Weird Oil Leak

[Zuffen]

I have an annoying oil leak at the rear of my engine.

It appears to first show itself at the bellhousing/sump flange area on the oil filter side.

I've replaced the rear main and the carrier as I felt it may have been leaking from the chemical seal in the main seal carrier.

There's no oil on the flywheel and the clutch is perfect so no oil there either.

If it was leaking from the flywheel bolts there would be oil on the clutch, which there isn't.

I had a couple of minor leaks from the spark plug tubes but they've been fixed.

The gearbox isn't leaking through the front seal as the bellhousing is dry.

I've also had the sump off and the seal there looks fine. I know it isn't the sump as no oil gets on the sump, it runs around the bellhousing and drops to the floor.

The leak isn't major but it bugs me and Helen (my long suffering wife) won't let the car on our front driveway!!

I'm open to suggestions. Burning the car IS an option I'm prepared to look at!

 

[cribbj]

Rod, it sounds like you've covered all the usual suspects. What about from the upper oil pan to the block?

 

[Lextreme II]

check your crank pressure...... now is rear main and somewhere is next. Check your boost and pvc routing.

 

[Zuffen]

JC,

I use a one piece steel pan. I've had it off twice in the last week (getting it off requires removal of the headers to clear the sump flange) and both times the chemical seal looks perfect.

DP,

I run 2 x 19mm breathers for the PCV so there shouldn't be any pressure build up. Assuming I was pressurising the sump and the rear main leaked it would end up in the clutch before eventually leaking out from all around the whole bellhousing.

The leak is focused on this one small spot.

I won't tell you the work involved in removing a 150kg transmission from the vehicle to access the rear main. A serious 14 hours to remove and replace it.

The leak has me stumped.

On the bright side the car is finally at the dynotuners.

 

[Lextreme II]

I had a couple of minor leaks from the spark plug tubes but they've been fixed.

Rod,

If you have multiple areas of leak then u should look into oil pressurization. Spark plug tubes normally doesnt leak due to the position unless there is a huge amount of oil pressure. That pressure could be from the charger somehow find its way to the oil sump.

 

[Zuffen]

I'll try venting the cam covers to atmo.

No filters or restrictions and see what happens.

Problem is I can't find the leak. I can find the approximate area where it's leaking from but not the actual leak.

The leaking plug seals were all damaged when installed as I put them in from the outside of the covers when they should have gone in from inside the covers. The covers had some rough edges that damaged the seals.

 

[cribbj]

Rod, this may sound a little off the wall, but why don't you try pressurising the crankcase with some compressed air through the dipstick tube, and see if you can find where it's leaking by "painting" the suspect areas with soap suds. I'd start with the air regulator set pretty low, like maybe 10psi and then gradually increase it until it's obvious where the leak is.

Obviously you'll be getting leakage past the plug seals, but you'll be looking for it in the other areas, like the cam seals, the rear main, the pan, etc.

Just as obviously, you'll need to plug off the cam cover vents to reduce the air consumption.

 

[Zuffen]

John,

I'd thought about it but the area is pretty inaccessible.

When I had the trans out I did a good inspection of the rear of the engine and there's no sign of any leaks or oil on the rear of the heads or the block.

This is what leads me back to the sump/block interface or the rear main seal carrier but I'm damned if I can see where it actually comes from. Whne I removed the carrier there was no oil staining or sign of an oil path from it. This keeps leading me back to the sump.

I had one thought that perhaps the weld around the sump flange has a pin hole in it? I know the oil pickup tube that CRS made to go with the sump had pin holes in the welds on it. Trouble with this is the oil isn't running down the rear of the sump (it's dry) but is running down the front of the bellhousing.

 

[cribbj]

John,

I'd thought about it but the area is pretty inaccessible.

Yeah, I wouldn't have thought this would work too well with the engine in the car, but if you get desperate enough and have to pull the motor to see where it's coming from, it might be a useful diagnostic.

I remember you describing the operation of pulling the motor is similar to the car giving birth - the whole engine bay has to dilate for the motor to come out.

I don't envy you M8.

 

[zen]

an idea...maybe be a bad idea,maybe be good..(ie if it works)

steam clean the engine..(may not be nessary)add some uv dye to the oil(like the stuff ac people use to find leaks), run the engine but dont get it to hot (ie so it dont kill the dye)..

check for leak using uv lamp(ala ac boys)maybe do this a few times to allow dyed oil to find its way out..??

just an idea..

 

[Cobber]

Mobil 1 has a UV dye in it as do most aviation oils.

You have suffered with that car mate hope it all works out.

If you spill in the valley when filling it up it can end up running out down the back of the engine from the drain holes below the starter. Pour a little bit of green coolant in the valley and see if it comes out in the same place.

 

[Zuffen]

Cobber,

I use afunnel when filing it and there's no oil on the cam cover so I don't think the oil is from there.

Thinking aboit it if the oil got between the adaptor plate and the block (the plates 20mm thick) it could appear from there.

I may go back and revisit the rear cam seals.

 

[Zuffen]

Found it!

The oil is leaking out of the rear cross bolt for the main cap.

I removed and replaced the bolt today and the leak is worse.

When I get it home I'll remove the bolt and use a new seal and some sealant and it should be solved.

I noticed the bolt had oil around it previously but discounted it as residual from the actual leak.

 

[Zuffen]

Still had my leak today.

A little closer inspection showed the oil wasn't leaking past the cross bolt seal after all.

Rather it was leaking out a 6mm hole in the engine block.

The tapped hole is usually filled by a sump mounting bolt but the CRS sump doesn't have a bolt hole in that location so the hole will breathe to the outside world if it isn't filled with sealant. Thank you Mr CRS.

When I get the car home I'll remove the sump and drill an extra hole in the sump for that bolt. There's probably one on the other side as well so I'll check that whilst it's apart.

At the moment we've filled the hole with sealant the oil is staying in so we can continue on the dyno.

 

[zen]

if you want something doing properly..then do it yourself...

what a git..glad you found it!

 

[edz]

crs sump

Still had my leak today.

A little closer inspection showed the oil wasn't leaking past the cross bolt seal after all.

Rather it was leaking out a 6mm hole in the engine block.

The tapped hole is usually filled by a sump mounting bolt but the CRS sump doesn't have a bolt hole in that location so the hole will breathe to the outside world if it isn't filled with sealant. Thank you Mr CRS.

When I get the car home I'll remove the sump and drill an extra hole in the sump for that bolt. There's probably one on the other side as well so I'll check that whilst it's apart.

At the moment we've filled the hole with sealant the oil is staying in so we can continue on the dyno.

Good find Rod, I saw a similar thing with the flange plate when i bought one from CRS, and other holes at the front didn't line up, that's why I sent it back! http://www.lextreme.com/forums/showthread.php?t=12558&highlight=crs+sump

Ed

 

[hungryforinfo]

Maybe as the oil heats it becomes thinner, and is only able to leak out when its hot and under pressure. There couldn't be a leak at the top 'O' ring in the rear main seal area could there?

 

[Zuffen]

No the leak has been temporarilly sealed with sealant.

Defineitely from the sump mounting hole.

I'll pull the sump amd drill another hole in it and put a stud in the hole with loctite.

That'll stop it leaking for good.

 

[samsdad]

Lessons learned here...

1. Make your own sump

2. Make your own sump but only tack it together and get someone else to weld it up so you have someone to blame

 

[hungryforinfo]

Rod, did you get any pictures of the offending bolts and bolt holes. It might help others in future.