Fluctuating temperature gauge

[spikeRovah]

Hey all,

I got a very annoying problem.

I installed a brand new, re-manufactured engine from Atlantic British back in the beginning of April. All new gaskets, new oil pan, new timing cover/oil pump. On a 97 4.0 btw.

Filled the cooling system with prestone 50/50 and got a fluctuating temp gauge. I figured this was air in the system.

Since then I have replaced these following parts..
-Thermostat (oem from land rover)
-Coolant sender unit
-Coolant temp sensor
-Radiator
-Reservoir tank cap
-Water pump
-Clutch fan
-Radiator hoses

I am still having the SAME exact problem.

The gauge fluctuates erratically whenever it feels like it. I could be at idle or doing 65 mph and it will still creep to H and then drop back to the center in less than a few seconds. Water cannot physically drop that amount of temperature in that amount of time.

My truck isn't actually over heating. No bubbling coolant and no steam. Plus my two auxiliary fans never stay on after shut down (which they used to with my old engine). I checked to make sure they were working by turning on the AC and they turn on with the AC.

My fan is on in the correct direction as well. I checked that already. I feel like there is absolutely nothing left for me to check. Could this possibly still be air pockets in the system? We bled the system many times, and still same problem.

I have an ultra gauge. When my needle sits at the center, my ultra gauge reads between 194-195. When my needle spikes up to H the ultra gauge has gone up to 217, and then quickly back down to 195 as the needle on my regular temp gauge dropped. This happens randomly, and sometimes I could drive the truck for 20-30 minutes without any of this happening, and my ultra gauge will read 194-195 the entire ride. Nothing is making sense, especially with all these new parts! Can someone help? I am afraid to drive my new engine until this is resolved..

Thanks! Any advice helps! You may have seen me post about this on another forum, because I have been having this problem for so long now.

Thanks,
Spike

 

[Disco Mike]

Spike, PM me your number and lets talk about your heat issues.

 

[spikeRovah]

Spike, PM me your number and lets talk about your heat issues.

Hey man, thanks for the response and wanting to help.

I actually fixed the problem. Turns out my second thermostat WAS faulty. I didn't think it could have been, considering I changed it twice and the truck did the same thing. Both were faulty. My luck.

I put in a SBC 180 stat, drilled a bleed hole. Truck is more than perfect now and runs between 183.4 and 185 even, 186.8 at idle. And that's in 90 degree weather.

Thanks again for your response!