Valve stem seals? - Team Camaro Tech
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post #1 of 22 (permalink) Old Sep 7th, 03, 08:59 AM Thread Starter
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This question pertains to my 88 C1500, 350 CI pickup truck mentioned in an earlier post.
When I crank it up from cold it smokes a good bit out of the exhaust. I can't tell for sure if it is fuel or oil, but yesterday it was more of a light color smoke indicating oil. As the engine reached op temp it cleared up a lot. My parts man at the Chevy dealership said that back in 87, 88, and 89 that they replaced a LOT of valve stem seals on these engines. My truck sits in the driveway most of the week except on Sunday, I drive it to church and thats about it. Could the seals be shot allowing oil in at start up due to extra vacumn because of the air cleaner flap being closed at cold start and loose vavle stem tolerance due to cold engine. The plugs do seem to get wet, could be a mix of raw fuel and oil. I may just change the vavle stem seal and see. Only 85K on the engine.
Any thought on the matter?
Thanks,Guy

[ 09-07-2003, 02:26 PM: Message edited by: gjohnson ]
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post #2 of 22 (permalink) Old Sep 7th, 03, 09:43 AM
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Valve stem seal are a likely suspect. cheap easy fix. Being the truck sits alot they could be hard and cracked causing your problem.

68 Camaro~LSx ~all motor
1.54 60'--6.95 @ 98.45 660'--10.96 @ 121.53
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post #3 of 22 (permalink) Old Sep 7th, 03, 12:56 PM
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Depending on how far it is to church, if the engine never gets hot and you're going by the 3000 mile rule on oil changes you could have oil ponding in the heads as well. The oil gets so gooped up that it plugs the drain back holes in the head and floods the valve stem seals to the point that even good seals will leak. Penzoil is especially bad about this.

-dnult

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post #4 of 22 (permalink) Old Sep 7th, 03, 01:19 PM Thread Starter
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dnult,
I guess I'll be able to see if that is the problem when I pull the valve covers. I have been using Castrol 10W-40. If I used the 3000 mile rule I wouldn't change oil but once every 3 or 4 years as much as I drive it, no joke I probably haven't put 500 or 600 miles this year on it. Church is only about 2 miles away. So Sunday morn + Sunday night there and back thats 8 miles x 52 = 416 miles plus a little in between. I have a company truck I can do most of my running in during the day before I come home.
Thanks,
Guy
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post #5 of 22 (permalink) Old Sep 7th, 03, 04:04 PM
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gjohnson
The other half of the 3000 mile rule is..........................or 3 months! I hope your problem is the cheaper fix, valve seals. It sounds like it may be.
Jim
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post #6 of 22 (permalink) Old Sep 8th, 03, 04:35 PM
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There is a nifty tool that looks like a compression tester that will make the job much easier. It is a fitting that screws into the spark plug hole and allows you to presurize the cylinder when it is at TDC. This way you can remove the valve keeper and seal without removing the head. The air pressure keeps the valve shut.

-dnult

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post #7 of 22 (permalink) Old Sep 8th, 03, 05:06 PM Thread Starter
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dnult,
I've seen those before. I thought I could make one real easy using an old spark plug with the ceramic removed and a fitting either welded or tapped and screwed into it to hook air to. May even get elaborate with a swivel fitting of sorts. I ordered replacement seals from my favorite Chevy parts guy today, about $35 plus tax. I'll let you guys know when I get it done.
Thanks for the support.
Guy
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post #8 of 22 (permalink) Old Sep 11th, 03, 06:17 PM Thread Starter
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Put on a new sending unit and got my oil pressure back to normal. I pulled the valve covers off tonight and everything looked OK, the usual crud but not really that bad. Drain bake holes were clear, no puddling. I guess I'll change the seals sometimes next week.
I have a new set of springs I took off a set of Vortec heads. Should I install these on my truck, don't plan on using them anywhere else?
Guy
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post #9 of 22 (permalink) Old Sep 11th, 03, 06:55 PM
 
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I have a 90 Suburban with a 350 TBI motor. Had the exact same problem. When I pulled the valve covers I found an umbrella type seal on the intakes and the old small o ring piece of dried up crap on the exhausts. I put a decent seal on the exhausts, and the problem went away completely. No more smoke.

As far as the springs go, I say if it ain't broke, don't fix it.

Harlan.
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post #10 of 22 (permalink) Old Sep 12th, 03, 02:04 PM
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Since the exhaust valves aren't under pressure, the exhaust seals often are a bit looser to allow adequate lubrication to the hot valve. Better seals aren't necessarily better for the exhaust valve. But if it was smoking, I'd say it was getting lubed plenty good. [img]tongue.gif[/img]

If you're going to build your own pressurizer, take a look at plug defowlers for your home made fitting. I know a guy who tried to knock the ceramic out of a plug to make a TDC tool. He was a amazed at how difficult it was. The defowlers are pretty cheap and most auto parts stores have them.

-dnult

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post #11 of 22 (permalink) Old Sep 12th, 03, 04:09 PM
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gjohnson
Just my opinion, but. I don't like the compressed air idea because the compressed air usually forces the piston to the bottom of the bore, and if you bump the valve It's gone! I use sash cord. Soft 3/8 rope. Feed about 18 to 24" of rope into the cylinder (tie a knot in the end so you don't accidentally loose the rope). With all the plugs out, hand turn the engine until you squash the rope in the combustion chamber. This will allow you to work on the valves without fear of them dropping. And you don't need a compressor or any fancy fittings.
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post #12 of 22 (permalink) Old Sep 12th, 03, 05:24 PM
 
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I personally have removed many sets of valve springs for various reasons by putting air pressure in the cylinders. I have never, not once, had any problem with a valve falling into the clyinder. But I guess it's possible. Air is the ONLY way I have ever seen anyone do it.

Harlan.
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post #13 of 22 (permalink) Old Sep 12th, 03, 06:13 PM
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Well, I guess all you have to do is drop one to realize there are more (not necessarilly better) ways to skin a cat.
Jim
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post #14 of 22 (permalink) Old Sep 13th, 03, 06:13 AM
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I cut my compression gauge tube about in the middle & added a quick-disconnect. Instant air-hold adapter, & it makes it easier to use the gauge too (no more banging the gauge around trying to screw it in).

[ 09-29-2003, 09:25 AM: Message edited by: jimfulco ]
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post #15 of 22 (permalink) Old Sep 13th, 03, 10:51 AM Thread Starter
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My brother just happened to have a couple home made spark plug fittings, one straight and one angled with a AN type connector to attach a hose.

I've heard of using cord as suggested by GMJIM. That should work just fine, also.

Any suggestions as for turning the engine over by hand. I wonder if one of those rubber belt wrenches would work on the harmonic balancer.
Thanks, Guy
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