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Cooling Problems


1984ranger28

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Hi, I recently replaced my stock radiator for my 2.8l V6 with a used one from a 2.9l V6. It heats up to 210 degrees while idling. Is this normal. It also appears that the radiator from the 2.9l is plastic, I wouldn't think they would have started putting in plastic radiators in 86, but I could be wrong. Thanks, Lucas.
 


RonD

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A little hot for at rest engine, 185-190degF would be spec, with 190degF thermostat

Used radiator?

Did you do a Flip Test on it to see if there were any clogged passages?


The 2.8l did have a coolant flow design issue at the center of the heads so did get a hot spot, but with good water pump, so good flow, it wasn't a big issue, you would just get a bit of overheating earlier as water pump wore out or other cooling system parts started to get clogged up, vs say a 2.9 or 4.0l

In general an engine that heats up when stopped and at idle would be diagnosed with a failing fan clutch first, and worn water pump second

When driving the vehicle, vehicle's speed pushes air thru the radiator allowing for best heat exchange at radiator
When stopped the Fan takes over that job, it's not as good as driving but better than nothing, lol, so if engine starts to heat up when stopped it could be the fan is not pulling enough air thru the radiator, which means fan clutch is not fully engaging
Fan clutch has a bi-metal spring on the front, it is heated up by the radiator, not the engine, as it heats up it closes a valve inside the clutch which cause the fan part to spin closer to engine RPMs, so more air flow.
The clutch itself can fail, or center of radiator can get clogged up so bi-metal spring doesn't get hot enough for full engagement

After radiator/engine are fully warmed up, shut off the engine
Try to spin the fan, it should not spin, it will move but be hard to turn, thats engaged
Also pull the Fan shroud back and run your hand over radiator fins, should have a nice even heat, any cooler spots are clogged passages, no warm coolant flowing thru them.

Fan shroud is a VERY important part of the cooling system, fan can't pull air thru the radiator without it, it will pull it from the sides

Plastic radiators have been around a long long time, so 1980's would be possible.
Plastic rads are cheaper to make and for the most part last the same as metal, but metal can be rebuilt vs replaced when they get clogged up or leak, so more "earth friendly" :)

Manual trans radiators were often thinner than automatic trans radiators, so when getting a radiator always get the automatic version even if you have a manual trans, most 3rd party are automatic in any case since it will work on either
 
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1984ranger28

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I think I may have found the problem, or whats contributing to it. The radiator cap is 16 PSI, while stock is 13 PSI. After doimg some research, every pound if pressure added to the system increases temp by 3 degrees, which would explain why its 9-10 degrees hotter than normal.
 

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While you should run stock Rad cap pressure, thats not the problem

Each pound of pressure raises the BOILING POINT of 50/50 water/coolant mix by 3deg not its temperature
 

1984ranger28

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Alright, thanks for clarifying. I drove my ranger until it got up to operating temp, got under and tried spinning the clutch fan. It was not hard to spin at all. It spun an 1/4 turn once I stopped spinning it. So Im guessing new clutch fan lol. Also, how cold shoukd the coolant be after going through the radiator? Thanks.
 

RonD

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Yes, reads like a failed fan clutch

Radiators provide 15-20deg cooling

If upper rad hose coolant is 190degF IN
Lower rad hose should be 15-20deg cooler OUT


You can spin the fan without getting under the truck???
 

1984ranger28

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Checked the coolant coming out of the radiator with infrared gun, about 17 degrees colder than the coolant coming out of the engine, so I'm gonna guess faulty water pump. And the fan does have slight resistance, but its not locking up (When operating temp).
 

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Replace fan clutch if it not tight after full warm up, should have LOTS of resistance, i.e. you can move it but not spin it

If you have a friend with a vehicle with a mechanical fan, check his fan after his vehicle is warmed up
 

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