Temp Sender and Gauge Problems.

[Piratenorm]

I took the advice of a member of this board and bought a paired set of Faria Temperature gauge and sender, installed it all properly in my Universal M25XPB and ran up the engine. The temp rose slowly, all the way to 250 degrees (!) and stayed pegged there. My laser temperature gauge indicated my cylinder head, engine block, thermostat housing and everything right down to exhaust water temp were all in the normal range. Any ideas? New thermostat from Universal last year, new water pump impeller, everything shrink taped and run right.
The old gauge and temp sender I got from Universal at least stayed around the 200 degree mark, which read still higher than the engine itself dictated which is why I wanted a more accurate package. Signed, perplexed.
Here's a question I haven't been able to get an answer to either. Is it advisable to take the end cap off the heat exchanger and drain/clean it? There are always new zincs and the antifreeze is good but what do I know about these things. Thanks. Norm

 

[woodster]

check your wiring something is amiss...or the sending unit is mismatched for the gauge

 

[Maine Sail]

I would contact Faria with the part numbers and make sure you got the right ones. You can also check the resistance of the sender at various temps and Faria should be able to send these to you...

You can also bypass the harness and run a wire direct from sender stud to gauge sender post to eliminate the wiring harness...

 

[Capt jgw]

You didn't use thread sealant or Teflon tape on the sender did you? That will make it not work, the sender has to be grounded to the block through the threads. Anything on the threads will change the resistance and make the gauge read wrong or not at all.

 

[Piratenorm]

Nope, no thread tape and the only thing I can think is that it should be in the block instead of the thermostat housing where it has lived it's entire life. Ideas?

 

[Capt jgw]

As long as it's in the water flow it doesn't matter. Coolant is not going to change temperature between the block and the t-stat, and you're measuring the coolant, not the metal.
Mine was reading low all the time, I replaced the sender with no improvement. I then replaced the gauge, which came with it's own new sender, more out treats correctly

Even though you got the gauge and sender from the same vendor, they could still be mismatched, or one of them defective.