So our 2004 XJ8 began leaking fluid from the cooler lines. Fortunately they started to while the car has been sitting more lately, so they didn’t bust while driving. While I was inspecting the lines I noticed part of the transmission pan was damp, but I was not sure if it was from the cooler lines up front or a slow leak at the gasket, so I decided to change the pan too.

I cut off the two old rubber cooler lines near the radiator and replaced them with new ATF lines using the double clamping method.

I bought a metal pan from Phoenix Trans Parts, along with a new mechatronic sleeve from another seller. I installed the sleeve by the book and measured the gap which was 2.5-3mm. I also cleaned both electrical connections with a non contact cleaner. I replaced the pan (no torx heads stripped thank goodness) and torqued per the manual. I refilled with Mercon SP per the book, including car level, AC full blast, shift between gears for three seconds each prior to 35C, and fluid had a small stream at 40C which is when I plugged it.

I had attempted to flush the torque converter via cooler lines while the pan was empty, as I only drained about 5 quarts from the pan. It sputtered alittle but nothing really came out of the lines.

The metal pans supposedly hold one less liter due to the shape, and as such it is required to fill it by the bottom fill port on the pan, and not the transmission side fill plug. I put approximately 4 quarts back in.

After filling the pan but before checking the level, I started the car to see if I could get more fluid out of the cooler lines. It immediately started spitting red Mercon SP, which is weird because I thought people were flushing their torque converters via the cooler lines, but mine had to come straight from the pan.

I checked for leaks prior to the test drive, and everything checked out fine.

When I took it for a test drive it immediately lit up the dash with Transmission Fault and the car is slow to go into either forward or reverse gears. It is acting like the torque converter is slipping like crazy and even when it grabs it doesn’t seem to fully catch. On a slight incline when put into gear it will roll in the opposite direction (downhill) until you give it gas and even then it is slow to catch. The transmission is also whining which follows the revs of the motor...it does it in drive and park. By whining I mean it sounds like a power steering pump on its way out or PS low on fluid.

The car ran and drove just fine prior to this, just under 90,000 miles. I’m guessing it is the first trans flush for it. The fluid was dirty but not as bad as our XK’s fluid I changed last year (it had around 100,000 miles).

I plugged in the VCM and it didn’t show codes, so I cleared them and restarted a new session. I started the car and put it in reverse with my foot on the brake, and then in drive while not moving. It again threw a fault so I read the codes, which are:

P0735 Gear 5 incorrect ratio
P0736 Reverse incorrect ratio
U3FF6 description not available (not sure if this is related)

Pictures of the codes are attached.

My initial thought is the fluid level is too low. I am about to go put it on jacks stands and recheck again to be sure. My other thought is air in the system. Is it possible to get air trapped in the lines/torque converter, etc? If so how do you bleed it out?

Any other thoughts?

EDIT: Just reconfigured the TCM and reset adaptations to check those off the list, still getting the same symptoms. Still waiting for the trans oil to cool a bit before checking.

 

Fluid is most likely low. Fill it per the correct procedure in the Workshop Manual.

 

+1 fluid way low. Fill per JTIS/ZF procedures

 

Just performed a second fill and level check per the book. Same symptoms and I was only able to add maybe 1/4 of a quart. Transmission fault comes on when it is placed into gear and pedal on the brake. I am still convinced there is air in the line as the cooler was empty when I reassembled it. Plus the sounds of whining and weird almost gurgling sound. It may not be gurgling but it is making some weird noise.

In retrospect on the initial drain and fill 6 quarts came out and only 4 went in.

Is there a way to burp the lines? The way it sounds is that there is air in the system. Is it common to get air trapped? I am going to take the cooler line off of the trans to see if I can find any air in there.

 

If there was any air in the lines it would purge out I would think in the trans pan area. 6 qts out and 4 qts in is definitely off.

How are you measuring temperature of the fluid?

 

And I would fill via the side plug, no other way. If you fill from any lower point you'll never get the proper amount of fluid back into the trans.

