RPM Surge
#21
06-30-2014 | 10:53 PM
Joined: Feb 2014
Posts: 19,728
Likes: 13,650
From: Crossroads of America
Thanks for you help, Don. I did only add the Mobil 1 once, so it is mixed with the original fluid along with the Lucas additive.
I have an appointment for this Thursday to have the ATF flushed and new Lifeguard 6 put in. I invested in 12 liters of the stuff so as to be sure to have enough for the infusion. It will be interesting to see if that makes any difference. One way or the other, it will be known whether the fluid is the cause of the surging in my particular case.
I have an appointment for this Thursday to have the ATF flushed and new Lifeguard 6 put in. I invested in 12 liters of the stuff so as to be sure to have enough for the infusion. It will be interesting to see if that makes any difference. One way or the other, it will be known whether the fluid is the cause of the surging in my particular case.
Hi kbeachy,
That's an expensive test to rule out the fluid, but I suppose it's a lot lest costly than a new TC, so I think you're doing the right thing. If it turns out that you really do have to have a new TC, at least you'll know the Lifeguard 6 fluid has low miles and can be reused.
We'll look forward to your report.
Cheers,
Don
#22
07-03-2014 | 04:42 PM
Thread Starter
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Senior Member
Joined: May 2013
Posts: 390
Likes: 102
From: Ohio
So I had the ATF flushed and refilled with 100% Lifeguard 6 this morning. It's supposed to take 10 liters, and I came prepared with 12. Good thing, because they used up every last bit of it. But I can be sure all the old ATF is out of there.
The great news is that the surging is gone! No surging sound and a steady tach needle. Kudos to Don B for putting his finger on the problem being the Mobil 1 mixing with the old fluid. It's amazing to me how sensitive the trans is. I wasn't convinced before that Lifeguard 6 was absolutely needed, but I won't mess around with anything else in the future.
Had I gone ahead and had the TC changed, that would have appeared to solve the problem because new fluid would have been put in. It was certainly worth the risk just flushing the old fluid out. Thanks again everyone for your help and advice!
The great news is that the surging is gone! No surging sound and a steady tach needle. Kudos to Don B for putting his finger on the problem being the Mobil 1 mixing with the old fluid. It's amazing to me how sensitive the trans is. I wasn't convinced before that Lifeguard 6 was absolutely needed, but I won't mess around with anything else in the future.
Had I gone ahead and had the TC changed, that would have appeared to solve the problem because new fluid would have been put in. It was certainly worth the risk just flushing the old fluid out. Thanks again everyone for your help and advice!
#23
07-04-2014 | 03:14 AM
#24
07-07-2014 | 01:03 AM
Senior Member
Joined: Sep 2013
Posts: 120
Likes: 28
From: Toronto, Canada
I was at my local Jaguar independent yesterday to have four tyres fitted. We got into conversation, as you do, and I said the only problem I've never been able to bottom is the "hunting" gearbox during warm-up. The technician used to work at Jaguar, and told me that to speed-up warm up of transmission fluid, there is code in the TCM software to rapidly switch the torque converter lock-up on and off to generate heat. The problem with this clever wheeze was that the friction surfaces in the TC were not suitably profiled for this action, so owners see the 100-200 rpm hunting. A mod was done to later torque converter production that re-profiled the friction surfaces.
Because the syndrome disappeared after a few miles, I had always thought this was a TCM software problem, so suggested the simple answer would be to alter the TCM code to not carry out this rapid switching and asked why Jaguar had not done so. The answer is because it is there for emissions purposes, (quicker warm-up, less emissions), the program cannot be altered as it would affect the emission rating of the car. Of course, one can always fit a new torque converter to cure the problem, but it is not really a problem, it is a feature !
The reassuring news from all this is that anybody worrying that the gearbox or torque converter is about to pack up can rest easy. Just learn to live with the hunting. I just put the transmission into '4' until I've done a few miles.
Because the syndrome disappeared after a few miles, I had always thought this was a TCM software problem, so suggested the simple answer would be to alter the TCM code to not carry out this rapid switching and asked why Jaguar had not done so. The answer is because it is there for emissions purposes, (quicker warm-up, less emissions), the program cannot be altered as it would affect the emission rating of the car. Of course, one can always fit a new torque converter to cure the problem, but it is not really a problem, it is a feature !
The reassuring news from all this is that anybody worrying that the gearbox or torque converter is about to pack up can rest easy. Just learn to live with the hunting. I just put the transmission into '4' until I've done a few miles.
Again, thanks for getting to the bottom of this issue. My mechanic had thought maybe my torque converter needed to be replaced when I asked about this issue, but if the TC was bad the problem wouldn't go away when the car warmed up. Now I know why that is.
#25
02-01-2020 | 10:36 AM
Junior Member
Joined: Feb 2020
Posts: 6
Likes: 0
From: Calera Alabama
New member similar issue.
Hi everyone. I recently purchased an 04 XJ8 with 243,000 miles. I have a similar issue with my transmission. When cold it surges under load around 75rpm but smooth cruising on level roads. When up to temp, the surge backs down to about 25-50 rpm. Under heavier load or hills load its a little more pronounced. Otherwise the trans shifts very smooth with no shutter or hard shifts. I have no idea about the service history on the vehicle but it looks to be very well taken care of. Engine is flawless and only trouble codes are evap system related. It is in need of motor mounts and trans mount, and the driveshaft has a mild vibration so the flex joints, u-joimts and support bearing are on the list to replace soon. I purchased 7 litres of ZF lifeguard 6 and ZF filter and wire harness seal. I am wanting to do a drain and fill to try to rule out low/bad fluid as the culprit before looking at torque converter replacement. The car accelerates great and trans shifts great and pulls with no slipping or abnormal noises vibrations. I'm sure there is a lot more life in it. Just want to get this annoying surge to disappear. What are your thoughts and experiences? Is 7 litres enough for a drain and fill or will I need more? Thanks in advance for your help and advice.
#26
02-01-2020 | 11:20 AM
Joined: Feb 2014
Posts: 19,728
Likes: 13,650
From: Crossroads of America
Hi Robert,
Welcome to the Jaguar Forums! It's great to have you with us.
7 liters of Lifeguard 6 should be enough if you're just going to drop the pan/filter, replace the electrical connector sleeve, install a new pan/filter and then refill. If your electrical connector and pan gaskets are not currently leaking, another option is to flush all of the fluid via the cooler lines to rule out fluid-related issues. If things improve, you can then replace the pan/filter and sleeve and reuse the new fluid. Here's some info on flushing via the cooler lines:
ZF 6HP26 Transmission Fluid Flush DIY
Note that Ford Motorcraft Mercon SP is identical to Lifeguard 6 and much more affordable, at least in the U.S. No problem mixing the two fluids, since the only difference is the red dye color in Mercon SP.
When you get a chance, please visit the New Member Area - Intro a MUST and post a required introduction so we can learn something about you and your Jag and give you a proper welcome.
Cheers,
Don
Welcome to the Jaguar Forums! It's great to have you with us.
7 liters of Lifeguard 6 should be enough if you're just going to drop the pan/filter, replace the electrical connector sleeve, install a new pan/filter and then refill. If your electrical connector and pan gaskets are not currently leaking, another option is to flush all of the fluid via the cooler lines to rule out fluid-related issues. If things improve, you can then replace the pan/filter and sleeve and reuse the new fluid. Here's some info on flushing via the cooler lines:
ZF 6HP26 Transmission Fluid Flush DIY
Note that Ford Motorcraft Mercon SP is identical to Lifeguard 6 and much more affordable, at least in the U.S. No problem mixing the two fluids, since the only difference is the red dye color in Mercon SP.
When you get a chance, please visit the New Member Area - Intro a MUST and post a required introduction so we can learn something about you and your Jag and give you a proper welcome.
Cheers,
Don
Last edited by Don B; 02-01-2020 at 11:23 AM.
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#27
02-01-2020 | 12:06 PM
Junior Member
Joined: Feb 2020
Posts: 6
Likes: 0
From: Calera Alabama
Don,
Thanks for the info. I wish I would have known about the Mercon SP before paying $21.00 per liter for the ZF, but I have it and I will use it. I also have 6 liters of the red ZF fluid left from a BMW 330CI that I used to have and never got around to changing it. I have already posted an introduction on the intro thread with a question about my GPS and climate control unit having no power. Which I have decided to try swapping the dvd unit with a known good used unit. It just came in this morning and I am about to swap it out, praying that it fixes it. I really like the car and want to fix it up and get a lot of use out of it. I'm a professional multi craft industrial maintenance technician by trade and have been an auto mechanic most of my life, so working of the car is no issue. I just need to get familiar with its design and electrical system. Looking forward to getting lots of great tips and info from this group. I will post all of my progress and experience with mine as I go.
Thanks for the info. I wish I would have known about the Mercon SP before paying $21.00 per liter for the ZF, but I have it and I will use it. I also have 6 liters of the red ZF fluid left from a BMW 330CI that I used to have and never got around to changing it. I have already posted an introduction on the intro thread with a question about my GPS and climate control unit having no power. Which I have decided to try swapping the dvd unit with a known good used unit. It just came in this morning and I am about to swap it out, praying that it fixes it. I really like the car and want to fix it up and get a lot of use out of it. I'm a professional multi craft industrial maintenance technician by trade and have been an auto mechanic most of my life, so working of the car is no issue. I just need to get familiar with its design and electrical system. Looking forward to getting lots of great tips and info from this group. I will post all of my progress and experience with mine as I go.
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