Coolant leak from Throttle body

**jakegsxr11** · 09-06-2011

Hi,

I had a coolant leak develop today. It is coming from behind where the mass air flow sensor bolts on to the upper intake manifold. I can see coolant dripping down the front side of the seam when the engine is running. What do I need to to to fix this? Is there just a gasket in there that I need to replace?

Thanks,
Jake

**TheOtherNick** · 09-06-2011

Sounds like the throttle body gasket is leaking, or the upper plenum is cracked like they do there.

**jakegsxr11** · 09-06-2011

How can I tell if there uim is cracked. do they usually crack as high as 2/3s up the throttle body?

**TheOtherNick** · 09-06-2011

look at it and see if you see a crack, start with the throttle body gasket they are cheap.

**jakegsxr11** · 09-06-2011

Ok, that gasket between the UIM and the throttle body was split in 2 places. The black plastic bosses or water jackets that come out of the UIM and go into the bottom of the throttle body in the front and rear have the bottoms cracked off them. Is this what a cracked UIM refers to? I highly doubt a new gasket will seal with the bottoms of the water jacket bosses busted out. Please see picture, it is sort of hard to see the missing plastic. What are my options?

**FordMan77** · 09-10-2011

Use RTV to make up the gap, or replace the entire UIM. When mine did this I just replaced the whole UIM. No need to take a chance on it not working and leaking coolant.

If you haven't done the LIM gaskets on your car yet then this would be the time as you will have everything BUT the LIM off in order to replace the UIM anyway.

ineedparts.com sells a UIM kit that includes everything you need, even the improved design UIM that won't crack around the EGR pipe where they usually do. Under $100 for it all IIRC. If you need the link let me know.

**KZOO3800** · 09-10-2011

This is what you want to replace the UIM. It includes a new EGR stovepipe that doesn't contact the brittle ABS plastic of the UIM, and the area around the new stovepipe is surrounded by a metal tube in the UIM itself. The likely cause of your UIM crack is the heat from the EGR stovepipe, which contacts the UIM right next to the coolant ports, resulting in cracks, warpage, and all kinds of mayhem:
GM Intake Manifold Kit - iNeedParts.com

I'm assuming the worst case scenario, which is a cracked manifold. You NEED to REPLACE your upper intake manifold ASAP. I wouldn't even let that thing run for 30 seconds the way it is. If your UIM is cracked that bad you're talking about sucking coolant straight into the intake and from there, straight into the heads where it will destroy your engine very quickly. Not something to mess around with at all. Do not drive it, unless you're being chased by ninjas, and even then you should consider running instead of gambling on a cracked manifold. Seriously though don't risk it.

At this point you might as well take a day or two and replace the LIM gaskets with the upper intake manifold. I did mine and I never worked on an engine before then, 1500 miles later its runs like new.

BillBoost also has a guide on this forum about plugging those two coolant passages that run to the UIM/TB from the lower intake manifold. You may consider this, because it will prevent coolant from entering the intake in the case of a cracked manifold.

Check out my old LIM GASKET thread, it details what is required for the job and includes a list of necessary parts I got pretty cheap from Rock-Auto.com. If you do all this yourself it'll cost under $400. There are some pics on the second page, you'll see what you're dealing with.
http://www.grandprixforums.net/lim-g...ent-46950.html

Also this may help if you do it yourself:
http://pontiacbonnevilleclub.com/for...hp?f=53&t=3591
http://www.grandprixforums.net/coola...ain-42943.html

Good luck, and if you need help just ask I'd be happy to help you.

**jakegsxr11** · 09-12-2011

Ok, I replaced the UIM and the LIM gaskets. The car runs great and there are no leaks but now the cruise control will not turn on. Anybody have a clue as to what may be causing this?

I googled the problem to death with no answer in sight. However I forgot about my friend the search feature right here in this sub forum. Anyhow, I did not snap the cable on tightly during reassembly....problem fixed.