91 Ford Explorere 4.0L Manual 4X4 Temp. Problems.

[Murdoc006]

I have had this vehicle for about 2 weeks now... Been having alot of Engine temp problems. It runs fine and is showing no signs of a blown Head or gasket yet the temp Runs above normal. About 3/4 of the way to Hot.... I have no Heat in the cabin and after running the vehicle when i first got it it would Bubble into the Surge tank. I have Flushed out the radiator Twice and replace the Thermostat, Clutch Fan Blade and Clutch, And the previous owner just put a new Water pump in it. The bubbling has stopped so i am assuming that the air is out of the lines but it may be possible it still has some in The engine somewhere. Also when i follow the Housing to the thermostat up to the Hose leading to the top of the radiator i can grab the hose and it feels empty. Now after driving about 30 miles on backroads my Temp Gauge reads high so i open the hood and i can grab the Radiator Cap and it is cool. The Top of the Radiator is hot to the touch but i can touch it for a second or 2 before it is too hot if you know what i mean. I am Out of ideas here. The only thing i can think of is the radiator may be clogged, the new water pump isnt working properly or there is a block going to the heater core which i have yet to bypass to see if that is it. Again i have put a New thermostat, Complete new Fan Clutch and Fan, a new Radiator Cap, and i have flushed the Radiator twice.... Any Ideas?

 

[Verno]

If you have NO heat, and you are overheating it sounds like heater core blockage. Easiest way to flush one is using garden hose to backflush the heater core. I think there is a thread or sticky on here, try putting backflush or heater core in the search. You might also consider getting the radiator cap pressure tested. As a side note, is the radiator itself unobstructed?

 

[Murdoc006]

I havn't had the Radiator Cap pressure tested but it is a new Cap. Also we Took the hose clamp off the Thermastat housing and My friend blew into the Radiator and water came out the house the went to the housing so i am assuming that the Radiator isnt blocked. Also when i said we flushed it twice we Did a back flush from a small hose leading to the Heater Core and Flushed the radiator Through the cap and out the Hose to the thermostat on the other side of the radiator. Clean water Came out both times.... I Ran it today for a little while and it never Went passed the 3/4 Mark on the temp gauge and when running in valley like areas it ran at Normal Temp.... For instance i live in a Valley Lower than the rest of the area around me and it runs normal No matter how hard i push it. I get into town and it heats up. Im not sure if this is just a coincident yet but already looking into replacing the Temp Sensor on the block. Luckily tomorrow is payday.

 

[Verno]

As for the running cooler when in the valley and warmer when in town, that is normal. In town driving, you are running lower RPM's and stop-n-go which creates a burden on the motor (heat wise), the lower RPM's are drawing less air through the radiator to cool everything; whereas on the open road you are pulling a greater volume of air through to cool it. What are you running in it (water or antifreeze mix?) if it is straight water this will not cool down as effectively as a mix (50-50)
As for unobstructed radiator, have you tried to force air or water (under some pressure) from the back of the radiator to ensure your cooling fins aren't clogged up?

 

[Murdoc006]

It's a 50/50 Mix and I'm going to reverse flush the radiator again with the garden hose to the heater Core T Nozzel that i have installed. I mean i am sure the vehicle is fine because it runs great and doesnt ever go passed the "L" in "NORMAL" on the temp gauge and usualy sits between the "M" and "L". I just want the peace of mind that it isn't going to overheat.

 

[Verno]

Sounds like you just need a new sensor then. There is a test you can perform on the temp sensor (ohms test) IF yOU WANT TO. Can't remember exact numbers, but I rember reading that thread on here before, also is in the Haynes manual. I'd say either get used to it being in the upper range of normal, or replace temp sender. BTW My 94 Ex runs normally at about the "R" once fully warmed up!