Rear main seal leak? Mysterious loss of oil.

bigbacon
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Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Thu Aug 11, 2016 6:31 pm

So 20 valve loses oil quickly, like 1/2 a quart every 75 miles or so. I get a single drip of oil on the garage floor after driving it. I've been under the thing while it is running looking around and I see nothing leaking anywhere. I live on a dirt road so just going up the road slowly doesn't produce any drip trail or anything.

I know the rear main seal has a leak but can it only really leak when the car is under load and other wise it just doesn't or never notice? Cruising RPMs in this thing is 3500 to 4000 rpms. I tried roaming around in a parking lot as well and still didn't notice anything.

Doesn't seem to burn the oil either. No weirdness out of the exhaust and plugs are normal color.

For the amount that is lost I would expect to see some sign somewhere on the engine or see signs of burning it off. It looks fine outsite and there doesn't even seem to be some massive build up by the inspection plate. Like it just goes somewhere but only when I'm actually driving it around.

I know it is not: front seal, cam seals, oil pump, oil cooler lines, HG, cam cover, distributor, VVT sensor, oil pressure sender, oil filter, oil filter mount, or the oil pan.

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Re: Rear main seal leak? Mysterious loss of oil.

Postby allencr » Fri Aug 12, 2016 11:39 am

bigbacon wrote:...can it only really leak when the car is under load and other wise it just doesn't or never notice?


No.
Any leak will get spread all over the underside, except for slow ones that drop off, rather then spread out, when you hit a bump.
That seems like a pretty impossible amount to be unnoticeable.
What's the compression?
Wadda the plugs look like, intake/PVC look like? Relatively clean & slightly oily or saturated/dripping like that amount would usually do?

bigbacon
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Re: Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Fri Aug 12, 2016 11:47 am

plugs are fine, compression is fine.

jinx
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Re: Rear main seal leak? Mysterious loss of oil.

Postby jinx » Sat Aug 13, 2016 3:39 pm

I had a 4AFE drinking oil, to the point it would smoke heavily momentarily.
Everyone said oil rings, rings, valve seals, etc...
On a guess, I disconnected the PCV from the cam cover(& rerouted to a can etc.). Never lost a teaspoon of oil afterwards
Dunno if some internal baffle failed or what, but it was the source of my headache

bigbacon
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Re: Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Sat Aug 13, 2016 7:29 pm

i never get smoke though.

Wsa there anything weird looking with the PCV Valve when you removed it? I can easily pull it and look.

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Re: Rear main seal leak? Mysterious loss of oil.

Postby MisterJerk » Mon Aug 15, 2016 6:28 am

you have a catalytic installed? though a quart every 150 miles should be noticeable smoke from tailpipe if its burning it, even with a cat.

bigbacon
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Re: Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Mon Aug 15, 2016 10:14 am

no cat, no smoke. and I agree. if I was burning it that fast it should be a HUGE cloud and internal things like the plugs would be so fouled up but they are normal.

Someone on another forum suggested I get it all warmed up and just hand rev the thing for a bit at 4-5k rmps and see what happens. Just too freaking hot outside to do that.

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Re: Rear main seal leak? Mysterious loss of oil.

Postby Deuce Cam » Tue Aug 16, 2016 1:49 pm

If the roads are really windy where you live try venting the crankcase breathers to atmosphere as a simple test. You will also have to plug the open ports left behind on the manifold/airbox. See if there's any change.

bigbacon
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Re: Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Tue Aug 16, 2016 5:48 pm

Deuce Cam wrote:If the roads are really windy where you live try venting the crankcase breathers to atmosphere as a simple test. You will also have to plug the open ports left behind on the manifold/airbox. See if there's any change.


explain? what is this going to do? all open ports are blocked. there is a breather filter on the cam cover port on the end.

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Re: Rear main seal leak? Mysterious loss of oil.

Postby Deuce Cam » Wed Aug 17, 2016 10:08 am

What about pcv line on the side? Although unlikely, it's possible the oil is all dumping out the pvc into the intake on right turns. Run the pcv line to an empty bottle or can to observe what comes out, and plug the return port on the manifold, or don't.

I had a similar problem when I was in Greenville, SC. Not as bad as yours but my engine is an early 16v. I'd lose up to 2 quarts every couple houndred miles hitting the backroads (windy with hills). I'm back in phx now, and just like before, I lose little to no oil between changes (road is all grid no bends). Fwiw my engine seeps oil everywhere and I even get a few drops from the dizzy between drives.

bigbacon
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Re: Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Wed Aug 17, 2016 4:11 pm

Deuce Cam wrote:What about pcv line on the side? Although unlikely, it's possible the oil is all dumping out the pvc into the intake on right turns. Run the pcv line to an empty bottle or can to observe what comes out, and plug the return port on the manifold, or don't.

I had a similar problem when I was in Greenville, SC. Not as bad as yours but my engine is an early 16v. I'd lose up to 2 quarts every couple houndred miles hitting the backroads (windy with hills). I'm back in phx now, and just like before, I lose little to no oil between changes (road is all grid no bends). Fwiw my engine seeps oil everywhere and I even get a few drops from the dizzy between drives.


PVC line is fine. No oil or gunk in it.

Breather filter on the side, same thing, no gunk in it.

Intakes are clean as I left them when I put the engine together a year ago. Nothing in them, look at this today.

I guess I need to figure out how to test for massive leak while its running hard. I feel extremely confident it isn't burning it. The only thing that is weirdly concerning is that I can smell oil when I'm driving it with the windows down. No smoke ever, not at start up, not when dumping rpms, not when driving it hard.

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Re: Rear main seal leak? Mysterious loss of oil.

Postby MisterJerk » Thu Aug 18, 2016 9:12 am

if your PCV is vented to atmosphere, the hot oil smell does not go away.

bigbacon
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Re: Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Thu Aug 18, 2016 12:40 pm

ahh ok. So I'm not going to worry about that then.

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mad_86
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Re: Rear main seal leak? Mysterious loss of oil.

Postby mad_86 » Wed Sep 14, 2016 2:59 pm

you can still be burning oil even if you dont see smoke ! i seen a few times where you see a small poof of
smoke from the exhaust at idle or cruising,taking of from a stop.the thing with those you cant see smoke
unless someone is behind you while on the road

also maybe your oil too thin?? 10-30??

bigbacon
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Re: Rear main seal leak? Mysterious loss of oil.

Postby bigbacon » Sun Sep 18, 2016 6:49 pm

if it was burning there would be signs for the amount I lose. there is no way it could stay hidden if it was burning.

I'm using 20w50, same results. 1/2 quart every time I drive it into town and back.

I'm getting ready to drop the engine. Just so darn busy. Have another full gasket set on the way. Going to just re-do anything dealing with oil except the things I know are definitely not leaking.

Still trying to figure out if I have VVT Rattle on start up as well so I can pick up a new gear. Torn on water pump as well. current one is solid and not leaking so not sure if I should bother.