plenty to keep me out of trouble if I have trouble getting parts for this one.

There's also a Stuart Turner water pump to be sorted, don't forget that one and that little genny and the motor to convert into a genny.

Ianhw77k wrote:There's also a Stuart Turner water pump to be sorted, don't forget that one and that little genny and the motor to convert into a genny.

& the Douglas (let's face it, you'll never get round to it, you're far too busy with the boys & their Lister D).

Anyway, I heard back from my friend in Canada tonight. Things may well be looking up, but I will still have some parts to find.

Good luck with the search Nuts your a bit like a dog with a bone, you won't stop till you've found what your looking for.

Stu.

Well the mag sparks & the carb must work, I'm not going to let a little detail like pistons hold me up!

Anyway, some nice person emailed me a PDF file of a workshop manual for one of these engines (it's actually for the complete generating set, as these engines were never sold for anything other than to run direct drive generators (also built by Kohler). The engines were made by the engine division & sold directly to the generator division, none ever went anywhere else (AFAIK).

So I've been reading this 101 page manual & it's quite interesting. I found out that all the pistons, con rods, big end shell holders, valves & valve seat positions were stamped with numbers from the factory. Last night I put this to the test & went out to the workshop (the one night I wasn't already out there, I was far too tired) & gave the valves a clean-up. Low & behold, they are all numbered, from 1 to 8, all with their corresponding positions in the head! (these engines were obviously meant to come apart).

If I'd know that I wouldn't have wasted that piece of well marked out cardboard!

So far as my friend in Canada goes, I know he's short at least one oil scraper ring. I think I have one left, which is intact & well stuck in it's piston. But I very much doubt I can get it out in one piece (I will be trying very hard though, & using all the patience I can).
I don't know if he has a valve for me or not.

I am also missing the cast metal bottom radiator to block pipe from this engine, but I'm sure I can make something up for that (I gave the guy a definitive list of what I needed, but missed this piece off. I don't wanna take the p1$$ & start adding to the list now, he's 80 years old & already doing me a massive favour). Both the rad & the block have 2-bolt flange fittings, so I can either get something metal made up or do something with rubber hose & some fittings.

Anyway, that's way down on the list for now, I've got at least a couple of bolts sheared off under the level to get out first, not to mention a load of new nuts & bolts to source, this is all easier to find stuff which I can collect along the way, my main priority is to at least know I can sort the piston & rings out, even if I have to wait for them, I just need to know they are there.

Suppose I should get out there & get on with it. A quarter of the weekend is already gone!

I thought I would get started on this one tonight. I lifted the top half off the sump again & put the crank shaft back in, I need to get the cog off the governor shaft & can't hold it tight enough, so thought I might have better luck with the crank back on, but haven't actually tried to get it off again yet.

Instead I thought I would dig around in the sump & see if I could get the oil pump out to give it a clean. Well, I did & I did....



Then I took a look at the sludge in the bottom of the sump. I drew a small scraper through it, so you could see how thick it was....







I managed to scrape most of it out through the oil filter/drain plug hole & into a drip tray. I also scraped out the dried up oil & leaf litter from the flywheel housing. Then I gave it a good wipe out with some old rag & gave it a good spray with my new improved parts wash (I've recently added some AQF automatic transmission fluid to the mix, & it has really improved it), then wiped it out again. Then I gave it aonther spray & left it over night. here's what it looked like when I left it....









I've also cleaned the big end dipper tray & a few other bits & bobs. The sump needs a fair bit more work before it's properly clean, then there's the block, that's got no big layer of sludge, but it's going to be even harder to clean.

Will do a bit more tomorrow.

gotta love the sludge , is that a felt crank seal?

No, there's no felt in there, just an oil flinger ring thing (no, I'm not writing poetry now )

I've got the manual on PDF, & have just got to that bit. I will read up on it & post some details.

Looks like the engines had a bit of water in it by the colour of the sludge, lets hope it's nothing major or maybe just a weaping head gasket.

