Hello to everyone,
So, I have some problems with the ZF 6HP transmission of my Jaguar S-type 3.0 2003. Sorry if my English is bad but it's not my native language.
I came here for some help with deciding what to do cause in my country most of the mechanics will tell you the worst case possible so they can get the most money out of you.
Here are the problems I have:

- When driving slowly and trying to maintain a constant speed of let's say 60km/h the RPMs start going up and down and a scraping noise can be heard from the transmission. This can be observed too when going downhill. You can feel the engine breaking and then a short release followed by engine braking again making the RPM going down not smooth but like the car is trying to hold itself in gear. I have read that this is a common problem on 2003 models, and the torque converter is failing to lock. The solution is a software update of the TCM. I will try to upload some videos of the RPM gauge.

- The transmission shifts is very hard. And when shifting it's not a simple RPM change. You can feel the car getting pulled back and then released as the next gear is in place. Downshifts are the same. They are not smooth and sometimes when going downhill without any throttle the car goes in a higher gear and the car is pushed forward.

- The play in RPM can be seen 2-5 minutes after cold start. In this time interval, the transmission feels tighter. The hard shifting is present all the time.

The things I did trying to find a solution to those problems:

- Transmission oil change. I did change the oil, pan\oil filter, the 4 or 5 rubber hoses above the valve body and the rubber square-shaped gasket above the valve body. This did give some positive results. Sadly I'm the first one to do these things... The oil was black and smelled a little burned and on the oil pan\filter was written 2003 so I guess it was the original filter. The car was on 220 000 km. How real are those kilometres... No one knows.

-Adaptation reset. Shortly after the oil change, this was done too. After the reset, I drove 200-300 km slowly without kickdowns or RPMs above 3000. This too gave some positive changes. The ***** became more crisp and not so hard. Some strange noises although rare went completely away.

- After some time I decided to try LubeGuard Instant Shutterfix. After adding this additive and driving around 50 km the shifts became even more crisp and the transmission felt very tight. The grinding noise and the inconsistent RPMs almost went away. After a cold start and after those 2-5 minutes the play in RPMs could be seen but 2-5 minutes more and they were gone.

I was happy with how things were going and it seemed like the more I drove after adding this LubeGuard fluid the problems were going away. But of course, something had to go bad and it was the oil-cooler of the transmission that is integrated into the engine radiator. This resulted in some transmission oil in the antifreeze. Luckily I found the problem early. Maybe I drove something like 100-150 km like that. So I changed the engine radiator with a new one. And asked a mechanic if there was a chance of some antifreeze getting into the transmission oil. He assured me that the pressure from the transmission is far greater than the pressure in the engine radiator and there is little chance if any of antifreeze making its way to the transmission. So it's been two days and I still haven't checked if the transmission fluid is clear.

After I changed the engine radiator and did all I could to clear the cooling system of oil. I drove the car two times and all of the problems written above are back at full force. So now I have decided to do some repairs in hopes of saving the transmission but I don't want to go ballistic and make a full transmission rebuild cause it's not worth it. I love that car but the full rebuild is going to be something like 1\3 of the car's worth. So that is the last option... If anyone with some knowledge and experience with this transmission can help it would be greatly appreciated!

Thanks in advance to anyone who tries to help!

 

Well that is a lot going on. I would start by getting a way to read the trans codes. If the torque convertor has those problems there should be a code

 

Well, I'm gonna do that today but before changing the oil in the transmission all of the problems were present the same way as now and we checked the TCM for codes and there were none.

 

I think his advice is valid only when the engine is running, and the transmission line is pressurized. But when the engine is turned off, the transmission fluid pressure returns to ambient. However, the cooling system will still hold pressure for quite some time. So I think there's a very strong possibility you will find some coolant in the transmission fluid.

If so, I do not know what process is required to clear all coolant from the transmission, but it must be possible somehow.

 

It's possible to flush oil through the trans - there are posts about doing it (somewhere!).

I suppose you'd potentially need rather a lot to be at all sure you'd shifted all coolant out. Maybe?

 

that is odd. Anyway the problems you describe are torque converter clutch issues. The clutch disengages at zero throttle like coasting so if it was engaged it would drag the car down slower as you describe. There could be a problem with the clutch valve or solenoid in the valve body even

 

Here's a good write-up on a DIY flush:

https://www.jaguarforums.com/forum/x...sh-diy-217150/

It's on a different model, but I believe the general principles should be similar.

 

Hi Venko007,

You can download the TSB for rpm fluctuation and reprogramming the TCM / Mechatronic at this link:

Surge During Warm up at 40mph to 60mph S307-14

If I recall correctly, in some cases Jaguar had to replace the torque converters in vehicles exhibiting the rpm fluctuation or surging.

Harsh shifts in the early 6HPs can often be resolved by updating the TCM / Mechatronic firmware with SDD.

You can find a method for flushing the transmission fluid at this link:

ZF 6HP 26 / 28 Transmission Fluid Flush DIY

Cheers,

Don

 

Thanks a lot for your advices and help. Im gonna try and check if there is coolant in the transmission.

Today I went ahead and got the TCM checked for faults and there were none.

I have read that a software update can resolve some if not all of my issues. The sad thing is that in my country no one can do it. The official dealerships of Jaguar & Land rover have SSD but they say that recently they did try updating the software of S-types and it was not successful... Of course they want money for trying even if it fails.
There is one other shop that claims to have SSD but the mechanic wants double the money that the dealership want and again says that it might not be successful. 🤦🏻‍♂️
So the only guarantee is that Im gonna pay them with or without results.

The only options I have at the moment are either rebuild of the TC or a new one. Again not a small sum compared to the cars worth. 😅 And Im afraid if the problem can be solved with update that means the main problem is in the TCM/software. And after some time a year or so the same problems will come back even with the new/refurbished TC...

 

I had my tcm checked and repaired by softelectronic in bulgaria. Google their website and contact them. It was 750.00 US. 250.00 was shipping as i am in the US. Your cost should be quite lower. They are very good

 

Here is a screenshot of their homepage on website so you will know. They are in Varna Bulgaria. They can also do all programming