4.3 over heating at low rpm Help

[Griff Thomasson]

UP DATE
I went back and torqued exhaust manifolds and thermostat housing stopped the leaks . Started her up on cuffs . Let her idle. Used IR temp gun and when guage went to 220 . I check thermostat housing it read 147 ???
SO I have a faulty sensor ???
Ill change that out alarm never went off .
How ever when I turn it off engine want to run off ???? What to do about that ?

 

[Griff Thomasson]

Would that be a gauge issue or sending unit ?

 

[dubs283]

Would that be a gauge issue or sending unit ?

Could be either, test the gauge and if it passes replace the sender first.

Only reason I mention sender first I guessing is cheaper

 

[Lou C]

When checking your temps with an IR temp gun you’ll find different parts of the ‘stat housing read very differently. On my OMC/Volvo design the top and sides read cooler than actual temp, I find that the location that reads most accurate is the intake manifold right under the stat housing. There it reads 145 when my dash gauge reads 160 which is normal for this engine. The hottest it ever gets is 175* after coming off plane but it cools back down after a period of idling. Manifolds are 135* F after coming off plane & are usually at 90-110* F.

 

[Griff Thomasson]

Update
I replaced the gauge and turn the ignition switch on and it pegs out telling me sending unit is bad . I have another sending unit I bought last year and I can not find it !!