'84 300D Turbo Has Arrived - PeachParts Mercedes-Benz Forum

BrierS · #1 09-28-2004, 05:33 PM

Transporter pulled in front of the house Sunday morning with it perched on the upper tier. First impression is overall very good. Checking the systems one-by-one and searching for some glitches. I am going to contact the seller regarding a couple of items . . .

Though I have the complete set of MB issued printed manuals, they are still wrapped and never used. Hate to break the seal. I am waiting for my CD manual to arrive. In the meantime, the trans shifts hard 1 > 2 & 2 > 3. I started searching for vacuum line problems. Found one that was floating in space. It comes off from the multi port attached to the cam cover and heads in the direction of the brake vacuum booster. Just behind the booster and slightly to the right of the firewall there is a device (manual would help me on this one) that is missing a vacuum line. Though it would seem that I should just mate these two and let them live happily ever after, I would prefer to know what the device on the firewall is. It has a single vac port on the side, a multi pin electrical connector at the bottom, and a capped port (think of top hat) at the top. Can anyone help me identify what this is?

84300DT · #2 09-28-2004, 06:05 PM

that is the overboost valve. it should connect one side to the alda and the other to the manifold at the back of the engine passenger side. someone will jump in with the correct name of this part...

congrats on your purchase!

engatwork · #3 09-28-2004, 06:23 PM

You need to purchase a Mighty Vac and various tubing/hose fittings and connectors. Start going through the vacuum system looking for leaks. Try to pick up a vacuum diagram to start sorting it out. The yellow ones at the brake booster area are for locks and the brown line lines are for the shut off system. Sounds like your overboost protection switch is bypassed. Look for the line coming off the back of the intake manifold. Does it come around behind the engine and tie into the ALDA? If it does you are running with no overboost protection. It is fine unless you blow out the wastegate hose

then it will run like a scalded dog for a little while

. There are mods you can make to get rid of all the lines going to the switching system on top of the valve cover and clean that stuff up.

I would change all fluids this weekend to set a baseline.

To keep you from having any negative thoughts concerning breaking the manuals loose I will reluctantly

take off your hands if you want

.

BrierS · #4 09-28-2004, 06:50 PM

Let's see . . . I have two Miti-Vacs (should throw the old one away) and have gotten very familiar with it on my '87. At this point, the line that is hanging unconnected is the area I'm concerned with. I have the CD manuals coming but I get impatient when I find something like the line.

The interior is in overall good condition. Though the eBay listing said no tears, there is one on the back of the rear seat at the top (one of the two center seams). This concerns me since I do rely on the accuracy of the ads. Probably too picky. That is the primary thing I want to discuss with the seller.

Other than that, the seats are good. I am going to use my Leatherique two part treatment hopefully before it gets any colder around here. I would certainly like to get it done before putting it up for the winter.

Fluids and filters are all being changed. Brake, anti-freeze, Mobil 1 5w30 (?), Mobil 1 for trans and rear. Added a can of Redline to the fuel (was full when arrived).

While up on the carrier, I noticed the trans pan has just been replaced. Sticker was still on it.

Shifting hard 1>2 & 2>3. Some vibration that appears speed related 30 mph +/- but also some engine shake. Still have much to check. 124 miles since it arrived.

#5 09-29-2004, 12:15 AM

She's a BEAUTY! Arguably one of the highest sale price to-date and I'm with you, I will pay for quality and peace of mind.

Sure you can buy one for much much less but it comes with a grocery list of things to be fixed and not to mention rust. No thanks.

Good luck!

BrierS · #6 09-29-2004, 05:09 AM

84W123DT
Of everything about this car, the complete lack of rust still amazes me. Being from one of the road salt areas of the country I have always dreaded purchases of vintage and/or antique vehicles. With help, I can ususally get any mechanical/electrical issue dealt with however rust is one thing I can't deal with.

As I wrote earler, the book is still open on this one. Too good to be true rings clear with me and I am going to remain vigilant for issues requiring attention. I took this approach with my '87 and really love the vehicle. I bought it for utility use and it has served me well. No rust (to speak of) and most of the systems perform as intended. Cosmetically it does not hold a candle to the '84 but . . . they were purchased for different purposes.

rg2098 · #7 09-29-2004, 06:43 AM

Brier, I'm with you all the way. I just picked up an original paint 83 300D with only 211k that came in from Texas. It's ment as a daily driver but it will be tough to see it go out of the driveway this winter. Might need to find a rusty beater for the salty winters.

BrierS · #8 09-29-2004, 07:02 AM

After searching and with some prompting from 84300DT and engatwork, I found what the part is on the firewall. It is the switchover valve for the overboost. Single vacuum port (no hose attached to it yet) and electrical connector at the bottom. As stated earlier, the vacuum hose that is floating free in the engine compartment comes from the black, multi vacuum port mounted to the top of the cam/valve cover. Can anyone confirm this is the proper source?

Until my CD manuals arrive does anyone have the vacuum schematic for the '84 300D Turbo's engine compartment to share?

Alan Hamm · #9 09-29-2004, 07:54 AM

Quote:

Originally Posted by BrierS

Until my CD manuals arrive does anyone have the vacuum schematic for the '84 300D Turbo's engine compartment to share?

I have never tried this, but hopefully this will work and help. This thread was posted a few days ago.

W123 Vaccum Diagrams

Some of the best diagrams I have seen. Seemed pretty clear.

BrierS · #10 09-29-2004, 08:27 AM

Shouldn't be the correct vacuum line since it is the smaller size line. The switchover takes the larger line

Though I broke out the manual set that came with the vehicle, I have yet to find the schematic that actually shows the line route that should feed the switchover valve. Additionally, I believe the line to the ALDA is incorrect.

Now I need to locate the "aneroid" (what is an aneroid?) since it fits into the scheme of things.

BrierS · #11 09-29-2004, 08:32 AM

I must have been typing my last as you posted. I am printing those as I type. Though I just looked quickly at a couple of them, they do look as if they will help.

Thanks.

BrierS · #12 09-29-2004, 09:33 AM

Should have remembered the switchover valve from my '87 . . . I was mistaken about having a single vacuum line nipple. In the light of day with a "close to what I need" schematic in hand, I discovered it has two nipples.

As it stands, the vacuum system has some major flaws. Though I am going to attempt to correct these using the schematic supplied above via links, it is not exact.

The EGR is still plumbed into the system and there is presently no vacuum source to the vacuum distributor that is mounted on the top of the valve cover. Additionally, from the check valve that feeds the brake booster, the Y has been removed and that of course includes the two 0.5mm orifices. Though I can create the Y I do not have additional orifices to install (yet). I am hoping this will not create a problem while testing . . .

phantoms · #13 09-29-2004, 10:41 PM

The diagrams are for a 85 federal model. California models will be different and earlier (non-cal) models may not have all the items pictured.

Quote:

Now I need to locate the "aneroid" (what is an aneroid?) since it fits into the scheme of things.

Aneroid and ALDA are one and the same.

BrierS · #14 09-30-2004, 05:52 AM

That is what I finally figured out by looking through the postings on the forum. I need to find what the switchover valves hose configuration is. Two hoses and one goes to the ALDA the other to the banjo fitting on the intake. Question is which connects to the bottom port of the switchover valve????

84300DT · #15 09-30-2004, 08:09 AM

Quote:

Originally Posted by BrierS

That is what I finally figured out by looking through the postings on the forum. I need to find what the switchover valves hose configuration is. Two hoses and one goes to the ALDA the other to the banjo fitting on the intake. Question is which connects to the bottom port of the switchover valve????

top one goes to the alda bottom one to the manifold.