So I did lose my mind and bought it...now come the questions...
 

W108 People,

Car is in the garage drying out after a long sordid time outdoors...things are progressing. Quick recap:

1972 280SE 4.5, Papyrus White/Blue Leather, sunroof,floor shift, 69K documented miles, one owner, all service records. Purchased for $500.

Major issues:
1. Runs rough but runs. Has died a couple of times, would not start, pushed it back into the garage, then strangely started fine the next morning. Runs better in park, worse in R or D but is drivable and shifts fine when it goes....planning on replacing plugs, wires dist., etc. to start. Fuel system appears recently attended to (new rubber lines), but will most likely drop fuel tank at some point.

Q: Should I just go to Petronix now?

2. Rust in a few places...a little is on the front of the rockers, but currently only surface. Will treat, sand and primer. Will POR-15 trunk...did this on the wife's 450SL and worked great. Floor good except for Passenger rear...it is rotting. Looks like the "coating" on the bottom cracked and moisture took its toll...sadly common I imagine. Will treat entire inside of floorpan when I replace the rear seat.

Q: Have been looking for floorpan parts and not sure where to get them...I assume it is best to get a stock piece, but a good metalfab pro should be able to fix it, right? Is the classic center the best place to find floor sheetmetal? Do I go cut up a 108 in a junkyard (assuming I can find one)?

Q: Sunroof. Kind of scared to open, are they prone to fail? I realize this is a crap shoot of sorts, but I'd like to get it functional and lube it, etc.

Thanks in advance for any help,

John

Wow. Congratulations.

On the sunroof, luckily I have no experience when they don't work. I do know they are great when they do work. They are huge and really open the car up. You have to try it sometime I suppose, so good luck.

A number of my favourite and not so favourite subjects! DJets, Rust, Sunroofs ;)

Sunroofs - I hate them. More trouble than they are worth. But there are some threads about working on them, replacing seals etc. Good to open and ensure drains are clear and there is no rust (there often is)

Floorpan parts. Don't know if they are available. I recently had my 300D floorpans repaired. Good sheetmetal shop can do the job without great expense. Replacement probably make it easier if the pans are really bad.

POR - I am about to remove seats and coat entire floor of my 300D with POR (or actually a less expensive equivalent sold in Canada at Napa). Inside of rockers is always a concern. Using one of those endoscope/borescope devices might allow an inspection. My rockers were part of weld repair and I am contemplating ways of getting the inside rust protected.

Pertronix is good if you suspect distributor bearing wear. Otherwise setting the points to 0.014" and start from there until you are sure everything else is good (otherwise you may suspect Pertronix).

Trigger points in lower part of distributor can cause problems with fuel injection. Very expensive to replace. Wear out after 100-150k miles. Do a search here for more info.

Rough running could be many things. For start, remove the AAV (Aux Air Valve) top front of engine. Check it on bench. It should be fully open at ambient temperatures and fully closed at 150F. They stick either open or closed both of which cause problems. Because car stalls when put in D or R, try just increasing idle speed (large screw next to AAV). You may be able to clean AAV. They can also be dismantled using a little brute force! Method in this thread on AAVs.

If you don't have an engine manual, the M117 manual is on-line at MBUSA. Section 07.4 has test methods for many components.

Congratulations John.

My 72 280se 4.5 also runs very rough and like your will evenutally die when in drive or reverse. It idles nicely when in park or neutral. Mine had the tank screen filter and all of the fuel lines changed out. The PO had changed the cap and wires. So changing those items may not solve the idle issue but will help in the future.

On the floor pans....

I had this same situation and found that by far the cheapest route was to find a car in a wrecking yard and cut the floor out of it.

On the black goo that is cracking on the bottom of the car.... This is an undercoating that was applied at the dealership. This is why you see it on some cars and not on others. Some dealers did it as an option at the customers request and others did it to all the cars on their lot and then listed it as a 'mandatory option'. It was sold as a soundproofing method and it did do a pretty good job of that.

It also does a great job of cracking and then trapping water when the car is driven on a rainy day. The trapped water causes rust and there goes the floorboard.

There will be those that will tell you this came from the factory, but I remember clearly the sales person pushing this on me in 1972 and then pointing out how dumb I was for rejecting it.

The bad part about sourcing floorpans is that it is hard to find a car that did not get this undercoating treatment, and if you use a pan from such a car it is just a matter of time before it will rust out again.

When I run into this I just look for a car in a salvage yard that will cut the floor out for me. I get them to cut a piece bigger than I need and then, after I cut out the bad part on my car, the 'new' piece just drops right in. Then I can weld it in or bolt it down with a series of bolts. Make sure if you use bolts then you also use some mastic putty to create a seal around the rim of the new piece so water will not leak into your interior. 3M makes some good stuff that any body shop supply place will carry. Just tell them what you plan to do and they will know what you need.

take one thing on the time on the engine, Djets need systematic evaluation .I have a lot of good info on the process if you want to PM me your email

Another Update: CAr is dry and awaiting tune-up...
 

Took some more pics this evening while I wait for a new cap, rotor and wires to get here. Emptied the trunk, took out the crumbling OEM mat and inspected it a little further....not too bad. Took some pics of the rockers too and of the cleaned interior. It cleaned up ok so far. Needs paint, but all in all not a disintegrating disaster. Mostly. Still need to get the hole in the floor patched up, but need to get it running to drive it to the body shop.:D

Sadly, my pics are not uploading at the moment, so when it feels like taking them again, I will post them. So far so good.

John

sounds like a work in progress!

Very much so, Ron. But, it will be fun to bring it back to glory! Thanks for the DJet info!

John