1968 Cougar Over Heating Problem... Suggestions

webshot · May 14, 2016

Again hope it is cool to ask Cougar questions here since they are so close to stangs.

But hey I just bought a 68 cougar from a guy. Runs and starts perfect but it over heats. I feel pressure building in the top hose so I thought thermostat. Changed that and the hose and I am still experiencing the problem. What are some other things I can check? I guess it could be a faulty thermostat, but anything else I can try? Also there is like a vacuum tree coming out of the thermostat housing that looks damaged and is not hooked to anything. Could that be the issue? Does anyone know what it is supposed to hook to? Ill post a pic shortly.

Specs.
1968 Cougar non xr7
302 2bbl v8
no a/c
Automatic

webshot · May 14, 2016

Here is the pic of the vacuum tree on the thermostat housing.

horse sence · May 14, 2016

Vacuum tree works the vacuum advance . Look in the radiator and see if the tubes looked plugged .I am betting radiator .

webshot · May 15, 2016

Tubes as in the upper and lower inlets? Also should that vacuum tree not being hooked up cause an issue such as this?

mckallister · May 16, 2016

Stuff builds up inside the vertical tubes inside the radiator and impedes the flow of coolant, and reduces heat exchange with the air. You can either replace the radiator or take the existing one to a radiator shop and have it routed out (basically having it roto-rooted...).

If it's in really bad shape and is low on coolant, you can look inside the fill spout and see things sitting on top of the radiator core, usually in the openings of the tubes.

As for the vacuum: That fitting in the picture is a temperature sending unit, that probably switches something on/off in the vacuum system based on engine temperature. It does not have any vacuum attached to it. Whatever that vacuum tree attached to *may* be making the engine run hot, but I'm doubtful about that if the aren't open vacuum lines.

Extra air getting into the intake (which is where the vacuum is created) causes the car to run lean, which will also make it run hot. If it's running too lean, you can damage engine components (like pistons, connecting rods).

When the engine's running is there a hissing sound?? It should really stand out, if there's an open vacuum line. If there is a hissing sound, you should be able to plug the open line with your finger: the hissing will stop, and the car will immediately run better (smooth out idle, RPM change, etc).

Good luck!

webshot · May 16, 2016

I do not hear a hissing sound when the car is running. It actually runs really well as it sits. I will look into the radiator and inspect it more. But would all these prevent the thermostat from opening? Pressure builds in the tube leading to the thermostat.

mckallister · May 16, 2016

You prolly shouldn't worry about the vacuum tree, then.

No they wouldn't - the thermostat operates pretty much on its own. If it's in upside down (yep, learned that lesson the hard way) or if it's blocked it won't open. ...or if it's bad.

The pressure building up in the upper radiator hose is because coolant systems are pressurized - which is why you never open the radiator cap when the engine is hot... It's the same effect as blowing into the straw of your single serve milk carton/capri sun. It's normal. The pressure is actually what keeps the coolant from boiling out, given that engine coolant temps dramatically exceed the boiling point of water. So, the thermostat is designed to open with 10-22/25 psi of pressure.

If the radiator cap is bad or too low pressure, that would cause the engine to heat up, and use a lot of coolant.

If the overflow reservoir is pressurized, you should check its cap, also.

webshot · May 16, 2016

Upside down? Meaning wrong end facing into the intake? Or some other orientation?

LILCBRA · May 16, 2016

I'm sure he means exactly what you're asking, oriented the wrong way.....

Another suggestion to look at if the rest of the cooling system checks out: does the car have a fan shroud? They are designed to not only protect your hands from the spinning blades, but to also direct airflow across the fins when sitting at idle, allowing the fan to do it's job.

Is your gauge faulty? You can buy a radiator cap with a thermometer and gauge at OReilly's (and I'm sure other parts suppliers...) as a secondary gauge to confirm how everything is cooling. I have one on my Cobra II and I like it. Like I said, it confirms the gauge as well as giving you an indication that the cap is hot. If you opt for one of these, the cap tends to read about 10 degrees hotter than the gauge in the car in my case, so something to be aware of.
http://www.oreillyauto.com/site/c/detail/MRG0/2475S.oap?keyword=radiators+&+caps

webshot · May 16, 2016

Update:

So I noticed the cap was old and not sealing, so I replace that along with the hose coming from where the cap goes to the over flow reservoir and I think that solved the problem. But... Car gauge inside still reads like 3/4 temp. But it does not appear to be overheating now, but that is still a scary feeling. LILCBRA, that sounds like a good idea to test. But my inside gauge is already reporting high. I let the car idle for about 35 minutes. I am going to flush the system tomorrow, any ideas of anything else I can try? Last resort will be upgrading the radiator...

tos · May 17, 2016

I'll bet radiator too. That pressure you're talking about is probably due to the fact the individual cores are clogged (at least some of them) and the water pump is trying to force coolant thru clogged cores (tubes). This clogging can be expected with a car of this age and the only way to get it all clean is take it to a radiator shop and the will pop it apart and run rods thru the tubes and chemically clean it up, solder it back together and it'll be like new. Adding a fan shroud will also help the cooling as it sucks air more efficiently thru the radiator rather than partially moving hot engine bay air around. It acts like a carburetor venture and really draws the air thru the radiator at a higher rate.

webshot · May 17, 2016

tos said:
I'll bet radiator too. That pressure you're talking about is probably due to the fact the individual cores are clogged (at least some of them) and the water pump is trying to force coolant thru clogged cores (tubes). This clogging can be expected with a car of this age and the only way to get it all clean is take it to a radiator shop and the will pop it apart and run rods thru the tubes and chemically clean it up, solder it back together and it'll be like new. Adding a fan shroud will also help the cooling as it sucks air more efficiently thru the radiator rather than partially moving hot engine bay air around. It acts like a carburetor venture and really draws the air thru the radiator at a higher rate.

Forgot to add, the car does have the original fan shroud. The radiator is the original from 68. Think I should upgrade or just have this one fixed up as being stated?

Thanks to everyone that is/has commented.

LILCBRA · May 17, 2016

Original from '68.... I guess it's up to how much money you want to spend. Personally, I'd upgrade if possible. But then again, I can never seem to leave things alone.....

GNN60GT500 · May 19, 2016

Upgrade and water wetter if need be. Just curious does it cool down at freeway speeds or stay warm at speed as well?

barnett468 · May 21, 2016

remove the rad cap and look at the top of the tubes as was suggested . if any are plugged, the rad is partially plugged but it may still run hot with it cleaned if the engine has been bored out.

1968 Cougar Over Heating Problem... Suggestions

webshot

Member

webshot

Member

Attachments

horse sence

webshot

Member

mckallister

webshot

Member

mckallister

webshot

Member

LILCBRA

I wish I didn't have all of these balls in the air

webshot

Member

tos

webshot

Member

LILCBRA

I wish I didn't have all of these balls in the air

GNN60GT500

barnett468

Active Member

Similar threads

1968 Cougar Over Heating Problem... Suggestions

Member

Member

Attachments

Member

Member

Member

I wish I didn't have all of these balls in the air

Member

Member

I wish I didn't have all of these balls in the air

Active Member

Similar threads

Privacy & Transparency

Privacy & Transparency