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Strange Transmissions from Mars
Hi all and well met!
I have an 82 Turbo Diesel Sedan I've been working on. One of the things I've been working on a problematic 2/3 shift and it has me a little stumped. The car used to flare and slip quite badly on the 2/3, sometimes not going into 3rd It still does it when it's cold but will work better when warm but still with a fair amount of flair as a result of some of the stuff I've done However it's still not as good as my previous 80 300d (which always shifted well and I was a little hard on it) or my 81 300TD turbo which shifts well with a slight 2/3 flare Ist and second are both strong and the 3/4 shift seems good too The tranny kicks down well too There is some delay when drive or reverse is initially engaged Here's the goods: I've; -Changed the Fluid, the filter and the K1 spring kit -made sure the bowden cable was adjusted properly -Troublshooted the vacuum system, replacing many of the rubber hoses and the rubber cap on the modulator, There seems to be adequate vacuum from the pump. ( I have a mighty vac and a vacuum gage) - Checked and adjusted the VCV valve using the 2cm disc on the full stop pin and a vacuum gage - Overhauled the 3/2 valve with new levers and hoses, the EGR is disconnected and nozzle is plugged - Tried hardening the shift at the modulator on the tranny (up to 3turns!) This helped some with the flaring but it's clunky now So Now I have the VCV adjusted properly so it reads about 4.1 hg 10mm from full stop. The modulator is turned in (clockwise)3 turns from where it was when I got it (I don't have a pressure gage but I think I'll be buying one to test it properly) one funny thing it does is that if I disconnect the 3/2 valve and plug the line it won't shift out of 2nd at all, even when warm, it doesn't slip but it just won't shift.It stays in second If I reconnect the 3/2 it will make the shift but with some flaring and all the other shifts are pretty hard (because of the modulator adjustment) Any ideas?? Also I have a few questions about the 3/2 valve: -Should it hold vacuum at rest? (idle) Mine seems to open up and leak it as soon the throttle is slightly touched and the lever on the valve begins to depress. - When I'm testing the vacuum on the fitting normally going to the modulatoron the tranny, there's decent vacuum but as soon as the throttle is only slightly moved and the 3/2 lever is depressed it immediately drops to 0 Is that normal?? - When the 3/2 is disconnected the vacuum seems good and the 3/2 seems to work well except then it won't shift into 3rd at all?? Aiiiiiiieeeeee!!! |
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Hi Toxophilite and welcome to the forum.
Take a look at this thread over on BenzWorld for the vacuum information DIY W123 Transmission Diagnose and Adjustment 722.xx OM 616-7 - Benzworld.org - Mercedes-Benz Discussion Forum I'm no expert in the variations and workings of that yet. You should be able to find the good "vacuum values" for your car there. It seems like you've done most of the things that can be done without seriously taking the transmission to bits... Here's a picture showing the relationships between the elements of the transmission for a 722.1 transmission - I think you might have a 722.3 though - can you confirm? Most people scream B2 piston for virtually any problem with these transmissions but according to the information above it stays on for the first three gears - so I don't think it is that. When shifting up the release of the B1 piston and the application of the K1 clutch could be an area worth investigating.
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
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Have you read through this thread?
It's CRITICAL... how you set your transmission's vacuum system on your diesel MBZ... I finxed mine with a manual 4 spd, so not much help on the automatics. Charlie
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there were three HP ratings on the OM616... 1) Not much power 2) Even less power 3) Not nearly enough power!! 240D w/auto Anyone that thinks a 240D is slow drives too fast. 80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works Last edited by charmalu; 02-24-2012 at 09:47 AM. |
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Good point Charlie - it is best to rule out the vacuum before pulling stuff apart.
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
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2x on the welcome to the forum.
You will find that working on your 300TD a mityvac will become a good friend. Ebay is a good place to get them.
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1985 300D 198K sold 1982 300D 202K 1989 300E 125K 1992 940T "If you dont have time to do it safely, you dont have time to do it" "The democracy will cease to exist when you take away from those who are willing to work and give to those who would not." |
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Holy Smokes!
