overheating problem

[spoolinhard]

Car is fine up to speed. in town it starts overheating. it overheats very slow. if I dont turn on the heater to help it out it will go all the way hot unti lI get the airflow again. Fan is working fine. Heres what I think it is. Built this car before I really had any idea of what was important to make power, Used a stock TII rad and had it recored with a thicker core and shortened about three inches so that I could have a straight in shot to the IC with no angles. I really think this is it, what do you think? Three inches make a big enough difference?

[turbovanman²]

Resisting the jokes, must resist,

Define overheating? are you using the stock guage or aftermarket?

Too small rads show up on the highway or at speed, around town, they will run hot as they electric fan comes on at a higher temp. If your that concerned, just leave it turned on all the time.

[tryingbe]

What car? What thermostat?

[black86glhs]

Have you checked to see if the rad is hot all the way up and on both sides?
Almost sounds like it is partially plugged.

[OmniLuvr]

sometimes the outside of the core will get plugged too, maybe intercooler is blocking airflow? place a rag or piece of paper in front the radiator, if it sticks u SHOULD have enough airflow. stock or aftermarket fan? i used an aftermarket slim fan without shroud, it SUCKED, once it warmed up the fan could not pull enough volume of air across the fins to cool it back down. it also matters how many fins per inch they used when building the core. the more the better to cool with. partial clog could be a possibilty if they used small tubes when building your three row, they had to make my tanks wider to fit the three row in with almost the same size tubes as the two row. the smaller tubes will cool better but will also glog up faster. i work at a radiator shop and thats my two cents.

[RoadWarrior222]

Don't forget the usual suspects, lack of pressure due to leaks and/or faulty cap, lack of flow due to hose kinks and/or faulty pump, and/or inadequate fill.

[spoolinhard]

using aftermarket fan. Not sure on what T-stat it is

[1966 dart wagon]

Id put in a 180 degree thermostat with the hole drilled in it like garyd did on his site, then run either water wetter, or royal purple's purple ice, I did and it make a difference, also the s10 air dam helps with cooling too, less air to go under the car and it goes though your radiator instead. Good luck

[OmniLuvr]

if the fan is 12" or smaller i would fabricate a shroud for it, i had a 12" that worked alright until the blades broke off, then i used a 10" and it didnt work well at all. once it heated up it struggled to cool my engine, once the fan came on it didnt shut off till i started moving down the road. that fan eventually wore out the rubber pads and wore a hole in my radiator tubes. i put the stock one back on (5 blade with shroud) and have had no problems since. i would say that not having a shroud could be your issue, what amperage and cfm is the fan?

[johnl]

Confirm that the system is completely purged of air. Try idling it, adding small dashes of water slowly and often. Then, feel the radiator, fins and tanks, in different places to ensure that it is full to the top with coolant; you can use a non-contact laser thermometer too, of course. Check obvious assumptions too - confirm that the pump is circulating and the thermostat is opening as well.

[looneytuner]

does it overheat with the a/c on?
There are TWO relays for the fan.
I had overheating start when the weather got cool. The relay for the water temp had gone bad during the summer and didn't show up till I turned off the A/C.

[OmniLuvr]

any luck yet? id like too help you spoolin, but some updates would be nice. im guessing this isnt a daily driver? what kind of vehicle? i assume fan becuz it cools around town (airflow) but not when standing still. i would assume plugged radiator bcuz u said that when u use the heater it will keep the vehicle from overheating. i wouldnt assume pump becuz you will lose the heater sometimes if your pump doesnt flow coolant to it. you might be having a headgasket starting to go bad too, does it build pressure fast? does your pressure cap look bad or does it constantly leak pressure into your overflow (while running or off?).