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Valve Seals or Piston Rings?

Muskrat

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Jun 13, 2004
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Lexington, KY
Ok, so today I noticed the car is burning oil, big time!

I did a compression check on all cylinders and got 150 across the board. The plugs for Cyl. 1 & 4 were black (oil fouled) while Cyl. 2 & 3 were clean and white. Looking through the spark plug hole the pistons in Cyl. 1 & 4 looked "wet".

A little history:

The car has been sitting for the last couple years, and rarely started. This past week I finally thought I had it running properly, and idling between 800-900 rpms (minor surging due to small vacuum leaks, I believe). Yesterday I changed the oil, washed the car, and parked it for the night. This afternoon, after doing some more cleaning, I noticed it blowing smoke when I revved it, and also noticed the idle had shifted a about 1-200 rpms higher, and had more pronounced surging.

So, what do you guys think?
 

atc250r

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Sep 11, 2003
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Orange County, NY
If the compression is good its probably your valve seals. However, if its been sitting a long time I would put at least a couple hundred miles on it before I condemned them. It could just be stuff burning off inside the exhaust after sitting so long. It could also be coming from your turbo. Usually when its the valve seals it'll smoke really badly after you let it idle for a few minutes.

John
 

NateCrisman

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Nov 22, 2008
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Blairstown, NJ
Take the car out on the highway, get up to 65mph or so then coast down to about 35mph from engine braking with the throttle shut. Then get on the throttle and watch your mirrors. If the car has bad valve stem seals, the vacuum from engine breaking will pull tons of oil past the seals and result in a big black cloud when you get back on the throttle.

If the car is burning oil due to bad rings (I doubt it because the compression is good), it will smoke consistently regardless of throttle or rpm. But I'v never seen an engine smoke due to rings and still compression test well. Usually these motors will compression test poorly well before they begin to smoke, the opposite of your situation.


 
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Rausch

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Dec 21, 2004
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Cleveland, OH
I'm with checking the piping. Rule out the turbo first.

If the tracts are dry, next most logical guess would be seals. As stated usually if you have bad oil control rings, other ring related issues will usually surface as well (compression)...

Although I have seen oil rings totally wiped out (engine ate them) and cmpression rings still functioning. (Weird one, and Toyota related, not Mitsu).
 

1990ggsxnj

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Nov 21, 2008
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Blackwood, NJ
One of my 1990 GGSX's Smoked for a couple days from valve seals. I bought a set thinking they had to be replaced when I first got the car. Turns out they just had to do a semi re-break in. 75 miles later they're fine.
 

Muskrat

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Lexington, KY
Well, I solved this mystery, and it's really my own fault.

The majority of the smoke was actually steam, from water getting in the muffler after I washed the car.

The part that was oil was from over filling during the oil change. (I was dumb and forgot to lower the car before filling), which probably caused the oil pressure to spike and push past the valve seals. I'm sure I will need seals done down the road, but for now they seem ok. I replaced the plug in Cyl. 4 and the plug in Cyl 1. has cleared up.
 

gtluke

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Sep 16, 2001
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dirty jersey
certain oils make my car smoke really bad. like castrol
it's been like that for 5+ years too. even redid the head and it still smokes with castrol.
 

1990ggsxnj

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Blackwood, NJ
LOL I have yet to overfill any of my cars that badly BUT given my track record I should have done it 10 times over by now. At least you didn't accidently put antifreeze in there (no, I haven't either) ;o)

Castrol huh? I never had any problems with Syntec but then again, that's all I ran. What do you use now to make it stop smoking? And couldn't it be your rings if you did the head and it still smokes?? Have you checked compression?
 
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Quoting Muskrat:
I did a compression check on all cylinders and got 150 across the board.

 

1990ggsxnj

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I was replying to gtluke in regards to the compression check, not muskrat. /ubbthreads/images/graemlins/hsugh.gif
 
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Muskrat

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Lexington, KY
Quoting 1990ggsxnj:
LOL I have yet to overfill any of my cars that badly BUT given my track record I should have done it 10 times over by now. At least you didn't accidently put antifreeze in there (no, I haven't either) ;o)




I'm just glad the car wasn't on the road at the time, so I didn't drive anywhere and caught it right away, so I don't think any harm was done. Definitely a lesson learned though.
 

1990ggsxnj

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Blackwood, NJ
Nah, if it was drained out before bringing the rpms up for a while I wouldn't worry about it.
 

So you over-filled the oil, and the engine didn't blow up?

Of course it didn't, but some people (near where you live) have a mental dilution that it will.

5-years of Irony just boiled down to this post. Thank you. /ubbthreads/images/graemlins/smile.gif
 

Speaking of over fill which I have not done yet( knock on wood), I customers car came in today and had 22 quatrs of oil in it, F350 van..An Friday a Matrix came in with 10 galons of gas in it, UM Deisel,,OPPS
 

1990ggsxnj

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Quoting mac515:
customers car came in today and had 22 quatrs of oil in it, F350 van..



/ubbthreads/images/graemlins/ooo.gif
 

turbowop

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Yakima, WA
Overfilling oil will not make pressure spike and certainly won't help push oil past the valve seals. It doesn't work like that. Oil is sucked up into the oil pump just the same whether there's too much or just enough. Excess oil can, however, create issues due to the crank churning it too much and stirring it up, aerating it and creating bubbles that can get sucked into the oil pump and pump through the engine which isn't good. Unless you had the car jacked up at the front only at a 45degree angle though, I think you'll be fine. I doubt you put in so much extra oil that it would create any issues.

Also, there is no pressure behind the valve seals. They just seal out the oil in the head that hasn't drained back down through the block yet.
 
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If the crank was aerating the oil it could also get sucked into the intake through the PCV valve, causing a lot of smoke out the exhaust.
 

turbowop

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I highly doubt that the oil chillin' in the head waiting to be drained would be any different if the crank were churning it up or not. Even if it were frothy in the head, it wouldn't get sucked into the PCV any easier than during normal operation. /ubbthreads/images/graemlins/dunno.gif
 
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It's not because the oil is sitting in the head waiting to be drained, its coming from the crankcase. The crank churns up the excess oil in the crankcase, aerating it, causing a lot of tiny drops of oil suspended in the crankcase vapors. Those vapors containing the aerated oil droplets find their way up to the head through the oil drain-back holes and are sucked into the intake through the PCV, the same way crankcase vapors are pulled into the intake under normal operation. But when the crank is acting like an eggbeater whipping up an overflow of oil, there is much more oil suspended in the vapors than normal. The oil drain-back holes are large so that the oil can drain very easily and quickly. They are not filled with oil during normal operation, there is enough room for oil to drain and vapors to be pulled up. The PCV valve is called "positive crankcase ventilation" and that's its purpose, to vent the crankcase, which it does even though its located in the valve cover.
 
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