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  #1  
Old 11-08-2009, 03:38 PM
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Hard Shifting Into Gears

Well, my '95 has turned against me and now is throwing all sorts of things at me to deal with. My IP is leaking, but at least I know where it is coming from now and how to go about dealing with it. However, somewhere in the process of removing/reinstalling the manifold (3 times now) I must have mucked something up. Because now transmission is shifting hard in to gear. I suspected that I messed up the vacuum somehow, but I had the manifold off again yesterday and I checked all the lines and couldn't find anything. I did manage to break a couple of the lines (they are very brittle) - one to the SOV and one to I don't recall what - but I pieced them back together with some new vac tubing. I don't believe I disturbed the black tubing for the transmission at all - I did have it unplugged, but it is plugged back in along with everything else.

Anybody have any thoughts. Are real hard shifts characteristic of loss of vacuum? It really slams into gear sometimes - and it feels like it is coming from the rear end when it does. So much so that I got paranoid that something was wrong with the differential - it does has a small leak at the input shaft - so today I drained out the old fluid and put in new. I got 1 liter of old stinkin brown diff fluid out and put 1 liter of new clean fluid in.

Anyway - is this a vac issue of my creation or possibly anything else.

As always - thanks!

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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Last edited by tankowner; 11-08-2009 at 05:06 PM.
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  #2  
Old 11-08-2009, 04:18 PM
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Hard shifting indicates a vacuum leak / low or no vacuum to the transmission modulator.
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  #3  
Old 11-08-2009, 04:27 PM
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Quote:
Originally Posted by babymog View Post
Hard shifting indicates a vacuum leak / low or no vacuum to the transmission modulator.

Okay - so it sounds like I screwed something up (since I didn't have this problem before). The modulator is down on the transmission - correct? I suspect it is what my black line runs to. Perhaps I cracked/broke a line somewhere else I didn't see.
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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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Old 11-08-2009, 05:23 PM
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Make sure the line is still connected to the modulator. Sometimes it gets pulled off when you're futzing around in the engine bay. Then check the supply line from the pump to the VCV is connected at both ends and any junctions.

Are other vacuum consumers not working right like ACC register selection, rear headrest collapse, etc.?

Sixto
87 300D
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  #5  
Old 11-08-2009, 05:51 PM
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Quote:
Originally Posted by sixto View Post
Make sure the line is still connected to the modulator. Sometimes it gets pulled off when you're futzing around in the engine bay. Then check the supply line from the pump to the VCV is connected at both ends and any junctions.

Are other vacuum consumers not working right like ACC register selection, rear headrest collapse, etc.?

Sixto
87 300D
Okay, I will have to get down there and check the modulator connection out - I thought I could see it from above, but maybe it wasn't what I thought it was.

The line from the pump to the VCV was one of the ones that broke - just the end near the pump. I lost a few inches, but I think it back in tight - I checked it several times.

I did grab a diagram and try to make sure everything was hooked up properly.

Let's talk about the VCV for a minute - this is the one near the IP, right? There are two lines that come out of the top. One goes to the green dashpot and from there it got to a sort of slatned "T" that connects to the black vac line that runs to the transmission (the modulator I guess). The other line coming out of the VCV (just a hair back from the dashpot) is the white supply line that runs up towards the pump (I believe). I think I have that all hooked up right.

Now then, there appears to be a nipple on both sides of the VCV. The one on the side nearest the engine is not hooked up to anything (I think it is a nipple I can see to tell if it is actually hollow). The one on the side away from the engine has a little rubber "L" shaped tube on it. When I first came across this I swear there wasn't a line hooked to it - or if there was I had somehow managed to already knock it off with out knowing it. Regardless, there was a black vac line hanging in the general vicinity - so I plugged it into there as I could not see where else it might go. That is the only thing I can think of that maybe was not as I had found it before I started. Perhaps I should undo that line??? I looked at the diagram again and it seem to suggest that is also part of the transmission line - which would be in keeping with the other black line that is to the tranny. Should that line be hooked up there?

