78 w116 280SE, cranks, won't start

[ctaylor738]

I don't think the '78 has a frequency valve.

[davestlouis]

Aw crap...this is getting more in-depth than I had planned. I guess that's the nature of this sort of thing. I'll tinker with it Sunday some time and see what develops. Keep your fingers crossed!

[psfred]

Well, I don't remember anyone telling me MB's were cheap ----

Chuck:

It's been a year.....

I should have been spending my time here, at least I'm appreciated (grin).

Peter

[Larry Delor]

Dave,
Taking off the fuel distributor isn't all that scary...4 small bolts if I remember correctly, and a fuel line or two.

Just lift the thing up (slowly), and look underneath at the center...that's where the fat metal pin is (what I called the plunger). It should move smoothly (not sloppy loose and not grabby here and there). If it doesn't, examine the surface...it should be smooth as glass. If it isn't try some of that cotton stuff that's soaked in something (used to polish chrome) to clean it up.

[davestlouis]

Okey dokey, I'll try it and see what happens. The money hasn't been an issue as much as my limited mechanical abilities and limited time for tinkering. The non-working cars "live" at my office, which lends itself to short bursts of activity right after work or on Saturday morning, but what I can't do is wander out in the garage in the evening and dabble in working on them.

[davestlouis]

I thought it may be simpler to work on the non-running 280 if I had a running example, so I bought another 1978 280SE today, red with tan leather, nearly 300K miles, rough interior but not nearly as rusty as the blue one...paid $203 on ebay. The car is 30 miles away, and I plan to pick it up early next week.

[Larry Delor]

Wouldn't be ironic that the test subject 280 has the same problem with the distributor?
Don't worry... I just have an odd sense of humor

I'm also jealous that you have room for an extra addition.....perhaps I should move to the sticks, or build a tall wall around my property.

[davestlouis]

Good grief, if this one has the same problem, I'll roll them both in the river and be done with it! Most of my cars are at my office, only 2-3, including my wife's Jeep, are at the house at any given moment.

[davestlouis]

Looks like I'm not getting the 2nd 280SE after all...the car had previously sold for $500, but the buyer backed out, so it was relisted. When it closed at $203 and I won it, the seller wiggled out of the deal, said I didn't pay fast enough. My paypal account is tied to my checking account and takes several days for payments to clear...I offered to drive to the seller's home and hand him cash, he'd get paid quicker. He cancelled the sale, said I non-paid?! On a positive note, the gray-market 450SE is getting delivered Saturday.

[davestlouis]

OK, I finally found some time to play with the 280SE...I loosened several fuel lines out of the FD, all had fuel dribbling out, although one had fuel that looked rusty. I disconnected the blue plug, so the pump runs the whole time the key is on, the pump is humming quietly away. The car will run on starting fluid, and seems to "want to catch" even without the fluid(which it didn't do until today). The fuel is of an unknown age...is it possible to dump some injector cleaner in and just pump it out by loosening a fuel line at the FD? Would that clean the system in the process before I put fresh gas in it? I feel like I'm making progress but haven't gotten there yet.

[Tomguy]

Dave: Did you pull the injectors out and soak them overnight (upside-down) in carb cleaner? They're probably clogged with rust or something else (god knows what!) - pull them out and let them soak. Let the FD distribute fuel with the injectors out, make sure gas is flowing well from all the lines. That will help flush the system out and once you put the clean injectors in, it'll probably start immediatley.

[davestlouis]

Tom, how do I pull the injectors? I don't mean to sound like a dunce, but until I started buying these older cars, I hadn't done more than an oil change since I was 17, trying to keep a 1970 MG Midget running.

[Tomguy]

Not exactly sure for your engine but the rails should have a nut on the top. Hold the injector with a wrench and remove the nut on the rail with another wrench. I am unsure of what other fasteners may be used to hold it in place but, by the looks of the injector, it doesn't look like anything else can fit on it to hold it at the very LEAST undo each of those lines and, using a can of brake cleaner with the plastic tube attatched (and all the way in the injector) fire it in there if you can't figure how to remove them. I'd assume it'd be cut-and-dry though.

[davestlouis]

I'll take a look tomorrow...I was at the office this evening, picking up the SL, because the window regulator finally crapped-out on my 420SEL and the window is stuck down...and it's supposed to rain over the weekend, so I put the SEL in the building to keep it dry. It was dark, but I took a minute to stick the key in the 280SE, turned the key, and it cranked, and damn near started! It felt and sounded like it almost caught. It only did it on the first turn of the key, then on subsequent turns didn't, but I'm taking this as progress. I'll report after the weekend.

[ctaylor738]

I don't think that injectors will keep the car from starting. I think you have a fuel pressure problem. Have you checked the control pressure?

But if you want to pull the injectors -

The injectors are held in place by clips that screw to the head. Use a 12mm crowfoot or open-end wrench to loosen the nut on the fuel line - the clip will hold the injector. Then unscrew the clip with a hex bit (4mm?), and pull the injector out.

I suggest that you replace the injector seals

A set of hex bit sockets with a 6" bit will make the job easier