Losing coolant

97 GP GT 112,000. Lately I've had to keep topping off my filler neck with coolant and don't have a clue where it's going. I keep checking the oil, no coolant in that. Could it be a blown head gasket? When I top off the filler neck it's never much, maybe a pint more or less . The reservoir is about five inches over the line is that a problem?. The car runs great, idles great, no problems except losing that little bit of coolant. Any ideas? I'm praying it's not a head gasket. Thanks for any info.

Since you have a '97 GT (SII 3800 NA) they are prone to the Upper Intake Manifold (plenum) problem if getting an unexplained coolant loss even with no driveability problems.

There is an improved plenum for '97 - '98 models which has a better EGR stovepipe design. When the plastic melts or deteriorates coolant leaks right into the intake system. Also, I would not rule out lower intake manifold gaskets.

Unless the car is running badly or overheating I doubt it is a headgasket problem.

Yea, I replaced the uim already and been told that the lower is leaking. However there's no leaks on my driveway could the still be a lim problem? I'm concerned because I haven't seen any coolant on the ground, Thanks for the quick reply.

Yes, the LIM has a coolant transfer pipe in it that runs between the two cylinder heads. Normally these will leak into the oil, rather than into the engine, but not always. Are you using any oil as well? Many times, when the LIM fails, it will allow oil to be sucked into the intake ports, causing oil consumption. Also, when you took the UIM off, did you notice any oil pooled up in the LIM? IF so, that is your issue. I agree with bnaylor, that if you have no drivability issues, you don't have a head gasket issue.

Since you've done the UIM side, the LIM gaskets are the most likely reason for the coolant loss. It is an internal leak. Here's an old post by Troy1 which shows how bad LIM gaskets can get. And this was from a '99 GT.

http://www.automotiveforums.com/vbulletin/showthread.php?t=577356&highlight=lower+intake

97 GP GT 112,000. Lately I've had to keep topping off my filler neck with coolant and don't have a clue where it's going. I keep checking the oil, no coolant in that. Could it be a blown head gasket? When I top off the filler neck it's never much, maybe a pint more or less . The reservoir is about five inches over the line is that a problem?. The car runs great, idles great, no problems except losing that little bit of coolant. Any ideas? I'm praying it's not a head gasket. Thanks for any info.

They make coolant dye to put in the coolant to help find the hard to find leaks.
Watch the engine oil real close for coolant getting it.
With the dye in coolant it will show up in the engine oil if it is getting there.
A good old rad pressure test cold and warm and hot may show some leakage to.
As said the upper and lower intake is a problem area on them.
MT

Yea I'm checking the oil everyday no consumption, so far so good. I was told by a dealership that the LIM was leaking, however I've been checking the coolant and now it seems fine, not having to top it off for a week now, beats me...Anyway I'm going to get a second opinion on the LIM. In the mean time I'll be watching everthing very closely. Would have responded earlier but for some reason I wasn't getting your replies and I'm always signed in. As always thanks for all your input. I love this site. : )