Overheating at rest

blown5.5 · Dec 22, 2004

Agghhh that age old problem of overheating. If I sit for more than 3-4 minutes in warm weather the temp gauge starts it's migration to meltdown. While this would appear to be an easy problem to fix, it's solution has eluded me for over two years. Currently the car is running a FoMoCo 8500-C 3 row aluminum radiator (3 times the surface of the original), a Meziere 55GPM Electric Water Pump, a Black Magic 15in (2800CFM) fan, and Propylene Glycol Coolant (far better heat transfer). The fact that it occurs at rest usually points to a flow problem (air or water), however with the current setup it probably flows more than the stock items did at 40MPH. I don't believe there's an obstruction in the block as it was set up professionally (DSS short block). The Glycol is not contaminated as the block has been water free since it was set up. I installed a 140 Amp alternator and oversize battery, so the juice to the fan and water pump doesn't drop as the engine idles. I have tried several different combo's for thermostat (180 - 160 - none) and will try a restrictor plate as soon as Jeg's gets around to sending it. The only other non-stock item is the heater is disconnected. The bypass hose doesn't look kinked, but I'm having one made up that is a perfect half circle of the proper size. I'm hoping one of you can think of something I've overlooked. It's really embarrassing to sit in line for registration at the drags and have to constantly fire up and shut down the engine while moving forward, but it's either that or push the car forward which is worse -- Aggghhh

racerraj · Dec 22, 2004

I really don't think the Black Tragic is moving enough air. Try a Taurus fan with a DCCONTROL fan controller, and I bet the problem will be solved.

DELOS02GT · Dec 22, 2004

You took out the thermostat and the car still overheated? It does sound like a flow problem and my '91 had kind of the same issue. I had almost the same set up as you but without the water pump. I replaced the thermostat and the problem was solved. I always had a weird feeling about those elec. water pumps, it could be it's not getting enough power at idle too.

crunchie12268 · Dec 22, 2004

Yeah that black magic fan is the best. I have a taurus fan with everything but the 5 dollar relay. If you want it I can give it to you cheap. Also, I don't think the electric water pumps pump near as much as a mechanical water pump. I think Micheal Yount said that in another post but I am not sure. I would get a mechanical pump and see if that changes anything.

90mustangGT · Dec 22, 2004

To test. Make sure plenty of air is being blown though the radiator. Then with the fan running, check the temps of the upper and lower hose. The lower hose should be much cooler than the upper. Pull the upper hose and see if your getting good flow. 37GPM should be flowing pretty good.

Your suposed to rebuild the electric waterpumps every so often arn't you?

baskin · Dec 22, 2004

The black magic doesn't flow anywhere near what a taurus fan flows and flows even less under backpressure. Go with racerraj's setup or with a t-bird or late mark viii setup.

An electric wp will flow more at an idle than even a high quality mechanical pump by about 3:1. A Mezeir will flow about 5:1 over a mechanical at idle. If the pump is working correctly, it's not the problem.

With regard to the temp drop across the radiator, once the thermostat is open, there is no correlation between the fan and the temp drop. The temperature rise from the inlet to outlet of the engine is dependant on heat generation and inversely dependant on coolant flow. The smaller the number, the better, With a mechanical pump, 12 degrees is about normal. It should be less with the electric pump.

89MustangGX · Dec 22, 2004

I would also think the fan is the problem. Maybe even put the original fan back on there to test before buying a new fan?

green · Dec 22, 2004

same thing happens to the old mans car, its not a stang, its a plymouth acclaim. its the same like you said 3 to 4 minuts of ideling and boom the temp gauge is 3 quarters the way up the gauge. but when your driving the temp gauge barley moves up, it pretty well stays at the bottom of the gauge. very wierd, id like to know the answer to these questions to, later

jibbers93gt · Dec 22, 2004

You said it yourself > it is probably a lack of airflow. If it were mine, I would put a 180 thermostat in it and upgrade the electric fan. People with milder combo's have had problems with that fan.

Michael Yount · Dec 22, 2004

The electric pumps don't flow as much at peak rpm as mechanicals which flow more with increasing engine rpm; but most electrics are capable of flowing far more at idle than the mechanicals because they aren't limited by low engine speeds.

Sounds to me like a fan problem - just not moving enough air across the radiator. Listen to Baskin above - he'll shoot you straight. And his variable current/speed controller will run both your pump and your (new) electric fan to control engine temps. Go to www.dccontrol.com. I use one of his fan controllers on mine - nothing else even comes close for controlling both your pump and whatever fan you end up with. The Taurus 3.8, the Mark VIII or the SPAL twin 11" fully shrouded units all seem to move enough air for just about any set up.

Lose the Black Tragic.

Overheating at rest

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