new to forum - 300d owner (questions) - PeachParts Mercedes-Benz Forum

bandy rooster · #1 01-22-2007, 10:54 PM

hey all new to the forum - semi-new to diesels....

i've got my hands on a 81 mercedes 300d, i'm the second owner and i believe the vehicle is from california. I've done all the regular maintainence (air cleaner,fuel filter,oil changes) been reading online for about 2.5 hours on the whole VCV, transmission modulator valve and how to fix the hard shifting. I still can't figure it out, i assume that some are bypassing the VCV located on top of the valve cover and blocking the vac line to the EGR valve? any body have a picture of what they did that there willing to send me? i would greatly appreciate it!

i've owned and restored a 67 mgb gt and moved on to owning and restoring toyota land cruisers but i just love this little 300d i just want to get the trans to shift properly

located in saint augustine florida PM for email

kerry · #2 01-22-2007, 11:11 PM

Have you tested the vacuum system overall? Vacuum leaks elsewhere in the system can effect shifting.

JimmyL · #3 01-22-2007, 11:24 PM

I think usually VCV refers to the plastic valve assy. on the top back of the injection pump.
I'm not sure if your '81 has this valve or not. I know they didn't in 1980, as my wagon did not have one, or a Bowden cable. Tranny vac was controled via a single 3/2 valve on valve cover, and a modulator on the passenger side of tranny.
Now, some folks call the 3/2 valve on valve cover a "VCV", which, whether correct or not, will add more variables to your search.
So, do you have a plastic assemble on the back of your IP?

see this post for a pic and some info:

Title: What 617 engine did NOT have a VCV sitting on top of the IP ! ?! ?

Oh, and WELCOME, btw......

jbach36 · #4 01-23-2007, 12:26 AM

I just bought my first diesel this past June. Was cleaning the engine the first day I had it. Next day took it for a spin. It shifted really hard. Waay messed up. Found out during the cleaning, a vacuum hose by the air filter disconnected by my cleaning, and that's all it was. Check your vacuum hoses first.

jeff 1991 300d, 100k

truckinik · #5 01-23-2007, 01:42 AM

My 79 300cd non turbo has shifted so hard on a few occasions that it chirped the tires. 77 HP. Tire chirps are kind of a cool novelty for a little while around friends . You get tired of it quickly though . As he said check all the vacs. I spent money to get the trans. looked at and they found nothing wrong at a tranny shop, as I chirped again leaving ..Got it taken care of at a dealer , and I think they put a $200.oo , 0.25 cent hose on it ,and waited the rest of the day to finally call me for pick-up .

JimmyL · #6 01-23-2007, 01:50 AM

I can make the tires chirp on my 240D, but that is kind of hard on the brake shoes......

truckinik · #7 01-23-2007, 02:01 AM

Quote:

Originally Posted by JimmyL

I can make the tires chirp on my 240D, but that is kind of hard on the brake shoes......

Yeah , but this thing would do it on it's own while driving down the street . Just letting it shift normally while at full throttle . Sounds like you've had some fun with yours , too though . That's exactly why I love these cars , you can beat the daylights out of them , they stay reliable , and it's like they almost beg you for more sometimes. As if the car was having as much fun as I was . Ever see the movie cars ? lol

JackG · #8 01-23-2007, 07:39 AM

Quote:

Originally Posted by bandy rooster

hey all new to the forum - semi-new to diesels....

i've got my hands on a 81 mercedes 300d, i'm the second owner and i believe the vehicle is from california. I've done all the regular maintainence (air cleaner,fuel filter,oil changes) been reading online for about 2.5 hours on the whole VCV, transmission modulator valve and how to fix the hard shifting. I still can't figure it out, i assume that some are bypassing the VCV located on top of the valve cover and blocking the vac line to the EGR valve? any body have a picture of what they did that there willing to send me? i would greatly appreciate it!

