Recently I told you guys about the water temp readings I had after installing a electric water temp gauge. Well friday night I went to change my thermostat and had a small problem when I went to take the neck off of the thermostat a bolt on it broke off in the water pump. So last night I replaced the water pump and at the time replaced the water temp sending unit. Now the the temps are very different. Note there was no signs of corrosion or contamination, however it appeared that the stem of the thermostat was slightly bent 2-3*. So after putting in a new water pump, thermostat, neck, and upper hose, this is what its doing.

Originally.......................Now.............. ...........Noteable differances

top of N on OEM guage....top of O-bottom R.......Never got that high before ever but regulary fluctuated readings

220* on physical gauge.....200-210 max............ can see the temp fluctuate as the thermostat opens


So it would appear the factory sensor was slightly off and the themostat must have been failing at least somewhat This still raises the question though about what temp do these trucks overheat? On my road trucks their temps can be anywhere from 230-250* before they overheat this would make me assume these are set to go much higher. Also at least one place I looked at stated the thermostats are designed to lock open at 280* during overheat. 280* seems REALLY HOT to me so curious if you guys know anything more about this.

 

One source says the stat starts to open at 205* and opens fully at 220*. I suppose that would be using a 203* stat. I'm guessing yours is in the 195* range like mine. Your previous thread convinced me to include a real temp gauge in my gauge package. Possibly IH would actually have an answer to the when is it to hot question.

 

Seems like you were in need of both the T stat and the pump... I bet they were all on the way out... But glad you got yours back together... in a few weekends, I may be asking for your help on some injectors... and I will be putting in new GP on the passenger side, since the CEL still comes on after about 3 starts...

 

"overheat" is one of those technical terms that realy has no meaning, it comes down to at what temp does your coolant start to break down and at what temp does the block/heads start to warp. I thought these trucks had a 15 psi cap, might be 16 psi, either way. 15 psi raises the boiling point 45º so at sea level the water won't boil until 257º. polyethelglycol raises the boiling point somewhat too, so somewhere around 260º they will start to boil.

cases have shown that overheating them tends to lead to a crack in the valley near the lifters. how hot it has to get, or how often, or how long does it have to last, I dont know. If its never running over 210º I wouldnt worry. the factoy gauges have been know by many to be totaly useless. your truck proves that, with the new stuff the factory one reads higher, yet its running cooler....... go by what your aftermarket electric temp gauge says.

Diesel Rod

 

Interesting post 444.

I run an aftermarket water temperature gauge and heading down the super slate my water temps run from 215-210 depending on when the t-stat opens. Bring the mph back down to 55 and she runs at 205.

Regardless if I'm towing or not, she usually runs at 215. This raises the question on the creditability of my aftermarket gauges. Do you think it could be off a couple degrees?

Personally, I wouldn't be to concerned unless it ran over 220.