looking at an 84 300CD

[thebern]

Hey All,

I have not posted for some time as my concerns of my 240d have been searched and or answered. Thanks to all.

Two years ago I nearly bought a 300CD, but the seller sold it to his friend for the same price because he offered it to him first. Well last weekend the buyer offered it to me for 2 grand as opposed to the original price of 3400.
The buyer has only put about 3000 miles on it since.

The vehicle, I know, needs the following:
Brakes - compete
Rough shifting tranny fix
Drivers side window adjustment
Paint (clear coat peeling)

The good:
Straight body - no rust or dings
Interior is clean with no signs of water leaks
New tires
171 k miles

I love the lines of the coupe and may test drive it today-wed-, do a car fax and decide this weekend.

What do you guys and gals think of this?
Any input about repairs or previous experience with this model will, as always, be appreciated.

Thank you again,
type you soon
Bernie

[okyoureabeast]

Wow very jealous. I love the coupes as well.

I'd say typical pre buy look over. Make sure you can get a hold of the maintenance records, see if the rubber on the underside is ok (CV joints, etc). I just did my axles and it was a miserable yet mildly rewarding experience.
Get a good look at the mechanical under belly and innards of the beast for leaks and out of place items. Oh yeah and blow by too!

This thread is worthless without pictures! Let's see the good.

[benhogan]

Originally Posted by okyoureabeast

This thread is worthless without pictures! Let's see the good.

+1

[johnathan1]

Hard and cracking door window seals and weatherstripping are a real problem on the coupes, as the replacements are not available in the aftermarket, and are WILDLY expensive from Mercedes.

Seems like they usually start to shrink at the tops of the side windows and a large gap is created right where the front and rear windows meet. Lets in water and all kinds of wind noise!

[my83300cd]

Originally Posted by thebern

The vehicle, I know, needs the following:
Brakes - compete
Rough shifting tranny fix
Drivers side window adjustment
Paint (clear coat peeling)

The good:
Straight body - no rust or dings
Interior is clean with no signs of water leaks
New tires
171 k miles

The brakes are simple mechanics and easy to work on.
The tranny may be just a vacuum issue. (or not)
Window adjustment again a simple thing- just a major PITA to get it just right. The regulators twist and bend over time, and may need replacment at the worst case.
Do the back windows go down all the way?
A new coat of paint will do wonders..... and new window rubber ($$$$$)

Only 171k miles? No leaks? No rust!!!! Straight Body?? 2K?

Now you'll tell us that the AC works too.

It sounds like a decent deal, it also sounds like it will cost a few $1000 more to get it sorted out. If it was me, I would probably grab it, knowing that for a total cost of $5-6K I would end up with a pretty nice driver.

[toomany MBZ]

As usual, do an inspection if you don't find anything unusual, sounds like a good deal if you can put up with the paint.

[ImBroke]

Bern, how's it going? You're right, you've been absent for a while. I'd have to grab it anyways. I'd like to have a coupe.

[Yak]

Other pricey/hard to find coupe specific stuff: the rear window is supposed to be in excess of $1000, coupe seat frames are technically unavailable, but can be sourced from Germany for $400 if you substitute a Japanese or Euro part number.

There's an added vacuum element to lock/unlock the seat backs with the doors. I consider it an important safety feature that it work properly, otherwise the seats will fold on you in an accident. Mine didn't work initially due to leak in the defroster vent, but it would work with the ACC set to defrost. You might want to check that.

Otherwise it's mostly standard 123 tech.

[rcounts]

Originally Posted by Yak

There's an added vacuum element to lock/unlock the seat backs with the doors. I consider it an important safety feature that it work properly, otherwise the seats will fold on you in an accident.

I've seen more than one person post this (or maybe the same person posted it more than once) and I don't quite understand it.

If you're seatbelted in and you hit something the belt locks up. You don't fly forward and neither does the seat. So what's the danger? That the weight of the seat pressing against your back as it tries to hinge forward will hurt you? How? By putting pressure on your back?

I mean, it weighs what, maybe 20 pounds, and 10 of that is padding? It isn't like it is coming loose and flying around - its still attached at the bottom and only trying to flop forward, so how much harm is it going to do?

What am I missing here?

[Yak]

Originally Posted by rcounts

I've seen more than one person post this (or maybe the same person posted it more than once) and I don't quite understand it.

If you're seatbelted in and you hit something the belt locks up. You don't fly forward and neither does the seat. So what's the danger? That the weight of the seat pressing against your back as it tries to hinge forward will hurt you? How? By putting pressure on your back?

I mean, it weighs what, maybe 20 pounds, and 10 of that is padding? It isn't like it is coming loose and flying around - its still attached at the bottom and only trying to flop forward, so how much harm is it going to do?

