[Kchart18]

The 4.3 that i am currently using smokes pretty heavy initially after start-up.it there is only one puff of smoke after it first fires. the issue is getting worse and i would like to do something about it. Are there any solutions to this problem without re-seating all the valves. I'm looking to upgrade the engine in another year or two so a drastic upper end re-build is just not feasible. Another issue that i have is a pretty heavy fluctuation in the oil pressure Gage. initial start up and idle registers around 55 to 60 psi. After being driven for about two minutes when i pull up to a stop sign and the engine idles, the pressure drops to about 30-35 psi. the truck is a 89 with 122 thousand on it . any help would be great
Thanks, kyle

 

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A puff of smoke on start-up is a classic sign of bad seals on top of the intake valve guides. Guides are surely worn too, but you can probably cure or greatly reduce the startup puff with new seals. Can be done with the head on the car.

30psig oil pressure at idle is way more than enough. An engine only really needs a few pounds. My hemi drops to about 15psig at idle which doesn't bother me at all. All the pressure that the pump generates does is supply oil to the bearings. The actual lubrication is done in the few 10-1000ths of oil captured in the bearing clearance which is hydro-dynamically pressured up to ~2000psig and keeps the metal pieces apart. Anything much over 50psig at any speed on a grocery getter just consumes power and wears out the pump drive rod quicker.

 

[Kchart18]

Thanks for the input, so what your saying is it is probably not a sign of a bad valve seat just the valve guide seals?

 

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Yes, there isn't enough leakage past the worn valve guides when the engine is running to show smoke but when you turn the engine off, the bad seals combined with worn guides allows oil to drip into the intake manifold. When you start up, gasoline washes the oil into the combustion chamber and the engine is so cold it has a hard time igniting the gas/air mixture let alone the hard to burn oil, thus "poof!" If your engine just uses O-ring 'seals', replacing them probably won't help that much. Those O-rings are more baffles than seals. To reliably stop the leakage you will probably have to install positive seals that attach to the top of the valve guide. If your engine isn't designed for them from the factory, it will take a little more work but will be worth the effort.

 

[Kchart18]

Thanks a lot for all your help, it is appreciated

 

[bracketeer]

bad seals

You can buy a bottle of seal restore. It is suppose to make the seals pliable again. Never tried it but if it works its a cheap short term fix.
I have tried the power steering seal restore and it worked.