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Smoke Test Pro's... help

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19 Mar 2020 07:58 - 19 Mar 2020 08:03 #38436 by Potanist
Smoke Test Pro's... help was created by Potanist
This question is actually for the smoke I found. I already have a thread started for the truck. This is for my 2002 Chevy Avalanche with the 5.3. My fuel trims are high like I have a leak. I've done the carb cleaner, brake cleaner and water test and nothing. I put the smoker on the motor, going through the brake booster hose, and still see no signs of smoke anywhere. But taking the oil fill cap off it was full of smoke there inside the engine. Is that because I still had the PCV hose still hooked up? Just found it odd.
Last edit: 19 Mar 2020 08:03 by Potanist. Reason: make things clear

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19 Mar 2020 13:32 - 19 Mar 2020 13:40 #38447 by John Curtis
Replied by John Curtis on topic Smoke Test Pro's... help
Does fuel trim get better with RPM increase? At 2500 and 3500?

Clamp off the brake boost and see if it corrects just to rule that out.

I smoke through the intake when looking for vacuum leaks, throttle should be open. Smoke right behind the MAF as anything behind the MAF is a possibility for a vacuum leak.

If your rpms don’t improve with engine speed you’re likely looking at an 02 problem, an exhaust leak, or a fuel issue.

Smoke coming out the oil fill port can get there one of two ways. PCV or Piston rings.

Thinking out loud always helps me in the process.
Last edit: 19 Mar 2020 13:40 by John Curtis.
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19 Mar 2020 18:39 #38455 by Potanist
Replied by Potanist on topic Smoke Test Pro's... help
Thanks John... it's a long story on this truck. Well, as I gas it the LTFT go low but the STFT balanced it out, keeping the total at 25% on both sides. I was a parts changer on this one and I still have the problems. Just changed the But I just needed to know if the reason the block was full of smoke was because of the pcv vacuum line.

Thanks

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22 Mar 2020 09:39 - 22 Mar 2020 09:52 #38544 by Tutti57
Replied by Tutti57 on topic Smoke Test Pro's... help
I was thinking about this one the other day too and I think on a cold engine, if you let it smoke long enough, you'll get smoke in the crank case past the open valves and through the rings. Someone correct me if I'm wrong.

That's with the PCV isolated.
Last edit: 22 Mar 2020 09:52 by Tutti57.
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24 Mar 2020 10:07 #38590 by tech25
Replied by tech25 on topic Smoke Test Pro's... help
yes, its normal for the crankcase, and valve covers, ect to get smoke.
great way of checking for vacuum leaks/oil leaks, in valve cover gaskets, ect. is with the smoke machine

remember, a oil leak is a vacuum leak regarding engines
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