Rings Or Vlv Guides ?

[96ccdd]

I have a 84 K-5 with a 6.2 that smokes, looks to be oil . Is it typical for the piston rings or vlv guides to go ? The truck run well, is smoke does pickup under acceleration. Any ideas ?

Thanks
Mark

[john8662]

I'm guessing that your smoke is blue?

What kind of oil consumption are you seeing?

Certain fuel mixtures give a bluish white smoke under acceleration that is not oil burning.

Hard to tell which is to blame (rings or stem seals) w/o a proper compression test. Even a compression test won't necessarily tell you if the rings are worn (the oil control ring).

An engine flush is sometimes a good idea to clean up the internals (and rings) and help clean stuck oil control rings.

If I remember correctly, the stem seals are usually not to blame, as there is not the vacuum on them that a gasser sees. The stem seals are only on the exhaust on these engines, the intake is o-ring.

J

[96ccdd]

John,

I just purchased the truck and I'm have yet to drive it. I have just been working on it.Thanks for the feed back.

Mark

[More Power]

You might want to try using a "Top End Cleaner", which is a chemical solvent used to dissolve carbon deposits on pistons and in ring grooves. I've seen pistons come out of high-mile 6.2's that were pretty well caked with carbon in the ring grooves - especially in the oil scraper ring assembly.

Unless you have excessive crankcase pressure, I would rate valve guides pretty far down the list as a possible reason for excessive oil consumption or blue oil smoke.

Jim

[96ccdd]

More Power,

Sounds good. Is there a brand you recommend ? Also in one of my other post you recommended to freshen up the fuel sys. What exactly do you mean by that ? The wealth on knowage here is great, thanks to all.

Thanks
Mark

[DmaxMaverick]

There are lots of engine flush additives. I've used many of them, and found 2 qts of ATF will do as well. Just don't overfill it (drain some oil off to make room for the ATF or flush additive). Drive it normal to hard for about 500 miles and change to fresh oil. Work good. Last long time.

I know some folks that poor Diesel into the oil and run it for a couple hundred miles with good results. I wouldn't do this (too thin), but each to his own.

[More Power]

96cc,

I'll be visiting the local NAPA store very soon to buy some of their top-end solvent. I need to clean up some pistons that'll be photographed along with a couple 6.2/6.5 cyl heads and pre-cups for the ongoing fuel economy series. I'll know more in a few days, and I'll mention it here.

By the way, I received a package yesterday from Peninsular that contained a 6.5 "Fuel-Miser" cyl head and a selection of pre-cups. The differences between cups made for a 6.5TD power application and those made for a fuel economy engine are dramatic.... :)

Jim

[twaddle]

96ccdd,
The other thing that can cause oil consumption is glazed cylinder bores.
This is usually caused by an engine idling too much which due to low engine temperatures can cause unburnt fuel to wash down the bore which in turn takes the honed cross hatch off the cylinder wall due to lack of lubrication causing a smooth mirror type finish which in turn causes oil to be burnt in the cylinder.

I would do as suggested above try flushing the engine lube system, also some regular use may just free off a sticky ring and cure the oil burning.

What ever you do, don't let the engine idle for extended periods.

Bye the way, how much crankcase back pressure is evident at the oil filler tube when the engine is cold and also when hot?

Good luck

Jim Twaddle
Biggar, Scotland

[96ccdd]

I will take a look at backpressure this weekend and report back.

Thanks