Hi guys...been checking this forum for a while now but can't seem to find an answer to my problem from the existing posts. This is a bit of a long story here...bear with me while I give some history of what's going on.

2002 Grand Prix SE, 83K miles. Have had this car for 4 years and it's ran like a top. No major problems that I couldn't fix. Regular full-service oil changes at an oil change place (no free plugs here).

A couple of months ago (summertime in TX, hotter than hell), I started seeing the temp gauge creep up quickly (upwards of the red at the top of the gauge) when stopped or crawling in traffic. Once I got going the temp came back down quickly. After a couple of days of this I checked the coolant and had to add about a half gallon. Quite a lot, I think. I checked around where I park at home and work and there are no coolant puddles. After I added the coolant, the temp gauge never gets higher than 1/2 way up the gauge (which is good) but I started smelling hot coolant after the car has been running for a while. I checked to make sure the radiator cap is on tightly, the top of the reservoir tank is on, upper and lower radiator hoses and water pump bypass hose. The oil is clean and there is no smoke coming from the exhaust.

I can't see where any coolant is leaking but It's really bothering me because I have never smelled hot coolant unless the radiator cap is off. I'm even more concerned because this thing is still running like a top.

I've also felt around the bottom of the water pump for the weep hole but can't seem to find it. Where might that weep hole be?

BTW, in the pic below where does this plug go? I found it when I fixed a burned-through vacuum hose (battery leaked). I don't remember unplugging it and I can't see an obvious place where it goes. It might be related to the problem at hand.

Anybody got any ideas on what the plug is and what the deal with the coolant smell is? Has anyone had a similar problem? Maybe a t-stat issue?

Thanks in advance,
Lerxst

(Sorry for the monster-sized image...lower-quality pics just didn't show the plug that well.)

Allow me to be the first to welcome you to the site.

I have no idea what the problem could be, but I will surely be watching this thread to see the cause.

Again, welcome aboard. You found some good folks and great info.

It's probably the dreaded intake gasket leak. Check your engine oil. See any creamy substance in the oil? Either on the dipstick or in the valve cover?

If not, look around the throttle body and see if those lines are leaking on the exhaust manifold. It will burn off the coolant pretty quick without leaving puddles.

Thanks, Rich!

Appreciate the welcome.

Lerxst

ya im thinking it's the gasket cuz i have the same problem almost exactly... but im gonna check that throttle body and see if i have any leaks

It certainly sounds like an intake gasket leak,but to rule out a few other culprets try running the car for about a 1/2 hr with a piece of cardboard under the engine and also check the upper portion of the passenger compartment carpet for wetness (heatercore),good luck and welcome aboard .Chico(pops)

Won't apply to you. He has a 3100, which has external coolant hoses running to the TB. Yours are built into the intake manifold.

I'll check the oil again but I don't remember seeing any chocolate milk.

I have, however, had a lot of water on the front passenger floor after a particularly nasty rain storm. Didn't really think much of it because it's only happened a couple of times and not really recently.

Now some more questions:

1. Anyone recognize the plug in the pic?
2. Where is this intake gasket that could be my problem?
3. On a scale of 1-10, what is the difficulty rating on replacing it? And, is it a weekend-type job or can it normally be done in a day?
4. If I take it to a shop, what am I looking at spending?

Thanks!

The gasket would be the lower intake manifold gasket. Since you are asking a difficulty level I'd say for you an 8 and plan a whole weekend. Mainly so you can take your time. I'd take a guess that a pro will charge you in the neighborhood of $500.

As for the water on the floor that would be the air vent in the cowl. Easy DIY.

Welcome aboard! If your problem turns out to be the LIM gasket, and you decide to tackle it yourself, be advised there are updated gaskets, bolts, and revised torque procedures: 2000 and Up 3100 LIM Gasket Procedure and 3.4 LIM write-up (3.1L is similar). Good Luck!

I had the same symptoms, but also white smoke burning out the exhaust, and guess what?... lower intake manifold gasket fixed it. Also, I can't see the pic you posted, so I have no idea on the cap.

Here's how to seal the cowl up, Thanks to Herc, worked for me, no problems since

http://www.robandcatsworld.com/cowl.htm

Here are some pics I took while i was replacing the blower and sealing the cowl

http://www.grandprix.net/ubb/ultimatebb.php?ubb=get_topic;f=1;t=008913;p=1#000000

....You might wanna fix that cowl ASAP, before your blower motor goes bad!

Sounds like the LIM, just as everyone else has said. Its really not too bad, you can get it done in a day. Pretty straightfoward, just use the torque specs and sequences correctly.

Welcome to the site!

Thanks to all for the good info. I think I'll pass on the intake manifold gaskets, but sealing the cowl up sounds easy enough.

Can anyone see the pic in the original post?

If not, click the link below and someone plz let me know what that plug goes to. It's driving me crazy!

http://i271.photobucket.com/albums/jj136/hrh_king_lerxst/phantom-plug4.jpg

Thanks!

link doesnt work for me