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Ok I have chaced around this oil leak many times. Replaced oil pan gasket (per mechanics request) and many others, valve covers etc. They are telling me its the main seal, but when I had my clutch redone I told them to check it and they said that wasnt it, and now my new mechanic is telling me that's the only place it could be, because where its always wet is right at the back of bottom of the motor behind the oil pan. I was wonder how you all felt about adding some stop leak for the oils system.? I am not a fan of this kind of junk and it's against my better judgement, but the car doesnt leak oil sitting in the garage, it just looses it driving over a 100 miles round trip then I need to add a half of quart or more. Or is my car actually burning oil? Which also doesnt seem to be (maybe alittle) because my exsaust smoke isn't blue are really that abnormal. So do you think so oil stop leak would hurt anything and maybe fix the leak after the aluminum gets up to running temps. I don't even notice a burning smell while driving. Could be rings, but compression tests dont show any problems. What do you guys think? THanks

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what year is the car? mileage?...did your mechanic check the seperator plate on the back of the engine....the plastic ones are prone to leaking...

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the separator plates do leak usually, but i don't know if they leak 1/2 a quart in 100 miles? that seems excessive even for a really bad separator plate leak.

 

obviously you already know that the oil stop leak stuff is bad news and shouldn't be used. that being said...i do know people that have run the engine too low on oil because of significant leaks like yours and seized the engine. if it's bad enough to be half a quart this time, it might be 2.5 next time... so, if it could help some and prevent engine loss then maybe it's worth a shot. a quart every couple hundred miles sounds really bad and really expensive. so while i don't recommend it, i do see where tough times might be worth it.

 

your best shot unfortunately is to have it fixed properly. but you know that already. it's still cheaper than a new car. is that not feasible to have it fixed now?

 

and you're absolutely positive it's not something else ending up down there? the rear passengers side cam cap can leak a good bit and end up down around the rear of the motor too. that's really easy to check and replace - 2 bolts and that's it. and even oil from up front can drip and blow back all underneath everything, but i would think that would be obvious and it seems you've already had a good look at it.

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Ok I have chaced around this oil leak many times. Replaced oil pan gasket (per mechanics request) and many others, valve covers etc. They are telling me its the main seal, but when I had my clutch redone I told them to check it and they said that wasnt it, and now my new mechanic is telling me that's the only place it could be, because where its always wet is right at the back of bottom of the motor behind the oil pan. I was wonder how you all felt about adding some stop leak for the oils system.? I am not a fan of this kind of junk and it's against my better judgement, but the car doesnt leak oil sitting in the garage, it just looses it driving over a 100 miles round trip then I need to add a half of quart or more. Or is my car actually burning oil? Which also doesnt seem to be (maybe alittle) because my exsaust smoke isn't blue are really that abnormal. So do you think so oil stop leak would hurt anything and maybe fix the leak after the aluminum gets up to running temps. I don't even notice a burning smell while driving. Could be rings, but compression tests dont show any problems. What do you guys think? THanks

 

Stop leak for oil leaks works by swelling the old seals or gaskets. It's not horrible, but since most oil leaks in engines come from rotational seals, it may make things worse.

 

I bet you need to be sealed, which means cam seals, front main seal, re-seal the oil pump. The rear main seal doesnt go bad too often. The seperator plate is plastic and should be replaced with a metal one.

 

Don't srive the car like this for the reasons stated above.

 

nipper

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I wouldn't totally rule out the possibility of some oil burning too. Year and mileage of car? You could always check/replace the PCV valve--has it ever been replaced? It's cheap and takes 5 minutes tops.

 

When the clutch was done, and that shop said that the rear main seal was fine, is it possible that something wasn't re-assembled properly or a seal was damaged/compromised in that process? Just thinking out loud...

 

I would look into the possibility of the cam cap o-rings too. They were what was truly leaking on my car when the dealer told me it was the separator plate.

 

Brian

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I was wonder how you all felt about adding some stop leak for the oils system.? I am not a fan of this kind of junk and it's against my better judgement,

 

So do you think so oil stop leak would hurt anything and maybe fix the leak after the aluminum gets up to running temps.

 

but compression tests dont show any problems. What do you guys think? THanks

 

Hi,

 

I value that "stop leak" about as much as "overhaul in a can". Your judgement is intact.

 

It won't hurt anything, but your wallet. Will it fix the leak? No.

 

Sincerely,

 

Doug

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Hi,

 

I value that "stop leak" about as much as "overhaul in a can". Your judgement is intact.

 

It won't hurt anything, but your wallet. Will it fix the leak? No.

 

Sincerely,

 

Doug

 

 

Especially big leaks it wont fix. He has gone from "oil leak" to "subaru automatic anti-rust system"

Edited by nipper

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Sounds like a seperator plate. The rear main seals almost never leak. Stop leak won't help, the seperator plate is sealed with RTV. Replace it with a metal one when you have it apart if it is plastic. Your local delaer will have the metal one in stock it's very common.

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Someone suggested changing your PCV valve in order to stop the rear seal leak. One of my toys is a 90 Nissan 300ZX that at year 12 developed a rear seal leak. An online forum suggested that rather than replace the rear seal, first replace the PCV valves to lower the crankcase pressure and see if that didn't stop the oil leak out past the rear seal. With the PCV valves (The car had 2 of them) the oil leak has not reappeared since that day, and the car is now 19.

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Someone suggested changing your PCV valve in order to stop the rear seal leak. One of my toys is a 90 Nissan 300ZX that at year 12 developed a rear seal leak. An online forum suggested that rather than replace the rear seal, first replace the PCV valves to lower the crankcase pressure and see if that didn't stop the oil leak out past the rear seal. With the PCV valves (The car had 2 of them) the oil leak has not reappeared since that day, and the car is now 19.

 

I have a 1990 Nissan Maxima with a minor rear main leak for years. Did you replace your Nissan's PCV valves with stock ones, or a different valve with different pressure rating?

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I have a 1990 Nissan Maxima with a minor rear main leak for years. Did you replace your Nissan's PCV valves with stock ones, or a different valve with different pressure rating?
probably a stock one. removing a 12 year PCV is standard maintenance and they really aren't "high pressure or velocity" devices, just a simple check valve.

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probably a stock one. removing a 12 year PCV is standard maintenance and they really aren't "high pressure or velocity" devices, just a simple check valve.

 

In my case, my Nissan has been regularly maintained. The PCV valve has been replaced several times, about once every 40,000 miles. So the one on the car now is not restricting the air flow. I wonder if using an appropriate one that is different from the stock will reduce crankcase pressure and cause less oil leak. But I guess, by conventional wisdom, if that works for reducing oil leak, it'll create other problem.

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1/2 quart in 100 miles would leave A LOT of oil all over the bottom of the car. Does it look like that much oil is leaking, or is it disappearing mysteriously? You'd think that much would at least leave some drips in the garage when you pull in after the 100 mile trip.

 

If it is just disappearing, I would definitely do the PCV valve first.

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Vasy,

I used stock Nissan PCV valves that were listed for the 90 300ZX. As I stated, they completely eliminated the leaking oil from the rear crank seal in my case.

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