Intermittent Overheat Problem

[SwampSurvivor]

Originally Posted By: airbatica
I literally just replaced the thermostat in my 2002 3.0 Ranger last month for the exact same symptoms. For grins, I couldn't boil the old thermostat open on the stove, so it was definitely done after 170K miles. I also took the opportunity to flush the cooling system, and switch from the old school green formula coolant to Zerex G-05. Note that mine was delivered with the green (owned it since new). They switched to G-05 later in the 2002 production run as I recall.


The cooling system on the 3.0 Ranger must be different than the 3.0L Vulcan Taurus. I remember the thermostat on my Taurus was stuck shut and I drove it an entire summer like that ... because it never showed above "normal" on the gauge.

 

[exranger06]

Update: Well I don't know why I assumed my coolant level was fine, possibly because the reservoir was still at the correct level? Maybe because this problem didn't seem indicative of low coolant? I don't know. But I was going to start changing out the thermostat tonight, popped the rad cap off, and saw that the coolant is very low. Did a pressure test and found out the radiator is leaking. I'm pretty annoyed at the moment. Annoyed with myself for not checking the coolant sooner, and annoyed at the junk aftermarket radiator that failed after only about 28k miles. (Truck was in a front end accident a few years ago and radiator was replaced).
So I have to order a new radiator and put this job off for another few days. I guess I might as well replace the thermostat anyway since I'm already there. But if it turns out to be a pain to do, do you think I can skip it? In other words, could my original problem be caused just by the low coolant and leaky radiator, or is it still likely a thermostat problem?

 

[Nick1994]

I would still replace both.

Make sure to replace the radiator cap, it isn't letting the overflow coolant into the radiator.

My mom's Buick Rendezvous had overheating issues and I realized along with that the overflow coolant wasn't getting into the radiator. A new cap fixed that, now the radiator stays full (head gasket is blown, coolant getting into the exhuast).

 

[DoubleWasp]

Originally Posted By: Miller88
Hmm. It's something I will have to look into if I get a Duratec Ranger. I don't trust pressurized reservoirs


If you convert it to a non-pressurized, you will have tons of airlock and overheating. The entire cooling system design depends on having a pressurized coolant reservoir.