Head gasket or intake gasket?

My girlfriend's Buick overheated and she pulled it off the road. She let it cool for half and hour and attempted to drive it the last few miles to get it to her moms house. It started blowing white smoke out of the exhaust. I got there and checked the coolant . There wasn't any coolant left. (it had been full earlier, i checked it) I checked the dipstick and there was no coolant in the oil. It's been a few weeks and I am preparing to try to fix it. I am suspecting it's the head gasket. I've read a few posts on here about the possibility of it being a intake gasket since they were a problem on the 3100 engines.


The temperture gauge had always acted weird so I figured it was a stuck thermostat or something. I didn't realize it might have been a leaking intake gasket. It did show symptoms of a vaccum leak up until that day. Any suggestions or thoughts would be helpful before I dig into it. Thanks,

Jerry

all 3100 engines i have seen with intake gaskets leaking have always been an external leak, but that doesn't mean its not the intake gaskets, but i betting on the head gaskets, especially since you've had problems with the temp gauge doing wierd things

Something to try... With the radiator cap off, and the cooling system full, allow the engine to idle, and look for bullles in the coolant. You might also have someone you know look for exhaust in the coolant by either using an exhaust gas analyzer, or by using one of the over the counter testers, which use chemicals to locate exhaust. The analyzer is faster and is done by allowing the probe to sniff the vapor above the radiator. If either HC or CO reading rise significantly, you have exhaust in the coolant. If using the chemical, follow the directions... if exhaust is present, it typically changes color. Ray

You could also try adding one gallon of coolant and sllow the system to pressurize. By sniffing the exhaust, you will typically smell coolant in the exhaust. Using a pressure tester, you might also try pressurizing the system, using that tool. This will, however, only reflect loss, not where. Ray

My girlfriend's Buick overheated and she pulled it off the road. She let it cool for half and hour and attempted to drive it the last few miles to get it to her moms house. It started blowing white smoke out of the exhaust. I got there and checked the coolant . There wasn't any coolant left. (it had been full earlier, i checked it) I checked the dipstick and there was no coolant in the oil. It's been a few weeks and I am preparing to try to fix it. I am suspecting it's the head gasket. I've read a few posts on here about the possibility of it being a intake gasket since they were a problem on the 3100 engines.


The temperture gauge had always acted weird so I figured it was a stuck thermostat or something. I didn't realize it might have been a leaking intake gasket. It did show symptoms of a vaccum leak up until that day. Any suggestions or thoughts would be helpful before I dig into it. Thanks,

Jerry

you dont say what year or engine code the car is..which makes a bit of a difference because typically the century sported buick motors and not chevy....

regardless however, the symptoms you describe indicate that you will be tearing this motor down to the block and at the very least pressure testingthe heads

Thought I would reply to this since there are so many new threads asking the same question. Any thread that is finalized helps someone new find what they are looking for.

It was the head gasket. The intake gasket was on it's way out but was still holding. The head gaskets both had hot spots on them. Two areas were completely blown out.

The damage to the heads was not bad so I let them be reused. There was just a very small pit where the gaskets blew. The new fel pro replacements are designed to seal any irregular surfaces.

By the way this was on a 95 Century 3.1 V6

I addressed the issues that caused the head gasket failure to start with. The theromstat was replaced. It passed the test in a pan of hot water but it opened pretty slow.

Second, I modified the factory cooling fans. I don't care what anyone says, Gm messed up when they made it so the fans don't come on until the temp is up to 215 or so. This has caused a ton of problems in their vehicles. My dad's Northstar Cadillac just had it's water pump replaced at fairly low mileage. The cheap plastic seals they use supposedly melted. Its funny that the replacement water pumps have all metal parts. The thing gets up to 210-215 before fans kick on. That's not good at all in my opinion. Sure better emissions, but not engine life.

I bought a Hayden fan relay kit from Advance and wired both fans to it. Now the car stays on a a healthy 195 degrees at all times. The heater works fine and it is getting excellent gas mileage.

My money is also on the intake manifold gasket, leaking coolant to external. On my 1999 Malibu with the same 3.1 engine, the dealer replaced it the gasket at 98,000 km (45,000 miles) under what they called an "adjustment warranty", meaning I complained so strongly to the dealer I wore them down and they covered the cost.
While it was in the dealer shop, they advised that the water pump seal was also leaking, and that this was not covered under the adjustment warranty. But when I hear their quote, I instructed them to not touch it. I then took it to my "other-car" mechanic, who confirmed the diagnosis, and replaced it for a fraction of the cost that the dealer quoted. It was a good day!