Perkins 4-154 Temp Reading in Error

[gbillman]

I have a Morgan 41 OI with a "new" 4-154 (rebuilt w/ 70 hours on it). The engine runs great. Problem: engine temp gauge reads abnormally high (maxes at 235 after 30 minutes at 2400 rpm) even though the engine is actually within operating limits (175-190 per laser temp gun). I have changed out the sending unit and the instrument. I have also "jumped" the new sender and instrument with a new 16 gauge wire. I still get high readings. I have no other ideas....please help! Thanks

[DeepFrz]

Sender in the right place on the engine??? Have you checked that the thermostat is opening at the correct temp?

[Mark Zarley]

The problem might be the wrong sending unit. Some sending units are for dual stations (1 sending unit sending to 2 guages) or for single stations(1 unit 1 guage). The guage and sending unit must match for accurate readings.

[gbillman]

I can only find one sending unit and that's behind the most aft cylinder.

I haven't checked the thermostat directly because the engine is running at normal temp per the laser heat gun.

[colemj]

Also, there are different temperature range senders and gauges. The sender has to match the gauge or the readings will be off. Is it possible that the original sender or gauge was bad and you got a mismatched set when fixing it?

Coincidentally, we are having the same problem, but I have isolated it to the gauge itself (a benefit of having a "spare" engine onboard - troubleshooting is quicker).

Mark