marv plotzka
Seaman Apprentice
- Joined
- Sep 24, 2002
- Messages
- 32
In an earlier comment on using OD while trailering, I stated there is no fluid flow to trans cooler when transmission torque converter is locked. That is 100% incorrect. After reviewing some notes I made on my current tow vehicle several years ago, I find my memory isnt what it used to be. I did find some interesting things in my previous research that might help OkieBoater. Per GM service bulletin #36-71-03a ( and not from memory ), their high efficiency trailer towing package trans oil cooler is available as a over the counter kit you can install yourself in just over an hour. It is P/N 12546251 and fits 1988-95 C/K 10 to30 series trucks with small block V8s. If your truck was built with this cooler, it will be listed on the small white sticker on the glove box door as RPO code KNP. I find that around here, buying GM parts at an auto parts store that sells AC/Delco stuff is 20-40% cheaper than at the dealer. Also, they suggest using Dexron 3 trans fluid because it offers improved high temperature oxidation stability. Cant say I have seen Dexron 2 around here in the last couple of years, but it may be what your truck came with. From my notes, my 96 chevy ½ ton truck ( with KNP cooler ) has a trans fluid temp of 160 to 180 degrees without trailer, 190 to 230 degrees with my boat (~2800lbs) at 65 70mph on the expressway in OD, converter locked. I have 265 to 270 degrees listed as the fluid temp at which damage occurs to trans. Also not to tow heavy trailers with large frontal areas ( like horse or travel trailers ) in OD because of possible clutch pack slippage. High transmission load, low transmission fluid pressure from low engine speed in OD is the concern there.
