1966 Coolant Leak

SalineHornet · 07-09-2008

My 66 is leaking a bit of antifreez onto the engine. It appears to be leaking where the radiator hose connects to the block. The hoses are nice and tight and arent leaking... it looks like the leak might be from the part that the hose connects to.... is there a gasket there that could be leaking? Maybe the thermostat housing?

thanks
-Russ

rocky289 · 07-09-2008

The inlet hose is conected to the thermostat housing which is bolted to the inlet manifold.
There is usually a gasket at the thermostat housing which could need replacing.
If you are taking that apart make sure the mating surfaces are clean & flat. If you don't know the age of the thermostat it would pay to change that as well while you are in there.

bubbamace · 07-09-2008

Rocky289 is right, but also check the condition of the hose that runs from radiator to the thermostat housing. Look carefully to see if the coolant isn't dripping from the hose down the thermostat housing. If you have a bad hose, it could look like that housing is leaking.

SalineHornet · 07-09-2008

Thanks guys... the hoses area all good. Upon closer inspection I does appear that it is leaking at the thermostat housing gasket. I'll order the gasket and a thermostat while Im at it.

I notice they have 2 thermostats to choose from, a 160 or 180 degree thermostat... should I use one over the other? Seems to me running the cooler one makes sense and the 180 costs a few bucks more.

Also, shoud I expect to have a lot of antifreez leak out when I do the replacement? I want to be prepared if a river is going antifreez to pour onto the floor...

Thanks
-Russ

kenton_90 · 07-09-2008

I would go with the 180 its closer to operating temp. you might want to drain about a quart of coolant out of the bottom of the radiator before you do the thermostat and then you wont leak hardly any coolant at all. Good Luck

rocky289 · 07-10-2008

Also because the thermostat is vertical, make sure it is located correctly when you put the housing back on or will deffinately leak.

steve sturgin · 07-11-2008

Just a quick couple of tips, I would not use an aluminum housing as the fairly new one I had was warped, Rocky is correct, the thermostat surface must be absolutely flat. Also when installing the new one I use a piece of string around the thermostat up through the housing to hold it in the “seated position” while bolting it home, don’t tie it just loop it or you will not get it out, it’s nice to have someone to hold the string keeping the thermostat seated while your bolting it up (a hot girl is preferable but not necessarily practical).

rocky289 · 07-11-2008

Hi Steve.
What horse do you have?

steve sturgin · 07-11-2008

1966 Fastback C-Code, 302 crate 345 HP, C4

SalineHornet · 07-16-2008

I just got to thinking... the leak could also be from the timing cover gasket.... ???

rocky289 · 07-16-2008

Shouldn't be any coolant in there.

Bob A · 07-16-2008

Yes, this is what the water pump mates up to and is pretty common for an anti-freeze leak. And when it does leak it's hard to find. I just changed mine (66 mustang 289) about 6 months ago. Same problem, loosing anti freeze, it was puddling up behind the water pump & timing change cover. After removing the cover I found corrosion on the gasket mating surfaces. You can try and clean it up, but I opt to replace it. Good Luck

badidea · 07-16-2008

Just thinking about a leak like this. You might check the heater bypass hose. It's a short length of rubber hose with clamps on each end; therefore, yet another potential point of failure.

SalineHornet · 07-17-2008

Quote:

Originally Posted by Bob A

Yes, this is what the water pump mates up to and is pretty common for an anti-freeze leak. And when it does leak it's hard to find. I just changed mine (66 mustang 289) about 6 months ago. Same problem, loosing anti freeze, it was puddling up behind the water pump & timing change cover. After removing the cover I found corrosion on the gasket mating surfaces. You can try and clean it up, but I opt to replace it. Good Luck

That is exactly what is happening with mine.. not a huge leak but the antifreeze is "puddling" up.... so I will have to investigate further... best case is its the thermostat gasket.. if not then ill change both...

FordGuy1971 · 07-17-2008

Quote:

Originally Posted by SalineHornet

That is exactly what is happening with mine.. not a huge leak but the antifreeze is "puddling" up.... so I will have to investigate further... best case is its the thermostat gasket.. if not then ill change both...

Same here. I ending up finding that the thermostat housing was the issue. I went through several different housings to find one that actually "Worked" I also had to change to a thicker gasket. Good Luck