95 MONTE CARLO LS HEAD GASKET LEAK--NEED ADVICE

Sell the car and invest your money in a car with fewer miles, WBMA

mike hunt

What engine? How do you know it is a head gasket leak? Have you inspected the intake gaskets? Best approach? Replace defective gaskets.

Last time I had an engine with that many miles and a head gasket problem, I pulled the engine, had it bored, had the crank checked, had the heads done, put it all back together with felpro gaskets. That is the way to do it once and right.

Thanks, Mike.

I cannot say for sure where the leak is coming from. Just took delivery of the car. No external leaks apparent at full operating temperature after a 22 mile drive. Temp gauge stayed within the normal range except for towards the end of the drive getting into the "H" zone, the idiot light came on, but then shortly after the temperature gauge returned to normal. Both cooling fans observed working later at idle. Bubbling occurs in the coolant reservoir. Tried bleeding it off at the fitting where the upper radiator hose goes into the engine to no avail. Sometimes the heater blows hot air, sometimes cooler air. No abnormal heat coming from engine department, and can't smell coolant at tailpipe. Do the thermostats screw up? Sure hope its the intake gasket !

Fred

Mike Marlow wrote:

Sounds like coolant problems. You still don't say what engine, or how many miles on the car. If it's the Series II 3.8L then it's likely the plenum is shot. You will not likely smell coolant at the tailpipe or see white smoke. If the car has over 40,000 miles on it you're a likely candidate for a plenum and intake gaskets - both upper and lower. The plenum is a bit pricey - in the neighborhood of $200. The intake gaskets are around $40 -$80 with valve cover gaskets, depending on where you live. Can't say what labor would be since I do all my own work. Seems to me I've heard of these jobs going for $600-$800 for parts and labor.

It's not a bad job for a DIY'er if you've had a pretty good experience level, working on your cars. The book pays 5 or 6 hours I believe, but you will not likely do it that fast the first time. 3 - 4 hours is probably the average for a guy that's done a couple. I did a set in 30 minutes or so, but the engine was out of the car. Doesn't count - I just like to brag that I did the job that fast. I'm married, so I don't get to brag about much...

The 3.1 is known for intake gasket failures. Check your engine oil for coolant. The oil will be a light tan color with coolant in it, looks just like coffee with cream. I haven't seen the head gaskets fail yet on a 3.1 but if you drive it long enough with it low on coolant you may blow a head gasket also.

Thanks, Mike.

With a bad intake gasket, can that also make the coolant reservoir bubble? The previous owner said he had changed oil with Wal-Mart oil, which is clear. Looking at the oil, it looked to me like Pennzoil or Quaker State color, so perhaps this explains the color, and, it is about a pint overfull.

Fred

Mike wrote:

No. The bubbles are coming from pressurized gas escaping from somewhere. Failed intake gaskets can contribute to a failed head gasket and other mechanical problems though.

A head gasket leaking combustion gasses into the cylinder will not always manifest itself via contaminated oil.

The correct diagnostic procedure here to rule out or verify a leaking head gasket is to perform a cylinder leak down test; Remove spark plugs, bring a cylinder to top dead center with the valves closed, install leak down tester into the spark plug hole, pressurize cylinder with compressed air, look for air bubbles in the coolant tank or radiator fill neck. Repeat on all cylinders until the leaking cylinder is identified or all cylinders are ruled out.

Start with the rear bank of cylinders since odds are that this is where the leak would be because (IME) the rear head gasket fails more often than the front.