Desperate Overheating advice.

[Sniperdyer]

Desperate need of Overheating advice. So I've been dealing with an overheating issue for quite some time. I had a small crack in the radiator and replaced that. I replaced the water pump, clutch and fan. I replaced the thermostat with a cheap dura last one from AutoZone (I didn't test it in pot with Boiling water to see if it worked.)
I've also replaced the top and bottom hose. I've replaced the spark plugs and wires. I've burped the radiator using a burping kit to remove air. I've done the combustion test with the blue liquid to see if I have a gasket leak and the test passed. The liquid didnt change to yellow and stood blue. To confirm the liquid worked after I placed on radiator opening I placed it near the muffler to make sure the liquid would change color to yellow ( which it did once it picked up the gas).
I have noticed that the bottom hose is not as hot as the top hose. Could this be the problem, but from where? I think I'm going to get another thermostat and replace it , but before I install I'll try testing it in a pot of water. Can you guys recommend which temp I should get? I know stock ones are 190 and up according to Hayes book.

 

[Turdle]

Did the new radiator have a new cap?

What is happening to confirm overheat?

 

[Josh P]

What symptoms are you having that it is overheating?

 

[BKennedy]

Did you use a quality water pump? My Explorer stopped running hot when I replaced the water pump with a Gates pump. No more Autozone crap.

 

[Sniperdyer]

Did the new radiator have a new cap?

What is happening to confirm overheat?

Yes. I've swapped the cap out twice with new ones. The temp gauge increases and coolant reservoir starts back flowing and gargling. I've done it also while cap was open and it's shot out

 

[Sniperdyer]

Did you use a quality water pump? My Explorer stopped running hot when I replaced the water pump with a Gates pump. No more Autozone crap.

I've replaced it with one from rock auto and when I took off the old one the blades where still good on the old one but the clutch needed replacing so I wasn't to upset I removed it.

 

[BKennedy]

What brand water pump? I order off RA regularly, but I'm picky about brands.

Also what fan clutch? I replaced the fan clutch with a heavy duty Gates the same time as the pump. It's louder than the old one, but it works.

You might still have air in the system. Try squeezing the radiator hoses while engine is running. See if you get more bubbles. Be careful of the moving parts. I've found the best way to burp the system is to get one or both front tires up onto a 6' boulder, but most Explorers can't so that. The sharp angle seems to get all the air out.

 

[Sniperdyer]

What brand water pump? I order off RA regularly, but I'm picky about brands.

Also what fan clutch? I replaced the fan clutch with a heavy duty Gates the same time as the pump. It's louder than the old one, but it works.

You might still have air in the system. Try squeezing the radiator hoses while engine is running. See if you get more bubbles. Be careful of the moving parts. I've found the best way to burp the system is to get one or both front tires up onto a 6' boulder, but most Explorers can't so that. The sharp angle seems to get all the air out.

It's the US MOTOR WORKs. They currently only have two water pumps with the fan clutch assembly for the 91. I selected the one with A/C max cooling

 

[BKennedy]

Forgot to ask you what radiator you bought. How many rows?

 

[Sniperdyer]

Forgot to ask you what radiator you bought. How many rows?

KOYORAD A1164 2 rows

 

[Sniperdyer]

I found this in an old post from 2013. Whagg t do you think about the heater he mentioned here ? Are these the two lines that go into the firewall above the power distribution box?

 

[Turdle]

Just turn your controls to hot and floor, with front wheels at least 6" higher, as suggested above. Cold engine running . This will force air out of heater core and toward radiator cap. The cap should be the highest component for proper burp

 

[Sniperdyer]

Just turn your controls to hot and floor, with front wheels at least 6" higher, as suggested above. Cold engine running . This will force air out of heater core and toward radiator cap. The cap should be the highest component for proper burp

So shall I try this while the burping kit is connected?

 

[Turdle]

No, just remove radiator cap right after starting. Important hot and floor are selected.

Look down into radiator, if low, add coolant directly into radiator until level is just below neck

 

[Sniperdyer]

Would a clogged or faulty heater core cause these overheating issues? I don't have a problem with heat coming out of vents but have had a strange knocking noise for years that comes and goes and I think it's from the location of the heater core. Could an air pocket be trapped in core?

 

[Turdle]

If you do the above, and get heat once engine reaches operating temp, it isn't clogged.

 

[Josh P]

The us motor works fan clutch is a standard duty item, I'd ditch it for a severe duty unit like a hayden 2794. Also a different fan with more blades will move more air through the radiator.