Hi Guys,

I'm trying to fix my son'* minivan here'* the story.

2002 Pontiac Montana still smoking after new gasket set.

I'm working on a 2002 Pontiac Montana which has a GM 3400 SFI engine with 86,000 miles on it.

After driving on the highway all day fully loaded, I noticed the van overheating and blowing white (sweet smelling) smoke. I stopped at the next off ramp and had the van towed home.

I thought it was coolant leak and/or a blown head gasket. I pulled the heads and sent them in to get checked and resurfaced. The machinists said one head was cracked so I replaced it with a rebuilt one.

I reassembled the motor using all new "Victor Reinz" gaskets.

Now the engine starts on the first try, idles normally for 30 seconds then runs rough, but it still smokes (thick white) smoke.

I'm not sure what to do next.

Sounds like a failure of the intake manifold gasket. The bad news is you have to replace the gasket. The good new is there are upgraded gaskets now available that are not susceptible to the failures the OEM installed ones experience, and once you fix it you should be free from future failures. Did you change the intake manifold gasket when you did the heads?

Yes, the upper and lower intake manifold gaskets were replaced when I did the head gaskets.

One mechanic said that it is normal for the engine to smoke after doing the heads and to run it for a few days.

If I watch the temperature and coolant level closely, I might try driving it. The engine has never been run long enough to come to operating temperature since being reassembled.

What do you think?

I'm just concerned if it is a leak you could get enough coolant into the cylinders to cause hydrolock. If that happens, white smoke in the exhaust is the least of your worries. I think I would let it idle in park until it came up to operating temperature to see if the exhaust clears up any.

you change the oil and clean the coolant from the cylinders and such. it tends to get every where when you take the head off

I did change the oil and cleaned out the cylinders with a rag before reassembling the engine, so the combustion chambers were clean.

I will recheck the coolant and oil level and try running it at idle and see what the temperature does.

I'll keep you posted.

Fingers crossed.

Ok, 2002 Pontiac Montana GM 3400 blowing thick white smoke after a long trip.

Recap:
After reassembling the engine with one newly-rebuilt head, all new gaskets and torqued to spec the engine started on the first try, pumped white smoke continuously, ran rough for a minute then stalled.

After sitting all night we tried to start the van again and on the first revolution we heard a CLUNK! Hydrolock?

The engine turned over normally fired a few times, (still pumping white smoke), but never started.

I pulled both heads and apparently no matter how much coolant you turkey-baste out of the cooling channels, some coolant will drip into the cylinders when you lift up the head. So all the cylinders had a tablespoon or so of coolant puddled on top of each cylinder.

That being the case; with the heads removed,#5 cylinder (closest to driver), was almost half full with coolant. Cylinder #3 had about 3 tablespoons of coolant and #1 had almost no coolant.

The is the newly rebuilt head installed with new gaskets and torqued to spec. Both heads were milled flat before installation.

The engine has never ran long enough to get to operating temp.

Question 1: How can I tell if its a cracked head or cracked block?

Question 2: What should I do next?

My son has a new job starting 3 weeks and he needs this van, so now there is a deadline...yikes.

you check the block for square? i usually suck the coolant out with a shop vac. i would think who ever milled the heads would check for cracks. i think i would put the heads and gaskets on again take the plugs out crank it a couple times then check the compression

Is the oil on the dipstick milky looking? With the engine cold but running, remove the rad cap and see if the cooling system is pressurized. Do a compression test. Did you replace the intake manifold gaskets?