Mystery oil leak

[steve lyle]

I've got about 60 miles on a rebuilt engine - see viewtopic.php?f=36&t=52563&p=395603#p395603 for the entire saga.

If I go on a 6 mile or so test drive, when I open the hood I'll see drops of oil on top of the left side footwell. Looking under the car - the bottom of the alternator is all but coated with oil. No other evidence of oil leaks anywhere - the valve cover gasket edges are dry, as is the sump gasket. The rest of the engine bay is dry - other than a few drops on the chassis flange just fwd of the LS footwell, some drops on the steering shaft above that. That's it. The left side of the engine is dry. The right side of of the engine, where I would expect an oil leak to be, is dry. A little seepage/dampness at the oil pump and drain plug, but nothing significant.

I dried things up, jacked up the car and crawled under while it was idling - I couldn't see any leakage/seapage
anywhere. Well, there's a bit at the bottom of the bell housing, which is pretty frustrating given the new rear main seal and the effort I put into sealing the seal carrier and sump, but I don't see how during a drive that oil could get forward and up in the air and land on the footwell.

I'm running with no mechanical fan, and the electric one hasn't come on during those test drives given the engine temps I'm seeing.

Any ideas out there?


Any ideas?

[types26/36]

Oil being pushed up the dipstick tube ?.....was the dipstick in all the way? Or crankcase pressure pushing oil up? ....blowby from rings not bedded in?

[steve lyle]

Oil being pushed up the dipstick tube ?.....was the dipstick in all the way? Or crankcase pressure pushing oil up? ....blowby from rings not bedded in?

Makes sense. Yes, it was in all the way. Still…

Next drive I’ll seal it with tape and see if that has any affect.

[cliveyboy]

I had same thing
An old spark plug boot works very well.
Clive

[mbell]

When you say left side do you mean do you mean the drivers side on LHD?

As mentioned not uncommon for oil to be forced out the dip stick but would hope that wouldn't happen on new build once rings seated correctly. I'd be checking the crankcase breather is clear and installed correctly and not causing excess crank case pressure.

[MACCA.GLM]

Just a thought

As its lhd .Have you checked the oil pressure pipe to gauge on the dash it could be leaking into your footwell

Cheers

G

[steve lyle]

When you say left side do you mean do you mean the drivers side on LHD?

As mentioned not uncommon for oil to be forced out the dip stick but would hope that wouldn't happen on new build once rings seated correctly. I'd be checking the crankcase breather is clear and installed correctly and not causing excess crank case pressure.

Yes, drivers side, LHD car.

Breather is clear and routed into airbox.

[steve lyle]

Just a thought

As its lhd .Have you checked the oil pressure pipe to gauge on the dash it could be leaking into your footwell

Cheers

G

Mine's on the right side. The pipe routs into the car on the right side. And no leaks.

[englishmaninwales]

I had an identical leak. I determined it was a result of a poorly fitting worn dipstick (worn around the locating lug as a result of vibration and movement over 50 years) in a new dipstick tube I had fitted when the engine was rebuilt.

The remedy was to fit a length of heat shrink tube over the dipstick locating lug including about 10 mm either side of the lug. This provided an oil tight and firmly located dipstick. With use the heat shrink tube wears and I replace it annually.
Malcolm

[h20hamelan]

engine oil dye, black light?

[steve lyle]

Thanks, guys. It looks like it was the dipstick. I wrapped some duct tape around the lug and about 1/2” down the stick. It seals pretty well in the tube. After my standard test drive, no oil drops anywhere. I like the heat shrink idea, will try that next. Thanks avain!

[h20hamelan]

I have no - nothing on mine!
Suppose I should?

is that much blow bye bye too much much?

[lotusposition]

Have you been drinking?