84 GMC white smoke raw feul smell

[19gmc84]

84 GMC...350...Holly fuel pump, Edlebrock carburator...notice the last couple starts...short burst of white smoke with rich gas smell at startup...other than that...engine started and ran fine...I have noticed it runs very high at idle like choke is stuck when first started up...have to punch gas and it idles back down...figured that was because of cold weahter...out of blue...start it last night...an extreme amount of white smoke coming out of exhaust and almost smells like gas itself...engine cut off...tried starting again...turned key and heard thump sound under hood...almost like starter wasn't working...engine wouldn't turn at all....then was able to get engine to turn over by doing nothing at all...just waiting a minute or two and trying again...but white smoke still pouring out of exhaust and hearing very loud knocking noise in motor and won't stay running unless you constantly give it gas....all the while...white smoke with extreme gas smell pouring out...

Help ! Any suggestions on where to start?

 

[gpmorgan]

White smoke is usually an indication of coolant getting into the cylinders. I would do a compression test. Look at the spark plugs as you pull them out for moisture. Also the plug will be extremely clean if ran very much. The engine may have tried to hydraulic lock if it has a lot of coolant in a cyl. That would be a reason for the no start.

 

[Boone83K10]

blown head gasket

check the spark plugs like mentioned above, see if they are "green" tinted. another test is to take cap off radiator, fill to top. Crank truck and fill again to top, then hold RPM at 2000 and watch for what looks like boiling water. that is hydrocarbons entering the coolant system.

 

[19gmc84]

White smoke is usually an indication of coolant getting into the cylinders. I would do a compression test. Look at the spark plugs as you pull them out for moisture. Also the plug will be extremely clean if ran very much. The engine may have tried to hydraulic lock if it has a lot of coolant in a cyl. That would be a reason for the no start.

Thanks very much for reply...will try it out...

 

[19gmc84]

Thanks to everyone who replied...I just bought this truck and not really used to driving a vehcile with a carburator...when it didn't initially start...I pumped the gas a couple times...is it possible I simply flooded the engine to an extreme? I mean truck was running excellent before this.

 

[89Suburban]

What does the oil on the dipstick look like?

 

[Boone83K10]

I second that on checking the dipstick. My dad's 98 just had a catastrophic head gasket failure a few weeks ago and now the oil is canadian geese **** looking... hope yours isn't like that.

 

[19gmc84]

What does the oil on the dipstick look like?

Haven't had a chance to look at that yet...but will...I know the angle your going with that as far as maybe head gasket...will say this...I've had truck for three weeks and first thing I did was change oil and of course check that before I bought it...and oil gave no indication that coolant was mixed in...

 

[19gmc84]

I'm fearing it may be head gasket though...maybe that's why I started seeing the smoke coming out a little bit on the last few starts and then all hell broke loose on the last start? Thanks to everyone posting...until I can take a look at it tonight or tomorrow...please keep the thoughts coming and I'll update my findings. Thanks everyone.

 

[Swims350]

yes you could have flooded it, yes it could have a stuck choke or something.

I usually unhook the choke and just use my foot, pump a few times, fire it up, keep patting the pedal lightly until it can idle on it's own, then let it warm up more if cold out or drive off if warm.

do as they said, check the radiator, it can be oily black nasty in it, or smell of gas in the radiator, the oil can be milky or mustard looking. So you have to just check it.

other then doing it yourself or having to pay someone to do it, a head gasket on these are cheap, like $20 or so, you can even find complete gasket sets for $30-50 for it.

 

[19gmc84]

Yep, checked dipstick last night...water in oil...so...I'll be tearing it down and let everyone know what's up.

Anyway I can tell if it's a cracked block...hate to put everything back together only to find out the block is cracked...buddy told me I could use a cynlider leak down tester to verify that...but I hear from others that that test can't separate what's actually wrong whether it be cracked block or gasket.

 

[89Suburban]

If there is a crack in the head or the block you should be able to see it. Look in all the cylinders and around the valve areas of the heads.