Rear Main Seal Leak

[magoo]

I have a couple of bad oil leaks from a newly rebuilt engine with an external oil cooler. The one giving me concern is the rear main seal. What is the worst case scenario before the engine is taken out and examined? Oil only leaks after a short drive.

 

[Trikky2]

Not sure what you mean by main rear seal.

If you mean the seal round the flywheel - it could be its just not been fitted correctly and replacing it may solve the problem. Alternatively the crank might not be shimmed correctly. Whats the end float like? Unfortunately the only way to fix it is by removal.

If on the other hand you mean the fan pulley end then, provided the oil level is not too high, its likely the oil slinger was left off or incorrectly installed. Either that or you have excessive crankcase pressure, due to faulty breather or too much blow by past the rings.

 

[magoo]

Questions have arisen about the quality of the rebuilt engine, two people were involved in the build, so trying to work out how serious the problem might be and how easy it is to resolve.

I took these photos a while ago, so I think I've photographed the correct source of the leaks. From what I understand is that the end float is fine. I'm hoping the rear main is just a fitting problem. I was told that it is a hard job to fit and you need the right tool? I'm far from an expert in these things, but I'm trying to avoid a complete precision rebuild by an expert at the moment. Perhaps a service will identify the problem and I can worry about the more serious stuff in the winter when I've got money and time...just in a dilemma how to approach this right now.

 

[Trikky2]

Yes there is a special tool for putting in the flywheel oil seal - but I have never used one.
Tapping in gently or using a suitable socket works fine. Its only a seal - just like a wheel bearing one for instance - just a bit bigger diameter.

Just have to make sure its all clean, no burrs or marks on the surfaces, including the flywheel. Some like to add a smear of sealant between the case and the seal.

While the flywheel is off its also worth double checking the camshaft end plug too.

 

[Dickie524]

Sorry if you've already thought if this, but it looks from your last pic as if the leaks are coming from the unions on the oil pipes to your spin-on oil filter (though it's hard to say if in fact it is leaking from further up and dribbling down onto there ) - but perhaps trying to tighten those up may help?

 

[Trikky2]

Agreed. The photos and the descriptions don't match. There's no photos of anything resembling a main seal :lol:

 

[magoo]

Yeah we have tightened those but no joy. Told you I hadn't photographed everything!

 

[Trikky2]

Yeah we have tightened those but no joy. Told you I hadn't photographed everything!

The oil leak in the photo of your oil filter looks like mine did when I first fitted it. Tightening didn't cure mine either.

The threads were not well made and in the end I had to use thread sealer to get it oil tight.

The other two areas you arrowed are also common sources of minor leaks or seepage.
Fortunately they are simple and easy to fix.