I was reading that "It's critical..." thread about tranny vacuum adjustment and there is some pretty unusual viewpoints. One fellow claims adjusting the VCV valve requires specialized equipment. The peter schmidt 7 pager only uses about a page and a half for the actual test but details 2 different models, shows a diagram and lists specs. That's why it's 7 pages! not because it's exhaustive and extensive The only really specialized tool is a 2cm disc with a hole in the center. You could probably use a tonka toy wheel of the proper dimensions!! It's a pretty easy test, not rocket science or mercedes magic at all! Whew!! Sorry, I only got halfway through the thread . It's long!!! All that orifice talk!!! eek! One guy had a blue orifice...like a baboon!!! Thanks for the welcomes I have a mityvac and vacuum gage I agree it's a fun and useful unit I wan to pump up everthing with vacuum now..all my friends avoid me! I'm suspecting somethig amiss with the tranny itself I'm going to tinker a bit more before I drive it off a cliff I have a 81 300TD turbo wagon that run and shifts well and is Mechanically sound but has some ugly door bottom and fender rust. also the hatch is rusted out a little and leaky. No floorboard problems Oh and it needs the self leveller rebuilt so if any one knows where I can get an O-ring kit that'd be great. I paid a little too much for this car but I think it's been mechanically well maintained The car with the tranny problems is a 82 300D turbo sedan that I got for $400...I found something in the car that reduced it's price to $11.50 I've spent about $150 on it in bits. purges, fluids etc. I've also replaced the rear drivers side floorboards,seat mount and seatbelt mount using pop rivets and vintage organ chassis..it's really strong now, still have to do a bit on the passenger side. It's a much cleaner looking car but I feel it's not as well maintained, steering is looser, clicks when turned fully, etc. had a new tranny put in 3 years ago by a previous owner (maybe for all the wrong reasons) Trying to decide which to keep and which to sell I also have a 80 300D parts car that used to tow my sailboat. |
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whoah!
Do tell! Perspiring minds want to know!
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2007 Dodge Ram 3500 Cummins Turbo Diesel 4x4 1994 GMC S-15 pickup 4.3 5MT 1985 300 SD 1978 300 CD 1962 220-S Fintail - awaiting restoration |
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There's gold in them thar Mercedes!
Some Jewelery that had obviously been under the rear carpet for a long long time, several owners ago! |
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Try disconnecting the vacuum line to the transmission and then go for a drive.
If your transmission shifts firmly through all the gears and shows no signs of slipping/flaring then you have determined the problem is vacuum related. Too much overall or too much at the wrong time. If your transmission shifts firmly through one gear or two but not all then the problem is internal and you're next step is likely to purchase a Superior Shift Kit for 722.3/722.4 Transmissions I believe you have either a 722.315 or 722.416 you'll have to verify that you have a .3 or .4 unit. I'm not sure if the kit works on .1 transmissions. But since your working on a 82 model 300D/SD I'd think you're in .3 or .4 territory. The shift kit will replace other springs in the transmission that will help with slip/flaring and a host of other issues. I had similar issues with my gold SD. It was not the B2, thats been replaced already.
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
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I haven't replaced my B2 yet
But I have put a new K1 in I was curious if you knew if that kit could be installed without removing the transmission? |
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Yes, most of the spring kit in that link can be installed without removing the transmission.
Superior Shift Kit 300SD Here were my results: Superior Shift Kit 300SD
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Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out. Check here for compatibility, diagnostics, and availability! (4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!) 82 300SD 145k 89 420SEL 210k 89 560SEL 118k 90 300SE 262k RIP 5/25/2010 90 560SEL 154k 91 300D 2.5 Turbo. 241k 93 190E 3.0 235k 93 300E 195k |
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Cool. though I'm never keen on lying beneath the car forever, removing transmissions is one area I haven't yet ventured into.
Oh and I have tried disconnecting the vacuum from the trany with a little improvement but not a lot. The goofy 2/3 shift is still there |
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I did not know that you could adjust the modulator three and a half turns. Thought it was something much less like say 3/4 turn max. I think you may have it out of adjustment. I would take it all the way back and make a series of quarter turns and test it out each time. If you have the white cap, it theoretically is supposed to be adjusted through the opening and not taken off; they say it cannot be removed and put back on successfully but I had mine off about six times and it seems to be OK. 81 300SD.
Your vac is working perfectly. Supposed to be something like 12-16" and go almost immediately to zero at WOT so it can shift smoothely - it should downshift pretty hard with the vac disconnected; the entire system (tested near the brake hose) should show about 20" . You seem to have adjusted it already by removing the white plastic cone. Agree w J Dean that you should drive test it without vac; if it does not shift, it might an internal tranny problem. |
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As I said earlier I have run the car without vacuum
It doesn't solve my problem My modulator adjuster has a black rubber cap with a little T underneath it And I believe i was adjusting it half turns So about 1.5 really The amount it's supposed to be is 2.9 the amount each whole turn adjusts it is .4 It was slipping like mad in it's original posaition that's why I was trying different adjustments |
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Yes, you have the original cap which can be removed; 1.5 turns sounds right too. I am going to reread your posts and think. OK - so you disconnect the vac, take a test drive, and it does not shift through all four gears. Agree with J Dean; think it is something in the guts of the transmission. Does not act like a vac problem. Sometimes these transmissions will not shift through the gears when they get warm if low on fluid but I believe you said you replaced the transmission fluid. Seems to me like it holds five or six quarts but do not quite remember. Could it be really low on fluid?
Last edited by tyl604; 02-24-2012 at 10:08 PM. |
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