Ok, so I was pretty sure my thermostat housing was oozing antifreeze. This seemed like a great time to change the 'stat. So I did that. Getting the gasket material off of the bottom of the housing was a bitch and I ended up wearing the ridge down a little bit with the putty knife and 0000 steel wool.

So I put it back together with red RTV on both sides on the blue Fel-Pro gasket. I let the truck sit for about an hour, then filled it, bled it, and went to the car wash to hose off the engine. The coolant smell came back again after a few days-- stronger than it was before-- and it looked like it might be oozing worse. So I went and got a new housing, upper radiator hose, and gasket. The housing came with a gasket but I used the Fel-Pro one anyway. I only put RTV on the bottom of the gasket where it sits on the manifold, and the slightly rounded side of the gasket up. I let it set up overnight before I bled it, though I did fill the radiator up the night before. I spilled a lot of antifreeze on the engine from the upper hose and housing (the old thermostat apparently let the coolant run back down-- leaking). I bled the system like before and filled the reservoir to the high line. I drove it around for about 20 miles like this, and the reservoir was almost empty (hot) and the truck reeked of antifreeze. I can't see a leak anywhere. This was before I hosed off the engine, which I did shortly thereafter.

Anyway, after all that, my questions are:

Should I have put RTV on both sides of the gasket, or only on the bottom, only on the top, or not at all? The Haynes manual said to put it on both sides, but other places I've read only on the bottom.

Is it possible that the cooling system still had enough air in it to pull in that much coolant?

If that mfkr is still leaking I'll be pissed. I hate the smell of antifreeze, and hate handling it. Blech.

Thanks guys

 

Yikes. I didn't use any RTV on my housing when I last changed it. Over 10,000 miles on this housing and no leaks. You might have a leak somewhere else now. I just did my water pump a couple days ago and discovered that not only was the pump leaking, but the bypass hose (runs into the intake right next to the housing you're wrestling with) was leaking as well. The bypass hose leaking actually looked a lot like the housing leaking but the housing was fine once I got everything apart.

How long has it been since you've done the water pump, if ever?

 

The water pump hasn't been done since I got the truck, but that's only 5k miles. It has 91k on it. I can't see anything oozing out from under the pully, and nothing is on my fingers when I feel under there. I'll check that hose too, see if it's leaking. It's entirely possible that it's leak free now but I haven't driven it enough since this last work to know for sure.

:/

I'll have to pop the belt off and check the water pump bearings again. I did it right after I got the truck, and it was fine then, but it DOES have 91k on it, so who knows.

 

i use a light coat of rtv on both sides. i also put rtv on any bolt threads the extend all the way into the water jacket.

yes, it will pull in good bit of coolant from the overflow tank as it purges the air. fill it back up and see if you keep losing it or if it stabilizes.

use the water hose and rinse off all the coolant from the engine and the compartment. if the green comes back, you still got a leak.

take a good look at the water pipe coming out of the pump, to which the heater hose is attached. it has an o-ring in the bottom

 

I have used probably every kind of gasket and sealer. I have never had one leak; however, I do mine at night and let it sit for as long as posible before I fill it up. At least 24 hours.