Bukh 32 rear main oil leak

[goodoldwoody]

Hi Cruisers

I have discovered an oil leak on my Bukh 32. I suspect it's the rear main bearing seal. I've ordered a new one.
I intend to remove the coupling, raise Rear of engine and remove gearbox. Then extract the offending seal using the hook it out method. Then Slip an new one in!

Has anyone done this before and do you have any tips.

Thanks Woody

[Compass790]

No Bukh experience but I hope yr main bearings aren't too worn as badly worn bearings can cause seal to leak as crank flails around & putting a new one MAY not fix it.Worth the shot tho.
How's yr oil pressure? If that's ok likely main bearings are ok.
Hope ya didn't have to buy the seal off Bukh, hear they make Yanmar parts look cheap & that takes a bit of doing

[goodoldwoody]

Originally Posted by Compass790

No Bukh experience but I hope yr main bearings aren't too worn as badly worn bearings can cause seal to leak as crank flails around & putting a new one MAY not fix it.Worth the shot tho.
How's yr oil pressure? If that's ok likely main bearings are ok.
Hope ya didn't have to buy the seal off Bukh, hear they make Yanmar parts look cheap & that takes a bit of doing

Hi Compass 790

Thanks for your reply. The engine is now 8 yrs old has done under 3000hrs, oil pressure is 30psi as per spec. So I'd be unpleasantly surprised if there's a cause other than a faulty seal. But that has been worrying me too. The engine has had oil changed every 100 hrs filters & so on too, annually. The old engine, also a bukh, lasted 30yrs just wore out.

Thanks Woody.

[Compass790]

Sounds like you'll be ok then as oil pressure fine. Sorry if I'm telling you what you already know but you most likely can just get a seal from any bearing supply place to save getting reamed by Bukh.
Hope ya get a Bukh owner who's done it chiming in.
I used a generic oil seal on the Yanmar, it was 2mm smaller in width ( same O.D. & I.D. ) but it was 1/10th of Yanmar price. Just loctited it in & works fine. No more crankcase oil getting into gearbox now. This was after I'd replaced totally trashed main bearings.

[goodoldwoody]

Hi Compass 790

I really don't want to pull the engine out so I'm hoping that it's only the seal also that there's no groove worn on the shaft and that I get gearbox off and the old seal out easily. It all happened suddenly, leaked a lot, maybe 1.5 ltrs in about 4 hrs then now it's not leaking at all. (While returning from a lovely cruise of the Bass Strait Islands).
The boat is a Alan Mummery custom 34 built in NZ 1980 out of KAURI. By John Hamilton. A work of art!

I'll let you know how I go with it.
Cheers
Woody

[roverhi]

Engines differ but rear main seal replacement on the engines I've worked on is a major job. Will require pulling the engine, inverting it, and freeing up the crank to lift it up to slip the bearing in place. Check your manual to see what's involved in the main seal replacement. I might be an alarmist as I've only worked on older Brit engines and they've always shown genius engineering creating hard to replace seals that always leak.

[goodoldwoody]

Originally Posted by roverhi

Engines differ but rear main seal replacement on the engines I've worked on is a major job. Will require pulling the engine, inverting it, and freeing up the crank to lift it up to slip the bearing in place. Check your manual to see what's involved in the main seal replacement. I might be an alarmist as I've only worked on older Brit engines and they've always shown genius engineering creating hard to replace seals that always leak.

Hi Peter?
Thanks for your comment and it encourages me to look over it again so it's a big help in clarifying my view.
This engine is a little different in that the rear crankshaft seal is in a separate alloy housing a little away from the rear main bearing so it's not associated with a bearing cap as such. This housing houses a Govenor and some counterweight and an external oil pump. The injector pump, which is easily removed, is bolted in there too. So the gearbox has to come off and a dog coupling then hopefully I can hook out the seal. Also so unusual that the flywheel is at the front of the engine. It's not quite like those "BMC" engines with all their attempts at stopping oil getting out. I'm thinking Morris, Jaguar MG and so on!
I just don't want to drag it out of the boat.

Cheers
Woody

[Compass790]

Yes I hear you re getting engine out & those Bukhs are HEAVY. Good donks tho. Don't know of the builder but our previous boat was a Mummery 24. Well respected designer in the day over here.
Weird your seal suddenly leaking majorly like that. I'd be suspecting a sudden increase in crankcase pressure to produce that behaviour so check vent.
It may have unblocked itself now & your seal MAYBE fine. Suggests that it is if it's stopped leaking assuming you have changed nothing else.
Re shaft scoring: My guess is that's unlikely as when I changed out main bearings in our engine they had close to 1mm play. Yes 1mm, not a misprint, & the shaft still wasn't scored. Of course I don't know shaft hardness, seal type, etc etc in your Bukh but chances are with the hours you state & your good maintenance it's highly unlikely to be scored.
My first line of action would be checking & cleaning yr crankcase breather before you attack that seal job. ( Doesnt sound like fun! )
Hope, for your sake that crankcase vent is your smoking gun

[goodoldwoody]

Hi Compass 790,
Yes I did check the breather and it was venting. It vents to the inlet side of the turbo. The odd thing about all this is that the volume of oil leaking has reduced to a few drops. I'm still going to change that seal since yesterday I spent the afternoon with mirror and iPhone under the engine. The iPhone was really good although I can't see volumes on oil coming out like before there is a track coming down from the bleed hole and I see the occasional drip. I'm going to replace the thermostat too as I think the engine may have been getting too hot. Although the temp gauge doesn't show that. It has a gauge and alarm which does work. Also I'll take the inlet off the turbo and also thoroughly check or replace the breather hose.
All this "got a boat got a problem" is I believe good for your health. Mental health - you've got to figure it out and come up with a plan.
Physical you've somehow got to get your body to do what it did when you were 17. So your back gets stretched and all joints get a work out. To top it of your wallet gets less exercise than if you pay someone else. Plus one can persist till its right.
Thanks for your help.

