leaking coolent please help

**kjohnson** · 10-06-2009

I am leaking coolent at a pretty slow rate out of what i think is called the upper plantum. I have a pic of a car with it circled. Ive heard of our cars dumping coolant into the engine and that frankly scares the crap out of me. Do i need to get this fixed like yesterday or am I ok to drive on it like this? If this is something that needs to be fixed like now Ill do it but im a little over 200 miles from home so its kinda hard.

this is the url I still cant figure ouy how to get it so the pic is just with the post

http://i702.photobucket.com/albums/w...C04063ss-1.jpg

**BillBoost37** · 10-07-2009

Where on the intake do you think it's leaking.

**kjohnson** · 10-07-2009

right below the black piece on top right under the fuel rails and sutch

**Jakegday** · 10-07-2009

that is your upper intake plenum. it doesnt matter what is causing coolant to get into your oil, no matter what, thats a bad thing! theres no way i would drive 200 miles with that problem going on. so is it leaking out of that part? or out of the gasket in between that part and the rest of your engine?

**BillBoost37** · 10-07-2009

Jake..he didn't say it was dumping into the oil. Most common failure is a crack from the EGR area of the UIM into the coolant passage next to the it in the UIM.

Are you seeing an external leak or do you believe it's internal and see white smoke out the tail pipes?

**PonchoDvr4Lfe** · 10-07-2009

I am goin to call it either at the egr pipe or lower manifold gasket as those are gonna be the two primary causes...

If you leakin out below the fuel rails I am gonna say LIM gasket... but the only way to know is to start tearing in. If ends up being that, I would replace the plenum too if it seems brittle around where the egr pipe goes in. That is where coolant leaks are 95% of the time on these engines.

Side note: Make sure you get the aluminum LIM gasket if that is the problem. And if you need help, there are plenty of write-ups over in the how-to section. Good luck!!

**kjohnson** · 10-07-2009

it is leaking right inbetween the black peice on top and the rest of the engine right below it. as of right now it is running just like i bought it i just didnt know if it could possiblly lead to coolent in the engine

**BillBoost37** · 10-07-2009

Now it sounds external, but you won't tell us ...eh? lol

If it's external, the usual suspect is the TB to UIM gasket. That's if you see it near the TB. It is possible to leak as well at the UIM to LIM, but much tougher with the distance and gaskets etc.

**kjohnson** · 10-07-2009

What do thous stand for im not savvy with the shortend stuff. pics would also be very helpfull. do i need to worry about it a hole lot since its external or could it become internal

**agrazela** · 10-07-2009

Black plastic piece on top = UIM = upper intake manifold
Aluminum piece the UIM is bolted to = LIM = lower intake manifold...which is bolted to the cylinder heads
Throttle body (bolted to driver's side of UIM) = TB

Any coolant leak that is puddling coolant onto the topend is due to either a bad gasket or a cracked/burned/warped plastic UIM--and thus could easily become internal. So yes, unless you get this fixed your engine is in mortal peril. Furthermore, EVERY 3800 produced prior to about 2005 WILL develop one or more of the dreaded coolant leaks...they are built-in design flaws courtesy of GM bean counters.

Now you gotta help us to help you...is there coolant puddling on the LIM? (In the area and recesses around where the fuel injectors are?) Is it mostly toward the TB end? If that is so, it is probably, as BillBoost37 suggested, a UIM-to-TB gasket.

Is the coolant puddling all over the LIM? If so, that may also be UIM-to-TB gasket, or UIM-to-LIM gasket, or a crack/burn in the UIM--but in this case, the leak is already internal and coolant is likely puddling inside the LIM and leaking out under the UIM-to-LIM gasket.

First thing I would do, were I you, is to remove the TB (10mm socket), inspect the UIM-to-TB gasket, and also look into the "throat" of the UIM with a flashlight to see if there is coolant wetting or puddling inside the LIM. Then report back

**kjohnson** · 10-07-2009

It is puddling right on the LIM wich is gray and right under the black piece

edit. Ive also not seen it on the passenger side mostly the driver side. It is a very slow leak but i don't want it to worsen this winter since its gonna get hella cold up here in northern Iowa. I also don't want to have to get a new engine so ya

**kjohnson** · 10-08-2009

so if it is the uim shod i replace the gasket and the black part or just the gasket? i have an 03 if that helps

**BillBoost37** · 10-08-2009

You say it's on the gray piece under the black piece. If it's under, how can you see it?

Since we can't determine external or internal, I'd be leary about suggesting which parts to replace. Don't want to suggest something and have you spend money on something that isn't in need or being replaced.

**kjohnson** · 10-08-2009

it puddles right on top the gray piece right under the planem

**PonchoDvr4Lfe** · 10-08-2009

Originally Posted by kjohnson

it puddles right on top the gray piece right under the planem

PICTURES OF PROBLEM AREA.............

We are simple people.

I also going to throw it out there again that I think you should replace the gasket between your lower intake manifold (LIM, color=gray) and the heads. They will go eventually if they aren't the root cause of this alrerady. Just my .02 cents. Why tear into it twice? Another 10 minutes and you are there!!

**kjohnson** · 10-08-2009

See normally I would be totally game with taking pictures but im at college right now and i dont have a camera here. What I think im gona do is replace both the lower and upper gaskets and possibly the pentum( I think that's what the black piece is called). is there anything else that I should be looking into getting fixed while im doing that? also what brands-types etc. should i be looking to buy?

**PonchoDvr4Lfe** · 10-08-2009

Originally Posted by kjohnson

...is there anything else that I should be looking into getting fixed while im doing that? also what brands-types etc. should i be looking to buy?

Buy all OEM. Mostly everything. Make sure though, on the LIM-head gasket, that you get the aluminum one. The gasket that is in there now is plastic and they fail because of too much heat. Also check your black vacuum line that runs around the motor. (U-shaped piece, 1/4" hard, black plastic) The rubber t-fittings tend to dry rot. If they are you will tear them anyways when you go to take them off. There are also two plastic elbows for coolant from your engine to the heater core inside your car. These you can buy from an Autozone or whatever. They only charge like 4 bucks for both elbows where GM charges you like 8 dollars for one elbow.

I don't really remember how much the plenum is. I replaced one on a 98' I had once. I wanna say like 150-180 for it. Aluminum gaskets are around 50ish. Those are defiantly your two most expensive parts. someone correct me if I am wrong please.

P.S. There are really good write-ups in the how-to section on all of this. Really, I didn't believe it either!!

**kjohnson** · 10-08-2009

so replacing all of it is a good idea right? and would it be smart to just pay someone to fix it or should i just do it myself. how extensive is this? is there anything else you would recommend me do while i have it torn apart?

**PonchoDvr4Lfe** · 10-09-2009

Well if you were not in Iowa, I would do it for you for a case of beer but thats outta the question. If you are willing to tackle it and have a good understanding about what you are doing overall, I would say go for it yourself.

If you don't have any mechanical knowledge whatsoever, just let someone else do it. At least then they are responsible for it if it takes a dump.

All the parts I listed above are most of what you should need to replace also. If you go in a dealership, they can tell exactly all the parts you need.