Mercedes 722.5 Gearbox Help required
Discussion
Yes, I'm not helping the 5 speed folk here, but bear with me!
Some here will know I recently bought a non-starting 1995 S124 E320 5 speed auto, that hadn't been run for two years. It took an OVP relay for it to start again, albeit £75 for the relay. I know I could have gone secondhand but my friend with his dreadful E280 found that both of his secondhand OVPs had issues of their own, as did the one provided to me.
Anyway, it was misfiring, which I solved with new MB plugs (Bosch W7DC4, coil extenders and a coil, putting the car now on 3 aftermarker (Bremi) coils.
So it was not running like a dream, but it wasn't. Wow, the gearbox was dumb! Very dumb! Kickdown from anything above 30MPH took what felt like days! At other times it felt like the gearbox was 'semi-driving'. It wasn't slipping,but it took time to 'catch' the lower gear. At this point I suspected I was missing a gear, which I will come back to later. Going from 3rd to the next gear resulted in a 1500rpm drop, even at 3,200rpm when it changed from 3rd to the next gear. I felt hte car was shifting as follows:
2,3, then 5 instead of 2,3,4 and 5. Mercs only go into 1st when you go into kickdown at the traffic lights.
I then went to a transmission specialist who drove the car. He put the car manually through the gears and swore that the 5th gear was shot.
At this point I spoke to another specialist who I wanted to speak to first of all, but like all of the good folk, he is a very hard man to get hold of. He told me I either had a serious 'box problem or another issue. Either way, he said to build a code reader and to read them first before making any rash choices
Tonight, I did just that. It came back via Pin 13 through the LED blinks as follows:
-Code 9 ; Control Valve.
From further research this points to the Y3/1y2 valve. I cleared the code and long and behold I was indeed missing 4th gear as I suspected; I then had it for the first time in my ownership! Kickdown suddenly was working at higher speeds just like I was expected and the car finally became a joy to drive! This is how I expected the Merc to work, not as some sleepy slopping missing gears gearbox! Why can't an S205 C350 shift like a 722.5 in comfort mode?
I say became as after 3 miles it went back to its usual self; no 4th gear,and upon rechecking the codes, you guessed it, I had code 9. I've reset the code once more and changed the rather tarnished fuse in the fuse box, but I suspect the problem may come back.
My question is, how hard is it to change the Y3/1y2 valve? Is it a gearbox stripdown to change it or is it something that can be tackled easily over a weekend?
Part of me is tempted to change the oil but I suspect the valve may be sticking or has gone bad.
Some here will know I recently bought a non-starting 1995 S124 E320 5 speed auto, that hadn't been run for two years. It took an OVP relay for it to start again, albeit £75 for the relay. I know I could have gone secondhand but my friend with his dreadful E280 found that both of his secondhand OVPs had issues of their own, as did the one provided to me.
Anyway, it was misfiring, which I solved with new MB plugs (Bosch W7DC4, coil extenders and a coil, putting the car now on 3 aftermarker (Bremi) coils.
So it was not running like a dream, but it wasn't. Wow, the gearbox was dumb! Very dumb! Kickdown from anything above 30MPH took what felt like days! At other times it felt like the gearbox was 'semi-driving'. It wasn't slipping,but it took time to 'catch' the lower gear. At this point I suspected I was missing a gear, which I will come back to later. Going from 3rd to the next gear resulted in a 1500rpm drop, even at 3,200rpm when it changed from 3rd to the next gear. I felt hte car was shifting as follows:
2,3, then 5 instead of 2,3,4 and 5. Mercs only go into 1st when you go into kickdown at the traffic lights.
I then went to a transmission specialist who drove the car. He put the car manually through the gears and swore that the 5th gear was shot.
At this point I spoke to another specialist who I wanted to speak to first of all, but like all of the good folk, he is a very hard man to get hold of. He told me I either had a serious 'box problem or another issue. Either way, he said to build a code reader and to read them first before making any rash choices
Tonight, I did just that. It came back via Pin 13 through the LED blinks as follows:
-Code 9 ; Control Valve.
From further research this points to the Y3/1y2 valve. I cleared the code and long and behold I was indeed missing 4th gear as I suspected; I then had it for the first time in my ownership! Kickdown suddenly was working at higher speeds just like I was expected and the car finally became a joy to drive! This is how I expected the Merc to work, not as some sleepy slopping missing gears gearbox! Why can't an S205 C350 shift like a 722.5 in comfort mode?
I say became as after 3 miles it went back to its usual self; no 4th gear,and upon rechecking the codes, you guessed it, I had code 9. I've reset the code once more and changed the rather tarnished fuse in the fuse box, but I suspect the problem may come back.
My question is, how hard is it to change the Y3/1y2 valve? Is it a gearbox stripdown to change it or is it something that can be tackled easily over a weekend?
Part of me is tempted to change the oil but I suspect the valve may be sticking or has gone bad.
Edited by SebringMan on Monday 8th October 22:30
While no-one has replied, I figured I would update this thread, as it seems resolved for now, and I'm aware these gearboxes do come with a reputation.
After this post, I went to looking for the solenoid to buy which then resulted in me looking for a 722.5 transmission! Before I'd make any rash decisions I went over the car again.
This time I did the following:
1) Scanned the car with my homebuilt diagnostic reader, and cleared all of the codes. This time, only code 9 was present on the gearbox ECU
2) Disconnected and reconnected the transmission ECU, giving the contacts a bit of a clean by blowing some air at them.
The gearbox now thankfully works, and yes, the car is lovely now to drive! Where the connector wasn't connected at the time the loom was changed or the solenoid has freed itself off I can't tell you. It was stood for 2 years remember.
After this post, I went to looking for the solenoid to buy which then resulted in me looking for a 722.5 transmission! Before I'd make any rash decisions I went over the car again.
This time I did the following:
1) Scanned the car with my homebuilt diagnostic reader, and cleared all of the codes. This time, only code 9 was present on the gearbox ECU
2) Disconnected and reconnected the transmission ECU, giving the contacts a bit of a clean by blowing some air at them.
The gearbox now thankfully works, and yes, the car is lovely now to drive! Where the connector wasn't connected at the time the loom was changed or the solenoid has freed itself off I can't tell you. It was stood for 2 years remember.
Here’s a diagram:
http://www.peachparts.com/shopforum/attachments/te...
I made one for a few quid using parts from Maplins (remember them?). There’s any number of guides, and lists of codes, on the web, just Google “Mercedes blink box”.
http://www.peachparts.com/shopforum/attachments/te...
I made one for a few quid using parts from Maplins (remember them?). There’s any number of guides, and lists of codes, on the web, just Google “Mercedes blink box”.
originalracingsnake said:
OK, made the code reader!
Have read the codes from pin 13, and cleared them. It never lasts though... Currently trying to locate the autobox control module so I can check the loom, remember those soy coated looms and how they screw things up? I'm guessing the loom is the issue here.
The loom issues are restricted to upper and lower engine harnesses, and a/c fans. What codes are you getting. Have read the codes from pin 13, and cleared them. It never lasts though... Currently trying to locate the autobox control module so I can check the loom, remember those soy coated looms and how they screw things up? I'm guessing the loom is the issue here.
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