 

Just took off the upper oil cooler line at the radiator and no oil dribbled out. It’s almost like it drained back in the line. I started the car and it sputtered some fluid out but it wouldn’t take hardly any in the cooler. I’m almost thinking a blocked line either from foreign matter or air.

I might need to look up and see how the trans pump functions, too. To my understanding it should pump in park, drive, or in park with the engine revs. It sounds like it is but hardly any fluid is coming out.

I can see maybe a blocked line on the cooler side since it won’t hardly take any more fluid (I’m assuming it will gravity drain into the trans).

What baffles me is why is the upper cooler line just blowing mainly air?

Edit: I am using SDD with a VCM to check trans temp. It is the same way I changed the fluid in the XK8. Per CTSC when changing to a metal pan:

http://www.thectsc.com/products/6hp2...it-222-59.html

http://www.thectsc.com/bmw-6hp26x-tr...-steel-oil-pan

I didn’t purchase feom CTSC but I asked PTP and they linked that web page as the fill procedure.

 

2 quarts less in trans plus the metal pan holding one less quart plus potential empty cooling lines equates to 3.5+ quarts down.

No bueno.

 

You may be sucking in air due to very low fluid level. I would reattach cooling lines and fill via side fill.

 

I took out 6 quarts but replaced with a pan that holds 1 less quart...that would mean I can only replace with 5 quarts, unless my math is way off. I should only be at a one quart difference at this point, minus any that I may need in the cooler lines.

 

Did you install the filter assembly correctly As it's now separate from the Pan correct?

 

That crossed my mind. The way it fit it can only go in one way (tube with gasketed end goes in the hole), plus I don’t believe you can install the pan unless the tube is in the hole, because it is somewhat like a sandwiched fit. But certainly a good thought. I am currently filling per the noral method with the plastic pan to see if that makes a difference.

I am still unclear how and where the cooler lines suck fluid from...

 

Well gents, problem solved. Just filled per the normal Jaguar/ZF procedure and it swallowed an extra 4-5 quarts! No wonder it was misbehaving so badly, it was missing almost half of the fluid! That would explain why it was spitting air through the oil cooler lines. It makes me wonder how low the fluid was before. In all fairness I had previously lost some from the cooler lines leaking, but I didn’t think it was THAT mich.

Visually the metal pan itself looks like it might hold a little more than the plastic one, but I can’t be sure. Here is what I purchased, if anyone is interested:

https://m.ebay.com/itm/ZF6HP26-Trans...p/272330683049

Which brings me to another point. Hypothetically speaking, if you fill by the trans side port every time, it shouldn’t matter if the pan holds less fluid, say two quarts, or more fluid, say 20 quarts, as long as it is filled by the side port (within reason ofcourse...if the pan is too deep with oil it would slosh around more, if less the trans may overheat). But the idea should be the same for the fill procedure, correct?

It makes me wonder why CTSC would even mention the need to fill per the pan plug...what good would that do?

I will be emailing the seller and informing them their fill procedure was not correct, for any future purchasers to not go through the same headache. I may also email CTSC and see their reasoning on the different fill method.

Thank you both for your help, you guys were spot on!

 

Glad to hear it. My trans has a slight weep at one of the lines and I was low 2.6L! But I think whoever serviced the trans didn't fill it right.

It drove fairly well but I knew to check the fluid level before doing any serious driving and I'm glad I did.

Pan, sleeve and cooler lines will all be serviced in the spring along with TCM reflash.

 

When I did a complete flush and fill on my 2005XJR I disconnected one of the cooler lines to do the flushing and had the wife start the engine.

What took me by surprise was the force of the fluid ejecting out of that line. It was extremely forceful and flooded everywhere within 1-2 seconds before switching off the ignition.

I continued with ejecting about a quart at a time and filling a quart at a time.

Point I am making is that even with a small leak quite a bit of fluid is likely to be ejected when driving.