Potential 1972 280SE 3.5/4.5 Purchase - PeachParts Mercedes-Benz Forum

Solid Snake · #1 09-05-2011, 09:21 PM

Hey guys,

Now that I've gotten my 560 essentially down pat, and messing around with interior options and what not, I've been drawn to the idea of buying a project car. When I was a child (8 years old in 1999, mind you!), we had the sweetest car. 15,000 original miles on a 1969 280SE coupe. I loved that car and it's lines more than any other Mercedes ever made, and have wanted to obtain one ever since we sold it.

Anyways, I'm leaving work today, and the guard stops me on my way out (I work at a country club). He's in his 80s, and stops to ask me about my 560. I talk it up for a few minutes and now I've done most of the work to it since I've owned it, and love the car in its entirety. He tells me he has a 1972 280SE 3.5 or 4.5 (I don't remember) sitting in his driveway for the past God knows how long. My eyes immediately lit up with intrigue. He told me he hasn't tried to start it in ages, and a few months ago a kid came by and offered him $500 for it, and the kid never returned. He told me he'd give it to me for all the transfer of title fees, and I could be on my merry way to restoring that.

My question is, as I don't have room to store or part the car, is it a worthy endeavor? I'm going to go check it out to see what kind of shape it's in, and I guess I'll shoot from the hip at that point. What are some things I should look out for? Engine and Body wise. What should I bring to try and start it? I've never had to start a sitting car before...

Thanks,

Carlen

cth350 · #2 09-05-2011, 11:10 PM

read up on...
- electronic (D-jet) fuel injection
- W108 chassis rust
Like me, you're in the rust belt and you should look carefully at the underside of the car.
It's not fixable. Not unless you know how to weld.

The rest is easy, well, sort of easy. To restart that car, you should (in order of easy to hard)...

- Make sure it has sufficient oil and not too much. Make sure there is coolant in the radiator and that transmission fluid shows on the dip stick.
- Remove the intake and look in the air cleaner and throttle for mouse nests and nuts.
- pull the spark plug wires and remove the plugs. Note which leads are which.
- Remove the rocker covers and spray down both cam shafts with spray-on white grease. Spray some marvel mystery oil into each cylinder. If you get a syringe from an autozone, measure out like 10-20cc's for each cylinder.
- Dig up a 27mm socket and hand-turn the motor through 2 full revolutions on the crank.
- Raise the rear onto jack stands to facilitate crawling around under the rear.
- Clamp both the fuel line between the tank and the pump as well as between the return line and the tank (autozone sells a suitable clamps).
- Disconnect the fuel lines now that they are clamped (the gas tank is NOT to be trusted yet).
- Get a fire extinguisher and a fresh battery.
- Place a towel or two over the spark plug openings, hook up a meter to ignition circuit and set it to measure dwell and turn the key to the ""1" position and listen for the fuel pump to operate. It will turn itself off after a few seconds.
- Turn to "2" position which will engage the starter. The towels are to catch that oil you squirted in. You want to see a dwell reading that isn't 0 or 45 (points stuck open or closed or ignition circuit dead).
- Run a fresh 1/2" fuel line between the pump and a small gas can that can fit under the rear.
- Run a fresh 5/16" fuel line between the return line and the gas can.
- Turn the key to the "1" position while an assistant stands by looking for gas leaks under the hood and at the rear. You should hear the pump buzz for a few seconds and then shut down.
- Remove those towels, switch the meter to measure RPM, put in 8 fresh "R0" copper plugs, spray ether down the intake and start the car (optimist!)

After that you need to verify that it's running on 8 cylinders, warms up to the right temperature, change the oil and the coolant, drain the gas tank and have it boiled out. The get the injectors cleaned, adjust the valves,

Do all that in his driveway and chat with him while you work. If you'd rather not fraternize, then tow home and do it all in your driveway, but then you're stuck with the car.

-CTH

Tomguy · #3 09-06-2011, 12:34 AM

D-Jet typical issues... cracked EFI lines, vacuum hoses, etc. It may not fire up because of this and/or stale gas. I wouldn't want to try if it's sat for too long, knowing what you need to do after you fire it up from that. I'd drain the tank FIRST because it's easier to do that now than clean and/or replace injectors later. Change the oil before you start it, too. Once it's got ~500 miles on the oil change it again. Is it worthwhile? It depends if you want a project car. I'd jump on it personally if it had a good body!

Edit: That's what I get for using 10 tabs at once. CTH has a great reply!

Tony H · #4 09-06-2011, 05:15 PM

Hi,
Good luck with your find. You mentioned you wanted a coupe. Have you gone to see the car? does not sound like a coupe if is a '72 or 4.5.

Solid Snake · #5 09-06-2011, 08:55 PM

CTH,

That is FAR more detailed than I was expecting!! I'm going to compile a kit to bring with me to his driveway and do it; he's a nice guy, and couldn't believe he had hidden this car from me for the past 5 years I've worked there! By any chance do you recall the size of the plug?

With this, I should be able to see if I can sort it out.

Tom,

I've got TONS of vac line left over from when I changed them all in my 560. I hope it is a 4.5, as I am very familiar with the M117. We had an old 420, but that was before I was car savvy enough to fool around with the radio, let alone the engine! A lot of cars 'sit' in that part of CT; Members at the club I have constantly sell cars they've had for ages because they just hadn't used them in years... What do I drain the fuel tank into? I've never done this (start a sitting car) before, so all input is GREATLY appreciated!!

Tony,

In my dreams I would acquire a coupe... I can live with a sedan though. I have the 560SEL and I drive with maybe one other person in the car once a week. This car just 'fell' into my hands, so I was excited no matter what body and engine combo.

Tomguy · #6 09-06-2011, 10:45 PM

The 4.5 is quite different - more than just displacement & a cast-iron vs cast-aluminum block. The injection is D-Jet - no fuel distributor, it's an electronic open-loop system (no O2 sensors). When it runs right it's great but when it's off, your fuel economy will be horrible. And cold, the engine eats fuel like a pig. But it's a multi-port EFI system closer to modern cars than that on the 560 really. Pretty easy to troubleshoot as the biggest issues are vacuum leaks, injector issues, vacuum leaks, trigger points, vacuum leaks, wrong timing, vacuum leaks, and vacuum leaks. There are several areas where you can lose a few inches of manifold vac easily, including the central locks (engine manifold fed vs your 560's vacuum pump), the plenum gaskets, the transmission modulator, the line to the MAP, and less likely culprits like the brake booster.

As far as draining the tank, how much gas is in it? It may be in your best interests to pick up a siphon kit and a few gascans to put the old gas in prior to cracking open the plug on the bottom of the tank. 280SE Guy has the best 108 in the world so I will shamelessly use one of his pics to show its location: