Just wanted to post some helpful information up on the site for those of you with the 6HP19 and 6HP26 transmission.

Many of you have complained on the forum about a 2-1 downshift clunk as well as a 4th-5th gear flare issue. Both of these issues are 100% due to a worn out valve body. The valve body on these vehicles wear out in several critical areas:

Pressure regulator valve
TCC release valve
A clutch regulator valve
E clutch regulator valve
Solenoids

If you have caught the issue early and the fluid is still in good condition a simple valve body replacement will get rid of the issues.

We have seen the TSB's related to re-flashing and re-adapting the transmission. We have yet to see either one of these "fixes" actually resolve the problem.

The good news is the 6HP19 and 6HP26 transmission are actually well built transmissions. The only major issues occur when the valve body wears out and the issue is not resolved. This then causes premature failure of the A and E clutches in the transmission.

I will try to add some pictures and test graphs to this post to better illustrate what we are seeing.

 

Do you happen to know the p/n for the valve body?

 

Revmax:

No-one has the 6HP19. 2003+ do have the 6HP26.

This seems new data, please explain where you got it. Who is "we"?

 

I did not mean to say that the Jaguars have the 6HP19. What I was referring to was that the 6HP19 has the same problem as the 6HP26 does.

This data has come from our shop where we rebuild this type and several others types of valve bodies. We provide these valve bodies for local transmission shops, repair shops and some dealer techs who do side work.

I will try to get some photos of the valve bore wear that we see on these units as well. I will also get some scans uploaded of the solenoids being tested on our solenoid dyno.

 

Revmax Converters dot com

Commercial posts need approval from the Forum Admin, but you haven't posted a link to your site, and you seem to be helpful. Welcome to the forum you should stop by our new members section https://www.jaguarforums.com/forum/n...-intro-must-5/ and introduce yourself.

What exactly is the 4-5 "flare" ? Because I get a real "bang" in the 4-5 shift at redline ~150mph & its a little unnerving. I don't notice rough shifts 4-5 at lower revs/speeds.

 

The 4-5 shift flare normally throws a DTC trouble code stating that the TCM has seen a slip on the 4-5 shift. I do not think that your issue is the same as this.

I would guess (just a guess) that your issue still could be valve body related. We may have worn out E clutch regulator valve. It is also possible that the issue could be related to the B clutch regulator valve. We may also be having a EDS 4,5,6 solenoid issue as well....

 

Our cars are getting older so any info could be very useful.

 

wow, nice to hear from someone genuinely knowledgeable on the ZF 6HP26 and its issues,

my transmission has been in for a 'rebuild' at aamco transmission about 10k ago, despite that, it still has the lurch when downshifting from 2 to 1, and there is a big of a 'slip' when it upshifts from 5 to 6.

revmax, if i sent you my valve body, would you be able to rebuild it? do you have rebuilt valve bodies in stock, and do an exchange for core deal?

Is the valve body easily reached and removed on the 6HP26 once you drop the oil pan?

thanks,

 

Right above the pan as I recall. There are pics on the site I think.

 

On the valve body separator plate there is a three digit code. The common code for the Jaguar's seem to be A051/B051.

I do not know what the OEM part # would be unfortunately, sorry!

 

I tried to send you a private message, but could not figure out how to do so out of reluctance I posted it here.

To answer your question, yes, we can take care of that issue for you and yes, the issue described is almost 100% a valve body problem. If you can get us the valve body separator plate code from your valve body we could send an exchange unit to you.

If you prefer to have your original fixed and sent back to you, that can be done as well. Turnaround time is 24-48hrs.

I prefer not to glut this post with sales stuff as we want to provide good information for the community. If you would like to discuss further perhaps you could send us a PM if possible???? Not sure if this forum has such a feature??

 

The PM feature kicks in at 10 posts or so.

 

Ah, that makes sense! Thank you for the clarification!!

 

So your intro post in the new members section will get you there!

 

The mods have arrived...

 

I have the 2-1 clunk but only when first starting out. Once the engine heats up to normal temp. the clunk goes away. I thought it might be the higher rpms while the choke is operating. Could this be the beginnings of the valve body problem?

 

I can only relate my experience, and the Jaguar re-flash TSB solved my problems with the harsh 2-1 downshift. This was over 5 years ago on a daily driver and all is still fine.

My understanding is the earlier re-flash solutions were not adequate, but later (i.e. current) version has better results.

 

Quite a few have posted that they had lurches cured by the reflash both here & on UK forum. But some have not, so an option of a rebuild looks worth having.

 

Possibly, but the issue is normally always present and not temperature related. Now, it could be a solenoid or valve body issue because as temp increases the oil gets thinner. Although, I cannot be totally confident that it truly is a valve body issue.

Does anyone have any literature that they could provide stating what exactly Jaguar is changing in the programming??

If it is merely just a software programming issue then, yes, I can see the reflash fixing it. I would suspect that these vehicles would have presented the issue from the day they were purchased initially or close to it. Those that have the issue come up after several years are more likely to be having the issue stem from a worn out valve body.

 

Most of us got the car used so have no idea how long the problem may have been there, but in any case Jaguar have said there was a problem with the adaptive nature of the software such that it can learn bad values (by drifting from what sane ones would be). The reflash takes out the worst excesses of the adaptive learning.

Anyone who's not had the software updated probably ought to try that first as a potential cure as it's easy and cheap. If no fix, sadly valve body rebuild may be next or replace fluid of course if the mileage makes that sensible.