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Still working on getting an 85 Grand Wagoneer running after sitting for 20 years. I recently got all the fluids serviced including the transmission fluid and it's filter. But ever since then it started giving me new problems.

First, it has stopped holding in park. I noticed when shifting from drive to park I hear four clicks, similar from reverse to drive I think that one was less clicks. I checked the manual MR253, but I didn't really notice any tests or checks for not holding in park.

For the other newest problem, I had driven it the fastest I have driven it before, not a lot but 38mph maybe? This was halfway through my drive so I wonder if it had to do with the transmission warming up. It has started making a loud whine that matches with RPM. I also notice it had always been reluctant to start moving from a standstill so I wonder if the two are related. The transmission fluid level is full, the fluid looks ok. I want to think it's the torque converter, but I'm not too experienced with transmissions.

I'm was hoping that I wouldn't have to remove it but with these two problems I'm guessing it's going to need a bit of work. I guess what I'm trying to do with this post is pinpoint what's causing these problems to tackle them efficiently. Anyone had these issues before or know the cause?

bummer, who did the service: a transmission shop or yourself?

1st recheck the fluid, transmission in neutral and at operating temperature after having shifted thru all the gears, including 1, 2 and R, which usually requires 5 to 10 miles depending on weather.

2nd check transfer fluid level, the transfer case tends to loose a bit especially when sitting. While there check the rear differential.

Loosing Park could be an adjustment, does the engine cranks in Park and Neutral?

My usual mechanic shop did the service. I'll try to check fluids again, I didn't look at transfer case or diff. The engine cranks in park and neutral, no problem there.

Ok....so guessing you have the 727 auto.....as you did not specify?

Sharing some of my own experience for you, after getting my '84 GW w/727 transmission home after it sat for 18 years, mine is driving, still not perfect, and sure it could benefit to be gone through properly by a good trans tech. When more JEEP money available, will have this done.

For full write up, see my build thread - 84 Grand Wagoneer Revival

After treatment I still have the cold stall, where it takes a few seconds to engage reverse right after starting the truck, but seems to be ok when starting off forward. Shifts smooth with no slipping when power needed, and I have the mechanical kick down linkage with all rods from carb to transmission. Not sure if yours is the same.

Treated trans with Berrymans B12, which improved it a LOT. Here was my process-

"Pour a full 16 oz bottle of Berrymans B12 into the transmission. Yes as you just topped off your trans fluid, it will now be over full, but ok for the cleaning process. Just try to keep rpm's low when test driving, until you can drain & refill system with fluid again to correct fill level.
Safety chocks in front & back of front tires. Put the rear wheels up on safety stands with rear tires about 2 inches off the ground. Best with stands under rear axle tube on solid flat surface. I had mine in my garage, with rear of truck sticking out for exhaust not to fill the garage.
Started the truck, put in D, and let rear tires turn at idle speed.
As I had started it cold, rpm's at 900, so giving me about 18 mph just idling along.
At 44 minutes I decide enough for first day, but let it run as long as you can, for best results.
Shift trans to N, slowly stop wheels from turning and shift into P. Shut it off and drop wheels back on the ground,

Take it for a drive, and the trans shifted smoother today than it has so far, which was not too bad to begin with.
Left the Berrymans in it until weekend after next, and each day go out and set up on stands, then let it idle in drive for about an hour.
Then do a full flush on it to push out all the Berrymans & crud, new filter & fluid, and give him a little putt around town and maybe get out on the big boy road and see how it does for more than just a couple miles."

Suggestion for you is to run yours about 2 hours at a time, to give the Berrymans more time to get in and work through the system. While it is sitting the chemicals will soak inside and dissolve some of the crud from sitting so long. You want this crud to breakdown slowly, so it flows through and traps in the filter, and not sitting in the transmission.

Hope you have same good results as I did, and keep doing the short trips, only as needed initially, to give everything a chance to get working again sloooowly. You will know when its time to try higher speeds, as you feel the truck limbering up and relaxing, just like an athlete stretching the muscles before a competition.

When its time to flush the trans, easily done off the trans cooling lines at the radiator. I have that on my build thread as well.

