Another bizarre one . When I bought this 99 ram 360 mag i noticed on the live data im running around 172f all the time unless really on it up a highway grade it will get up to temp then drop right back down. I have tried a ton of different tstats and all ɖo the same except for one ancient stant superstat i have that's pretty rough but it will run a perfect 195-200 with it . I started having some overheating problems and ended up doing new water pump radiator fan and clutch as well as temp sensor and im back to 172 know matter what 195 or 180 i put in unless i switch back to the old stant. Truck has new heads and plenum plate as well. I just got a hemifever stc and am trying to switch to a 180 but once again every stat i try i run at 172 and only got it up to 182 when really trying up a highway grade a.c on romping on it.

I cant seem to figure why only that stant will make it run at normal temp. Unfortunately it seems motorad makes most people's tstats now so no matter napa murray ect its a motorad but i have tried about every veriation heavy duty premium economy as well as duralast and a few others and all the same result no matter what temp stat. What could be causing this? Seems stant is gone so cant find another but thinking of maybe trying elderblock but i have a pile of tstats and im tired of doing it over lol. Only strucual difference i see in the stant is it has 2 ridges around the outer edge instead of 1 like most others but not sure thats making a difference. Any ideas or suggestions? On a side note why is it all the aftermarket tstat housings have raised demples on the mating surface and my plenum doesnt seem to have a spot for them? I have looked at a handful and they all have it but could this be creating a space allowing coolant to flow around the stat that the stant is somehow sealing?

 

What does the dash gauge read? Maybe check the temp with a infrared temp gun. If you are asking about the ridges it may be because you didn't use a gasket. The gasket helps hold down the stat and keeps coolant from going around it. This maybe your issue.

 

i use a felpro gasket everytime. Dash reads roughly the same as does infared.

 

Try a Calorstat from RA.

I see they also offer an Aisin which i would hope is NOT Motorad, either. Never seen Aisin stuff for domestic apps but that of course is preferred for Toyota

Have you tested the stats in question on the stove? You can easily get a food (or whatever) thermometer and if the wife won't allow a pot to be used grab an inexpensive one from the thrift store and keep it in the shop. I do. I consider it a tool (although I have to use it in the kitchen)

 

How any miles on the engine? Have you checked the timing chain for slop? If the chain is worn, it will make the engine run cooler.

 

Truck has 120k and upgraded to a double roller chain/sproket about 2k ago

 

yes i always test them in a pot with a infared. Seem to always function and not open early . Ill. Heck those out

 

Just for giggles you should test them all out in the same pot and see where they open at.

 

i will try and see. I ordered a jet performance tstat which looks to be identical to the old stants so ill test them all when i get it

 

Might want to check around to see if you can find an NOS Stant Superstat. I've never had an issue with those thermostats...