Engine/Transmission (1994 - 1998) coolant temp question

[Berrigan]

I had a high temp reading the other day and wondered if any members could give me there opinions.



I was pulling a toy hauler (12,500 lbs trailer and 8000 lbs truck) up a 7% grade about 6 miles long. The outside air temp was about 100 degrees. The engine temp gage climed to 210. That is the end of the normal zone as indicated on the gage face. The temp stayed at 210 steady for about the last 4 miles of the hill. I checked it about every 15 seconds and it never got above 210. Then I crested the hill, upshifted to 4th and the warning bell sounded. I looked at the gages and temp was in the red at 230. Then as I was looking at the gage it dropped back to 210 in about 3 seconds. There is no way the coolant could have dropped that fast.



Do you guys think I have a gage/ sender problem?

Or could I have been at 230 all along and the gage just stuck at 210, then popped past it at the end of the hill? It seems to have worked normal since then. Thanks for any suggestions Bill

 

[rjones]

Hmm mine does 195*-200* normal everyday driving in mine in that kinda heat I would expect that higher temp..... 230 pulling a trailer up a grade IMHO is normal... ... ... You may have a defective sending unit my guage in my 96 is in celcius..... so mine might be a little different..... any input guy's?.....

 

[illflem]

Did you hear what sounds like a jet plane taking off part way up the hill when your fan kicked in? There's no missing it.

If not your fan clutch might be shot and not locking up.

 

[Berrigan]

The fan clutch is working, lots of noise and air.



I looked in the DC manual for trouble shooting the sensor and gage. It describes the ohm value of the sensor at different temps but refers to a scan tool to check the gage. I was woundering if there was a way to apply voltage to the gage to check for full deflection. Anyone ever do this? Bill

 

[WHardy]

I had a simular coolant temp response when pulling a long grade with a simular load (36' patio hauler) under simular environmental conditions. At the time, I didn`t have gauges. Las time I pulled a significant grade my auto trans outlet temp exceeded 230 degrees and I started to see an increase in collant temp over time but crested before collant temps were an issue. I`m currently looking for a thread that describes a way to engage the fan clutch by using a switch. The idea being to introduce the fan collining affect earlier. I was hoping that my problems were related to trans fluid temps but after reading your post not sure anymore.

 

[Deezul1]

The sudden drop in temp from the peak may have been when the fan clutch kicked in, they seem to wait a long time to do it.



WHardy

The fan clutch is mechanical so a switch wouldnt work unless you are thinking outside the box here and if so share them thoughts cause I like the idea.

 

[Berrigan]

Deezul1



The fan clutch had been engaged before I even hit the grade.



I know alot of you who live in cooler climates see the clutch engagement as a rare and noisy event. But when I pull heavy loads and its about 100 and above the fan is always locked. It sometimes unlocks on a long downgrade but relocks a minute or two after you hit the power again. Mine cycles off at 180 and on at 195 as indicated on the temp gage.



I think a Horton clutch with a manual overide switch would make you able to get a jump start on the hill.



I just never saw 230 on the gage before. Any ideas how critical 230 is and how long you can safely hold it there?