gabeanzelini

Edit: I did search (I swear) but now I see the related topics cover this. Looks like I'll drain and fill but not change the filter. If I could figure out how to delete this thread I would. Sorry for the repost.

Background: So I just got handed to me a 1997 Jeep Grand Cherokee with 223k miles on it. It has all the common problems (lift gate, battery drain, heat stuck on defrost, etc). I don't think it has been well-maintained either. I'd like to give it as much chance for a long life from here on out as possible. I'm looking to use this rig to learn as much about doing my own work as possible as well.

Problem: I read the "I just got a new cherokee now what" post. I'm thinking I'm all set on payday to get all my gaskets, filters, and fluids to change all the things. Then I came across about how sometimes bad tranny fluid can be the only thing holding the tranny together (I'm oversimplifying). Now I'm nervous to do the flush and filter change. I know you guys have had to be in this situation or close to it so I come to you, the wise ones, for advice. Do I let it run out the life of the tranny and then maintain a new one or will I gain from maintaining it now?

Thanks.

wingless

Welcome to the forum.

Good luck w/ your ZJ. Please identify the engine.

Get the correct FSM for your vehicle. It is required. My preference is the printed volume, others prefer the PDF. I have both.

IMO, the transmission fluid should be changed to fresh ATF+4 according to the maintenance schedule. This service permits proper inspection of the fluid condition / pan sediment.

Note that loosening or removing the valve body at that time permits removal of LOTS more of the old ATF. Blowing air through the cooler lines also gets more old ATF out of the system. (Neither of these are required, but are good therapy for those enjoying OCD.)

When I perform this service, I also adjust the bands per the FSM.

Another good service to perform is changing the transfer case fluid, also to fresh ATF+4.

One HUGE improvement to the vehicle would be to change all the bushings, to restore new vehicle handling. This reply shows the steering / suspension parts I replaced.

wingless

The heat stuck on defrost might be bad vacuum control to the actuators.

On mine, the Mopar 4720347 fell off the shaft. It was a major butt pain to repair, but possible.

gabeanzelini

Thank you for the welcome.

As I am attempting to follow that thread, the first thing I did was buy the 1997 Cherokee FSM from the suggested site. Then I bought the Grand Cherokee version 🤦🏽*♂️. Now to learn how to read it

I do intend to change transfer case fluids as well as well as diffs, brakes, coollant, and power steering. I'm assuming nothing has been done unless absolutely necessary by previous owners.

Thanks for the suggestion on the bushings, I do notice a bit of play in the steering. I'll check out your thread on it for sure.

As for the heating issue, it is definitely the vacuum line. The T has a little hose coming out of it still but the rest literally disintegrated in my hand as I went to trace it back to the original break. The FSM doesn't seem to have a vacuum diagram so I'm looking for that to show where it should be going.

I'll go update my engine information now. Thanks again.

wingless

The VECI label in the engine compartment shows the vacuum routing.

dave1123

That vacuum line from the T fitting at the firewall goes thru it and connects to the back of the mode selector switch on the heater control panel. It doesn't need to be the hard plastic line either. I can be rubber hose as long as it fits tight on what's left of the plastic. The mode selector is the **** that directs air to the different outlets.

The clutches in the transmission have drive plates and driven plates. The drive plates have friction material bonded to them and the driven plates are plain steel. In the trans pan, you should find a ring magnet. Steel shavings from the driven plates will stick to it. The friction material will appear as a grey mud in the bottom of the pan. You can judge the wear on the transmission by the quantity of the deposits. With these jeep transmissions you should always check the fluid level in Neutral, not Park. It should say so right on the dipstick.

There is a reusable gasket that's a sandwich of steel and rubber that you can get from a dealer. I've used mine 4 times already and it doesn't leak yet! Don't use any sealer on it though.

Proper ways to treat tired Jeep transmissions vary by personal opinion, but I have 227K miles on my 2000 WJ and have no slippage yet. Shifts are solid and on time. Here's the way I treat mine. Do not use the shifter as a brake, as in stop a roll by shifting to the opposite direction. Use the vehicle brakes to stop it. Don't put it in gear above 1000 rpm. Shift to Neutral on startup and give the fluid time to circulate for a few moments before asking it to drive the jeep. The torque converter isn't pressurized in Park.

I learned the hard way. I jumped into my jeep and fired it up one very cold morning, threw it into reverse, and all it did was make a "whooshing" sound and didn't move at all. Oops! I shifted back into Neutral and waited a minute, then it worked fine! Also, if the fluid is below 32* it won't shift into 4th gear. (O/D)

wingless

All the information you provided is good.

When I rebuilt my 46RH transmission, I used the Sonnax Sure Cure Kit (not the OS kit in the link). Part of that kit includes their Lube Regulated Pressure Regulator Valve. That valve is different than the OEM valve in that it charges the torque converter when in Park. It also included this Manual Valve that also provides torque converter fluid in Park.

My experience is that the transmission is ready to go once the engine has started when using these parts. There is zero difference observed in operation after just starting or after extended operation.