So the other day my buddies and I were going down the highway to go fishing and when i went to get off it held about 5-7 hundred rpms more than normal when coasting and there was a loud humming noise. It almost seems like the trans doesn't shift out of gear like it should. One person said it may be a solenoid going bad but not sure. Any ideas? Thanks in advance

 

check urtrans and dif fluid

 

And i forgot to add, it's a 98 4.0 auto 231 t-case and Chrysler 8.25 rear

 

trans fluid is red and full

 

uh

that sounds like an engine problem. throttle cable or something making the throttle hang.

just curious, but how could the dif fluid level have anything to do with this?

 

in my experiances hearing a hum, if im thinking the same hum he is the dif was wining lost 2 rears ends that way. just trying to be preventive. and to the op, you checked it trans hot in park running correct?

 

yeah

 

just to make sure since i haven't ever done diff work, to check the fluid you have to remove the cover and drain yes?

 

ok never mind that last post i figured it out. The diff fluid is full, black as could be, and stinks like a manure pile. so no idea what that means hah.

 

To check it has a rubber mount on the diff cover pull that off a little should run out if its full. If its as black as u say it is you need to change it. Take every other bolt out of the diff cover then take the botom two out so the fluid will run out. Then constantly work around the dif altering sides till they are all out. Get some brake parts cleaner a can or two and spray everything inside down to clean it. I re lube my gears after I clean them with clean gear oil but that's up to u. Physicaly look at the ring gear and inspect it for chips and stuff. Also look at the fluid that came out. See what u find. If everything is a okay scrap the gasket eaither buy a new gasket or use rtv tripple black or the rtv of ur choice. Put diff cover on in reverse order of taking it out. Put new gear oil in it at the rubber mount on the cover till it starts running out. Shouldn't take more than a quart but I could be wrong.

 

Back to the origional problem. How often does this happen?

 

8.25 is 1 and 1/4 quarts roughly.

I would crack the diff cover as well and take a look. Drain the fluid into a clean container (ie one you havent drained anything else into yet) and see if there is any metal. It should not be black. It should be a lighter yellowish for conventional regular gear oil. Auto zone will have the cover gasket for $4. I like to use a thin layer of RTV to help hold the gasket in place.

This may not be your problem, but if the fluid is black you need to address it.

 

thanks for all the help, I will change the fluid tomorrow, and the hum is every time I go over 40 mph but the rpms holding is always.

 

Im still trying to figure out the holding. Exactly what rpm is it holding at and how long

 

it holds at about 12-14 hundred rpms after i let off the throttle whereas it normally drops to about 800 rpms and it stays that way until i slow down and stop or speed up again.