Thread: Do I have an Upper Intake Coolant Leak?

2002 GP
I was leaking coolant on the ground from the passenger side of engine. I pressurized the system to see where it was leaking. The elbow was for sure leaking.

However, while I had pressure on it, I noticed that it was also leaking coolant on the other side of the engine around the flange where the air filter "stove pipe" bolts to the upper intake. Coolant leaked from nowhere else that I could see or hear. My oil is not milky and the car runs great, except for the elbow leak.


Do I have a bad upper intake gasket?... or is that some other gasket? I'd hate to remove and replace the upper intake gasket if I don't need to.

The leak was coming out the side of the joint between the throttle body and the UIM. I took the throttle body off and the gasket "looked" good. It was dry inside the UIM. I think I'm going to replace the LIM gaskets and UIM gaskets just to be safe. The car has 220k on it, 190k by me, and it has never had any work done other than proper routine maintenance. Surely it could use new gaskets. Also, I'm going to modify the LIM and block the coolant holes that go to the UIM. Then it for sure can never leak there again. Any objections or suggestions?

If it is leaking at the joint where the TB bolts to the UIM, then you need to take a look at the 2 ports on the bottom of the UIM while the TB is off. They are most likely rotted away and leaking internally as well, hence why it was dry. Also, you should use a new TB gasket after you remove it as they aren't reuseable.

I would replace the entire UIM w/ a new one and do the LIM gaskets while its off. Then you know you won't have any issues in the future. You're rod bearings will thank you

My only reason for suggesting that he change the UIM altogether, along w/ blocking the ports was the fact that he will be removing it to do the LIM gaskets, and that UIM has 220K on it. It may decide to crack when he bolts it back down again, and then has to deal w/ a vac leak like I did when I tried an old UIM that cracked in this fashion.

But hey, if it ain't broke, don't fix it

I have the LIM & UIM gaskets in, but now I can't get the fuel rail to go back in. The injectors don't want to pop down into the holes of the intake. Is there some secret to getting them to pop in? I'm scared to get too rough with it. Do you just push it down until they pop back in, because that's what I'm trying but it aint workin.

Are you lining the 4 studs up on the rail as you push it down? I could see it getting hung up on one of those and not going all the way down. Beyond that, you can lube the lower o-ring on the injector w/ some motor oil and they should pop in.

To finish this: The injectors were going in fine, I just thought that they were supposed to go in farther than they were. I took one off and stuck it in by itself and figured out that I was good. After I got the LIM off, I saw that both gaskets were busted. Glad I took it apart! I got everything back together and it runs like a dream. Better gas mileage, clean exhaust, no hard starts, it used to sputter and "chuggalug" at random times and at a certain hill everyday, that all stopped and it runs very well now. So my LIM gaskets were bad for like two years! LOL That's how long I have had these problems. If the elbows had not have sprung a leak, I'd still be driving it that way! LOL... I'm a happy feller for now. Thanks to this site and for your help guys.

What about the leak at the elbow on the passeger side? My 2007 Grand Prix sprung a leak in the area where
the little elbow goes into the intake manifold. Don't know much about this thing, but I do know I have a problem.
Car has got 155 K miles and runs very good. Any help would be appriciated.

You can buy those elbows at autozone in the "help" section. They are less than $20 for both of them. On youtube if you search for "coolant leak on 2002 grandprix" you will see a nice video that will show you how to replace them. It's about an hour job. If you are replacing one you need to just do both. Make sure you dig what is left of the old ones out of the holes.