I have been having problems with the coolant overflowing as the pressure builds after I shut the car off. I can hear a hissing a few minutes after shutting it off and it sounds like it is coming from somewhere underneath the Upper Intake Manifold. I am not sure which hoses run by there or how to check to see which has the hole. Anyone know about all of the coolant hoses that could point me in the right direction? Ever had a similar problem? I replaced a small cracked hose coming off the back of the water pump going to just behind the alternator but it turned out not to be the leak causing the problem. Thanks!

 

Ducky, If you have a leak under the upper intake manifold, there are 3 hoses to check. The first you already checked on, it runs from the water pump housing to a metal pipe (short hose). Second and Third are the 2 hoses that run coolant through the throttle body. Check those 2 next.

eric

 

I hate to say this bud, if it was a simple coolant leak from the hoses it would not cause overflow. It might cause the coolant not to draw back but not overflow. Are you sure it's hissing and not the sound of rushing fluid?
Overflow spills can only be caused by pressure build up in the cooling system and the only place where the pressure can come from is a leaking coolant seal. I learned this the hard way, and was in denial for 6 months before the coolant seal completely gave out.
It's time for a rebuild soooon. Sorry.

 

Ducky, If it is comming out of the overflow tank down by the pass headlight there isnt much you can do but save for a new engine. If you are talking about coolant just showing up in random other spots... been there done just about everyone. There is a hose that will go from your throttle body coolant line to the rear rotor housing. You will have to remove the UIM and crap on the LIM, I think the ACV or whatever. Some nice needle nose plyers make the job that much easier.

Chris

 

Well I'm pretty sure it's not a coolant seal. I am getting great vacuum numbers, a smooth idle, strong performance and the engine has only 25k miles on it. I did find a leak in the hose that runs from the filler neck on the water pump to the overflow (eliminated ast). I fixed that and it does not leak or overflow anymore. I still get a hissing sound from around the UIM a minute or two after shutdown. I think my major leak has been repaired. I am still wonering where the hissing is coming from and why it isn't causing a leak or overflow now. Chris explained where to find one of the hoses going to the throttle body, but where does the other hose connect to? I will probably also swap the coolant line to the turbos. Thanks for all the help.

 

The coolant line going from the throttle body will go down and right by the fuel pulsation dampener it will go into the rear rotor housing, here is a pic.

That pic is for something else but you can see the coolant hose, part of it is in that circle and it is going left, I guess they bent it out of the way because it should be going to the throttle body. The turbo coolant lines are good to replace, all you will have to do is remove the airpump. Then get your fingers down in there to remove the old ones, buying a few worm gear clamps will save you some time with putting the stock ones back on.

 

If you don't smell hot steam/coolant, it is probably not a coolant leak. I could very easily be a leak from a hose or solenoid that is hooked to the vacuum tank.