coolant lose

i got a 97 gp sc'd, with about 240k miles. i bought the car about 30k miles ago. did some routine maintenance to it. about 3 months ago it started losing coolant on the ground. changed the radiator. no more leak. now about 1 month ago the coolant has started disappearing again. i have to fill her up about every week, so the lose is pretty bad. when i changed the oil a week or so ago, oil wasnt that watery. slightly milky but still normal. so where could it be going? bad lim gaskets or head gasket? but no water on the ground at all.

suggestions?

If you're losing that much coolant through a bad LIM gasket, it must be in very bad shape. Check your spark plugs for residue - you'll see it if any coolant is getting into the cylinders. You can also send ab oil sample to Blackstone labs for analysis. It costs about $25.

I'd check the coolant hoses and radiator while it's running for a possible leak that maybe is evaporating before it can drip on the ground.

You are likely burning it off. if the LIM gasket is original at 240k and you added in a wrong coolant mix then it may have just killed what was left of the gasket.

When you say "oil wasnt that watery. slightly milky but still normal. " How milky was it? Oil should NEVER pour out like coffee with cream in it. It will likely be pitch black if you are at the change time, slightly golden and translucent if still in good shape (depending on the oil used of course).

That said, if you are loosing a gallon+ of coolant in a weeks time and see no drips on the garage floor then id put my money on an internal leak. Hope the passenger floor area isnt wet...

oil is slightly brown. im thinking its just bad head gasket. was just hoping i wouldnt have to tear her down that far. floor board is nice and dry.

It it's the head gasket, that would be first case I've ever heard for 3800 SC V-6. Is your exhaust making lots of thick, white smoke?

95ParkAveUltra wrote:

i got a 97 gp sc'd, with about 240k miles. i bought the car about 30k miles ago. did some routine maintenance to it. about 3 months ago it started losing coolant on the ground. changed the radiator. no more leak. now about 1 month ago the coolant has started disappearing again. i have to fill her up about every week, so the lose is pretty bad. when i changed the oil a week or so ago, oil wasnt that watery. slightly milky but still normal. so where could it be going? bad lim gaskets or head gasket? but no water on the ground at all.

suggestions?

Oil is ** ** never ** ** milky, so you likely have a head gasket leak, do a leakdown test (search on this site on leakdown test for the procedure) to verify that this is a problem (the cylinder that's leaking will read low) - or check the plugs for antifreeze residue.

The oil won't get but so milky because engine heat tends to drive the water back off -- but the oil should Not be milky At All. Do not mistake this for occasional foam under the oil filler cap from water vapor in the air combined with short drives that don't hold the engine at op temp long enough to drive the water off. Have not seen that problem on the 3800s. On the 3.6 VVT engine, I see minor intake manifold leaks leading to occasional foam in the cap (had one that sometimes would and sometimes would not0 with those what you do is replace the intake manifold gasket at tune up time (the 100,000 mile spark plug change). On the Rendezvous since the engine bay is so tight and you gotta drop the cradle to replace the plugs on the 3.6. anyway (on the 3.4 you just undo the dogbones and rock the engine) be real sure to replace the IM gasket as PM with the plug change, do not reuse the old one.