Overheating

[Pearson289]

I just had my radiator replaced and it's still wanting to overheat in idle. Any ideas what to try next?

[Adogg]

Start replacing some censors in the car IAT intake air temp and engine coolant temp censor an other ones along that line until you fix the problem good luck hope this helped

[matcox83]

Yeah, maybe your MAF needs to be replaced. Just kidding! Sorry, i couldnt resist. Our old engines don't have any electronic sensors.

[Adogg]

Sorry didn't no what kind of car the mobile app sucks doesn't show much information about the person now I feel dum lol good luck guys

[matcox83]

Seriously though, you need to make sure the coolant is flowing thru the engine like it is supposed to and that your fan is moving enough air across the radiator. You can check for flow with the cap off. You should also make sure the thermostat opens when it supposed to. Should be able to find procedure on YouTube. You could have something more serious but rule out the cheap easy stuff first.

[Aggiesrok]

Sounds like a wrong temp thermostat. It's fine when driving, but only hot at idle? Seems silly, but could the fan be on backwards and cause a higher temp at idle?

[Pearson289]

I had to replace the radiator after it dumped all the fluid out and it just poured out when I put some in. I replaced it and it still runs hot at idle. Is it possible that whatever is causing this destroyed my old radiator and can do the same to this one? I got out the heat gun and it read 199 on the top hose. Is it possible something can be destroying my radiators?

[Aggiesrok]

Originally Posted by Pearson289

I had to replace the radiator after it dumped all the fluid out and it just poured out when I put some in. I replaced it and it still runs hot at idle. Is it possible that whatever is causing this destroyed my old radiator and can do the same to this one? I got out the heat gun and it read 199 on the top hose. Is it possible something can be destroying my radiators?

The thermostat should open at 160 degrees, I think that's standard. Did you replace that?

[Pearson289]

Not yet, but considering that and I recently started to get smoke coming from the oil fill lid. You gotta love the oldies.

[matcox83]

180-190 deg on an old one. 160 works on a new one to trick the computer into dumping more fuel. You can run a 160 on an old one as a last resort.
When you build up pressure, the weakest link goes. The system has to be able to tolerate 16 psi or so to not leak. If, big if, you have a blown head gasket, that would cause a lot more pressure. But make sure everything else is in good shape before you worry about that.

[Pearson289]

I considered that, but it's running great. Wouldn't it give me some type of indicator?

[matcox83]

If a head gasket leaks to a coolant passage you'll likely just overheat. If its bad the increased pressure can damage parts (radiator, heatercore.) I wouldn't worry about that though until you're sure everything else is good.

[primer2tone]

Yeah, start with the thermostat.

And then a coolant pressure test.

[Rosco]

If its overheating only at idle I would suspect that the fan isn't kicking on. I would assume this car still uses a mechanical fan so if a fan clutch is applicable maybe it isn't engaging properly.

[Aggiesrok]

If it was a head gasket, you would have white smoke from the tailpipes and it would not get better.

[mike Franklin]

Overheating is aggravating. If the tstat is working you could have restricted flow in the block. At idle there is less circulation. You can flush the system if it's plugged. With the radiator cap off and the water at full temp you should see the water circulating. (Don't take the cap off while hot). My work van gets hot if there is air in the system but I don't think that is an issue on the older cars.

[DDTCM]

My 84 olds was doing this. White smoke,water from the tailpipe. It started this after it overheated. My fix was changing the thermostat and using a non thermal fan clutch for increased air.

[My68mustang]

Originally Posted by Rosco

If its overheating only at idle I would suspect that the fan isn't kicking on. I would assume this car still uses a mechanical fan so if a fan clutch is applicable maybe it isn't engaging properly.

I Agree it might be the fan. My 68 did the exact same thing. I had an electric fan put in and it helped a lot.

[mike Franklin]

I'm pretty sure this is a belt driven fan. I don't know what year the car is either but since this the classic forum I assume it's not new enough for any orher kind o' fan b

[Pearson289]

It's a 65 with the 289. I have been playing with it and the top hose gets up to 200 and I've heard it's not a problem until it gets to 220. Its got to be something new. I have driven this car is 90 degree days and not had it come close to overheating and now it's getting close in 60 degree weather.

[Aggiesrok]

So it overheated at idle before the radiator was replaced? Did you replace the heater core? If your thermostat is good and the fan works, it seems like a flow problem. At higher rpms it overcomes the problem.

[BA68 mustang]

Just an idea but the idiot I got my car from put the head gasket in backwards so it cooked itself...I didn't really drive it before I tore it down so I dont know if it only overheated at idle or not

[salcruz]

Just a simple question, is the fan shroud still on? No shroud could cause that at idle.