Damnit. I have taken my UIM off 2 times now to try and figure out what is causing my coolant leak, which seems to be slow. I can fill it up and drive about 100 miles before the buzzer ever comes on, but I get nice steam clouds every time I stop. Anyway, I replaced a soft (once was soft, but was hard and brittle) vacuum line, which looked like it had coolant in it. I also replaced the short 90 degree section of heater hose with a loop to avoid the hassle of getting it back on. Is there anything else under there than anyone can think of that might leak? Ive looked at everything I can see and have found not a damn thing and its frustrating. Time 3 better be my last, cause Im getting tired of tearing it apart

 

Cooling system pressure test. Most rad shops can perform this.

However anywhere coolant is evaporating it will leave deposits so if the rest of the engine is clean then you should be able to see them.

 

what will a pressure test do? I know its leaking externaly, I can see it pooled on the top of the engine. Its in the area under the uim/throttle body. So it has to be one of those hoses, but Ive checked all of the ones i know that have coolant in them. Unless something else bolted to the uim has coolant going through it, but also has vacuum, sort of like the BAC... and somehow its getting through and leaking out somewhere... I dunno, im completely stumped. Ive checked everything that had liquid on it and still cant locate the source.

Doesa coolant ever enter the throttle body? I was thinking about the several holes that run through the plate between the uim and tb, and maybe collant goes through one of those, though I think its only vacuum...

 

A pressure test will find the leak. Failing that, you can buy a dye kit at most auto parts stores. Clean up the engine, put a little dye in the coolant and run the engine. Then with the included UV light, find the leak.

If you have an external leak, it is coming from somewhere. The only way to find it is a bit of detective work. It's not like we can reach through the Internet and find your leak...

The FSM has a diagram of coolant flow as well.

 

Take a look at the top rear of the throttle body. There are 2 small diameter coolant hoses attached there--one from the BAC valve and one that is connected to the top of the engine under the rear of the UIM. So, the leak may be from the latter hose where it connects to the top of the engine. Get a mirror and flashlight and check out that attachment point. (This applies to a non-turbo engine. Not sure if the turbo has the same arrangement.)

 

well thats what i was asking, if there are any hoses or places on the uim/tb that has coolant flow that wouldnt be so obvious. guess ill check the fsm again