Oil leaks! Grrr!

[petew]

I've got a near stock 1600 in an oval with a small turbo, intercooler and efi. The car runs ok, but oil leaks are driving me crazy! Specifically it seems to be leaking oil out of the crank snout and dipstick. The motor is near new, running very low boost (4psi) and not revved a lot, but it seems to be a sieve. It did overfill it early on, but it's got just right amount of oil now and still I can't seem to stop the leaks.



Here's a pic of the setup. The only change being to a oil scavenge pump for the turbo. It's using a CB full flow plate with in and out, but the pump doesn't seem to be leaking anywhere.

Thoughts? It's driving me nuts!

[Piledriver]

Sand seal (see FJCampers recent post on that)
Compression/leakdown test, running really rich can make the rings hard to seat or not seat at all.
If you have a lot of blowby, you are fighting a losing battle.

Never vent the 3/4 rocker box, if you have any blowby it can pump oil out at cruise RPM.
I feed fresh air IN there via a check valve and vacuum break.

Woven SS pot scrubbers in the gen stand act as air/oil separator, works well.
(Not steel wool, these have no loose bits and lots of surface area)
Also use the baffle and make sure it points the right way and is right side up.

Talcum powder can sometimes reveal seepage. (blow it through a straw)

[petew]

I just turned the motor over and pulled the oil cap. At idle there was some pressure coming out the oil filler hole, but no vapour and no smoke. I'm not sure if it's blow by or not. The motor was cold.

[Bruce2]

What is your breather setup?

[petew]

CB breather/filler box with an extra breather off the fuel pump blockoff.



As you can see there are 3 different breathers. I've not vented the valve covers as the motor isn't doing a lot of revs.

[Marc]

I'm a firm believer in venting the valvecovers ... including the LH one, provided the breather box is mounted high and away on the RH side to minimize oil carryover. Bigger the better (I used to run 3/4" hoses off both valvecovers and the stock oil filler on my circletrack cars when I was running wetsump, that finally cured pesky VC gasket leaks that had plagued me before).

By nature with the boxer design the crankcase volume is ever-changing, pulsing back & forth between the front end of the motor and the rear. A CW crank effectively creates a labyrinth seal, blocking the usual path behind the center main web - so the pressure has to equalize by charging up & down the pushrod tubes...the inevitable result is VC gasket failure when it can't survive the pressure pulsations. Even just adding a big hose to connect the RH VC across to the LH (as they do in V8 circletrack cars) can be beneficial - anything to dampen the pulsations helps.

[Piledriver]

Worth trying, but with a stock 1600 dp bottom end never spinning over ~5K and only pushing 4 PSI boost I suspect something fundamental is wrong, like rings never seated or cracked ring lands or some such.

Its time for basic troubleshooting: Compression test, leakdown test, make sure you didn't put 15 quarts of oil in it etc.

[petew]

We're doing a comp test on Thursday. So hopefully that sheds some light on the real issue.

[Marc]

Exactly what numbers to expect depends upon many variables, but all should be within ~10%. Always good to do "wet and dry" (squirt a little light oil into each hole and repeat the test). If the difference between dry and wet is substantial, you've got a ring/cylinderwall issue.

[petew]

OK, will try that too.

[petew]

Just an update. We did a comp test on the motor and found 100psi on cyls 1-3, but only 85 on No.4. The motor is out now and off at the engine builder being repaired.

[ONEBADBUG]

Frank talked about using the Krankvent on here. It works great, that's all you need. My turbo engine had the stock breather going to a Krankvent. it didn't leak at all.

[Piledriver]

My sons 1.8L bus motor once suddenly had a hole burning a lot of oil and fouling the plug, and very poor compression on that hole wet or dry. (to the point of spewing oil out the header, forgot about that)
The grooves had managed to line up perfectly after ~20 K miles.
Corrected and reassembled, all good again...Didn't even rehone.

[petew]

That's interesting... it did puked oil out the header too earlier on.