Coolant Leak?

I just bought a 99' Lumina Sedan. It runs great! But my mechanic said it needs $500 repairs for a small coolant leak under the manifold. Also $200 since a coolant plug needs to be replaced. Before I left they said they would pour stop leak in the engine.
Note there was no noticable leak on the ground or the 200 miles and 6 days I drove it before seeing the mechanic.

I took it to another mechanic today he said he saw no problem but it could use a coolant flush.

I spoke to the old owners mechanic who said there has never been a problem with the coolant system, just the fan blower motor may need to be replaced.

A neighbor came and looked at it tonight and said it looks great oil is clean and doesn't think it will leak.

I wonder is my mechanic trying to take me for a ride. I am a single mom and can not afford the trip. Or did this stop leak mask the problem, if so how long should it take to leak again?

mine mysteriously sees to drop little by little every month or so, its not going into the oil, or on the ground, my only guess is its leaking out somewhere when it gets hot. I'm not too worried... yet, intake gaskets are common repairs made to luminas with about 70-80,000 miles, you may need one. take it to that mechanic and have him pressure test the cooling system in front of you, if the pressure doesnt hold, or drops, he may know his stuff.

also stop leak is a temporary repair, i would strictly advise agins any sort of "mechnic in a can" fix.

Is this pressure test a big deal cause the 2nd opinion mechanic didn't want to bother with it since there was no visable signs of leaks.
Thanks for the feedback I'll talk to the Mechanic today. I'll let you know.

The intake gaskets on these cars are a known issue. The fitting he's talking about is a quick connect heater hose connection where it goes into the intake manifold. If there is any signs of coolant in the oil, I'd change both the intake gaskets and that fitting while the intake is off. Don't let them charge you $200 to change that fitting if they're doing the intake too, as it takes 5 minutes to change it while the intake is off the car. Doing a coolant pressure test will pinpoint where the leak is, and will save you from paying for work you don't need.

Thanks for the info
It dosen't seem anyone wants to do a pressure test
I went to my original mechanic today I told him I can't afford $700. Also I consulted with other mechanics, and asked see the leak he showed me 2 spots where it looks discolored on the block he said dirt is now stuck to it. Both on the front passanger side one under the seem where gasket is, one is under a circular hole passenger side front this is what he called the Plug (quick connect?). Now he said I don't need the work right away just watch the coolant level and I should be ok as long as I keep coolant up to the line.
Thanks for all your help!!

Be careful putting off the repair, as the oil will get contaminated with coolant. This will break down the oil's lubricating ability which can blow your engine. From what you describe, the intake gaskets are leaking and you should get it done. The two spots you described are the tell-tale sign of an intake failure on the 3100 engine. Without doing a pressure test, they cannot verify if you have a head gasket or other problem causing the leak. It is so easy to do, I can't believe they are blowing you off.

I had the car looked at buy a mechanic friend and he cleaned the engine. It's been 3 days and no sign of any leak. He said it looks like there is already a new gasket there.
Thaks for the help.

I had the car looked at buy a mechanic friend and he cleaned the engine. It's been 3 days and no sign of any leak. He said it looks like there is already a new gasket there.
Thaks for the help.


Well I did see new fluid marks on the Engine Block. I took the car to a new mechanic that was recommened by a couple friends and I had them pressure test it. The results were it held 160lbs for 90 minutes. They said what I am seeing is displaced condensation.

I doubt that it held "160lbs for 90 minutes" since that kind of pressure will blow the heater core, force coolant past the water pump seal, pop the tanks off the ends of the radiator, and likely inflate your radiator hoses like balloons. I would believe more like 16 PSI, since that is close to the normal system operating pressure.

As mentioned earlier, intake gaskets are common failure points on almost all aluminum-headed engines (not just Chevy or GM). The problem is that the leaks may not become evident until the engine is at operating temperature and the castings have "grown" and possibly opened gaps or casting cracks. These are very difficult to diagnose, and often the only indication is a constantly decreasing coolant level. Depending upon the location of the gap or crack, there may or may not be air bubbles present in the coolant during operation. The leaks are often into the lifter valley (and eventually the oil pan) and/or into the intake passages where the coolant is expelled by the normal engine exhaust as steam. There may be no signs of external leakage whatsoever.

Since you have apparently exhuasted all of the customary diagnostic procedures, my advice would be to monitor coolant level and oil level AND condition regularly. I would suggest you open the hood and check these items whenever you fill with fuel (like everyone used to do) or once weekly at a minimum. Even without any problems, this is good practice that most people ignore.

Check you coolant level in the reservoir at the same temperature. Either allow it to sit overnight and check it dead cold, or check it at normal operating temperature so you have a basis for accurate comparison. Check the oil level and condition. If the oil level increaes, or the oil acquires a milky or foamy appearance, those are indications of a coolant leak. If you discover either of those conditions, seek help as soon as practical.

If you wait, your NEW engine or car will probably solve the problem.

I'm sure 16 lbs was meant....