Stu.

stationary stu wrote:Looks like the engines had a bit of water in it by the colour of the sludge, lets hope it's nothing major or maybe just a weaping head gasket.

Stu.

Well, considering it's been sat out in all weathers for over 20 years, it's not too bad. (The bloke said it had been sitting "there" for 35 years, but I don't know if he meant outside, as there was a shed there at one point, many years ago). I had a little water come out under the oil when I first emptied it, but once again, for such a long time out in the elements it was really very little (maybe a few ounces, if that).

I think the owner previous to him was restoring the engine, it looks like he probably had a fair bit of work done (possible including having the magneto reconditioned), but he must have given up when he smashed the piston. That was over 35 years ago, when parts for these would've been a lot harder to source. They were still an old engine, but you didn't have the internet to go searching on back then. A smashed piston on one of these could've spelled the end back then, unless you knew someone who knew someone. He might well have had a gut-full of it by then.

Good job it never ended up as scrap really.

I have continued my cleaning of parts. I started by removing the governor/magneto drive gear. It's a job I've been struggling with. In the end I put the crank shaft back in, cut myself some wooden wedges, wedged the flywheel & took a long bar to the big nut on the gear cog. Eventually it relented, I had to use a puller to get it off, then knock the shaft out to remove this....



I took it apart, cleaned it all up & replaced all the split cotter pins. i also cleaned up the cam shaft while I was at it....



Just for good measure, here's a pic of that oil tray I cleaned up yesterday....



I then decided to remove all the little bits & bobs from the crank case. This involved removing each tappet, in turn, cleaning it & marking it with a number so it goes back in the right place (note the oil pump tappet on the end of the row)....



I also removed the oil lines from inside the engine, which involved bending them a little as there's a 4 way cross soldered piece in there, but nothing was broken & it will all straighten out as it goes back in. I ran some parts wash through it all, but I will clean it properly later on. At least now I have an empty crank case, ready for cleaning....



Now nicely stacked away next to the sump (which received another clean out & is coming along nicely)....



Then I decided to clean some cleaner stuff. So i turned my attentions to the carb. I don't think it's solid brass now. I'm actually starting to think it might be bronze (did they make carbs from bronze?) It almost looks like copper, but doesn't really resemble brass (although it looks like brass in the pictures because I can't get a decent colour balance on my new phone's camera)....







Anyway, I've left the float in a jam jar of neat petrol over night. it was still floating when I left it, so it's looking good.
Interesting how the float needle works. The fuel comes in the bottom & the float acts on 2 arms. Don't think I've seen one like it before....



That's all been taken apart, cleaned up & put back together (as in the pics above, I couldn't get it any more shiny really, not without a lot of work). I'm not sure which way round the 2 jets go now though. they are both the same size (or both have the same number stamped on them), but one has a long tube coming off it whereas the other is just a normal jet. I've put them where I think they go, but I'm sure it'll soon become evident if I've got it wrong when time comes to fire her up.

Last part of the evening was spent dismantling the magneto (again). This time I had a nice clean & clear bench to work on, so I can take my time & do it properly.

I've managed to release both bearings, which will be cleaned, & have managed to completely dismantle the whole thing....





I've also cleaned up the slip ring & the earthing ring & cleaned up the spinning coil centre....



I took some readings & was getting a reasonably steady reading on the HT side, in the megohm range. I've now taken it indoors & put it on a radiator to completely dry it out & see if I still get readings. I think it will be OK, so far so good anyway. I think I've been really lucky with the magneto, especially considering it's been left outside for so many years (possibly up to 35 years). But I have a feeling this mag has been reconditioned before at some point.

Anyway, that's where I've left it. I will finish off cleaning up all the mag bits tomorrow & get it all back together.

I'm putting off cleaning up the crank case, but I suppose it will need doing reasonably soon, so I have somewhere to put all these bits as I clean them. Otherwise I'm going to start running out of boxes, pots & tins to put bits in!

Making good progress Nuts, I know it won't seem like it just cleaning off but it saves so much time when you come to rebuild.

Stu.