4R55E IIRC.

2nd year its done this but only when cold as in close to freezing or under.

High mileage. Trans works fine other wise, other than an expected lag to shift into reverse, and slightly less into drive when its cold.

About the 5th time now that when cold and going into R, it makes all kinds of grinding type noises.. I've used it when I could not get it to quit by shifting the whole range, just to back out of a parking space.

It threw codes last year, none related to the transmission.

I'd like to think it might only be the R shift selonoid. But I have read lots about valve body gaskets.

And even you tube about doing a shift kit, and so on.

Just need to figure out what direction to go.

Once I get it out of R to move into D and drive it forward a bit it will go into R with no issues.

Trying to decide if its time for a new engine, and then a transmission rebuild as you can't buy new ones... or a newer vehicle... the rest of the vehcile has been rebuilt parts wise and is very solid hence wanting to keep it running for my daily driver.

Appx 350K miles. Odo no longer works. It gets run hard and does just fine at high speeds on the way to fire/ems response calls too so its not having other problems so to speak.

The only other thing it does is in the winter when using the heater, and I stop after driving 20 miles or so there is a thumping noise in the cooling system that I cannot figure out what it is.. Cooling system has a tiny leak somewhere and maybe thats the problem, but I keep it full and radiator has been full each time I check it after it cools after the thumping.

Thanks. Just hate to pull the trans apart, do a plate kit and then it still doing it....

 

Thumping noises in the cooling system are usually caused by boiling...do you have the correct ratio of coolant/water? Otherwise possibly air entering the system burping out pressure in surges. Do you know where the leak is?

As far as the transmission goes, it sounds like you might have a piece of debris that is hanging up the R solenoid function..possibly some band material or ?? Might be a good time to pull the pan, clean the valve body out and put in a new filter and fluid. Valve bodies do no like foreign material, nor do they like anything disrupting the movement of check *****, etc. Could be something simply worn out from movement over all those miles. With the 350k you have, something is going to get worn and start to cause trouble.

Just out of curiosity, what where the codes it threw earlier?