Just wondering if this is "normal" or not. The temp usually runs a pretty steady 190-195. However, if I am hitting 70 MPH or higher, it will increase to about 205-210. As soon as I slow down (under 70) the temp drops as well.

Does it matter what the outside temperature is? Is the a/c running? Normally is should pretty much stay the same, especially as the air flow to the radiator should improve as the speed goes up some.

Have there been any changes or increase in horsepower? Increased horsepower equals increased heat that has to be carried away. It may simply be normal for this particular car. There could be a slipping belt, the fan clutch not operating properly.

I would do a complete pressure test of the system, including the cap to make sure there's no leaks. Last year I drove my '78 L82 from Indianapolis to Maryland and while it never overheated, it ran a consistent 205-210 degrees on the interstate and I had a small coolant leak at the intake manifold I wasn't aware of.

Like I said, it may simply be normal for this particular car, but it's worth checking out to make sure.

Boy it really should not get that hot just driving 70. Check the condition of your hoses, especially the one on the suction side of the pump. If it is weak it could be collpasing. It sounds like restricted water flow, check the thermostat, flush the cooling system, look for leaks and last but not least if things get worse replace the water pump and radiator. Try a lower degree thermostat, also check the rubber seals around the top of the radiator. Earler Vettes like ours really have issues with cooling, and it is important to see all the air possible passes through the radiator core. Hose out the core of the radiator from the engine compartment out.

milkman said: Boy it really should not get that hot just driving 70. Check the condition of your hoses, especially the one on the suction side of the pump. If it is weak it could be collpasing.

I agree weak hoses should be first thing to check..

it should be the other way around..

70 should be cooler than in-town driving..

wow, they are all right

Do you have all the air dams and spoilers intact under the front end? Could make the difference.

Eric,
I would check the color of your anti-freeze. See if there is a brown film/foam inside the radiator...If yes I would do a flush.

Roy

Thanks for all the tips, everyone!

The car has A/C, but it's not working but the belt is still on.

All the hoses, belts, thermostat, etc were replaced in Oct of last year when the car was restored. I'll check them again to see if they're failing. Maybe the thermostat isn't working properly?

Upon visual inspection, I don't see any leaks. Guess that would lead to needing a true pressure test.

As for the air dam and spoiler, I've got the 78 Pace Car front spoiler on there.

In heavy traffic, the temp stays at 190-195 - just goes up at high speeds. Doesn't seem to ever go higher than 205-210 so maybe, if nothing else is wrong then maybe it's just the way the car is now at the ripe age of 29.

Does it have a fan clutch, and is it working properly?

LQQK said: Does it have a fan clutch, and is it working properly?

Yes - it does appear to have a fan clutch. I saw a thread on this earlier I'll have to look for so I can understand how to check it.