91 Ranger wont stop overheating

[superiorite]

I have a 91 ranger with man 5 spd 4X4 and v6. First off I have changed the thermostat. then took out the radiator and flushed it alot, also Flushed the Engine, then put everything back togeather and still overheats it slowly creaps up there But I can idle the thing for 3 hrs str8 and it stays fine, and when I am running it normaly arround 55 down the hiway it slowly starts to overheat, then when it happends I downshift to get the R's up and then it cools but only when ya rev it up alot almost to Redline or run in low gear with the R's up high. I havent a clue on this one Its really bugging me. I am thinking of trying to find a 2 core or Bigger radiator for it But the ones I found for it are over 200$ and I really dont have the cash to spend on it. Please in need of awsners Have 12" of snow comming tomarrow. thanks

[SultanGris]

Originally Posted by superiorite

I have a 91 ranger with man 5 spd 4X4 and v6. First off I have changed the thermostat. then took out the radiator and flushed it alot, also Flushed the Engine, then put everything back togeather and still overheats it slowly creaps up there But I can idle the thing for 3 hrs str8 and it stays fine, and when I am running it normaly arround 55 down the hiway it slowly starts to overheat, then when it happends I downshift to get the R's up and then it cools but only when ya rev it up alot almost to Redline or run in low gear with the R's up high. I havent a clue on this one Its really bugging me. I am thinking of trying to find a 2 core or Bigger radiator for it But the ones I found for it are over 200$ and I really dont have the cash to spend on it. Please in need of awsners Have 12" of snow comming tomarrow. thanks

is your fan cluch working? is your radiator full of bugs, dirt or other debris?

[Escorts4ever]

Just a thought?? Is the impeller on the water pump rotten away and giving you limited circualtion? It has happened in the past. Make sure the heater core is clear too. It uses the heater core as a bypass, thats why there is no bypass hose on a 2.9 or 4.0L.

[Crasen]

Anytime you have an overheating problem start with the basics. Take the radiator cap off, start your engine and let your engine warm up to normal operating temperature. Now you want to check your coolant level with the engine still running and it at normal operating temperature, if it is low at all just add coolant to the radiator with it still running, you want to make sure you get all the air out of the system, air can sometimes cause overheating problems in itself. Turn your heater on high. Do you have good heat? If you do have good heat your heater core is probably not clogged, but it is always a good idea to flush it here and there. If you do not have good heat turn your heater on low and check your hoses going to the heater core, if one is warm and the other is not you may have a clogged heater core. If neither is warm see if you have any control valve that could shut off coolant flow to the heater hoses. Replace the radiator cap. Shut off engine. Check the belt that runs your water pump, especially if you hear a squeel while you drive, if the belts slips it could cause it to overheat. You can try Spraying water from a water hose through the fins in your radiator, you would be suprised how dirty they can get, that in itself could slow down airflow or heat from being transfered from the fins to the air. If you still haven't found your problem you can try changing your radiator cap, they are pretty inexpensive. And as someone has already stated the water pump could have a warn down impeller. The blades can wear pretty bad if the engine coolant has a pretty high level of acidity

[superiorite]

OK here is what I found out. 1st The fan clutch was not working properly It would spin about 50 times after turning the truck off from an Idle. I fixed this By Welding the Clutch Direct So no more clutch in the fan and it works wonders for fixing the problem.
2nd thing we did was removed the Tanks on the radiator and found that 65% of all the pasages were pluged So with a thin thin peice of metal I got each one working again and open.
3rd thing we found was that one of the tanks on the pass side of the truck was cracked and has been for some time with another radiator tank installed when we put the radiator back togeather.



Ok So now the truck dosent overheat Although we have another isue. I dont know if this is a normal thing or a Thermostat But when you are driving the truck at a normal speeds on the HIway It goes up to M and then drops rapidly to N this dosent stop at all. My thaughts were that from haveing a direct fan that the Truck is being cooled off so fast that its causeing the thermostat to close and open alot more than normal that in my mind would give me the Reasoning behind the heating and rapid cooling. As for the heat in the truck it works great. OK now for the next thing I am havng is the truck when idleing has a tendency to sound weird Like a thumping from below the thermostat. Only when idleing after a long drive and when you idle you can feel the Heather hose on the return side Pulsing in your hand. My thaughts at first were a head gasket but it continues when the truck is no longer running for about 45sec-1 min sometimes longer. Now this is my main concern What is causeing this pulsing in the hose. One theory I have is something to do with the thermostat closing and opening rapidly possably faulty. Also I must add it uses NO coolant at all. Although the truck exaust smells like chinnese take-out food.(AKA Burnt Eggrolls)

[SultanGris]

90 ranger 4.0

it all started when my intake manifold gasket went out, and when i replaced it, i also replaced head gasket because the truck had 190K on it, and i didnt want to have to take it all apart again anytime soon

in my quest to fix this problem, i pretty much replaced the entire cooling system,

water pump, heater core, radiator, all hoses, thermostat, radiator cap, temp sending unit,

still had same problem, and about a year later my head gasket went out. i assume, as all water in radiator was forced to the overflow box,

replaced head gasket and heads, lasted 2 months, happend again,

replaced head gasket and heads again, lasted 1 day,

at this point i gave up, figgure i mustve drove it to long and cracked the block, but i never took it out to check for sure,

but as i replaced everything but the block, thats my assumption. this engine sucks water from the top of the radiator instead of the bottom, and i did drive it for a couple weeks before i got the money to fix it, always having to add antifreeze every time i stopped, but i spent a fortune trying to fix that guage fluctuation problem, and i never did. It was fine before my intake gasket went out, and after that it never worked again. people on here told me not to worry about it, and that it wasnt accurate anyway, but if its fluctuating severly, its obviosly not normal. thats my story, hope it helps you out.

someone mentioned that its possibly just an air bubble in the upper radiator hose, due to how it routed, but i tried everything to get all the air out, squeezing the hose, elevating the truck on one side, both sides, every possible way, but it never fixed my problem.

also, depending on how long your fan cluch was malfunctioning, sometimes they can cause your water pump to go out, because they can wobble, causing extra stress on the bearings. so i would see if your water pump is dripping every so slightly from the bottom.

[rainbird-too]

Just a thought did the thermistat get put in upside down

[SultanGris]

Originally Posted by rainbird-too

Just a thought did the thermistat get put in upside down

well, there really is no upside down, but if you put it in backwards, which i didnt, you would have severe issues.