Jcb 3c 2 cant find oil leak

[Matchless?58]

Hi as the title says my jcb3c 2 has an oil leak I'm not entirely sure where it's coming from but it's becoming a fair old drip now so can no longer be ignored. As it's moving towards the winter time when I generally lay the machine up for a couple of months I thought i would try and do something about it.
It's definitely engine oil and is running down from the very back of the sump . I had the sump off a while ago as I did a thorough engine oil clean . New oil new filter New sump gasket. I took great pains to ensure that it was sealed but I guess it could have failed.
However before I go tearing into it and pulling all the sump off again is there another area at the back of the engine where oil could be leaking from ?
Is there a seal on the back that could have failed ?
Leaving little pools of engine oil everywhere I go is really getting on my nerves!!!!!!

[Billy26F5]

Sounds like it might be the rear crank seal, Mr MacGregor has a similar problem. It could be a sump gasket but if you did all you could to avoid that I doubt it'll be that (but check to be sure). Changing the rear crank seal is quite a big job as the flywheel needs to come off, bu I think the engine can stay put. As we need to check the clutch anyway we'll be halfway there so we'll probably fix it then, but it might be trickier if your clutch is ok. Loosing engine oil like that is not good and I'm never relaxed when I know that a refill almost imediately gets lost, so it is worth looking into. I suggest you check the manual to see what you think, although they assume the engine is on a stand. I'll probably post about our fixes on Mr MacGregor when we get there but at the moment we're waiting on getting a new hose as we just burst one.
Sandy

[Matchless?58]

Thanks for the reply Sandy although that is the news i didn't want to hear and also didn't want to acknowledge.
My clutch is perfectly sound and works very well so another blow there but on the plus side I recall from my nuffield that they are fairly simple units. I'm glad the engine can stay insitu because if not that would be the end for this machine in my ownership as I simply haven't got the facilities to lift the engine out although I guess i could ask a farmer friend if he would lift it out with his telehandler.
Do I need a specific puller to remove the flywheel ?
I always like to study everything before i go tearing into a job so i will do some research over the next couple of weeks although ANY advice anyone can give will be gratefully accepted.
I obviously can't continue to run the machine losing oil all the time and it also makes me worry about oil pressure for the engine.
OK plan of action.
I'm going to remove the sump and replace the gasket again. Has anyone ever tried replacing one without the Cork gasket and using silicone sealant instead? I have used 3 bond with great success sealing leaks on my classic bikes .
If it's still leaking i will then know its definitely the rear crank seal and will have to bite the bullet and get on with it.
Any input welcome especially if you've already done the job.
Cheers Chris

[Billy26F5]

Removing the flywheel isn't a difficult job, if it doesn't come easily there are two holes for puller bolts, they're 3/8" UNF. I wouldn't disturb the sump nor would I use silicone sealer as getting the sump off in the future could be tricky. The clutch is a simple unit, this is the 13" clutch. I recommend a look at the Nuffield forum, as someone there might have done this and the skid in a 3CII is still basically a Nuffield (modernised into the Leyland 384). I'm sure there'll be views of the rear of the engine in various stages which will help.
Just looked and found these, they're not all the same but give you an idea of what you're playing with.
https://nuffieldtractor.com/viewtopic.php?p=2809#p2809
https://nuffieldtractor.com/viewtopic.php?p=2630#p2630
https://nuffieldtractor.com/viewtopic.php?p=3071#p3071
Sandy

[Matchless?58]

Thanks Sandy will take a look at the links.

Only reason I was going to remove the sump was to make absolutely sure it's not coming from the back of the cover however I took great pains to refit it carefully when I did the oil system clean so im probably clutching at straws.

I went over to get underneath it today but the weather turned absolutely horrible so I didn't fancy laying on my back in the pouring rain . I'm going to check it out very carefully before tearing into it. I've learned from experience always look for the simple fixes first ( don't ask how).
I will let you know the outcome.
Cheers Chris.

[Matchless?58]

After reading the links Sandy sent me I wonder if ive overfilled the oil.? I always check it prior to use and keep it up to the top mark on the dipstick. Would this mean that any excess oil is passing into the clutch housing and draining out of the holes then down the back of the sump ?

[Billy26F5]

Overfilling shouldn't do that, this is the likely route after getting past the seal, the level you aim at is correct but it's no big deal if it's a bit over. I'm the same about keeping a close control on levels and always see if something is happening as I always make a point of remembering exactly where the level is to detect possible issues. I always aim for easy fixes too if possible, and I've stopped lots of leaks simply by tightening bolts, so something to check as well. A good clean in the area always helps as you can then see exactly where it comes from and how fast. All this will help as then you have a better idea of what you need to do. I don't blame you for that, I wouldn't have wanted to work in rain either, but not just for comfort as this sort of job is definitely off if water is around as it can cause all kinds of serious damage.
Sandy

[Matchless?58]

Thanks for the reply Sandy. Further investigation needed.
If I end up renewing the seal which seems likely I might write a step by step guide including all the mistakes and pitfalls and post it on here. I couldn't seem to find anything like that when i searched so it might benefit someone else.
I will let you know how I get on.
Cheers Chris

[Billy26F5]

That sounds like a good idea, then others can have a better idea of what they're in for if they do this. I will add that this is all far easier on a basic tractor, as the JCB has all the frame in the way (in this case mainly the fuel tank).
Sandy