i've owned and restored a 67 mgb gt and moved on to owning and restoring toyota land cruisers but i just love this little 300d i just want to get the trans to shift properly

located in saint augustine florida and my email is

wheelsandwater@hotmail.com

Did you check the fluid???????
That might be the place to start before chasing vacuum lines

bandy rooster · #9 01-23-2007, 02:44 PM

fluid is always checked by me... i pluged the vacuum line that goes to the firewall and took it for a test drive... shifts much smoother -then reconnected the line to kill the engine. so yes i do believe i have a vacuum problem ... i can get pictures asap. does anyone know the specs on the two adjustable links on the top of the valve cover?

bandy rooster · #10 01-23-2007, 02:46 PM

also what lines are people plugging? i've heard the EGR and something going to the "black box" on the top of the valve cover?

the EGR vacuum on mine runs over to what i think is near the front of the block. i'm going to check the connections on the VCV on the injection pump and i believe from there the vacuum line goes to the transmission modulator on top of the trans.

i wouldn't mind plugging the acc. that use vacuum (door locks etc) if it meant smoother shifting.

redandblue · #11 01-23-2007, 06:08 PM

I just got an '81 too. This isn't really related at all, but, does your '81 have the fat glow plugs, or the skinny ones. Mine has the fat ones but the quick glow box on the inside of the fender well. Is this normal??

toomany MBZ · #12 01-23-2007, 06:18 PM

Suggest disconnecting EGR, I'm much happier now that I did. Let's see if I can remember. Follow the vac lines from the black box on the cam cover, one goes to the housing above and behind the thermostat, remove, the line to the EGR valve, remove, another line comes from the same mount, goes to the distributor on IP the VCV, there is usually a green check valve on top, remove, {line, not check valve} goes from "x" to "y" distributor, to reconnect other lines. Another vac line from black box to different distributor, remove, and reconnect other lines from "y" to rubber "i" vac line. Then toss no longer used plug and plastic vac lines. Confused? Probably, check with Brian Carlton. He'll set you correctly on this. You will need to find out if your VCV is funtional, again B.C., mine was, so I adjusted the Bowden cable, that thing on the cam cover that leads to the tranny on the passenger side, I backed mine out 6mm, shifts better. Too stupid to post pics, sorry. Good luck.

bandy rooster · #13 01-24-2007, 02:01 PM

Quote:

Originally Posted by toomany MBZ

Suggest disconnecting EGR, I'm much happier now that I did. Let's see if I can remember. Follow the vac lines from the black box on the cam cover, one goes to the housing above and behind the thermostat, remove, the line to the EGR valve, remove, another line comes from the same mount, goes to the distributor on IP the VCV, there is usually a green check valve on top, remove, {line, not check valve} goes from "x" to "y" distributor, to reconnect other lines. Another vac line from black box to different distributor, remove, and reconnect other lines from "y" to rubber "i" vac line. Then toss no longer used plug and plastic vac lines. Confused? Probably, check with Brian Carlton. He'll set you correctly on this. You will need to find out if your VCV is funtional, again B.C., mine was, so I adjusted the Bowden cable, that thing on the cam cover that leads to the tranny on the passenger side, I backed mine out 6mm, shifts better. Too stupid to post pics, sorry. Good luck.

thanks for the help, though confusing you atleast started me off in the right direction... pics would still help..

toomany MBZ · #14 01-24-2007, 05:59 PM

Check EGR blocking plate kit #3, post #38 for pic. The black box has been removed. You will note a "y" connection at upper right rear of pic. Used to be a "x" with one of the vac lines removed. Do not have photo of "before", but you should be able to see yours as such.

vstech · #15 01-24-2007, 06:45 PM

Quote:

Originally Posted by redandblue

I just got an '81 too. This isn't really related at all, but, does your '81 have the fat glow plugs, or the skinny ones. Mine has the fat ones but the quick glow box on the inside of the fender well. Is this normal??

I bet someone installed a 79/80 motor/head in yours... my 80 has small plugs.
John