96 lumina coolant leak & SES light

And the problems go on...

#1
I am currently experiencing a coolant leak under the throttle body. I also still have the SERVICE ENGINE SOON light on (will be dignosing tommorrow with an OBD tester). Regaurding the SES. I have recently been experiencing bad gas milage I use to be at 27 hwy and now I am at 20. I removed 2 plugs (platinums & original 115k) and noticed they were at .070 gap and a bit on the white side (could be part of problem #2) will probably wind up replacing all soon. I also checked the O2 sensor and noticed it to be a little clogged so I clead it out best i can and placed it back in. This made no change to my gas milage/performance. I did try disconnected the battery in hoping that it needed to reset itself. The light remains on.

#2
Now for the coolant leak: has anybody had this problem. I've done car work before but not on anything this new. Is it difficult to do? I am trying to diagnos it. I have noticed a very little bit of fluid sitting in the intake manifold bolt located under the throttle body inlet. I have also noticed when filling up the radiator and little bit of dark brown grit looking stuff in the radiator cap. I am having a bad feeling that either the intake and or head gasket has gone bad. There is no noticeable white smoke coming from the exhaust. Other than a pressure test to the coollant system is there another to self diagnos this problem?

I have read a few article's / forums where people have logged complaints to GM to try and get a recall. From what I can see is that GM is handling it on a case to case basis. Has anybody had success with this?

Thanks for the help,
Vince

1. Your car is OBD-II, so you need a scan tool to reset the codes. The coolant leak is allowing antifreeze to get into the combustion chamber, which could damage the oxygen sensors as well as the catalytic converter

2. every owner of a GM 3.1 or 3.4 v-6 will have your coolant leak. GM used some shoddy intake gaskets, coupled with a low torque spec, which combine to cause the leak you describe. Fel-Pro has come out with an improved design gasket set (MS98004t) that will fix the problem.

As far as the coolant leak problem, I've got the exact same problem with my 96 lumina. It's been leaking for a week or so now. I took the throttle body off tonight to find the source, and it sounds just like his. I've got water around the temp sensor and around the frost plug that is under that end of the intake manifold. I figured it was a leaky frost plug and was going to pick up a couple tomorrow, but it sounds like a gasket issue.

I was searching the web for more info about this problem, and came across this forum. This is the first forum i've really seen dedicated to the lumina, so I was not aware that these motors are noted for intake gasket problems.

So this is most likely the problem I'm having?? I'll stop by the parts store tomorrow and pick up a gasket set and see if it solves my problem.

thanks, and good luck with yours vince.

very informative forum!!! bookmarked!


Adam