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Replacing valve stem seals in car?


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Or you can put a leakdown tester in and fill the cylinder with compressed air.

 

Honestly though.......this sounds like a terrible idea to do in the car though.  I doubt there is any way to even really do ut unless you have some crazy low profile tool.

 

You can do them without pulling heads but I would definately pull the engine and do it on a bench to make it easier.

 

Also...why do you think you need to replace seals?  Pretty uncommon for them to cause trouble......maybe your issue is something else?

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I bought the engine out of a T-boned car that a 80  year old lady drove. It had only 120 some K on it. Inside the valve cover the engine looks brand spanking new and there is absolutely no tarnish whatsoever. It has great compression and runs like a top. It doesn't leak a drop of oil whatsoever. It does however use a quart of oil every 400 miles or so. I have replaced the PCV valve and that didn't help. I have tried cleaners and that hasn't helped. I know the Valve stem seals don't really ever cause issues but my guess is that sinse the car has set for years in the dry mountains of Colorado that the seals have likely cracked. After posting this I did a little more research and the common belief is that if it doesn't smoke on start up then the seals are probably good. It doesn't smoke at all so now I'm wondering what it is. I'm about to do a crude leak down test in a minute here so hopefully that will tell me something more. My last motor I had put in here did the exact same thing but it eventually started smoking.  So I'm also wondering if something with the EGR valve is causing the problem. I have a egr intake on a non egr motor. I hooked the egr up to a vacuum hose so I don't get a code. Never had a egr code on this motor or the last exept for 2 minutes after I left the emmisions place, now I have that code. Weird huh. Thanks for the help ya'll

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So the leakdown test concluded that the engine is in pretty damn good condition. I looked at the valve seals from the exhaust side and they are super clean as are the ports. The spark plugs are also super clean. So my conclusion is that it's not the engine that is causing the oil to burn. It has to be the Intake Manifold or something. I'm somehow getting oil mist or something back into my intake and it's burning it clean. I'm at a complete loss.

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Could be gummed up oil control rings. This wouldn't really show up on a compression test.

Could also be a clogged PCV hose or breather hoses.

There's an O seal at the back of the oil pan that seals the PCV cavity in the block to a tube in the oil pan. If that seal goes bad it will cause high oil consumption.

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If you are burning a little oil, the catalytic converter will finish oxidizing the smoke so you wont see it, but that will in turn eventually ruin the cat and then you will see the smoke.  I agree that the oil control rings could be the cause, but you don't usually see issues with them in an engine that is as clean as you describe.  The oil control rings get carboned up from infrequent oil changes and infrequent oil changes usually leave a lot of sludge under the valve covers.

 

I think I'd be looking for a bad seal somewhere.  Some times they can be hard to detect because they only leak when the engine is running so you don't always see the oil spot under the car.  One commonly overlooked leak is the oil pressure sending unit.  If you see any oil on the terminal of the sending unit, it is leaking.  When they leak, the spray oil out in a fine mist so it doesn't always accumulate on a surface under the hood and the oil doesn't come down in drops.

 

Front seals will sling oil away from the engine, but you would see some oil build up on the nearby surfaces such as accessories and fenders.  Rear oil seal leaks are really difficult to notice.

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The car is absolutely spotless underneath as I replaced all the seals when I did the engine swap. Not even the slightest residue so I know for sure it isn't leaking out. As far as that oil O ring goes, if the seal is bad then it just shoots more oil up thru the PCV valve correct? I thought there was a problem somewhere because the PCV looked oily so I installed a oil catch can about 10 to 15k ago. I modified it so the inlet fitting had a tube that would go to the bottom of the can and into steel wool. My thoughts were that if the oil was getting misted then the steel wool would reduce that. So far I have collected maybe 6 to 8 ounces of oil. So unless the oil is still somehow getting past that I don't think it's that.

I have used Marvel and Seafoam to clean the engine (even though it looked clean enough to eat off of inside) so I'm not thinking it's the rings and as well as the lady took care of it I don't know why the rings would be bad. 

Thanks again everyone for the thoughts.

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