HELP! Temp Gauge Flucuation

[poopjohn]

Hello everyone,

I have a 1993 Ford Explorer 4-wheel drive, and my temperature gauge likes to fluctuate from cold to the half way mark. Anyways, i know my cooling system is functioning properly, since I have replaced the radiator, the radiator cap, the thermostat, the temperature sending unit, the coolant is full, and the hoses are fine and sealed. I've practically replaced everything, and yet to no avail. (My radiator was beat up so I had to replace it anyways.) So, I figure that only two more options remain, a faulty ECT or gauge. It just bugs the hell out of me to totally redo the cooling system, and I'm not even able to see the crisp steady pointer in the center of the gauge, or at least not moving. Does anyone know what could be the problem? Thanks.

 

[surf]

There could be air in the system. Try burping the system to see if that helps. Otherwise it looks like the only things left to change out are the water pump and fan clutch. I am dealing with the same thing but I hope changing the sending unit resolves it.

 

[burgundy1994xlt]

The sender (to the guage), to the left of the manifold, was the culprit when my guage was doing that. The sensor is the one on the right.

Coolant Temperature Sender:

http://www.rockauto.com/catalog/moreinfo.php?pk=40556

Coolant Temperature Sensor:

http://www.rockauto.com/catalog/moreinfo.php?pk=1983986

 

[poopjohn]

The sender (to the guage), to the left of the manifold, was the culprit when my guage was doing that. The sensor is the one on the right.

Coolant Temperature Sender:

http://www.rockauto.com/catalog/moreinfo.php?pk=40556

Coolant Temperature Sensor:

http://www.rockauto.com/catalog/moreinfo.php?pk=1983986

Well, when I bought the sender, the first thing they showed me was the sensor. and i said i needed the sender. So I guess I will go up there and buy the sensor... Hopefully I get it to work, i'll let ya know

 

[poopjohn]

No success

Replaced the ECT today, to no avail. The ECT didn't solve the fluctuations. Any other suggestions???

 

[qtrmill]

I have the EXACT same problem... If i catch the gauge at the midpoint and shut off the engine, i can hear boiling coolant from somewhere up in the heater core i think. I'm gonna try flushing out the heater core very well - think I have some flow issues in there.

I changed the water pump recently and the last few ounces of coolant that drained out would have been from the heater core, and they were black, rusty bits of sediment, so I suspect my lack of a decent flush back then, may have just given me another job to do.

The only other thing i changed recently were the freeze plugs in the block. I am hoping these aren't causing the flow problem cuz I really have no other option but to use the rubber, bolt squeeze kind... Ugh.

 

[poopjohn]

Well, I checked my water pump for leaks yesterday. Yup, a little bit of fresh bright green coolant coming from the weep hole. I'm about to buy a brand new one to replace it, and i'm going to replace the thermostat again, just for good measure. I need to replace to water pump regardless of the gauge fluctuations.

Diagnosing with parts... and it can get expensive.

 

[burgundy1994xlt]

Be sure the cooling system is burped. Mine used to make that boiling sound until I got all the air out. Squeeze upper and lower hoses with cap off, fill radiator slowly, remove heater core hose and pour coolant in etc, etc.

There are several methods. Do a search on here.

Also, make sure the breather hole on the thermostat is up (12 o clock position) and not blocked as that is Fords idea of an air outlet for the cooling system.