: thermostat housing drips

07-13-10, 05:55 PM
I put a new thermostat and O ring on the N* Eldo. While car is running, I get a very slow drip from where thermostat housing meets the water crossover. The 2 bolts are tight. I don't want to over tighten the bolts and strip those holes in the crossover. Can I use some black RTV on the thermostat housing outside of the O ring to make a leak free seal?

07-13-10, 11:09 PM
Use some bars leak HDC (same as GM coolant supplement) in your lower/upper radiator hose.
Fixed a couple small lame pinhole leaks like that for me real nice.

07-14-10, 09:06 AM
It's possible that the thermostat is cocked in the housing - assuming it's one of those which has the spring-loaded bypass "top hat" on the reverse end of the main body. I know it's a PITA, but a removal and check might be in order, and that will give you a chance to look at the machined groove where the thermostat rubber seal ring seats......

07-14-10, 09:32 PM
Nice picture Sub - it shows the seal - a square cut o-ring kinda thingy that is slit 1/2 way through on the inside diameter...hard to explain, but would cause a leak if it were missing or installed improperly - like if it were installed on one side or the other of the thermostat, instead of "straddling" it.

07-15-10, 06:45 AM
Pete - check the machined surface for imperfections/pitting/etc.

I have occasionally used just a touch of RTV around there; just be real careful to use only very little; if it squeezes around the thermostat you could be having t-stat issues soon.

07-15-10, 04:25 PM
thanks. I will remove and check for that pitting. I do have another one. I'll put the best one on.

07-15-10, 09:55 PM
Remember it could be other things, like the water pump cover seal or a hose that is internally damaged.
Also the water pump cover seal can leak and make it look like a t-stat seal leak.

If the hose leaks internally it can wick out the ends through the cord structure of the hose.

Be sure you know where it is coming from but if it looks like it is still the t-stat seal take the housing off and be sure everything is straight.