What am I missing here?

The belt "should" lock up, but if it doesn't then yes, you'll have the added weight of a seat back smacking you in the back as you hit the wheel. I also fly airplanes, and the procedure if you're expecting to crash is to lock the harness. The inertial reel "should" lock up, but I know of at least one that didn't. There was no injury, but there's a reason that step is in the checklist.

In an unrelated incident I have a friend who was rear-ended by a drunk driver. She was in a Honda with locking seats and an airbag, but he whacked her with so much force the Honda seat folded anyway. Result of the accident: back and neck pain, whiplash.

I think the seat back in the 123 is probably more than 20 pounds, and there's no airbag.

Like I said, I consider it important that it work. You might not, it's your call in your vehicle. I won't lecture you for not wearing your seatbelt, either, if you so choose.

But it was also an easy fix and one of the "don't cost nothing" things. The actuators under the seat functioned fine, but there was a vacuum leak upstream. I figured out that if my ACC was set to defrost, then the actuators did work. So, I eventually replaced the defrost flap actuator and everything is all OK now - and I get a defrost setting, too. Troubleshooting the seats helped me ID the bad pod.

If yours currently isn't working, select defrost and wait a few minutes and see what happens. If it locks (you'll probably hear it squeak), then go back to normal on the ACC and drive on - the check valve will keep it locked until you open the door.

Another test might be to remove and plug the ACC line in the engine bay and see if the actuators move (note, door switch must be closed). If they don't normally move, but do without the ACC connected, then you've probably got a bad vent pod. If they still don't move, then there's a seat leak somewhere - which might help with any other ACC problems. I posted the coupe-specific vaccum diagram on the links page.

The reason I mentioned it was that I had never seen a vacuum operated seat lock. Every other coupe/two-door I've been in has some sort of mechanical latch.

[thebenzbar]

The 300CD is right up my alley... top to bottom & front to back, some (or the sum) of the seals are exorbitant.

From my order sheet... and these price quotes are over 12-months old now:
PART NO. / PART DESC. / QTY. / $ LIST / $ DISCOUNTED PRICE
123-673-00-24 VERTICAL ¼ GLASS SEAL 2 $11.50 $9.62
123-720-01-54 L. LONG WEATHERSTRIP 1 510.00 382.50
123-720-02-54 R. LONG WEATHERSTRIP 1 510.00 382.50
123-670-09-38 OUTSIDE ¼ GLASS SCRAPER 1 117.00 87.75
123-670-10-38 OUTSIDE ¼ GLASS SCRAPER 1 117.00 87.75
123-673-09-65 INSIDE ¼ GLASS SCRAPER 1 80.00 60.00
123-673-10-65 INSIDE ¼ GLASS SCRAPER 1 80.00 60.00
123-725-05-65 INSIDE DOOR SCRAPER 2 85.00 63.75
123-725-02-65 OUTSIDE DOOR SCRAPER 2 20.00 16.00
123-690-03-89 Lt ¼ glass trim “C shaped” 1 $480.00 $360.00
123-690-17-80 Lt door top trim 1 $414.00 $310.00
123-690-17-80 Rt door top trim 1 $414.00 $310.00
123-670-04-39 Front windshield seal 1 $125.00 $93.75 (Note: currently NLA)
123-670-05-39 Back glass seal 1 $140.00 $105.00
123-720-11-78 Lt door w/strip 1 $100.00 $75.00
123-720-12-78 Rt door w/strip 1 $100.00 $75.00

The rear glass is easily over 1K as mentioned above and the back glass trim are also premium-priced:
Lt side…………… 123-678-05-30 $154.00 $115.50
Rt side………….. 123-678-06-30 $154.00 $115.50
Bottom………….. 123-678-07-30 $142.00 $106.50

[rs899]

If you aren't really concerned with a concours car, I would bet one could piece many of the seals together from common sedan versions for much less money. It would be a lot better for the car than letting water in and rotting the floor...

The glass, however, is another story. I believe the windshield is unique to the CD, although it looks the same as the sedan.

[thebenzbar]

Originally Posted by rs899

If you aren't really concerned with a concours car, I would bet one could piece many of the seals together from common sedan versions for much less money. It would be a lot better for the car than letting water in and rotting the floor...

The glass, however, is another story. I believe the windshield is unique to the CD, although it looks the same as the sedan.

For the most part, 123 coupe seals are specific for the coupe (except a few of the lesser expensive items).
All F & R and L & R 123 coupe glass panes are specific for coupes only.
I have owned 5 123 coupes and extensively replaced the seals on 2 of them.

[johnathan1]

I did figure out that the W126 SEC coupes, have several very similar seals. Maybe the prices for those are less? Anyway, not trying to threadjack, just thought I'd add a useful piece of advice.