Hey guys,
Haven't been here in awhile. Hope ya'll are doing good.
I've been noticing a little drip from the bottom of the truck recently. Open the hood and the water pump is wet on top. There are three areas it could leak - what looks like a hose to the heater core, where a sensor screws in, and the tstat gasket / hose. (Not counting the water pump o-ring seal - yet). 99% sure it's not the water pump leaking, b/c it's coming from the top. From all I've read here, I suspected the tstat gasket.
Anyway I cleaned it all off dry and started the truck. No leaks. Drove until temp gauge said 160 or so - checked - no leaks. Drove until up to temp (203 tstat). Check again, no leaks. Drove home, turned off truck and checked again, no leaks. Checked on and off throughout the evening and still no leaks.
This morning I was greeted with another small spot on the driveway. Open the hood and there is some coolant in the same spot on top. From what is wet, it seems that it has to come from the tstat area (otherwise it would have to travel up from the other spots). What is puzzling is that the tstat gasket / hose / clamp area is dry. Even more so is that if I squeeze the rad hose nothing leaks - it's like it decides to leak at a certain temp during cooldown and then seals again. Maybe what happens is when the thermostat closes again, whatever is in the rad hose leaks out? But I wouldn't expect there to still be coolant in the hose...
I have the dieselsite thermostat housing (which went on with the 203deg thermostat). When I installed I used some RTV blue. I plan to replace the tstat gasket and use RTW orange - unless I'm missing something, do you think it's something else?

Thanks!

 

I had a similar leak awhile back. It was the upper radiator hose at the t-stat housing neck. I snugged the clamp and no more leak. I have the worm gear SS clamps on the radiator hoses and they tend to need to be checked after time especially with new hoses. The compression of the rubber "sets" and they need a little extra twist of the screw. Temperature does seem to play in as a factor to all this.

 

Those spring clamps that come with the new hoses are much better than the old style worm screw clamps.
They follow the expansion and contraction of the flanges and keep the connections sealed.

 

Don't worry, your not going crazy, I have the same housing and T-Stat and mine leaked. First time I cleaned everything up and installed another gasket and it leaked again. This time, clean up and let dry all mating surfaces, let it dry, run a decent but not too much of a bead of Black Permatex high heat sealant around the mating surface, wait about a half hour then bolt down the housing slowly. Let stand overnite then fire it up the next morning, no leaks now..

 

There is also a constant torque clamps that does a great job.
I use these at work for some jobs that always come back leaking because of the expansion issue and they seem to work better than the basic screw type clamps.

Store Locator | NAPA Online

 

True. Constant torque clamps are really the way to go. Pricier, but effective.

 

When I changed my water pump and reused the stock spring clamps the upper radiator hose leaked at the radiator. I repositioned the spring clamp so it would seat back into the indentations it originally made and that stopped the leak. So from now on when I reuse spring clamps I put them back in the original position.

My tip for the day.

 

Good tip, Robin. When I reuse any hoses, I always make a point to put the clamp back in the same position.

 

Damn, we sure think alike, don't we?

 

Wow thanks guys - what I love about this forum is I always get responses. I'm going to try replacing with a better hose clamp tonight (thanks for the tip, didn't think about it), run through the start / warmup process again, then let it sit overnight. Tomorrow if I see a leak again I'll replace the tstat gasket / rtv and take my time like mentioned above. Will report back with results...

 

Good deal, looking foward to the outcome, hopefully good.

 

And I don't think that's a bad thing either.

 

I have heard that the stock thermostat housing piece itself doesn't exactly last forever...

 

Their a stamped steel so they rust, I'm sure you can clean them up, wire brush and all but getting one of these Dieselsite aluminum housings are better, never have a rusting problem, take a look. New aluminum housing on left, stock steel on the right.

 

Hey guys, now I'm at a loss. Been working on it and I believe that I've traced it to a leak between the rad hose and the thermostat housing. Sometime during the night it "burps" a bit out of the hose at the housing, on the back (engine) side. I can see a trace of dried coolant there (on the housing), and it's wet below. What's confusing is that I've replaced the rad hose and used a new constant torque clamp. I'm already using the dieselsite housing as well. It just doesn't make sense. From the looks of where the coolant goes, it seems that there is a small pressure buildup and the "burp" is a fast one, not slow. I wonder if my rad cap is suspect? It's relatively new.
All I can figure is that I either need to tighten the clamp a bit and/or reposition it. The "leak" is on the opposite side of the clamp screw. And I've never actually witnessed the leak - dry when cold, and when running.. just shows up overnight. Very puzzled. ???