98 3.1, losing anti-freeze. LIM gasket problem

98 GA, 3.1 V6, 96000 miles. My GA seems to losing anti-freeze. This problem has been going on for about a year. I add ¼ to ½ gallon every month. There is no visual evidence of leaking any where. Car runs pretty good, no anti freeze in the oil, passes California smog test okay, SES light is off. I have read the threads for lower intake manifold gasket problem for 3.1 V6. I am thinking this is my problem. I am a little past the age for tearing apart an engine for a weekend. I called my local Pontiac dealer and they quoted me 1300 bucks for the job. Any suggestions or ideas? I am looking for some help so I can get the job done right and not get ripped off. Thanks

If there is no water in the oil then you may be sucking it into an intake port. Do you see a large plume of steam coming from the exhaust or smell antifreeze? It is possible that you have a leaking intake gasket but I would look elsewhere before I pay $1300 to have it changed. There is a possibility that you have a leaking heater core or a bad hose so check things over carefully. Also, I would look for another shop besides the dealer to change the intake. It takes about 6 to 8 hours to do the job but the price quoted seems to be about double what it should cost to replace these gaskets.

Good Luck!

Look on the rear of the engine right below the throttle body. There is a small depression about 1"x.5" under the thermostat housing. The rear of the lower intake gasket is usually what leaks first. Coolant will pool up in the depression and evaporate when the engine is running.

I agree about the price. We charge about $600 for the lower intake on these engines. The average labor cost will undoubtedly be higher in CA, but I'm sure you can find a reputable independent shop that will do a quality job for a fraction of the cost.

Another thing that might help find the leak is that UV Dye you put into the coolant. Then after its ran through for a while check the block with a black light to find the glowing trails.

Sometimes though you can find old trails of green dried onto the engineblock , starter area.

I would agree with that being high, even for CA.

Look on the rear of the engine right below the throttle body. There is a small depression about 1"x.5" under the thermostat housing. The rear of the lower intake gasket is usually what leaks first. Coolant will pool up in the depression and evaporate when the engine is running.

I agree about the price. We charge about $600 for the lower intake on these engines. The average labor cost will undoubtedly be higher in CA, but I'm sure you can find a reputable independent shop that will do a quality job for a fraction of the cost.

This is also my exact problem. The coolant is pooling in the depression. I have been quoted $600 to replace the lower intake gaskets. They also want to flush the engine and the coolant and charge another $100 for that.

From what I understand is this is a universal problem in GM cars and they have changed their gaskets on newer model cars but still refuse to do a recall on the gaskets.

$600 is about the cheapest I would think you could have the job done by a professional.

I would absolutely flush the coolant. Dex-cool is one of the major factors in the gaskets failing. Old green (remember to replace every tow years...) coolant will also cause a problem. The coolant will corrode the aluminum, which allows coolant to leak past the gasket.

Make sure that the replacement gaskets are metal-backed. The old plastic ones were a big factor in failing as well. The old, acidic coolant would leak a little bit past the gasket, and then disolve the plastic frame/backing, alowing the gasket material to deform and push out.

It is not all GM cars. Just ones with the 3.1, 3.4, 3.8 (but mostly upper intake leaks) 4.3, 5.0, 5.7, 7.4 or 8.1 liter engines, and only for about 10 years. :rolleyes:

As far as I know, they never changed the gasket design while the engine was still being produced. They changed the entire engine design a couple years ago. Another factor in the gasket failure was just a bad engine design in general.

Have you tried using a product called Blue Devil?

I have the same problem with leaking antifreeze. My waterpump was leaking first so I replaced that and then I still had a problem. When I finally found where it was leaking, which was a gasket right under the thermostat I thought I'd have to have that replaced. Wasn't looking forward to the expense of that. I talked to a local mechanic and he told me that he'd used Blue Devil in 5 cars that had come into his shop and 4 of those cars it worked in. He said if it doesn't work then it's a bigger problem than just a gasket leak.

Blue Devil is about $80/bottle but you don't use the whole bottle.

If it works it's alot cheaper than having the gasket replaced.

Welcome to AF thorley.

Retiredgunner would be better off spending that $80 on LIM gaskets and fixing it the right way. :2cents:

If that blue devil stops leaks, it can't be good for the radiator or heater core, cloggs. :eek: