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ardenconny · 7th September 2021, 23:11

Hello everybody,

It’s sad really that my first message here has to be a negative one. Anyways, I have a serious issue with my 75 Jatco box. This saga started a few months back in may, when I acquired a beautiful -99 75 Conny with a blown reverse belt. My mechanic happily changed it for me and for a while the car worked like a dream (unlike my 45 haha). But then, some problems started to appear.

When I start driving with a cold engine, the gearbox is REALLY sloppy, like it needs 3-4k revs just to start slowly crawling ahead. Surprisingly, reverse gear works just fine. After a while, assumingly when the gearbox has warmed up, the box works just as usual. When the box is warm, it’s smooth as butter and it works very well. However, last Friday it REALLY left me down. I went to pick up groceries, the box being sloppy as usual, but this time, it really did not want to move. I gave her like 4-5k revs (I didn’t dare to give it more) and then it triggered limp mode. Triggering limp mode did not make the car move at all. After a while sitting, the box continued it usual sloppiness and drove “fine” for a half-mile, then everything stopped working. Limp mode continuously came on and off, the car did not move forward nor reverse at all. I had to tow it (yes stupid idea) with engine running to just to get it back home. I figured that if I keep the engine running and gear in neutral, maybe it doesn’t do too much damage.

Since then I have tried to read fault codes from the box via Toaf, but there’s none. I even had issues connecting to the box in the first place. Me and my mechanic are astonished. I think that maybe there are connecting issues due to my old nasty coolant leak. The upper coolant hose under the airfilter box had a rupture on it and it was spewing coolant right to the top of the gearbox, maybe that’s causing the connection issues???

But I seriously wonder why the box became so sloppy all of the sudden. When the renovation was complete, me and my wife took the car for a nice long trip without any gearbox issues. After we returned, then the box became all sloppy (that’s when the hose ruptured too). I wonder could it be because of the oil my mechanic used? He said that he used Comma MVATF+ oil and deemed it to be compatible, is it really? He now says that the gearbox issues could be because of gearbox valves or solenoids are getting stuck…?

I work in IT and my mechanic is not really that familiar with the Jatco autobox. He used to take very good care of my 45 and 600 so that’s why I still use him. I hope there’s someone that could give me and my mechanic a nudge to the right direction

Ps: We do not have access to a T4 system, the closest t4 to me being over 500 miles away, and with a broken gearbox I obviously can’t reach it.

7th September 2021, 23:11	#1
ardenconny Newbie Rover 75 Saloon Join Date: Aug 2021 Location: Vaasa Posts: 15 Thanks: 0 Thanked 12 Times in 4 Posts	Jatco transmission issues Hello everybody, It’s sad really that my first message here has to be a negative one. Anyways, I have a serious issue with my 75 Jatco box. This saga started a few months back in may, when I acquired a beautiful -99 75 Conny with a blown reverse belt. My mechanic happily changed it for me and for a while the car worked like a dream (unlike my 45 haha). But then, some problems started to appear. When I start driving with a cold engine, the gearbox is REALLY sloppy, like it needs 3-4k revs just to start slowly crawling ahead. Surprisingly, reverse gear works just fine. After a while, assumingly when the gearbox has warmed up, the box works just as usual. When the box is warm, it’s smooth as butter and it works very well. However, last Friday it REALLY left me down. I went to pick up groceries, the box being sloppy as usual, but this time, it really did not want to move. I gave her like 4-5k revs (I didn’t dare to give it more) and then it triggered limp mode. Triggering limp mode did not make the car move at all. After a while sitting, the box continued it usual sloppiness and drove “fine” for a half-mile, then everything stopped working. Limp mode continuously came on and off, the car did not move forward nor reverse at all. I had to tow it (yes stupid idea) with engine running to just to get it back home. I figured that if I keep the engine running and gear in neutral, maybe it doesn’t do too much damage. Since then I have tried to read fault codes from the box via Toaf, but there’s none. I even had issues connecting to the box in the first place. Me and my mechanic are astonished. I think that maybe there are connecting issues due to my old nasty coolant leak. The upper coolant hose under the airfilter box had a rupture on it and it was spewing coolant right to the top of the gearbox, maybe that’s causing the connection issues??? But I seriously wonder why the box became so sloppy all of the sudden. When the renovation was complete, me and my wife took the car for a nice long trip without any gearbox issues. After we returned, then the box became all sloppy (that’s when the hose ruptured too). I wonder could it be because of the oil my mechanic used? He said that he used Comma MVATF+ oil and deemed it to be compatible, is it really? He now says that the gearbox issues could be because of gearbox valves or solenoids are getting stuck…? I work in IT and my mechanic is not really that familiar with the Jatco autobox. He used to take very good care of my 45 and 600 so that’s why I still use him. I hope there’s someone that could give me and my mechanic a nudge to the right direction Ps: We do not have access to a T4 system, the closest t4 to me being over 500 miles away, and with a broken gearbox I obviously can’t reach it.