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Your Auto Inspector
Your Auto Inspector, Assistant Service Manager
Category: Car
Satisfied Customers: 874
Experience:  Tires Plus
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I have a Pontiac Grand Am with a 3400 V6 engine. It

Customer Question

I have a Pontiac Grand Am with a 3400 V6 engine. It is loosing coolant. The coolant is comming out of the overflow line next to the colant fill cap. I replaced the coolant cap with a new one because the old one had a bad "O" ring on it but ie runs and looses coolant from the coolant over flow line by the coolant cap. The engine temp comes up to 200 deg F and sits there after it warms up. Any ideas on what is the problem.
Submitted: 9 years ago.
Category: Car
Expert:  Tristan Franklin replied 9 years ago.

start car and turn a/c on full cold and high fan speed, make sure coolant fans are on, if not check fuses and switch around relay if all is ok, replace the fan. now from a cold engine, start it up hand feel all hoses looking for a warm to cool hose are area when everything else is heating up, this will indicate a air pocket or restriction, if warm to cool by thermostat outlet hose, replace thermostat. if coolant is really dirty replace or repair radiator. if all checks good suspect blown head gasket. good luck i hope i helped and please accept if satisfied. thanks T-MAN

Customer: replied 9 years ago.
Reply to T-man's Post: If the head gasket was blown it would have a moisture fog comming out of the exhaust when it runs after warms up but it does not. The motor comes up to 200 degrees and regulates there but it continues to loose coolant out of the overflow hose at the coolant fill cap on the top of the coolant tank.
Expert:  Tristan Franklin replied 9 years ago.

white tail pipe smoke comes from coolant in the cumbustion chamber, engine overheating in some cases are cause by worn or damages head or gasket allowing gasses to be pushed threw the coolant system

Customer: replied 9 years ago.
The engine temperature is only coming up to about 200 degrees where the thermostat is opening so I do not think that it is overheating. There is no white tail pipe smoke coming from the tail pipe. There is a slow leak of coolant out of the overflow hose at the coolant cap. The cap was replaced so I think that the new coolant cap is OK. I was told that this was a intake manifold gasket leak and that the fuel in the coolant will cause to lose its cooling properties. I have been told that the head gasket will cause the white tail pipe smoke which the car is not doing and that the coolant will come gushing out of the coolant system once it comes up to temperature and not just leak out a little at a time. I have not heard of the intake gasket leak before. If the head gasket was gone a compression test of each cylinder should show low compression on that cylinder with the leaky gasket should it not.
Expert:  Your Auto Inspector replied 9 years ago.

This is a common problem when you have an intake gasket leak. The intake manifold can leak coolant into one of the oil passages or externally. You are correct that the vehicle will pass a compression test if the intake manifold gasket is leaking.

Your first step should be to confirm the intake leak by pressure testing the coolant system to verify the leak. If no external leak is found then you should pull the oil dipstick and verify that there is no coolant mixed with the oil.

There is a Technical Service Bulletin to replace the lower intake manifold gasket with an updated gasket.

Here are the updated parts required for the repair:


Here is a diagram of the lower intake manifold



Here is the procedure to replace the intake manifold gasket:

Remove the upper intake manifold. - Upper.

Remove the valve rocker covers.

Remove the fuel rail with injectors and position aside.

Disconnect ECT.

Remove the power steering mounting bolts. Position the pump aside.

Remove the inlet cooling pipe from the coolant outlet housing.

Remove the heater by-pass at the coolant pump and the cylinder head.

Remove the radiator hose from thermostat housing.

Remove the water outlet housing. Important: Retain the washers in the same orientation on the center bolts.

Remove the lower intake manifold bolts.

Remove the lower intake manifold.

Loosen the rocker arms. Important: Keep the pushrods in order. The pushrods must be installed in the original position.

Remove the pushrods.

Remove the intake gasket.

Inspect the flatness of the inlet flanges.

Clean the following items:

    • Gasket material from the mating surfaces
    • Excess RTV sealant from the front and the rear ridges of the cylinder
    • The block
    • Sealing surfaces Use degreaser in order to clean the sealing surfaces.





Please let me know if there is anything else that I can do to assist you.