Thanks babymog and sixto - it is appreciated.
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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman
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  #6  
Old 11-08-2009, 08:44 PM
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The little L-shaped rubber tube coming from the side of the IP, that is the VCV, if it is leaking or disconnected you will have hard shifts.

I don't have one, but you need a vacuum-line routing diagram if there are multiple disconnects to ensure that they are all properly connected again.
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Old 11-08-2009, 10:32 PM
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Quote:
Originally Posted by babymog View Post
The little L-shaped rubber tube coming from the side of the IP, that is the VCV, if it is leaking or disconnected you will have hard shifts.

I don't have one, but you need a vacuum-line routing diagram if there are multiple disconnects to ensure that they are all properly connected again.
Hmmm. Okay. Well, I have another look at that one. Most of the rubber fitting are getting a little worn and loose. I wrapped several of them in electrical tape becfore I reinstalled the vac tubing and that help a lot as far as making the seal tighter. I'll have the manifold off again once I get the proper socket to do the delivery valve job. Perhaps it is succking a little air at that spot. Thanks again.
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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

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  #8  
Old 11-12-2009, 09:28 PM
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Well, I crawled under the car tonight to check that the tubing that goes to the transmission modulator was intact and it was. So I am a little stumped - the vac lines appear to check out. I slipped the MityVac on at the pump and it was pulling 22".

I snapped a couple pics of the throttle linkage and broken pieces. The first one is the throttle cable - you can see the plastic adjusting nut is broken. The second picture is the bowden cable (correct?) that goes to the transmission here too the plastic adjusting nut is broken. Now, the second one has been like that - the first one I am not so sure. I guess I could have broken it while moving the linkage around as I removed the manifold. So, could this cause the sudden hard shifting that I am experiencing. Or do adjusting these just advance or delay the shift points. It's really slamming into gear and I don't see why. I can't imagine it is particularly good for the tranny.

Thoughts? Oh, and can i replace just these adjusting nuts, or do I have to do the cables. Thanks!



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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman
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  #9  
Old 11-12-2009, 09:51 PM
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Quote:
Originally Posted by babymog View Post
The little L-shaped rubber tube coming from the side of the IP, that is the VCV, if it is leaking or disconnected you will have hard shifts.

I don't have one, but you need a vacuum-line routing diagram if there are multiple disconnects to ensure that they are all properly connected again.
Okay. So I went back and check L-shaped rubber connector on the side of the VCV and indeed it was not connected tightly - just looked that way - so it wasn't getting vacuum. However, I got it in there good and tight and then took it for a test drive only to find that the hard shifting was still present. It seemed like maybe it had gotten a little better - especially from 1-2, but upwards from there it still feels like (as someone else said) there is an angry mule in the trunk.

Opposite the L-shaped connector on the VCV there appears to be another nipple (I can't really see to tell if it actually is or not), but nothing connects to it. Is this a vac nipple with something missing?
__________________
'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman
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Old 11-12-2009, 10:22 PM
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confused

Just reading through some back posts on the VCV.

Why does Jeremey's 606.912 VCV L-shaped connector appear to be a vent:
http://www.peachparts.com/shopforum/showthread.php?t=249103&highlight=VCV





but Sixto's 603.96 appear to connect to the black tranny vac line?
http://www.peachparts.com/shopforum/showthread.php?t=259141&highlight=VCV




Where does that leave my 606.910?
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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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  #11  
Old 11-13-2009, 12:59 AM
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The only relevant connections on the VCV are the two in parallel. The one off the rubber elbow is a vent. Take a vacuum reading downstream of the green cylinder, preferably right at the tranny modulator. It should register at least 18"Hg with the engine idling. If you have a separate MityVac and vacuum gauge and a couple other hands, you can pump like crazy into the VCV fitting that doesn't have the green cylinder and check that the vacuum signal to the tranny modulator tapers to nothing as you apply more throttle. It should taper linearly in response to throttle position. The other thing to check is the tranny modulator. Apply a vacuum downstream of the green cylinder (the end away from the VCV). It should hold 20"Hg. If it doesn't hold or leaks, you have a bad modulator. But usually when the modulator fails the vacuum pump draws ATF.

