Oil residue in overflow tank and radiator

**outnumbered** · 11-17-2009

I recently bought a 2000 Grand Prix with a 3.1 V6 and 100K miles. It has oil residue in the coolant bottle and a white film skim in the radiator. I have read a lot on here about LIM gasket failure, but I want to make sure I have all the info I need before tackling this job. My question is this: I do not have any signs of water or antifreeze in my oil, what other signs should I look for? The dipstick is clean and so is the underside of my oil filler cap. Should I flush my coolant and just keep and eye out for the thing to "make" oil capacity, or would you assume that there is a gasket failure and change them anyway. Any help would be greatly appreciated.

**Zef_66** · 11-17-2009

Originally Posted by outnumbered

I recently bought a 2000 Grand Prix with a 3.1 V6 and 100K miles. It has oil residue in the coolant bottle and a white film skim in the radiator. I have read a lot on here about LIM gasket failure, but I want to make sure I have all the info I need before tackling this job. My question is this: I do not have any signs of water or antifreeze in my oil, what other signs should I look for? The dipstick is clean and so is the underside of my oil filler cap. Should I flush my coolant and just keep and eye out for the thing to "make" oil capacity, or would you assume that there is a gasket failure and change them anyway. Any help would be greatly appreciated.

The stock LIM gaskets suck and I can guarantee they are bad if they have never been changed before. My wife's 3100 had the same signs you mention, but no coolant in the oil. And the gaskets were toast. I am glad I did them before any real signs showed up.

And FWIW, oil with coolant in it does not lubricate at all. So once you get coolant in the oil, your bearing are as good as shot. Some have been saved. But very rarely will it not ruin the engine in short time. Best bet is to be pro-active and change them before things get too bad.

**outnumbered** · 11-17-2009

Thanks for the quick reply. That is what I was leaning toward doing, I just wanted to get some opinions. Is there an upgraded gasket set I should be looking for, and would you recommend a parts house like NAPA or dealer for new ones? I watched to video on the 3.8 supercharged version yesterday, is there any major differences besides my lack of supercharger? Thanks again.

**davmac** · 11-24-2009

I just did the job for a NA 3.8. It wasn't too bad, but still involved lots of dissassembly to get to those gaskets. Unfortunately there are big differences in the actual details of the procedure for the 3.1 and 3.4 liter engines. The best write up I have found is here .

You will need a complete gasket set. Gaskets from a better parts store like Carquest / NAPA will have an improved design like the ones here.

Good luck.

**matt5112** · 11-24-2009

Felpro or go home

**blueguy** · 11-27-2009

F**K Felpro gaskets for the LIM...get the ones from GM...cost more but you never have to change them...ever. Plus...if there is oil in the coolant or vice versa...I'd be worried that you're probably going to be prone to throwing a rod bearing out the door. Coolant + Oil = Spun bearings.

**matt5112** · 11-27-2009

I take it they don't make an aluminum version. I agree though, go with the GM for LIM.

**outnumbered** · 12-04-2009

Well I just finished up the repair yesterday and I did have a failed gasket. The plastic had cracked in 2 places which allowed deformation of the silicone gasket. I bought a gasket set from the dealer although I was suprised to see that this one was also plastic, but with inserts in it to keep it from crushing. Hopefully I will get 50-60k miles out of this one before another failure. It also looked like it had been done already at one point. There was black rtv on items that didn't look like it would be factory. All in all it was a pretty easy job, just needs some patience which I sometimes lack. While I was in I replaced plugs and wires, and some other tune-up items. Upon draining my oil, there was a small amount of coolant in there, hopefully from me when I pulled off the manifold (not quite empty). I used synthetic oil and plan to change it again in a coulple of weeks. Thanks to all for the advice.