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Old 04-03-2021, 12:20 PM   #1
euphanasia
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Default "Parts Cannon" for oil leak. What seals can be replaced?

My son has an '04 Impreza that's dripping oil on the manifold and smelling pretty bad. He's 10 hours away from me at college, and I'd like to do some work on the car to potentially fix the problem. Since I'm driving 20 hours, I'd like to take care of as many possible problems as I can. What seals that "could" be causing the leak can be replaced with the engine still in the car? I know it could be head gaskets, but I'd rather do other things first, since I'm really not up for pulling the engine. I'm thinking:

Valve cover gaskets
Spark plug seals
Oil filler neck and gasket
Cam seals (Not sure if it's due for timing belt)

Anything else that's a potential problem that can be accessed with the engine in place?


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Old 04-03-2021, 10:54 PM   #2
Pix3L8
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I assume by manifold your referring to the exhaust manifold. From my experience with my foresters old leaky engine I would see oil seeping from the valve cover gaskets, oil filter housing, and the oil pan gasket and working its way into the manifold and burning off. Now if you want to do seals with the engine in the car, the valve cover gaskets are a PITA because the valve covers won’t clear the rockers and subframe without moving the engine around a bit. Again not hard but it’s a pain. I just did this to check my valve clearances last week. If you go that route do spark plug tube seals as well, with the valve covers off its take 30 seconds. Someone more experienced than me should confirm this but the cam seals I BELIEVE are very difficult to do with the motor in the car. I’ve also had leaks coming from the AVLS system on the heads, I.e oil temp, pressure sensor, and oil control valve leaking oil down the block. If you lay down under the car you should be able to see easily where most of the oil is coming from and go from there. I hope for your sake it’s just valve covers. Gaskets are cheap, Lucas stop leak is cheaper.
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Old 04-04-2021, 10:38 AM   #3
Elbert Bass
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Sure would help to know what engine you are working with. Turbo, normally aspirated?

For a N/A that would could only be a 1/4 load - head gaskets are more likely your issue. But let's be optimistic since it's a "mobile" job.
Then there is the possibility it's nothing more than a torn right front inner axle boot...
I prefer to see what I am shooting at before loading the barrel.

Once and done is always the cheapest way to go.
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Old 04-05-2021, 03:01 PM   #4
jsc83
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My experience with the torn boot is that the oil smell goes away once all the grease slings out. If the smell continues, it's likely engine oil.
It's not that difficult of a choice. You CAN'T do the head gasket while the engine's in the car, so it doesn't matter if it's coming from there or not.
The valve cover, screw seals, and plug seals would be my targets.
Someone said the oil fill tube, my impreza doesn't have a seal there.
Good luck
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Old 04-05-2021, 05:41 PM   #5
euphanasia
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It's normally aspirated.

I recall doing valve cover gaskets on an '03 Forester without having to move the engine around. Did something change in the '04? If not, couldn't they be pulled out from the head, cleaned in place, with the seals slid in "over" the covers?

For the cam seals, my understanding was that when doing the timing belt, it's relatively easy to get at those seals and they are prone to leaking.

I don't like stop leak. I'd rather have good seals than thicker oil.

CV axles were replaced recently and the boots looked good last time I looked the car over.

Hadn't thought of the oil filter housing gasket. I'll look into that too.
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Old 04-05-2021, 06:00 PM   #6
Pix3L8
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Quote:
Originally Posted by euphanasia View Post
It's normally aspirated.



I recall doing valve cover gaskets on an '03 Forester without having to move the engine around. Did something change in the '04? If not, couldn't they be pulled out from the head, cleaned in place, with the seals slid in "over" the covers?



For the cam seals, my understanding was that when doing the timing belt, it's relatively easy to get at those seals and they are prone to leaking.



I don't like stop leak. I'd rather have good seals than thicker oil.



CV axles were replaced recently and the boots looked good last time I looked the car over.



Hadn't thought of the oil filter housing gasket. I'll look into that too.


My post may have been misleading, the oil filter hosing does not have a gasket Per se but I found my filters never sealed perfectly and would ooze a bit of oil on my old engine. The only gasket is on the filter itself which compresses against the block. Sorry for the confusion. As far as valve covers I have an 06’ 2.5 N/A forester which gave me a hell of a time getting the covers off but this may be different on an Impreza. I found that even with the correct OEM valve cover gaskets and if they are not torqued in the proper sequence and cleaned prior to reinstall they tend to leak from the bottom a bit over time. I found this out the hard way. If you can maybe upload a pic of the engine from the sides and bottom so we could see the leaks?
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Old 04-06-2021, 08:09 AM   #7
Elbert Bass
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Quote:
Originally Posted by jsc83 View Post
My experience with the torn boot is that the oil smell goes away once all the grease slings out. If the smell continues, it's likely engine oil.
It's not that difficult of a choice. You CAN'T do the head gasket while the engine's in the car, so it doesn't matter if it's coming from there or not.
The valve cover, screw seals, and plug seals would be my targets.
Someone said the oil fill tube, my impreza doesn't have a seal there.
Good luck
Sorry, beg to differ. Dealers do SOHC EJ head gaskets in chassis all the time. I have probably done 175 - 200 of them myself. It's not something you do without a lift, but it was a very, very common thing to do.
Don't think I have ever seen an oil fill tube gasket leak, but who pulls those off the valve cover anyway?
BTW: I have seen more oil burn smell from head gaskets and axle boots than VC seals on SOHC EJ, but then that may just be a dealer shop thing. Usually see VC seals when you perform a major maintenance and find oil soak in the plug tubes.
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Old 04-07-2021, 02:20 PM   #8
serrilion
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I recently did VC seals on my 02 impeza. Didn't have to move to much on the pass side besides losing up my Power Steering lines, the drivers side I just removed there battary, and windscreen washer jug. I don't have AC in my car but the lies might get in the way some. BUt they should come right off with no issues. I found a sure sign on a HG leak is oil burned on around or near the driver side manifold closest to the motor. But hope its something simple, only other thing I could think of would be a steering rack boot.. GL
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