Temp Sender Location M25-XPB

[Piratenorm]

When I install my new Temperature sender in the thermostat housing I get a false reading on the gauge pegged at 250 degrees. It is false. The thermostat works.
I took the thermostat out and the gauge reads 150, too cool for the Great Lakes. The thermostat works perfectly, confirmed in a pot of hot water at 160 degrees.
I've decided to install the sender elsewhere in the block, 'cause I know there's a square headed threaded bolt there somewhere, but for the life of me it is not showing itself, nor in the manual. Help?
Thanks

 

[Donnybrook]

Why did you change the sending unit? Already having problems?

 

[deke]

The temp sender on my 2001 Cat 310 with the M25XPB is directly above the circ. pump pulley on top of the by-pass hose. deke

 

[Piratenorm]

Why did you change the sending unit? Already having problems?

Wasn't sure, so rather than mess around with parts from other than stock suppliers I bought one from Catalina Direct meant for that engine. And installed it. And the gauge went up to 250 degrees!
So I took out the thermostat, started the engine and the temp shows 140-150. Tested the thermostat at home and it works perfectly. And there is no interference with the temp. sensor and the thermostat preventing it from opening properly. Besides, it opens downwards into the block, away from the tip of the sensor. So unless the tip of the sensor is grounding against the side of the thermostat and that is causing a false reading I am stumped!
And the engine never hiccuped, burned oil or fried itself so I know everything is working fine. The sensor just doesn't give an accurate reading when installed in the thermostat housing. Hence why I want to relocate it. Signed, Frustrated as hell and the owner of four likely perfectly good sensors! Merde! (French for S**t)