Help ! Sudden No Auto Gear Shift
10-22-2012, 07:31 PM
#152
Nordschleife Master
Thread Starter
Thrust pin was intact. Valve piston still in the hole. There was a slight bit of ATF around it. As I noted earlier today there was no spring.
10-22-2012, 09:01 PM
#154
Former Sponsor
Guys, a quick question. On the above MB repair guide supplied by Jim, on page 4.6/1 I note a spring that goes over the thrust pin and modulator valve. I do not see this spring on PET for my MY, and I did not find it when I removed the modulator apparatus. Before I put the new vacuum unit in, I just wanted to clear with the more knowledgable regarding the absence of the spring.
Once I put the vacuum unit back, I will next drop the pan and see what's there.
Thanks,
Craig
Once I put the vacuum unit back, I will next drop the pan and see what's there.
Thanks,
Craig
10-22-2012, 09:14 PM
#155
Nordschleife Master
Thread Starter
10-22-2012, 09:17 PM
#156
Nordschleife Master
Thread Starter
Malcolm,
Only the saw the brief page for the removal of the modulator in the WSM. Nothing in the WSM regarding the inner components. Greg chimed in as well on the spring I saw in the Mercedes pdf that I posted of earlier.
Only the saw the brief page for the removal of the modulator in the WSM. Nothing in the WSM regarding the inner components. Greg chimed in as well on the spring I saw in the Mercedes pdf that I posted of earlier.
10-22-2012, 09:49 PM
#157
Former Sponsor
If you have done all of the prior things, correctly, that I've mentioned, you need to remove and disassemble the valve body and find out if there is something broken/plugged in it...
That is not an easy thing to do, BTW! There's a whole bunch of pieces in there and lots of way to screw it up! I spend more time rebuilding the valve body than I do rebuilding the entire rest of the automatic transmission! The really great "fun" is taking one apart that someone has screwed up and trying to figure out what they did wrong!
10-22-2012, 10:36 PM
#158
Rennlist Member
Boy, I'd avoid taking the valve body apart. I'd leave dis-assembly to Greg. One lost ball bearing or spring and you are screwed.
That is not for the faint of heart. I've done it. If it were me, I would buy a few cans of brake clean and hose it down in hopes of cleaning out whatever debris might have caused the failure. You can do this while the valve body is in the tranny. Then replace the filter and gasket and replace the ATF, cross your fingers and see if that fixed the problem. ATF is cheap. valve bodies not so much.
That is not for the faint of heart. I've done it. If it were me, I would buy a few cans of brake clean and hose it down in hopes of cleaning out whatever debris might have caused the failure. You can do this while the valve body is in the tranny. Then replace the filter and gasket and replace the ATF, cross your fingers and see if that fixed the problem. ATF is cheap. valve bodies not so much.
10-23-2012, 12:35 AM
#159
Nordschleife Master
Thread Starter
Tomorrow the old filter gets inspected. New filter, new fluid, and new modulator. May install new vac line, but I want to check if it olds vacuum in situ with modulator. All vacuum from intake up to spec since my refresh last year. Will figure out how to spray out valve body when I get under it tomorrow.
10-23-2012, 01:00 AM
#160
Rennlist Member
Tomorrow the old filter gets inspected. New filter, new fluid, and new modulator. May install new vac line, but I want to check if it olds vacuum in situ with modulator. All vacuum from intake up to spec since my refresh last year. Will figure out how to spray out valve body when I get under it tomorrow.
10-23-2012, 01:21 AM
#161
Nordschleife Master
Thread Starter
I'm not saying ignore everyone, but you are not really gaining anything right now by seeing if wheels spin.
You said the ATF level is good (so TC is not drained). I'm not sure why the car rolled when you put it in park, but the previous wheel turning test seems to indicate the park lock is good. If something in the drive broke you would have heard it.
You have major slip in all stick positions, the WSM manual is clear on this - modulation pressure.
Let us know what you find.
You said the ATF level is good (so TC is not drained). I'm not sure why the car rolled when you put it in park, but the previous wheel turning test seems to indicate the park lock is good. If something in the drive broke you would have heard it.
You have major slip in all stick positions, the WSM manual is clear on this - modulation pressure.
Let us know what you find.
I'm hoping it is the dead vacuum unit of the modulator, as noted above. Though doesn't explain why I rolled in Park two times though... maybe a dead modulator can do this (?). I did have it opened quite a bit because of the hard shifting, and was going to run diagnostics on it when all had failed.
Will finish up tomorrow and see what is what. I hope all will be well.
Thanks,
Craig
10-23-2012, 01:42 AM
#162
Former Sponsor
Tomorrow the old filter gets inspected. New filter, new fluid, and new modulator. May install new vac line, but I want to check if it olds vacuum in situ with modulator. All vacuum from intake up to spec since my refresh last year. Will figure out how to spray out valve body when I get under it tomorrow.
All the things that matter are hidden on the inside.
10-23-2012, 06:41 AM
#163
Rennlist Member
Still hoping your repairs become straightforward.
Parking engagement is strictly mechanical.
Mechanism was pictured earlier.
The cars will roll a bit in park, 6 inches or so, before engagement,FWIW.
Parking engagement is strictly mechanical.
Mechanism was pictured earlier.
The cars will roll a bit in park, 6 inches or so, before engagement,FWIW.
10-23-2012, 11:12 AM
#164
Nordschleife Master
Thread Starter
I thought so too when it was suggested. As it is a 'valve' body there must be an inlet. Does accessing that inlet mean disengaging it from the trans ?
10-23-2012, 11:47 AM
#165
In the absence of evidence indicating something specific is wrong with it I would leave it alone and proceed with the modulator and fluid. No sense poking around when it may be working fine.