I posted a message on the forum last week about the engine running hot. I got the Pertronix hooked up tonight and took it for a drive. On the highway it runs 20 degrees hotter than in town, shouldn't it be the other way around? It reads 210 in town and 230 on the highway. At highway speeds more air is moving thru the radiator, right? I had the shop put an infrared sensor on the block and heads, 200 degrees idling after 30 minutes driving. The engine is brand new, I'm a little worried that something was put together wrong.
Thanks,
Matt

It could a number of things.

First, make sure it is actually overheating, which it looks like you've tried.

Since it's a new engine, make sure enough coolant has been put in. It may simply be low.

The lower hose may collapse as speed goes up...it should have a spring inside it. If the spring is old, it could have rusted away or not be there at all. You should be able to squeeze the lower hose and feel if there is a spring in it or not.

The timing could be too advanced...that can definitely make an engine run too hot at speed.

The radiator cap may be bad...not holding pressure. Have it and the cooling system pressure tested.

Is the new motor a high horsepower torque monster? More power puts out more heat to be carried away. The cooling system may simply not be up to a more powerful motor.

It could be other things as well. I'm sure Ken and others can come up with other possibilities. Follow the basics of diagnosis and you should be able to figure it out.

Good information. Also, is it designed for an EGR valve? If so, an inoperative one can make it run hot.
You may also want to make sure the exhaust is not restricted. Do you have the front spoiler in place?

Thanks Guys. New hoses, Stant radiator cap, 190 degree T Stat. No front spoiler. This may be a reach, but I'm wondering if the thermostat is opening all the way.

Matt

The front spoiler is critical on our cars. There are some other models equally critical. That thin piece of plastic makes a lot of difference.

Even sitting at idle, not moving, the spoiler makes enough difference in the air flow to make a noticable change in engine temp. Going down the road it can be huge. I would start there, and see what happens.

Thanks Ken,
I'll let you guys know what I find out.

Matt

Another update. I spoke with the vendor that I bought the temp sender from. He said he's been having alot of trouble with Lectric Limited senders. The first one I got from them didn't work at all, so this one maybe bad too. I did find a cool site though. www.stewartcomponents.com they have some pretty cool stuff.
Matt

my c3 does the same thing i cn't run at 70 or above on the interstare long. around town its fine. i run the advance ahead of whats recmended to get more low end power. and i'm sure it would run cooler if i retarded it.. other things to look at, the fan cluth is workig, when hot it should offer some resistance to turn by hand, and not spin freely when the engine is turned off. also have the radiator profeshionaly flushed, there are years of junk covering the tubes and who knows how many clogged.