93 Smokey Start Shakey Stop

[djg5211]

Hi All!

1993 Blazer (S-10 version)
4.3 liter V6
5 speed manual transmission

Starts fine... runs fine..... BUT,
When i start it a puff of 'WHITE' smoke comes out
the tail pipe. After startup it quits smoking.
No water in the oil or foreign matter in the fuel
and it's more of an irritation than an actual problem
but would still like to remedy the thing.

Another thing is when you come to a full stop and
turn the ignition off it 'SHUDDERS' for a couple of
seconds. It's not like dieseling it's an actual shudder.
Does this sound like it might be a bad motor mount?
Just a guess.......

Thanks in advance!
Dave

[Chris Stewart]

It's likely both are related. The presence of white smoke at start of a good running engine indicates oil in the combustion chamber which quickly burns away. This is likely due to worn valve guides.
The shudder is likely a tiny bit of dieseling due to glowing carbon left from the valve guide oiling, lighting off a bit of fuel left in the system before the keyswitch cut the fuel signal off to the injectors.

Sometimes the gravity oil drain holes at the lower front & rear corners of one or both cylinder heads are sludge clogged which lets the oil level on top of the heads rise until they are a higher level than the top of the valve guides, then the oil seeps right in.
This is easily fixed by taking the valve covers off and unclogging the 3/8" dia. holes with a coat hanger wire then doing an oil change to rid the clot sludge.