Gave some love to the 300D yesterday - Page 2 - PeachParts Mercedes-Benz Forum

Alastair · #16 06-25-2012, 05:02 AM

One of the vac micro-switches applies vac to the VCV.

No vac to the vcv, you'll have harsh shifts....

indybenz · #17 06-26-2012, 09:09 PM

Alastair:

I was under the impression that all of the 'stuff' under the 'black box' on top of the valve cover could be deleted if one got rid of the egr and its related components. I have removed the egr completely, as well as the stuff under the black box and am in the process of seeing what else can be removed that is egr related, mostly to narrow down points of failure for the vacuum system.

Are you saying I need one/both of those 'micro switches' as you call them if I want to help remedy my harsh shifting?

It doesn't seem that what you're saying can be true, given that I have indeed eliminated all those items and, with the help of a Mighty Vac hooked directly to the AT Modulator and providing it with 15-20 in HG as I drove, it shifted fantastically like it never has before.

Please advise! Thank you.

tip · #18 06-27-2012, 01:32 AM

I'm sure its different on each motor (240D, 300D, 300D turbo, California emmision, etc) ? This is the first MB diesel I've owned so I'm in no way an expert.

If I ever get the car back from my girlfriend I will put this issue to bed (for this particular engine, anyway). Car is still shifting great.

tip · #19 11-12-2012, 09:08 PM

Had some time to devote to the benz today after getting some parts ordered up.

Finally got around to doing the valve adjustment! I had been going back and forth about making my own wrenches but I just didn't have the time or tools to make a set. A few of you in this thread (thank you BTW) said it was possible to do it without the bent wrenches. Well, you were completely right.

Being the cheap bastard I am, I decided to give it a go once the gasket came in. I had no problems with the standard wrenches, but can see where the proper wrenches would make it easier. I lucked out and actually had a thin 14mm wrench for some VW stuff, which worked great on the bottom nut. I used dieselgiant's idea for a check off sheet, which was really helpful.

On the very last intake valve, the valve itself must have been spinning. I couldn't get it to release from the nut. I ended up getting some PB blaster on it and using a pair of vice grips to work the big valve spring retainer nut (or whatever its called) back and forth, then hold it while I slowly turned the adjuster nut. This is when the bent wrenches would have really been nice, along with the third wrench to hold the big valve spring retainer nut.

All the valves but one intake where tight. I'm ashamed I waited this long to do the job. But wow, what a difference it made. As soon as I started it up I could hear a difference. Much faster start, smoother idle, and much better throttle response. I took it down the road after warming it up and took her through the gears. It really was a slug before.

Also did the monovalve repair kit since the heater was only working at idle. I went with the MTC one ($15 from peachparts) even though I've read people haven't had much luck with them. Its working now, but we will see how long it lasts.

old vs new

old vs new, note the cheap, wrinkled seal on the new MTC part. And torn seal on the old.

Also did the following:

-replaced the air filter
-changed the oil and filter
-wiper inserts
-replaced the instrument cluster bulbs (Osram 3W)
-attempted to replace the left side gauge pod (wrong parts)
-cleaned the corroded and inoperative rheostat (works now)
-rust encapsulated some surface rust below the battery tray
-attempted to fix the intermittent odometer going out issue

No pics of that stuff since its pretty boring. I followed dieselgiant's tutorial on the odo thing but did the best I could when getting the locktite into its spot where the gear rides. Wasn't really enough room to really get it in there, so we'll see - its working now but who knows.

Again, thanks to all those who have posted tutorials and answers in discussions. Next up is cooling system flush, oil pressure gauge, and full detail hopefully.

Codifex Maximus · #20 11-14-2012, 10:26 PM

Good Job! Nice lookin' car too.

vstech · #21 11-15-2012, 05:54 AM

judging from the screen on your old monovalve... I'd get to the cooling system asap!

tip · #22 11-15-2012, 11:26 AM

Yes, the cooling system needs attention bad! I've been collecting parts and hope to get it done all in one shot. I planned on doing the monovalve at the same time but my fiance, who DD's it, was begging for some heat

tip · #23 11-15-2012, 11:40 AM

On another note, the odo seems to be working reliably through a hundred miles or so (fingers crossed).

Also, I had been trying to diagnose why the blower motor was on full blast at all times when the heat was on. At one point I had taken the hvac control module out and checked the solder joints inside and it looked brand new (I found in the old receipts that the PO had bought a NEW one). I checked all the switches, wiring, etc and deduced it maybe the "blower regulator" (forgot about it after I saw the prices).

After replacing the monovalve, the blower motor actually returns to low speed once the cabin is warm. No more annoying "blowing" noise while driving (she likes that

)

Was the climate control just not sensing the heat requested so it was kicking the blower motor into high speed? Makes sense, but I just don't know how "smart" the climate control is (or thinks it is). I wish I could sit in a w123 with fully functioning climate control so I could see all the features and compare them to mine.

In any case, an unintended bonus problem solved. Those are always nice.

piccolovic · #24 11-15-2012, 12:05 PM

when I got my '83 300D, it had a shifting problem, although I had the pprwrk from the shop that rebuilt the tranny, which showed there was very little mileage on the rebuild. Pierre Hedary tried to dial in the shifting though use of the adjuster on top of the valve cover, and it kept coming out of adjustment. Finally, he put a vacuum gauge to the four lines and found that they were all switched. Once he reconnected them according to the SM, the transmission shifted flawlessly. He said the rebuild was a solid rebuild, nothing wrong with the transmission. As I recall, there were 4 vacuum lines that were involved.

Torie