4.0L OHV Temp fluctuation

[manousos]

With the engine cold, temperature fluctuates from "cold" to "normal" (never hot)
The entire cooling system was flushed May' 06 during a thermostat change. At the time the coolant looked good with very few deposits/rust. Since then I have added about 50,000 kms to the engine - I drained some coolant and it looks ok.

There is no coolant loss, or coolant in the oil.

Followed this thread

....
(1) Replace Temp Sensor TSB: http://autorepair.about.com/library/faqs/bl511f.htm
There was a TSB on this problem. Replace the Temperature Sender with Ford part number F1SZ-10884-A and that should fix it.
...

Replaced the sender, fluctuation still present

I'm thinking:
- fan clutch (tested it by hand with cold and hot engine and looked fine)
- radiator cap

Am I missing anything?

 

[Blacksheep Josh]

With the engine cold, temperature fluctuates from "cold" to "normal" (never hot)
The entire cooling system was flushed May' 06 during a thermostat change. At the time the coolant looked good with very few deposits/rust. Since then I have added about 50,000 kms to the engine - I drained some coolant and it looks ok.

There is no coolant loss, or coolant in the oil.

Followed this thread


Replaced the sender, fluctuation still present

I'm thinking:
- fan clutch (tested it by hand with cold and hot engine and looked fine)
- radiator cap

Am I missing anything?

So what's the problem? Engine is cold and it reads in the normal range? It may just be heating up faster now that it has a newer thermostat in it. Mine has been doing the same thing ever since the seasons changed for the warmer.

Our temperature gauges have a huge fluctuation as to what the "NORMAL" range would be. As long as the engine isn't overheating I wouldn't worry about it, it may be a bad gauge, short in the system, or something else. and if it's REALLY bothering you, you could always install an aftermarket gauge that gives you actual water temperatures. like this:

 

[Donner]

Is the needle bouncing around or acting unusual? (Blacksheep Josh, where did you find that gauge?)

 

[manousos]

not bouncing - more like traveling between cold and normal, repeating

This only started a couple of months ago. Prior to that the needle would show a steady operating temp, now it travels up and down, up and down...freaked me out the first time I noticed it - cold winter morning (in canada) I watched the needle steadily go up to normal (and just slightly past) only to travel back to cold, and then back

 

[Donner]

I got it, the thing's not working right... It might be a thermostat issue or something along those lines. Search Thermostat and see what comes up... there might be more to it than just that.

 

[Blacksheep Josh]

Is the needle bouncing around or acting unusual? (Blacksheep Josh, where did you find that gauge?)

google image search. i have a few gauges in my closet though my friend's dad gave me when apc shut down.

 

[Donner]

(thank you!)

 

[Blacksheep Josh]

(thank you!)

this might help as well:
http://store.summitracing.com/egnsearch.asp?N=700+115+4294925228&NeXID=4