Cheers
Woody

[Compass790]

Sounds like you doing all the right things. BTW didn't read yr 1st post properly in that you'd already ordered a seal so my generic seal tip was redundant.
Our crankcase vent has a kinda gauze strainer which was a bit clogged with sludge. cleaned it out with petrol when I rebuilt motor but it wasn't bad enuff to block it. Doubt that will be yr problem as our motor had extremely low compression before I rebuilt it which caused the sludge problem + it's raw water cooled so runs a bit cold. If you can blow thru yr vent hose it should be fine
Overheating could definitely cause the seal to leak as the oil would thin out with temp increase. Will be interested to hear what job goes like & result
Yep i too enjoy the problem solving challenge that the diesels can throw at ya.

[goodoldwoody]

Originally Posted by Compass790

Sounds like you doing all the right things. BTW didn't read yr 1st post properly in that you'd already ordered a seal so my generic seal tip was redundant.
Our crankcase vent has a kinda gauze strainer which was a bit clogged with sludge. cleaned it out with petrol when I rebuilt motor but it wasn't bad enuff to block it. Doubt that will be yr problem as our motor had extremely low compression before I rebuilt it which caused the sludge problem + it's raw water cooled so runs a bit cold. If you can blow thru yr vent hose it should be fine
Overheating could definitely cause the seal to leak as the oil would thin out with temp increase. Will be interested to hear what job goes like & result
Yep i too enjoy the problem solving challenge that the diesels can throw at ya.

Hi Compass 790
Just for your interest.
Well I've almost finished the job of replacing the seal. It's either been blown out or wasn't set properly in the first place. It looks undamaged but I replaced it regardless since it's a big job and a little difficult too.
Rather than loctight I used some aircraft gasket cement (the type that doesn't set hard) on it to better ensure it remains in position.
I also replaced the thermostat which was stuck in the open position, could also have been sticking in the closed position too, who knows. There were no other oil leaks so I'm left still wondering. However from time to time I have mopped up a few drops of oil which may have been coming from the crankshaft seal.
I hope it just doesn't pop out.
I put some photos on YouTube if you would like to see.

https://youtu.be/sjYRlp4cgzs

Cheers Woody

[Compass790]

Good that you posted the photos. Did you make the puller? The burning question now is: Does it leak anymore??
I only used loctite on our seal as it was narrower so I wanted it to stay seated in the bottom of the housing. The motor will be happy you replaced the thermostat too.

[goodoldwoody]

Hi Compass790,
I made a puller for extracting the seal which consists of a small pair of vice grips withe the adjuster screw welded to a temporary slide hammer. Photo attached. The idea comes from some motorcycle guys on YouTube. (Photo attached if it will attach). It wasn't needed as the seal all but fell out in my hand. But idea is to drill a couple of small holes in the back of the seal insert a wood screw on each side and click onto it with the vice grips. It would have worked. I find a lot of good ideas on YouTube. Often someone has already done what I'm about to do, but not quite this time. The other puller was a harmonic balancer puller (old Holden one, I knew I would need it one day but bought it years ago. There are a couple of 6mm UNF holes in the dog for pulling on. Lucky I had the bolts in my puller box of tricks. I exceeded its maximum stress so it's pretty well had it now. Hope I never need it again.
To answer the burning question. No! No leaks. Touch wood, of course time will tell. I think I may have said there had been a few spots of engine oil there occasionally which may indicate it may not have been installed properly in the first place.
Of course it was a huge job today will be the fourth day reassembling the galley cabinet. I spent hours re-aligning the shaft coupling & engine after lifting the engine. I don't think there would have been much change from $3k for a mechanic. Pretty lucky to have been able to do the job after all.
Thanks for your comments etc. I'm not sure if the photo attached. Oh it did.
Also I checked all the crankcase breather arrangement and found all clear. I'm wondering if not to fit a temporary gauge on it to see if there's any pressure. It vents to between the turbo and the air filter so should be a little below atmosphere.

Cheers
Woody.

[Compass790]

Good on ya Woody!
Glad u got a win & better still you told us about it
It was the Holden puller that caught my eye. Wondered if it was a Bukh "special" part.
Glad I live in a youtube era too.Saved my bacon on a number of occasions.
Wotname put me onto this :https://www.youtube.com/channel/UCg-...hBnDSay7nmphUA

I had some struggles/challenges rebuiding our diesel but now I have a perspective of what difficult is
cheers

[goodoldwoody]

Originally Posted by Compass790

Good on ya Woody!
Glad u got a win & better still you told us about it
It was the Holden puller that caught my eye. Wondered if it was a Bukh "special" part.
Glad I live in a youtube era too.Saved my bacon on a number of occasions.
Wotname put me onto this :https://www.youtube.com/channel/UCg-...hBnDSay7nmphUA

I had some struggles/challenges rebuiding our diesel but now I have a perspective of what difficult is
cheers

Hi Compass 790

Thanks for the comments.
BTW the Holden puller has pretty much had it now.
I've been watching Tally Ho since stumbling on the first episode. He's a very competent tradesman and amazing in what he has taken on. There's a lot of patience required in building a wooden boat as for restoring one, even harder. Building one out of Kauri would be good such beautiful timber to work with.

A lot in rebuilding a diesel too. I don't want to go there. But good on you for doing it.

All the best.
Thanks again