Diff and Transfer case fluid seems fine. One thing I just remembered. When I parked it after the whine occurred, I noticed the front of the car was very hot, more than it should be. My Wagoneer did come with the towing package so it has the auxiliary trans cooler and I'm wondering if the heat was coming from there since the temperature gauge for the engine was reading normal.

From what I was reading overheating fluid was a symptom of a bad torque converter I think. Either that or there's a problem with the cooler. I haven't touched the cooler at all so no idea is the lines are clear or not

i always send a sample of fluids, power steering.engine oil, transmission, pumpkins, to get an oil analysis report to know EXACTY whats going on in each component. would have been nice to know what the oil had in it . imo its cheap money .

I checked fluid after warming the car up and shifting gears, it was right below the add 1 pint mark. Added more fluid today and let it circulate and no change. Now it makes a noise shifted into drive or reverse with no movement and the sound shifting into park has gotten worse.

It was on a very slight incline but it's not moving. I put some effort into throttle but I didn't push too hard because of the sound of the transmission. Still put more than it should have taken to get it moving. Nothing left I can do I guess, it's getting towed to the transmission shop to see what's going on.

I would encourage you to try the treatment I did, but your rig. Save you a bunch of cost too, if you drop it yourself, and just take the transmission to them, instead of the whole truck.

Probably should have tried that earlier before the service, I think once it started whining halfway down the road it was too late.

What fluid did they use exactly in this ? It should be dex/merc. Not dexron 4 or 5 or 6.

I was in the transmission business for a long time. I can promise it’s due a rebuild. Seals get hard and fail. The issue came about after service is coincidental, not the cause other than maybe the clean fluid cleaned up some dirt, the problem was there before, just masked by dirty, old fluid.

Mmm. I listen to Scotty Kilmer in the morning, mostly for entertainment. I've learned a lot about Toyotas One theme he comes back to again and again is when to - and when not to - change your automatic transmission fluid. He recommends changing ATF every 40K or 50K miles as regular service of a new car, regardless of what the factory recommends. However, with a transmission where the fluid has never been changed, and has 100K or 200K miles, you never change the fluid if it shifts now. The old fluid has partly broken down and particulates from the clutches are in suspension. This makes more friction than new fluid; if you replace the fluid there's a good chance the transmission will stop working altogether. With a transmission that slips with high mileage and old fluid, remove a quart and add a quart of the Lucas conditioner. Sometimes it helps (according to Scotty).

Scotty is full of crap half the time. Our 98Zj 4.0 had 80k miles my mom never changed the fluid (* was a kid at time) stopped shifting. Stuck in 1st.. mechanic said it was black.. so we flushed

Drove fine after. Then i got older and did the maintenance myself.. every 30-40k miles a fluid n filter change. It has 445k miles on the same transmission. At 380 or so i changed all the solenoids and the 3/4 accumulator spring which was broken

Yeller wrote: ↑Wed Apr 24, 2024 2:43 pm I was in the transmission business for a long time. I can promise it’s due a rebuild. Seals get hard and fail. The issue came about after service is coincidental, not the cause other than maybe the clean fluid cleaned up some dirt, the problem was there before, just masked by dirty, old fluid.

I wouldn't be surprised. It sat in a field for 20 years and I had no idea what condition the transmission was in when I got it.

Transmissions are finicky.... try the lucas, it is really thick like honey, but whine is not good, and the loss of park is another weird one...
Working on a similar issue for my friend's german engineered vehicle, the valve body will need to be dismantled to check for blockage, after the fluid change the occasional error is now permanent. Service was done 10k miles ago.

A whine could be a filter that is not sealing and air is being sucked instead of ATF

i'm assuming you have the normally bullet proof 727 trans, i had mine rebuilt by a local guy recommended by several offroad racers, i had 2 additional clutch discs added to the stack , shift kit, and billet torque converter several internal parts were worn, and all new bearings and seal were changed during the rebuild , total cost was 950.00 and 200.00 to split the case on my 208 xfer, just letting you know what piece of mind buys, especially with 18 years non-op i'll be following this thread.