We recently replaced the 200 I6 with a 302 V8 in out 74 mav. We bought a new radiator for it. It is constantly getting up to 240 degrees when driving. We installed two electric fans, one in the front and one in the back of the radiator. It is still getting up to 240 degrees. Any thoughts?
What temp thermostat do you have in it, if any? Did you drill the small hole in the thermostat to let the air bleed out? Are you running a shroud? Stock engine or modified? We need more info to help out.
the stock radiator can barely cool a bone stock motor in perfect condition. a fan shroud with a mechanical fan is usually the most amount of air you can pull through the fan. switching to an alum radiator takes care of the problem easly
We put a 180 degree thermostat in it. Did not drill a hole in the thermostat. Not runnig a shroud, but we have an electric fan in front and an electic fan in back of the radiator. It's a stock 302 from a 1977 Thunderbird. But we added a 4 bbl intake and a 600 cfm 4 bbl carburator.
Check your timing ... if it is retarded it will be hot. Is the radiator very clean? If not, and it is a copper radiator, run muriatic acid from home depot through it. make sure the acid only touches iron steel or copper. It will destroy aluminum. I cured a similar problem in my 383 Mopar this way. Take thermostat out. Drained half the water, started the car, poured in a gallon of acid, waited 3 minutes, shut down car. Drain and refill with hose water and run/fush several times.. Runs 167 now on a hot day. Make sure you wear protective goggles and gloves, and have a hose standing by. I have done this to many engines over the years. On a car engine it is hard to get enough flow going to move the acid around... The stuff they sell at car part stores is a joke.
I would first look at these areas Not running a fan shroud of some sort could be the problem all by itself. Also what types of electric fans? Alot of the cheap store bought fans don't pull nearly the cfm they state, and also a fan infront and behind radiator could be hurting you to, causing air to fight itself while trying to extract heat. IMO your best bet would be to look through the tech archives about a tauras fan setup from a junkyard and also a 130 amp alternator upgrade, or just go back to mechanical clutch type fan and shroud. Also when is it overheating? At idle? City driving? Freeway driving? What are ambient temps?
I would be looking at radiator condition and the fan set up. If your using the stand alone fans that attach to the rad without a shroud your losing a ton of cooling ability. The only area of the rad that is working well is the area directly under the fans if they dont use shrouds. When your fans turn on check the temp of the air coming off them. It should be nice and hot if the rad is doing its job. This is my fan set up with a stock rad 9.5:1 motor and it runs at 195 steady all Summer.
Just a couple of observations.........................you should never, repeat never run a fan behind the radiator and then one in front. The one in front is robbing the airflow you need through the radiator..................take it off! I know, a lot of guys put the fan infront of the radiator because of limited room.....................you loose airflow with the fan in front!!!! A shroud is needed! If you have a fan behind the radiator and with the motor running you should be able to put a dollar bill up against the radiator and have it stick there with the suction the fan is creating.........................if not you need to get shroud or maybe a bigger fan......................IMHO
are you using an elec temp sending unit, or mecanical, have you checked the water temp with a thermometer to make sure its really getting that hot?
Just a thought, but when I replaced my radiator I ran into overheating problems. "Burping" the system finally remedied the situation
That's why I asked about the hole in the T stat. A 1/8" hole drilled in the top of the T stat lets the air find it's way out....
Just a thought,did you get a new water pump? If so you may have gotten one for a serpentine belt which is a reverse turn pump. Check your part #s and make sure your pump is a clockwise rotation.