Having insufficient tension in the Bowden cable should result in early shifts, as in getting to top gear by 30mph in the extreme. Theoretically it shouldn't have much bearing on shift quality but VCV and Bowden cable adjustment both have to be right. Things go goofy all around when one isn't set right.

The black line in my 603.96 picture is the vent line. The line to the tranny modulator is the white line that goes straight down and grazes the fuel thermostat.

Sixto
87 300D
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  #12  
Old 11-13-2009, 01:32 AM
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Quote:
Originally Posted by sixto View Post
The only relevant connections on the VCV are the two in parallel. The one off the rubber elbow is a vent. Take a vacuum reading downstream of the green cylinder, preferably right at the tranny modulator. It should register at least 18"Hg with the engine idling. If you have a separate MityVac and vacuum gauge and a couple other hands, you can pump like crazy into the VCV fitting that doesn't have the green cylinder and check that the vacuum signal to the tranny modulator tapers to nothing as you apply more throttle. It should taper linearly in response to throttle position. The other thing to check is the tranny modulator. Apply a vacuum downstream of the green cylinder (the end away from the VCV). It should hold 20"Hg. If it doesn't hold or leaks, you have a bad modulator. But usually when the modulator fails the vacuum pump draws ATF.

Having insufficient tension in the Bowden cable should result in early shifts, as in getting to top gear by 30mph in the extreme. Theoretically it shouldn't have much bearing on shift quality but VCV and Bowden cable adjustment both have to be right. Things go goofy all around when one isn't set right.

The black line in my 603.96 picture is the vent line. The line to the tranny modulator is the white line that goes straight down and grazes the fuel thermostat.

Sixto
87 300D
Okay. Things are becoming a little more clear. Although I am still confused, I see there is somemore diagnostic work I can do. By reading through a bunch of old posts and with your confirmation, I now realize that little L-shaped fitting is just a vent. In a diagram I was looking at it was labeled as "transmission" - which it is for, but it is just a vent.

I'll crawl underneath and see what kind of vacuum is being pulled at the modulator. Then I will also, as you suggest, pull vac on the modulator to see if it holds.

My shifting has been goofy since I bought this one - so it looks like I may eventually get it close to normal. What I still don't understand is why this harsh shifting problem cropped up after I was in there messing around. I must have done something - I just can't see what at this point.

Thanks again. I'll post again when I know more.
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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman
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  #13  
Old 12-05-2009, 06:33 PM
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I'll crawl underneath and see what kind of vacuum is being pulled at the modulator. Then I will also, as you suggest, pull vac on the modulator to see if it holds.

Thanks again. I'll post again when I know more.
Well, I finally got back to this project and here is what I have found. There is NO vacuum at the modulator! Go figure. I really only had time to figure that out - and to pull vacuum on the modulator (which held 20" Hg - no problem). So, I guess I will head up stream tomorrow - I really don't want to have to pull the IM off again - oh well. Any thoughts?
__________________
'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman
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  #14  
Old 12-05-2009, 07:27 PM
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Is the VCV attached to the IP? I think in some 606 applications there is a linkage between the IP and a remotely mounted VCV.

Sixto
87 300D
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  #15  
Old 12-05-2009, 09:23 PM
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Quote:
Originally Posted by sixto View Post
Is the VCV attached to the IP? I think in some 606 applications there is a linkage between the IP and a remotely mounted VCV.

Sixto
87 300D
Pretty sure it is right on the IP - no external linkage between them.

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
______________________________________

"Back off, man. I’m a scientist” ~ Peter Venkman
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