W124 gearbox fault lost reverse gear

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tintinmt

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Joined
Feb 1, 2009
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364
Well not completely lost. It just about engages when the car is cold but there is no reverse once hot. When hot and I select reverse I can feel a juddering but the car does not move. I am aware that it is often the reverse gear that goes first... The car is a 4 speed. I have checked the fluid level and it seemed OK although I have never been confident in the process.
Is there anything else I can check or do, apart from booking the car in with my normal service garage?
 
Your checking the fluid level with the engine hot, and the box in drive?
 
Yes, engine hot. I cycled through to drive and back a few times, then Park, then checked dip stick. Level was between the two marks.
 
You need to check the level with the box in drive, park will give a false reading.
 
Thanks. Stupid question I guess, but does this mean that it's a two person job?
 
Thanks. Stupid question I guess, but does this mean that it's a two person job?

Depends how good your parking brake is I guess!

I had this problem with my 124 and changing the fluid and ensuring the level was right made no discernible difference I'm afraid. I had to replace the box in the end. However, I hope you have more luck with yours.
 
On my 124 Estate when selecting Reverse it would make a grating sound for a few seconds then a bump as it finally engaged the gear. Reversing band was disintegrating. Gearbox re-build.
 
Last year I had the exact same problem, I'm afraid there's nothing you can do to cure the problem, my cheapest option was eBay, I spotted a refurbished gearbox ( I think I paid £500 ) for it but I was more than happy because it will give me peace of mind for fair few years.
If buying second hand, try to buy one still on a car so you can test it before you waste your Money and time.
I used to use a none slip oil to keep me going but even that wasn't good enough when you try to reverse up a hill.
 
You need to check the level with the box in drive, park will give a false reading.
:confused: The owners manual (pg97 of mine) would disagree and states the same procedure as for pretty much every other auto box... level ground, selector in P, engine idling for a minute or two before checking the dipstick. Plus all the other usual stuff about temps and the effect they have on level, cleanliness and 'elf and safety
The only variation on this i've ever seen is to select each gear momentarily before putting it in P and checking the dipstick which is what i usually do

Assuming correct level of clean fluid i.e. no bits in it, doesn't smell burnt etc the B3 brake band/clutch and/or it's piston are the usual suspect for loss of/slipping in reverse IIRC? Somewhere on the internet are some pdfs that cover trouble shooting and rebuilding the 722.x boxes but aside from checking/changing fluid & filter and not much is really DIYable
 
Thanks chaps. I know I'm clutching at straws. I took my life in the parking brakes hands and checked the level again - same result - spot on.

Just looking for the best way to replace / refurb.

If anyone knows of a good 4 speed box......
 
It seems that my gearbox must be removed and repaired at great expense.
Would I be bonkers to contemplate fitting a used box myself to reduce the costs?
Mr Haynes seems to be offering some advice but describes it as a 'difficult operation'.
I do have an inspection pit which should help.
 

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