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I searched this topic but couldn't find anything on point. When I shift into reverse, the transmission makes a thud and the vehicle jerks in reverse. Once in drive, the transmission will not shift out of what I believe is second gear. I took the vehicle to an independent shop and they say the error code suggests a problem with the valve body. Can someone post the parts manual that shows the valve body and offer any advice on what a fix could be? I asked about flushing the transmission and the SA indicated he didn't think that would make a difference because the transmission fluid is rated for life. He asked for a few more minutes to see what code it throws once cleared, but he somewhat ominously stated it was a very expensive repair. Any insight would be appreciated for when he calls back.
 

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LEGACY VENDOR
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Double flushing the transmission is a standard ‘fix’ for 6HP26 problems.

The mechatronic unit (valve block) is easy enough to replace (part no. THC500061) but Land Rover charge £1000 for a new unit so you’d need to be pretty sure that’s where the problem lay.

The 6HP26 has lots of quirks. For example, the control system won’t allow the transmission to upshift out of 1st gear if it sees a brake signal e.g. if the brake switch is faulty or badly adjusted or even if the brake light bulbs are the wrong spec.

Phil
 

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Thanks, Phil. Official diagnosis: new Valve Body and sleeve. This may have been a stupid question, but I asked if they visualized the valve body to confirm it was the culprit. SA stated they did not and based their opinion solely on the codes that were thrown. I don't know about this issue. Any suggestions? They want $3800 to replace the valve body and sleeve. Think I should have it flushed before agreeing to the repair? Your reply suggests to me that you do. Thanks.
 

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I’m afraid it is all too common now where components are just swapped out as complete sub-assemblies without stripping them down to find and repair the actual fault. I guess this is a combination of the time it takes (time costs money) and the technicians not having the necessary skills (training costs money). It takes me around 6 hours to strip, ultrasonically clean, check (spring lengths, etc.) and rebuild a 5-speed valve block (but I’m an amateur!)





Having said that, the 6HP26 valve block is particularly scary to repair shops as the transmission control unit is integrated onto the hydraulic valve block (ZF therefore call it a mechatronic unit) allowing the electronics to be individually tuned to the hydraulic system in production. Unlike with the 5-speed, therefore, ZF do not make the individual spools, springs, etc. available to repair shops and only supply complete service units. I believe that only the solenoids are available as separate items.



Unfortunately, not knowing the codes that it’s throwing up, I’m not in a position to comment on whether or not they are telling you and doing the right thing. It’s possible that a transmission specialist might be able to carry out further diagnostics and maybe pinpoint the problem more accurately but that would clearly be a huge hassle for you if the car is presently immobilised.

As I mentioned previously, the mechatronic unit is not difficult to change (transmission does not need to be removed) and remanufactured units can be sourced for less than $1000, for example http://europeantransmissionscom.x-shops ... 721&page=1
so I feel that the price you’ve been quoted is ridiculously high.

I’m sorry I can’t be of more help. Please let us know how you get on.

Phil
 

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2002-2005 Range Rover MkIII / L322
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RRPhil said:
(but I’m an amateur!)

Phil
Phil,

I don't think we could ever describe you as an amateur! You are a wizzard with these transmissions.


OKROVER:

Considering the price they are quoting, have you thought about slinging in a second hand box? Maybe a low mileage out of a breaker?

Then you could get your current box fixed and keep it as a spare, or sell it on to cover your costs.
 
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