I mentioned this in another thread, but it's buried a few pages in so I'm not sure it will get any attention. Anyhow, after installing a new thermostat and o-ring I discovered that I have a significant leak from between the housing and the outlet as if there is not o-ring installed. I put in the thermostat, spring side down, and then the o-ring so I'm pretty sure that is correct. I'm wondering if I got the wrong o-ring now, the diameter is correct, but I'm wondering how thick the o-ring is supposed to be. If I have a chance after work this evening I'll take a picture of the new o-ring.

 

Just changed my thermostat last weekend on my 01 v-10 it was leaking after install also. looked as though the housing was leaking past the o-ring but pressed on the hose and it was coming by the clamp. my hose was not that old it has the pinch type clamp on the hose. i had the clamp clamped in a different position than before moved it to where it originally was and leak stopped.just my 2cents worth.

 

I'll have take a look at the hose and make sure that isn't my problem. It's a brand new hose though so I'm thinking it isn't very likely.

I stopped by NAPA on the way home and picked up another o-ring to compare to the one I picked up at O'Reilly and they were exactly the same. If I have time tomorrow evening I guess I"ll try it again and see what happens.

UPDATE:
Put the o-ring from NAPA in and tried it again...no leaks! I don't know what was wrong before. Well now to find out what is causing the miss.

 

Was the leaky o-ring pinched anywhere? It might have shifted when you installed the housing. Glad you got it fixed

 

I'm thinking thats what happened when I put the housing on the first time with the install of the manifold. When I installed this time I made sure I kept it level as I tightened it down.

 

I put the new coolant in last weekend after doing a full flush and everything seemed great after letting it get up to temperature and making sure the thermostat opened. I fired it up again this weekend to charge up the battery before doing some electrical work (have to smog and renew registration it before I can drive it again) and smelled coolant. The thermostat housing was leaking again! I've tried two different o-rings and this thing keeps leaking on me. The mating surfaces are clean and I don't see any cracks or pitting. Anyone have any idea why this is happing? I'm tempted to buy one of these see if it helps. I just want my truck running good and back on the road where it belongs!

 

Reseated everything and it seems to have fixed it. I don't know why these o-rings seem to be so sensetive to everything getting tightened down evenly. Drove truck to town and back, 20 mile round trip, and no leaks.

 

Glad you got it fixed finally. Were you leaving the hose on the housing while doing this? Maybe the hose was keeping it at an odd angle?

 

I was thinking the same thing. I just put the thermostat back in real quick after I finished the flush without removing the hose again. On the last attempt I took the hose off so it wouldn't twist it, then put the hose back on.