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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: DTrain on July 15, 2012, 04:47:34 pm
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My truck smokes when it first starts up, it's just a puff then it clears right up, doesn't do it any other time, only start up. Some days it is worse then others, some days it doesn't do it. It always does it when the truck is cold though. I've talked to a handful of people who think its in the head, like a valve seal or something. That seems more logical then rings to me. So I'm trying to get some more insight on what it may be. Im doing my homework on changing the heads right now anyways, so if it is indeed a head problem it's not a bad thing. Also, if it is a head thing, is it bad to run the truck like this until I do the head job? Thanks
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It's most likely valve seals, especially if it's at a cold start.
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It's most likely valve seals, especially if it's at a cold start.
X2 - And, especially, especially if the 'puff' has a slight bluish cast to it.
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You can change the valve seals with the heads still bolted to the engine.
Set it on top dead center compression on number 1 cylinder. Pull the valve covers, remove all the rockers arms, and spark plugs. Use a compression gage hose with an adapter to an air hose. Put 80or so PSI into the cylinder you plan on changing. Remove the valve spring keepers and springs. Install new seals, put the spring, and keepers back. Remove the hose move on to the next cylinder, and repeat process. After they are all done you will need to adjust the rockers in the correct order. Best way for this is use a book that tells the order, and how to.
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Adjusting the rockers..............pick any cylinder you want to start with......turn the motor over with a large breaker bar for more accuracy........when the exhaust valve begins to open, adjust the intake rocker on that same cylinder. When the intake valve begins to close, adjust the exhaust rocker on that cylinder. Then move on to the next cylinder and so on.