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

Sorry about that...I think I fixed the link.

I think that plug is not used. I believe I have the same one floating around there. Probably for the GTPs with fuel pump resistors or something.

Thanks RooK...That's what I was hoping to hear.

Hey "TAZ" Great Info...I have had & still have that problem from time to time, especially during the Spring when it seems to rain here, everyday...& I know, of two others with a GP, that has had it Too! I will pass the Info, on to them.

Thank You, again...

no problem man, that's what we're here for!!!

on my car that plug goes to the R/F wheel speed sensor. unless im thinking of the wrong plug...
your ABS light isnt on is it?

as for your coolent leak, i would lean more towards LIM, but the headcore is always a possibility.
ive had to replace both because they were leaking.

That plug is not related to the speed sensor. The speed sensor actually goes into the engine harness near the a/c switch plug and such at the bottom of the engine. The only piece of the engine harness even close to that is the coolant level sensor plug.

interesting. there is a connector under the engine bay fuse panel clipped into the body that goes to the right front wheel speed sensor. ive had to replace the r/f wss/hub assembly and that looks like the connector i had to disconnect. not that im arguing with you tho, im not that familier with 3100 and i dont feel like going outside and looking under the hood of my sister's cutlass.....

He posted same pic (that link) as in first post picture. I have the 3800 GTP and on mine that plug connects to the female end right near that area. Locate it. Mine has two wires on that plug that goes to another plug with two wires. NOt sure what it does but look really hard around that area. Under fuse box and in between battery area.

I poked around on that side of my engine compartment but couldn't find any corresponding connector that looked like the one in the pic (I saw it just fine.)

But my car is 6 years older than yours, and I have a GT, so the probability that I would find a plug like that on my car was about zero.

Is anything electrical not working properly? Can you not find a corresponding jack to plug it into? If answers to (a) and (b) are NO and NO, then I'd quit worrying about it.

Sealing up your cowl is pretty easy, I did mine in just a couple of hours and I really struggled with getting the wiper arms off. I actually thought my arms were going to come off first. But it's an important thing to do because if you don't take care of it, water will get into your heater/AC fan and quickly ruin it, and possibly the resistor that sits near it that gives you different fan speeds.

As for the coolant issue, I don't have a clue. The experts have spoken intake manifold gasket, but I'd sure check the heater hoses closely. They're hard to see and it would be hard to detect a tiny stream coming out while going down the road. And after you shut it off... well, I dunno, it might not leak with the engine shut off, or it might.

Good luck.

OK...I sealed up the cowl. No big deal. Thanks guys!

On the coolant issue, I decided to dig as deep as the t-stat and see what I could see. Here's what I found. Sure looks like the LIM gasket based on what you Gents described. The image is pretty close-in...the t-stat is just outside the pic to the upper left.

http://i271.photobucket.com/albums/jj136/hrh_king_lerxst/IntakeManifoldGasket.jpg

Does this reinforce the LIM gasket theory?

If more pics are needed, I can post them as well.

Thanks!

Do the LIM, I tried everything possible before I replaced it and I wish I had done the new LIM gasket first thing. The way I understand, even if it turns out to be something else, you'll need to replace it sometime soonish anyhow.

Yep, looks like it's time to reseal the LIM...

Figures...This car was doing so well for so long I guess I was due...

I didn't see LIM gaskets on autozone's website. Are the updated gaskets/bolts available through parts houses or do I have to get them from the dealer?

They have them at most parts stores and ZZP has an updated one with strengthened rings I think.

I would try the GM dealer first; chances are they're a "dealer item only". You'll need upper (plenum) and lower intake gaskets, new bolts, valve cover gaskets, and a new o-ring for the oil pump drive shaft.

Edit: And replace the fuel injector o-rings as well; better safe than sorry..

And I hear you should replace the injector o-rings while you've got the fuel rail torn off.

OK...Here's the Dorman kit that looks like it has the upper and lower gaskets, valve cover gaskets, o-rings and bolts too. Has anyone used this kit before? Is it ok?

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=DOR&MfrPartNumber=615205&PartType=102&PTSet=A

If not, does anyone have a link to a gasket kit that has all the pieces and the updated bolts?

Edit: I called the dealer and the LIM gaskets/bolts alone are $63. $20 each for valve cover gaskets. Ouch.

That kit should work just fine; nice to see Dorman released an updated reseal kit...when I worked on these a couple of years ago, they were only available from the dealer. I would get a set of injector o-rings as well.

If you're going to tackle this yourself, remember to keep the rockers and pushrods in order, and don't use the windshield cowl as a "tool shelf". I once had a 3.1L GP get towed in from another repair shop, because it wouldn't start and run. Removed the lower intake and found a 1/4" drive socket sitting on one of the valves...

Are you talking about the fuel inlet and pressure regulator o-rings? Or are there o-rings for each individual fuel injector?

Edit: So you really do need to take the pushrods and rockers off to get those gaskets in?

The injectors each have an upper and lower o-ring. If you type in the part number(615-205)on Dorman\'s site, it tells you what's in the kit. The injector o-rings aren't included.

Here's the write up: LIM

Thanks a bunch!

I just ordered the Dorman kit. It won't be in for a few days so that'll give me time to break down, clean and prepare the manifold. The injector o-rings don't seem to be that hard to get so I should be able to pick those up at the parts house.

Another question: How do I relieve the fuel pressure so I don't get gas spewed all over me when I remove the fuel rail connections? Where is the "test port" that the link mentions?

