1999 STS coolent leak

03-05-2009, 11:45 PM
Hi everyone-need an opinion on this on and off again problem im having. I have a slow coolent leak and Im having a hard time tracking it down. When it does leak it seems to be comming out of the middle of the underpan right after it ends. Now ive looked up there one or twice and cant tell whats leaking? I also checked my hoses on the right side and did notice that the upper hose does seem to have fluid comming out from under it, by the way of rubbing my fingers under the hose and they come back wet, but no dripping or evedince of dripping down. Now the sticky part is if I keep topping off the fluids it tends not to leak..but I can smell rad fluid burning, if I let it go for say 2 days it will start to leak nociably on the ground...
No fluids are found in the oil-so no problems with headgaskets.

Any clues ou there???


03-08-2009, 11:01 PM
I have the same problem on my '99 SLS: a friend of a friend said to check the water pump bearing seals. Something about a small leak hole at the bottom of the bearing that will allow a slow leak when the bearing starts wearing out. I haven't checked mine out yet so don't know if info is valid or not. Good luck!

03-11-2009, 08:25 PM
If you live were they have auto zone you can borrow a pressure tester from them .they will show you how to check for leaks....

03-15-2011, 01:46 PM
I to have a coolant leak in my 99 SLS. I thought it was hoses or a water pump but it turns out to be the coolant recovery tank. It seems to be leaking around the threads of the filler cap. How hard is it to replace the recovery tank. Thanks catty99

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