2 years ago, my wife goes to Denver to look at a mid eighties MB diesel. She returns with this 1970 280S with straight 6, a gasser no less...

Cheap car, clean, runs pretty good, a little doggy, but hey, it's 35 years old and we live in the mountains, and the car is not jetted for 8000 ft, it was from CA originally, and so on.

Fast forward to 9 months ago. Car is now missing under load, and dying at stoplights when left in drive. New spark plugs, rotor, cap, coil. No significant change.

I fiddle with the 2 Zeniths to bump up the idle to keep the car from dying at stoplights. I really get them out of sync (i think) and pretty much totally out of adjustment. No real change in drivability once the thing is running, but now it is REALLY hard to start.

Fast forward to yesterday. I'm at the repair shop, putting the wiring back on the starter that I started to take off myself to replace, but then found out about the lovely hex head bolt on the top rear of the thing that is totally inaccessible to anyone without a lift. I get the wiring on right and it turns over.

The timing is all out of whack because when something isn't working I often try too many things at once (I know, I know). I get it running and one of the guys at the shop times it by ear. It seems to run pretty well at this moment.

I then ask the shop to time it tomorrow, I leave to go ride the motorcycle.

I come back the next afternoon and they're telling me that the timing light mark is bouncing all over the place and they can't adjust it. I say, hmm, sounds familiar to me, like 9-12 months ago.

Additionally, now the car is really hard to start, like it's flooded, and of course I've been screwing with the timing again b/c I'm an idiot and of course I don't learn well. (Actually, I thought the timing might be advanced b/c the car was running hot and usually doesn't)

My wife senses my frustration with this car. I still have to go pay the bill for the starter and power steering pump we had installed.

I love this car, it's beautiful. I hate this car it is too frustrating for me.

I just took the engine out of my 1997 Honda Valkyrie to repair a broken gear in the starter clutch assembly. I can do this stuff, if I know what to do...

Please shower me with advice. Please.

Zeniths have accelerator pumps that often wear out, the little piston looking thing with an arm and rubber boot. This could be contributing factor to yer problems.

1) Your mechanical advance sounds like it's in need of some oil. A DROP OR TWO on the shaft (under the rotor), and try to turn the rotor clockwise. It should move with some resistance (from the springs), then return back. If not, your mechanical advance is toast, and will cause a bouncing timing mark.
2) You need to have your carbs PROPERLY SYNCHED. If you don't - well, you'll have 3 cylinders running rich and 3 running lean. Or 6 rich or 6 lean. But it'd be a mess and I'm sure you don't want that!

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Sounds like the carburetors need rebuilding.

With the engine running, look down the carburetor throats, and see if gas is dripping from the center at idle.

The 'dancing timing light' could be caused by a worn distributor shaft (side-to-side play), or a leaky vacuum hose to the retard timing port (of the ditributor).

You can abandon the the 'designed' metod of retarding and advancing the timing by running the retard vacuum hose to the intake manifold, and the vaccum advance hose to the base of the carburetor. Set Timing at 10-12 BTDC with hoses disconnected.

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1970 280S M130 engine- good runner
1971 250 M130 engine- #2 rod bearing, gone
1971 280SE (blown engine,parts car)
1977 German 280S W116-only 33 years old

rule #1 with zeniths. Make sure the ignition system is stable and everything is to spec before any carb adjustments.

Timing is "all over the place"? Well, that's one of two things...
- Electrical information is wrong. A strobe light is designed to fool the eye into thinking that something that is moving isn't. The trick doesn't work if the moving things aren't uniform enough.
- Mechanical system is wrong. Anything from distributor trouble to broken cam shaft.

The specs for the timing cover several RPM ranges, from starter speed (200rpm) to 4,500rpm where the advance curve is moot. At each of these points, get the data for dwell and spark timing with and without vacuum applied. Go as far as supplying your own vacuum while holding RPMs steady to test the effect.

The most handy tool for any ignition work is a scope that lets you see the ignition traces. Lots of diagnostic information is on that little screen when you can see all six cylinders at once.

The starter is easy to unbolt, if you know the clever trick. Crawl under the car by the tail end of the transmission and you have a clear line of sight to the back of the motor. A 3 foot extension rod, a universal joint and a 10mm allen key on a socket gets out the bolt 1-2-3.

That's all for mechanical advice. Now, for your real question....

If it's you vs the car, you loose. There are two approaches to take to an old car.

- Car is toy. Enjoy the "unique experiences" of the car. This is the casual DIY attitude I take for my pile of old mercedes. It's why I drive a suburban daily and own more mercedes than any sane person would otherwise consider.

- Car is car. You want the fool thing to work. This is how my wife thinks about her 2006 Honda and how I treat my suburban. It's why I never take a wrench to either one and am on friendly terms with the shop down the road.

You describe it as your wife's car. If she wants a car to be a car, dump it. If she doesn't make her change the oil (smell the dipstick and you'll see why) and the two of you work out the ignition puzzle (with our help of course).

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

That starter bolt is a pain. Look for an access port in the passengers footwell, some 108's have them. This will enable you to remove the top bolt from inside the car. You can make your own access port with careful measurements and a hole saw. Then find something to plug / seal it....

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Over 21 years I owned several:
w108
w110
w111
w115
w116
w123
w124
w126
w212

I'm sure with some help this car can be saved.

I'm like the poster above, this is not a daily driver, it's our 3rd car but my wife loves it b/c it's easy to get in and out of with 2 kids, one of which doesn't walk yet, blah blah.

The thing that is a real bummer in this case is I'm now going back to driving the 2000 Dodge Ram all the time which is a gas pig and I have to give my 2003 Jetta TDI to my wife (lifting the kids).

Aargh.

I'll check on the mechanical advance, I've thought about ditching the entire distributor for something else more electronic if there is such a thing.

I'm not yet ready to give up on this car, I like seeing it back in the driveway.

Thanks for all the replies, it makes the prospect of keeping the 280 more likely when there are knowledgeable people around to help...

I vote for a bad switchgear, that is a common problem. Go for a crane upgrade.

just my $.02

Second the crane upgrade [I]IF[I] the distributor is wobbly. Don't give up on it, it just needs the right guru to tweak it right and then it'll be good to go.

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63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

Keep the car, it has great style. Running problems are pretty simple.

Keep the chassis greased though, there are grease points on all the front suspension joints, and one on the kingpin too. There should be a couple on the driveshaft and two on the lower swing axle joint. Use a good quality grease, I'm using Mobil 1 pink grease. My 220S Fintail, same chassis, older body, is under the knife for front suspension work right now.

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

I would trade my wife's 1999 E300 for a nice W108 250 or 280......but do not tell her what I said.
A friend of mine purchased a 1967 250SE a few weeks ago. It as over 270K miles. I had one owner and was always M-B serviced. The couple sold it because as they are in their eighties and did not want t drive a manual any more. This car is awesome in appearance, true condition through out the car, and drive. My friend purchased it for a fraction of its value.