I have a 1998 3800 V6. I've noticed a coolant leak, making a puddle below the thermostat and in between the intake manifold and cylinder head (driver's side)

I've attached a picture indicating where the puddle has formed.

It's not leaking from the thermostat- I recently replaced it due to it being stuck open and there are no leaks coming from it. There are no leaks from hoses, the pump, or elbows. So I'm guessing that maybe it's coming from the intake manifold gasket? I can't see exactly where the coolant is coming from, I just know it's making puddle as shown in the picture.

Once the puddle gets big enough, it would drip onto the exhaust gaskets and create white smoke, which is how I noticed the problem in the first place. Also, it's gotten worse after replacing the thermostat, probably because now the thermostat is able to close, creating additional pressure that pushes the coolant out?

Based on the picture, is it safe to say that it's leaking from the intake manifold gasket?

 

Don't know if you fixed your issue or not seeing as how old this post is, but mine was doing the same thing and i came to the same conclusion of just a bad gasket. After some time i go to take the intake off and there was no gasket, not even the remains of one. So i bought one and put it on and haven't had a problem since.

 

Yes, that in fact was the problem. I replaced both the lower and upper intake manifold gaskets, not quite sure which one was causing the problem. But by the time the upper intake comes off the bottom is easy. It 100% fixed the problem. There's a nice video on YouTube specially for the 3800 F-bodies. Wouldve taken a lot longer without guidance from that video.

 

i think i watched the same video. Lol. Wonder if they come from the factory with out the gasket. Two cars with out gaskets seems a bit odd to me. I didn't bother doing the lower intake as my Camaro is my daily and time was not something i had a lot of :/

 

I have never heard of or seen a forgotten intake gasket. I can not imagine the car lasting a week no less almost 20 year without one. Blocks, heads and intakes all grow and shrink at different rates. Even with perfect machined parts mated parts would leak while the car warmed up and as it cooled down.

The poorly designed, prone to failure 3800 intake gaskets is well known and subject of a class action law suit. GM was forced to extend the warranty for the intake to 10 years 100,000 miles and they had to reimburse anyone that had to pay to have one done within that period but before the law suit. The intake gasket is the weakest link on the 3800. Be glade yours leaked to the outside of the intake. Many times they leak into the oil and when the coolant mixes with the oil it results in engine failure. At this age I would advise anyone owning a 3800 that is sure the intake gasket is original to replace it. Once you install a after markets gasket you are good and should never need to worry about it again.

 

That's interesting, when i took my intake off I saw oil and coolant mixed together around on the smooth parts where the gasket goes. But the engine never really seemed to have issues before that. But i would have to fill it back up with oil every 3 months or so until i fixed it, so the oil was going somewhere. When i did my coolant flush my coolant was its normal red color, but the overflow tank is all gooey. Not sure if its just what the dexcool does on it own or if it was oil. My spark plugs where also in decent shape when i replaced them, they weren't fouled up or anything, just old. so i assumed the car wasn't burning oil in the cylinder.