Engine Heating problem maybe??

[underpsi30]

I have a 1993 ranger w/ the 4.0 ohc w/ an auto trans. and I have noticed that after driving for a bit i see the temp gauge go to little before the middle of normal and then shoot back down alittle as I take it that is the t-stat opening up. but after awhile of driving after that point the temp gauge goes alittle past the half way point and stays around the "m" and "a" of "normal" on the gauge. It has never went past the "L" but was right at it before I would turn it off. I have heard several reasons and the cheapest being the t-stat could be not opening all the way or what not??? What do you guys think as I just want to get this figured out before I really start daily driving it. It does have 130k miles on it btw if that matters. Any help I would really appreciate it.

Thanks

 

[88_Eddie]

i'd start with the t-stat, like you said, they're cheapest

 

[Big Jim M]

Hmmm

All things must be considered. First where are you? What is the outsdide temperature? Have you took the radiator cap off and LOOKED into the radiator to see if it is entirely full? What modifications have you done to the engine?
Big JIm

 

[underpsi30]

it did it on my way home last year in september when it was 90 degrees at. I was on the way home on the highway running around 70mph w/ no a/c on about an hr or so driving i noticed it creeping towards the "A" and "L" of normal when I got home. I am in Indiana and it does it just the same as it did back then and now in the winter. It has a cold intake and flowmaster 44 muffler is the only mods to the engine. Now when I bought it I did notice there was no coolant in the overfill so I fill that up and it looked kinda dirty in there. And I filled the radiator up all the way to the top after "burping" it to make sure there were no air bubbles in the coolant system.

Thanks again

 

[Big Jim M]

Ok

it did it on my way home last year in september when it was 90 degrees at. I was on the way home on the highway running around 70mph w/ no a/c on about an hr or so driving i noticed it creeping towards the "A" and "L" of normal when I got home. I am in Indiana and it does it just the same as it did back then and now in the winter. It has a cold intake and flowmaster 44 muffler is the only mods to the engine. Now when I bought it I did notice there was no coolant in the overfill so I fill that up and it looked kinda dirty in there. And I filled the radiator up all the way to the top after "burping" it to make sure there were no air bubbles in the coolant system.

Thanks again

Have you looked inside the radiator lately? Small exterior leaks and small air pockets inside the engine can cause variations in the coolant READING.
The first indication of a small leak is a change from the usual temp reading.

If the radiator is completely full there may be a corroded connection at the temp sendor.. or even a faulty sendor.
Big JIm

 

[underpsi30]

where is the temp sender at and I could try that out as well..

Thanks again

 

[Big Jim M]

Thermostats

where is the temp sender at and I could try that out as well..

Thanks again

They are right there near the thermostat housing. There should be two of them. The ONE WIRE one tells the gauge the temperature. The one with TWO wires tells the computer the temperature. They are the ONLY devices screwed into the coolant!
They have different lectric plugs on them so they shouldn't be interchangable.
Big JIm

 

[underpsi30]

I have not had any time yet to change out the t-stat but have it. Anyways last night I was driving around for about 20 mins or so in city driving and noticed the temp slowly getting up to the "L" on normal so I pulled in my driveway and let it idle and it started to go slightly over the "L" so I shut it off... I just hope its not a headgasket... but heard that poor circulation and fan clutch can cause this as well as the t-stat??????

 

[Big Jim M]

General rule

I have not had any time yet to change out the t-stat but have it. Anyways last night I was driving around for about 20 mins or so in city driving and noticed the temp slowly getting up to the "L" on normal so I pulled in my driveway and let it idle and it started to go slightly over the "L" so I shut it off... I just hope its not a headgasket... but heard that poor circulation and fan clutch can cause this as well as the t-stat??????

As a general rule if it isn't PUKING it's coolant out it isn't a head or a head gasket.

This winter I had the same problem with my ranger when offroading. The grass was extreemly tall on that ranch and the grass seeds had filled the front of the A/C condensor and stopped most of the air flow. After backwashing with an air hose the heat went down and has stayed down ever since.
Big JIm