[Chango2]

Take of radiator cap and look for bubbles of exhaust. Another way is to check the oil for coolent contamination. Pull spark plugs and look for oxidation.
Run a compression check; find the errant cylinder and run a leakdown check. Run a check on a "Sun" machine and see if there is a cylinder that is dead or semi-dead. Pressureize the exhaust system and listen for any noise at the radiator neck.

There are lots of ways, but I believe there is the easy way...I believe there is, or used to be, a chemical that reacts with exhaust that you can add to the coolent. If the coolent then turns color, you know there is a gasket leak.

 

[Quack Shot]

A head gasket can leak in many directions. It can leak into the crankcase where it will dilute the oil and cause a lubrication problem. It can leak externally, where it will spill out in the ground and cause a loss of coolant and overheating. It can leak into the cooling system, where it can cause a loss of coolant and overheating. It can actually cause excess pressure in the cooling system and you'd notice bubbling in the coolant overflow. They can also leak between cylinders, where it will cause a loss of compression and a rough running engine.

There are other issues that can act the same as a head gasket. An example would be an intake manifold leak, where coolant would go into the crankcase. Same symptoms of a head gasket doing the same.

Can it cause a check engine light? Possibly. A missfire code may be set, or a number of other related codes. If the light is on, it's best to pull the codes with a scan tool and go through the proper diagnostic procedures for the code(s).

I think the most common cause of a check engine light on the 3.1L V-6 would probably be plugged EGR passages into the intake. The code will reveal a lack of flow. That does not mean the solenoid is bad, just that the passages are plugged.

 

[Straight99]

Pull the trouble codes and see what the computer does not like. It could be as simple as a loose gas cap.

 

[whiz white]

I agree with the above post, regarding gas cap.

If it's loose, or the wrong one, you will get the "Check Engine" light.

If you are getting a "miss" this this is most likely NOT the problem.

Whiz

 

[TC]

Guess I didn't word my original question very well. Wouldn't you get a "check engine" light or some other symptoms if you had a leaking head gasket? As I said it only has 29,000 miles on it and has never been abused in any way. Goes back to the dealer every 3,000 miles for oil changes and maintenance. Was hoping for some input from some of the GM guys here.

 

[Dr.Longshot]

There has not been any head gasket problems on the 3.4 V-6

 

[Dr.Longshot]

Is it loosing water-coolant, look at the water pump, see if it is leaking.

Is there coolant on the floor? Put a piece of cardboard on the floor and park over it and in the AM look for coolant leak.

If you are losing coolant I suspect the water pump, or heater core leaking, if it is heater core there will be steam on the windows.


Retired GM master mech.

are you losing coolant, some plastic coolant tanks leak also.

Check these first, you can do it yourself without taking to a garage.


Gary Bryant
Dr.longshot

 

[halfmile]

Water level goes down, oil turns gray, Steam out the exhaust?

Dead giveaways.

You can have it leaking from one cylinder to another, that is a nasty one to catch.

Hm

 

[TC]

Father in-law took it in to his dealer just like he does every 3,000 miles for oil change. 900 dollars later he has a "leaking head gasket" repaired. Did not have any symptoms. I am concerned but not certain that this was not needed. He buys a new car whenever the tires need replacement so it's not a question of whether he can afford it. I just don't like to see people taken advantage of.

 

[birdtracker]

TC: I have seen them leak externally, so it is possible that when it went in for the oil change and the technician had it up on the hoist there was oil all over underneath. Don

 

[635 G]

Could be an intake gasket-GM 3.1 engines were notoriouly bad intake gaskets, might be a hidden recall on this problem.

Lou

 

[TC]

Thanks guys, I just didn't understand that a head gasket or intake gasket could fail without any symptoms. If there would have been a single drop of water or oil on the garage floor he would have known it. I had driven the car just a few weeks ago and didn't notice anything.