The test port is on the fuel rail; it looks like a Schrader valve with a cap on it: Relieving Fuel System Pressure (Different engine, but procedure is similar)
One more thing: It's a good idea to replace the Engine Coolant Temp Sensor (TU178) while the engine's apart; you can see it in this pic:

I wish I'd seen this sooner... H.R.H. King Lerxst, you should have went to Autozone or whoever and got the FelPro 'Problem Solver' intake kit for the 3100. It's around $80, but it has all your gaskets and metal lower intake gaskets. It is as good or better than the GM stuff. MS98003T:


You don't need new intake bolts unless they're TTY. I don't believe they are. You have to remove the pushrods because GM designed the pushrod guides into the intake gasket. Go figure. This necessitates the removal of valves covers and rockers.

Blackarrow: Yeah, that sensor has gunk all around it. Was definitely going to replace that guy while the motor was torn apart.

RooK: I saw that one as well but I went with the one that contained the newer bolts b/c of the update that went out from GM. I figured if it had the new bolts, that it had the newer gaskets as well.

Now I'm not a design engineer, but on the surface it seems pretty stupid to have the pushrod guides built into the gasket. But that's just me.

Thanks to everyone for all the good info. I'll post an after-action report if anyone's interested. I've never tackled anything this serious by myself before. Wish me luck!

Thanks again everyone!
Lerxst

Alright, what's the trick to disconnecting the fuel rail inlet? I've got it unscrewed but it doesn't want to come out.

The fuel pressure regulator popped right out with minimal force but the other one is being stubborn.

Any tricks? Or is it just a PITA to take out?

guaranteed way to remove the rail inlet? Hook one end of a rope to the inlet, and the other to the bumper of a tow truck.

OK...I have a tow truck, no problem.

How much of a PITA is it to get it BACK IN?

LOL. depends on how badly everything is torn up...duh! lol.

Sorry for thread jacking. Couldnt resist.

LOL @ Richard!

When I took my fuel rails out, just releaved preasure, squeezed tabs of fuel lines and wiggled them off, and unbolted the fuel rail and wiggled that off, and the injectors came with.

Fuel rails are really stiff to pull out. On the new orings, put a bit of that lube for brakes before you try to install them. They'll slide in like it's nothing.

Well, I've got it torn down and am just waiting on the gasket set to come in. So far the job hasn't been overly difficult, just time consuming.

I didn't see any breaks in either LIM gasket. However, when I was taking the LIM off, the 4 diagonal bolts came off with next to no resistance. I'm wondering if this was the cause of the coolant leak.

Anyhoo, gonna replace the injector o-rings today.

Hi guys. Update time for those who are following...

Got the intake manifold, valve covers and the plenum back on. Pretty straightforward there. Should be able to get the PS pump and alternator back on and hook the wiring harness up today. Hopefully I'll be able to change the oil and start it up tomorrow.

I know it's documented from GM, but it's a little disconcerting that those intake manifold bolts use so little torque. It's hard not to just give 'em another half or quarter turn.

I would recommend changing the oil twice; run some cheap engine oil in it, while you're bleeding and topping off the cooling system. Then change the oil and filter, and put in the good stuff. Your engine bearings will thank you.

That is exactly what I had in mind, Blackarrow.

I got the engine assembled yesterday and pulled the oil plug. I had a bunch of stuff to do yesterday and today but tomorrow I'm gonna fill it up with cheap oil while checking for leaks. After I run it for a day or so, I'm changing the oil with good stuff.

Thanks!

i reccomend just running it for 10 minutes or so, and then changing the oil.

I would also like to say it could be a head gasket I just had to replace mine on my car and I had the same problem so if everything checks out fine and you have replaced everthing else you can think of my best gess would be that

Compression test will rule out a head gasket.


Minot Nd. Spent the night there once. Had a great steak for dinner. That's about all I remember of that place.

All done! Woohoo! No leaks around the LIM gaskets and no fuel smell.

Big thanks to RooK, Blackarrow98 and everyone that helped out. You guys are awesome!

Glad it all worked out for ya. Now, let the RTV cure and the gaskets seat, then

May that gasket last you a long time grasshopper.

Now it's time to buy a bolt-in Downpipe & cat , which eliminates the u-bend as well...

Is that compatible with the 3100? I've seen it listed where they're both different and the same, really confusing.

Yup, saw it listed for the 3.1L and 3.4L, here's a better pic of it, from Magnaflow's site: 23433 It's $135.77 from Performance Peddler, with free shipping. For the 3.8L, it's a 23405

too bad I didnt know of all this stuff when I had the Beretta. I would snap that up in a heartbeat.

Thanks for the suggestion, Blackarrow, but every spare dime I have right now is going into my project bike.

1986 Suzuki GSX-R 750 -- The first year for the "R" series GSX bikes. Lotta fun so far!

Nice.

I was at a used bike dealer yesterday (a nasty habit)they had one of those there. It was in great shape. Saw some young punk in there looking for a "new" "his first" bike. He saw that Gixxer and was look how ugly that thing is it's hideous etc. etc. I wanted to so punk his behind but his daddy was with him.

You're welcome, just remember the mod bug can bite you when you least expect it...

Herc: The "old-school" bikes have so much more soul and character than these new cookie-cutter death rockets these squids are riding these days.

I won't post pics in here, but if you guys allow email from forum members, I'll send some when I get it painted and ready to go.

Blackarrow: I'm not sinking much more $ into this GP, but all bets are off when I get a G8 after my truck is paid off. Sad to see the GPs are going bye-bye (I've had two) but that G8 looks sharp. Vrooommm!

I love the looks of the G8 but Im gonna let the first year bugs get worked out first. Hopefully by then they'll have a hopped up GXP version if the cafe standards don't hit too hard in the pontiac line up.

Agree...I'm not buying a first-year model either. Got that out of my system a few years ago.