Nice day to change hoses and thermostat. All went well, did a good flush and replaced all the hoses. Get everything back together and I get a leak at the thermostat flange.

Believe the leak was coming from the top of the thermosat- where there's no gasket...bottom has an o-ring Take everything apart and find an unused gasket for my old '76 F100. A little trimmig and some gasket seal and we're at it again. Start 'er up and IT'S STILL LEAKING!!

Run down to the parts store and pick up some high temp gasket material and a tube of RTV high temp sealant. Made a new gasket to match the flange and sealed all the surfaces - tightened per the instructions and am letting set overnight before checking.

What was supposed to be an couple of hours turned into SIX. Why isn't there a gasket for above the thermostat?

 

there is. its the o-ring you have under the thermostat. put the stat in the water pump then the o-ring and apply a small dose rtv to the stat housing and bolt up. shouldn't leak!

 

According to the book the o-ring goes under and there's a lip that it fits in perfectly. What seals under the thermostat if I move it on top?

 

TJ...I stand corrected, book shows it goes on the top. Good catch. Maybe I should look at the book BEFORE I do the work!! Thanks for the help. Still wonder how it seals under the thermostat?

 

The flange could have a slight bend in it. I just changed my 96 and it was bent.
Put a piece of sandpaper over a flat glass pane like a house window. Rub the flange of the housing over the sandpaper and then look at it and you will see what contact there is.

 

kord the stat really doesn't need a perfect seal under it. it is that critical that no collant passes by it. plus when that o-ring seals it squishes to the sides and seal there to so it would seal to some extant.

 

the tstat housings are junk, if i pull one off i throw it away and buy a new one.

i built a aluminum one for my 97 and ive had it on and off again a few times and never a leak


a new one and some grey rtv and it should hold for about forever.

 

just out of curiousity where should the stock temp gauge be for temp after warmed up?? i have awsome heat but never seems to get higher than a third of the gauge no matter if its 90 degrees outside and i am pullin my trailer or not. just thinkin mine is running cold

 

stock gauge is junk!!! you will never find a stock truck witha aguage that reads any different that what your is doing. they are an idiot light with a needle. i have put an aftermarket guage on my truck cause i have heard of a few stories of people overheating their truck but not knowing it till its too late. my stock gauge run lower than yours does and my truck runs at about 200.

 

thanks i kinda figured that. now that just gives me the excuse to do some autometer gauges