Block Heater Replacement Detroit Diesel 671 TI

If you have the screw in element heaters, you would be amazed how little coolant dribbles out when replacing the element.

Interesting.
Then your install looks like this?


Make sure it is really the element and not the power cord that is bad.
Then on a cold engine;
Do not open your heat exchanger cap.
Have your new heater assembly ready.
Remove your proven defective element assembly out. Stick a plug or rag in there.
Clean up the gasket area well.
Use grease on the new gasket.
Reassemble. Do not over tighten the new bolts.

You will not lose much coolant.

Pour us a beer.

Mickey. I thought I needed to replace my block heaters on my J&T 671(s) just last week, but it seems it was a stuck pressure switch. My system is the same as yours ( I think). The heaters will shut down if it detects oil pressure (engine running) in case you forget to shut them off before starting. If you have this type of protection, please check this switch before doing anything else. I was not getting any power to the heaters, and I think it was because the switch was telling them that the engines were running. A very simple test, and it could save you a lot of money and work.

An Y wire harness that includes the thermostat. Another path for failures.
Check out all before pulling that element assembly.