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Weird smoking problem

Cili

Cili

1/2 ton status
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Mar 29, 2011
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Sidney MI
I'll try to explain this as best as possible to see if anyone has any ideas but I don't drive the truck very much right now being in college.

A little history. This is in my 71 c10. It is a 350 from an '80 vette and until last spring was bone stock. Never used oil, ran great. I just finally got the need for more power. I do not know how many miles are on the short block but it seemed to be in good shape from what I could tell. Always had good oil pressure and still does.

So last spring I bought a set of used vortec heads, new cam and lifters, intake, valve springs, and roller tip rocker arms. I did not have the heads redone because I was a poor high school student. I did out new valve seals in though. Put it all together and got the bugs worked out and it was running great.

Then every once in a while it would start to smoke a little bit, seems like oil smoke, usually if I just idled around a lot but then would go away after just a mile or so of driving so I didn't really worry about it too much. Well it's progressively gotten MUCH worse. It is still intermittent though. The last time I drove it leaving the races Saturday night it was making headlights behind me disappear and people were honking at me. Got it out of town and put it in neutral and revved it a couple times to clean the plugs off since it was now missing terribly. Smoked like a bi***. Then about a mile down the road it stopped and was fine. Except for that one time it has always ran fine while it's smoking with plenty of power.

It also seams to do it more after I drive it and get it warmed up, shut it off, and come back in a little bit.

At first I suspected the valve seals but with the amount of smoke I seen last time idk if that's possible. I'm guessing now it's either the rings or possibly a head gasket. Even though it smells like oil and is defiantly using oil it's a possibility I guess.

I'll be home next weekend and will have some time to mess with it so I'm open to ideas of things to look for but I don't have a leak down tester or even compression tester at the moment.

Sorry for the long post and thanks in advance!
 
I am guessing the baffle inside of the valve cover where the PCV goes in is missing.

Possible intake manifold to cylinder head gasket failure.
 
If it has a mechanical fuel pump, pull the dipstick and see if its overfull or if the oil smells like gas.
A pinhole in the pump diaphragm will let it dilute the engine oil with gas causing it to burn more and more oil as it ruins the bearings and cam.
 
Also what color is the smoke. Like Fordum said check your oil, smell it, color, level.

Last time you replaced a pcv valve? When you did the heads, and put the valve covers back on, it have the baffles around the pcv and breather? Bad oil rings? Valve seals, I dunno.

You said it never used oil, so has it started going through a lot after the smoking problems?
 
Yes mechanical fuel pump so I'll look into that. I have new oil and a filter so I'll change it and check the old stuff out. I've never replaced the pcv so I'll do that too.

I'm pretty sure the valve covers have the baffles but I'll check to make sure.

And yes when it was stock it didn't seem to use any oil, maybe a tiny bit, and now it seems like it is. Is was quite a bit low last time I came home but I have been really bad about changing it and checking it since I moved away for college. So I'll change it and see what it does.

Thanks for the ideas guys
 
Make sure the hose and passages for the PCV system are clear and there is ample vacuum available at the hose with the engine running...also dont use regular fuel line for a PCV valve,it is often too soft and can collapse under vacuum and cut off the vacuum to the PCV valve..

Another thing to check is for sludge build up in the rear of the heads,blocking the oil reurn holes..rather unlikely since the heads were off not long ago,but enough short trips in cold weather could possibly cause a lot of condensation or sludge build up...

Last resort would be to perform a cylinder leak down test with compressed air thru the spark plug holes,maybe a piston has a tiny hole or other damage allowing bloy by to be excessive suddenly..I've seen intake gaskets fail and let vacuum suck oil in from under the lifter valley and turn a good runner into a smoker quickly too..

It could be the oil got diluted as Fordum suggested too,and the crankcase is now half full of gas AND oil...which will get by the rings easily and smoke like crazy,along with doing damage to bearings and other parts due to lack of lubrication..
 
Started working on it this morning. So far the pcv system looks fine, no oil in the line. Also valve covers do have baffles. Going to drain the oil next and see if it has gas in it and go from there.
 
When you check your oil level is it still full or close to it ? Radiator full ? try this is the transmission auto ? th350 ,th400.pull the hose off the vacum modulator and see if fluid runs out.
 
I had a 72 K5 start smoking suddenly and it turned out my master cylinder started leaking into the brake booster,and it eventually filled it enough to suck brake fluid into the intake thru the vacuum supply hose...

I had been refilling the master cylinder back up about once a week,it had a mysterious "leak" and I just assumed a rear wheel cylinder was weeping..but it was the master cylinder itself..the brake fluid made a dense white cloud that at first made me think it was coolant,it also had a similar sweet stink to it..I was glad it wasn't a head gasket !..:doah:
 
That's a good idea about the Trans vacuum modulator, I've heard that before and forgot about it. But I changed the oil Friday morning and drive it hard all weekend with out a single problem so i didn't worry about it too much this time.
 
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