Transmission and engine temps

[Swhite5.3]

My 1999 Silverado LT has 300+k miles and its got a temperature problem I'm worried about. Running down the highway at 75 the engine temp soars to about 235 but normal temp at 65 and below is 205-210. The temp comes down once I slow down but worried about it being a precursor to a larger problem. Also, the tranny runs at about 210°F when its warmed up and will start rising to 215 if left to idle. Everything I've read says it should be about 175°F. Any help would be appreciated

[Chris]

Trans fluid gets cooled by radiator and then an aux cooler if equipped. If there is a radiator or other cooling issue causing the coolant to run warm then the trans will run warm. A good aftermarket aux trans cooler will run anout 50-70 above ambient temps. Right nowit is 104 outside and my trans is 158 degrees.

 

When was coolant and thermostat last changed? When was the radiator changed? Change any hoses?

[Swhite5.3]

That helps a lot. I was actually thinking it may be a radiator/condensor issue with air not getting through. I was going to try to put aux electric fans as a way to pump more air through. The reason I thought this was because the ac doesn't get cold until the truck starts moving. So if all three systems, engine, trans and ac run through the same area it could be something there right? And I have no idea the last time thermostat was replaced and all hoses are oem so none of them have been replaced either

[Chris]

Might want to start with cooling system maintenance. Mainly therostat, hoses, make sure the radiator is clean and in good order, and fresh coolant. Maybe make sure the condenser is clan as well. I would use a garden hose and Simple Green. You do not want to spray with high pressure and bend fins.

[Gurrzt]

As said above, also I would flush the radiator first, transmission fluid starts to burn @ 210F, check the color of your fluid, if it is anything other than cherry red, you should consider replacing it.