Temperature Gauge Fluctuates - Non Valk

[Jersey mike]

Ok a seemingly stupid question does the serpentine belt have the correct routing?

I think so.  Nothing has happened that would have made it change but I will give it a look.

Went back and reread where the problem just happened out of the blue, so I doubt belt routing is the answer but needed to check

Sometimes the serpentine belt can go on opposite to the way its supposed to go on. This could cause a opposite rotation on the pulleys, specifically the water pump and cause a overheat or erratic cooling situation since the pump would be operating in reverse.

I do have another idea, remove the instrument cluster and clean the connections or plugs that go to it. Use WD40 and clean the contact areas on the connection, plug it back in and see if that changes anything. On your truck its not hard and sometimes corrosion on the connectors can cause intermittent contacts that will cause the gauge to fluctuate.

Seen it more than once.

We had an ‘03 F250 that had an issue with the cluster, we removed it, sent it out got it back in 4 days and it works great now.

[carolinarider09]

The cluster thing did come to mind.   The odometer no longer works (keep track of mileage via GPS).  I can't  (or I guess I don't want to) remove the instrument cluster.  I will check and see what it might cost. 

What I should do but not sure I really want to, is take the connection loose from the sensor and connect an ohmmeter and see how the resistance really changes.   Just takes some more work.   

[Robert]

Dont bother with the OHM meter, you will not really be able to see anything. The cluster comes out fairly easily in that car. Its a job you could do and really dont need to bring it somewhere.

https://www.explorerforum.com/forums/threads/2nd-gen-gauge-cluster-removal-and-led-conversion-v2.240166/

Most everything snaps in and out just dont break it since its old plastic. Crazy glue is your friend. 

[carolinarider09]

Will give it a look.

[F6Dave]

Which engine? The 4.2 L V6 was known to leak coolant through either the head or manifold gasket into the cylinders. I had a 1997 F150 with that engine and was losing a lot of coolant. Then one day when the engine stopped in just the right position, a cylinder filled with coolant and when restarted there was a big BANG, as it hydrolocked. The engine was destroyed.

I put a rebuilt engine in it but it soon started losing coolant too. My mechanic talked with the rebuilder (Jasper) and found a solution: 2 manifold gaskets with plenty of sealant. That solved the problem.

[carolinarider09]

I have not had that issue Dave but will keep it in mind and yes it is the 2WD 6 Cylinders X 4.0L FI OHV 245 CID engine.   

Listed via the VIN AS 4.0L.