1993 4L80E running very hot.

[WarWagon]

I appear to have all 4 gears and TCC lockup working. No codes. I just put in a temperature gauge known to be accurate from my totaled truck. It is reading 230-240 F. This is running around town less than 45 MPH.

It has the radiator in tank cooler only at this time. Oh, and it was over 100 degrees outside as well. Engine below 210 on the gauge.

Any ideas or suggestions?

 

[NVW]

Any way the temp sender or gauge could have been damaged? I would want to verify it's accuracy.

 

[bk95td]

Is your alternator voltage higher in this truck verses the old one? I get different engine temp readings if the lights are on and different oil pressure also. Grounds would be suspect also.

 

[WarWagon]

I'll check the engine temps too as the engine getting hot and bad engine temp gauge is sort of suggested above. I do hear the fan spool up...

New battery cables and separate cable run to the frame. Voltage reads a little low, 13, when there is 14v at the battery. But I have a direct run from the alt to the battery in place. Need to check the main bus to alt connection. Already repaired the gauge fuse holder and removed the PO's lift pump tap on that circuit.

Lets assume the trans gauge is right. I will verify with a temp reading gun when I get a chance. Looking at the just changed fluid I suspect it is accurate.

Transmissions overheating without a trailer and having all gears is not normal. So before I change it out I would like some ideas as to what is up.

A flow test procedure (time and measurement of oil.) and step by step to check the transmission cooler for example?

I will also do an oil sample.

 

[BigBlueChevy]

Did you run the dedicated ground wire off of the transmission pan into the back of the gauge? Almost all GOOD quality temperature gauges, Be-it EGT, oil, or trans temp have a separate dedicated terminal on the back of the gauge to be connected near the source.

 

[Jess_sr]

You can cross check your temp reading with a scanner.

I'd suggest a large trans cooler added to the system would help.
Flow test the cooler in the radiator too.
Also make sure your cooler lines are not hitting the exhaust or block.

 

[WarWagon]

I put CAT temp color change stickers on the pan. 190 tops and did not burn the 220 sticker.

BigBlueChevy, thanks for the idea. This may explain it working on one and not the other - single wire gauge. Otherwise the sensor or gauge has gone bad.

Trans cooler is next on the list to install.

 

[buddy]

I would say that these trannys can run quite warm. Even when not towing, but just climbing long mts I would see it climb over 200F

 

[NVW]

One thing I've noticed is around town or idling my temp is higher than on the highway. It has never gone above 200F though, not even towing. GMTCD Scan reads 30-40F less than my gauge. It must be where the signal is taken.