Need Tranmission Help - 1997 Disco 1

[DC97]

1997 Discovery 1
Location Washington DC

I have a transmission problem that has me confused so I thought I would place a detailed post to anyone that has experience with these.

I have received some great help and advice thought other posts regarding this problem (thanks; ptschram, Lucas, hywy61, macklow, jakew, cindyrover, SteveA, Chris – St Louis, sven97lwb, and others… ) and so this is also a summary of my findings to date.

THE PROBLEM:

A month after purchasing the car I was attempting to shift the transfer case to make sure it worked and was having trouble getting it back into high gear - while rolling it made a gear grinding noise (nothing too scary) but shortly after that I started to notice the transmission was slipping from 3 to 4 gear while in D (transmission cold or hot) for about a month.

If the truck was driven in 3 all shifts were fine…and while in 3 at a high RMP if I manually shifted the gear selector to D it would shift smoothly into 4.


THE MECHANIC:

I took it to a local LR shop and the mechanic checked for any detent cable adjustments and fluid level first. He told me that there was too much fluid in the transmission and that most likely this over time deteriorated a clutch pack and I would need a new transmission.

THE SECOND PROBLEM:

After about a month I was driving along in D (4th gear) and the truck just lost all drive power– like it went into Neutral – no noises or transmission fluid leaks – everything looked fine including fluid color and level and I had it towed to my garage

CHECKS I HAVE MADE:

I changed out the transmission fluid and checked to see that the pump was working by observing fluid level drop from N to D – check was okay.

The Transfer case seems to be engaging in both L and H so that seems okay (unless there is something in the T-case that can cause slipping even though external signs are that it is working)

The car will drive on a flat surface if the T-case is placed in the L gear…but it barely crawls along so I'm suspecting there is some weak level of power delivery.

this problem exsists (no delivery of power) in all forward and reverse gears (so I thought this eliminates the clutch pack A theory going bad as theoreticall revearse would still work.


WHAT COULD IT BE? :

I have no experience with transmissions or transfer cases and all this is based on my research to date – so some questions I have:

• Could it be a problem with lack of transmission pressure and so the cause of the earlier bad 3-4 shift? If so how is that diagnosed on the 4HP 22? What could cause that? Bad pump? A bad Governor (what does this do)?
• What are the scenario’s of a bad torque converter? Do these fail? Could this be the culprit?
• Is it possible to have a bad transfer case so that even when it feels like it is engaging it is slipping?
• Do HP4 22’s have solenoids that can go bad?
• Are there any electrical faults that could cause such a problem.

Thanks for taking the time to read this very long post and I appreciate any input you have. I’ve very thankful and hope this is a problem someone can shed some light on or lead me down the right path of inquiry.

Samer

 

[justinhaaga]

hey that's a pretty good explantion good job.

briefly to me, sounds like tcase linkage is not engaged right. especially if you can put it in low like you say. If that is is the case, put it in D and drive as fast as you can, and try all the gears, 1,2,3, R ect. IF they work, they are FINE.

 

[Rocky]

This is a wierd one but I'm thinking that there are issues with the Torque Converter as a result of either excess transmissionn fluid or excess pressure in the transmission caused by for example, failing lines to the cooler causing blockages, or the cooler itself beginning to fail internally causing blockages.

The torque converter is likely to be ballooning slightly causing loss of efficiency of drive transfer and therefore loss of power.

Check coolant lines, cooler and replace as necessary. If you know the tranny filter is old, replace that as well. If none of these makes a difference, think you will have to drop the transmission.

 

[ptschram]

Take it to a tranny shop and pay them $100 to tell you what's wrong with it. To a great extent, these trannys are black boxes and there is only so much we can do with them. It may also be worth spending some $ and having someone like Blackstone Labs (located here in depressed Fort Wayne, IN) and have them run their magic analysis to tell you if you have nothing but friction material in the fluid, or whatever else they might find that could give you some insight into the condition of your tranny.

 

[DC97]

Thanks for the posts and information and reading this long/detailed post.

I'm at least glad to hear that this problem is confusing but your suggestions are a big help.

I didn't suspect the cooler could create blockage as well....that's an interesting theory because that may have been the reason for low-pressure causing the 3-4 shift slippage...and then a final blockage causeing the transmission being starved of fluid..

I'm not sure about the t-case linkage and what that is..but I'll look at the manual and try and understand how that works...and the torque converter...and thanks for the inof on Blackstone Labs - that might come in handy at some point too.

I'm going to bite the bullet and take it to a trans shop and I'll post again in hopes it helps anyone with this kind of problem. In the meanwhile appreciate anyone else's input.

Thanks,
Samer

 

[Kavic]

So what did you find out?

I began having similar problems in the last two weeks. The trans is shifting between all gears but whenever kept in D, the car seems to surge. Power is not consistent, but still there. Whenever I shift into 3, the car runs normally and no surging is present.

I took the car to the transmission shop and they are stating about 4 hours to change filter and fluid (95 Disco, drop cross member, and Y-pipe). It's got 194K so they said taking to the dealer for diagnosis may not be a bad idea but this may all be money thrown away and require a rebuild.

What do you guys think?

 

[ptschram]

I took the car to the transmission shop and they are stating about 4 hours to change filter and fluid (95 Disco, drop cross member, and Y-pipe).

What do you guys think?

Mitchell says 2.4 hours...

The dealer will almost certianly tell you to rebuild or replace.

 

[D Chapman]

Sounds like a Transmission, to me. Transfer case problem is unrelated and is probably due to frozen linkage.

"D" is on a seperate band or clutch from 1, 2, and 3. Sounds like drive just either wore out or broke. Since the engine just rev's, I would say it's broke; if you could get up to speed and shift manualy into D, a lot of times the clutches will catch and you can still drive........for a little while.