Why won't my 240D Start?? Vacuum problem? - PeachParts Mercedes-Benz Forum

ajrn · #1 04-30-2007, 03:03 AM

Okay..
I rolled my '81 240D off the ramps, after changing the rear
diff fluid (boy-- I bet THAT stuff was there since the Reagan
Administration!)..

It stalled when it came off the ramps, and refuses to restart..

IN THE LAST WEEK-- I replaced the passenger rear window (as some
vandal put a rock thru it!). Also last week, I changed the
transmission fluid (including draining the TC) and put up a new filter..
I also put up a new starter-- because the old one wasn't always
engaging.. (New one works fine, and I had it bench tested BEFORE I put it up)

Anyway--

The car has historically HAD a vac leak-- to shut it off, you turned
the key, and locked the driver's door, and it would stumble out.. The
central locks 'sorta' worked, but not meaningfully-- it would take probably a minute of driving, and not all of the cylinders would "suck down" on any given day..

Okay...
What I know is that I have a car with a known vacuum issue, that
realistically had that system manipulated and now it won't start..
..Everything appears connected, so I don't see an easy fix.
As I look under the hood, I see one 'main' vac line-- going straight
to the brake booster.

There are two tees off of that.

One goes to the firewall, where it branches three times, with the
middle branch having what appears to be a check valve, that then branches twice, before entering the firewall. All 5 of those 'branches' appear color coded-- which will hopefully aid what I'm going to ask.. Two appear yellow (the last branches, with the check valve) there's a brown and blue one, a black one (that go to the IP) etc..

The second one goes 'on top' of the valve cover to what appears to be
some sort of valve. It has one branch capped off, and a tee with what
appears to be another check valve on one branch.. These lead to black
and black and brown striped leads that, again, go to the IP.
What I'm hoping to do-- is isolate out the central locking 'branch' or branches-- to see if I can't get the car started..

Since I wasn't having luck, I thought maybe I had a fuel filter issue-- though I thought it odd, as it hasn't had starting issues.
I'd filled both with ATF, as I'd previously heard that it's a good clean and lube for the IP.. I tried cracking the injectors, to reprime those-- and found little if any fuel coming out-- leading me to believe the IP isn't getting sufficient vaccuum to 'spray..'

SO-- anyone who can direct me to a color code, or tell me which goes
to what would be doing me an incredible service..

I considered hooking a vac gauge to one of the tees, while I cranked,
to make sure the vac pump itself hadn't failed.. (Will this tell me anything??)

I'd primed the filter, with the handpump (that I'll need to replace!) after filling the filters.. I took a 60cc syrringe, and blew back half a quart of ATF into the tank, then sucked fluid out, to make sure the strainer hadn't plugged.. It drew fluid without issue, much quicker than the motor should need it..

What's next to do/try?? I threw the battery on the charger, to make sure it's 'fully ready' when I attack the little beast again..

Okay-- I'll shut up now!
AJ

ajrn · #2 04-30-2007, 03:12 AM

I've seen n00bs told to add a sig file.. I thought I'd use Rudolph Diesel as my Avitar..

Thanks for any help you can provide..

AJ

Bruce Kennedy · #3 04-30-2007, 06:22 AM

Vaccum only shuts off the car, it does not aid in starting. However if you mistakenly hook up the wrong vaccum line to the shutoff on the IP the car will start and as soon as it builds enough vaccum it will shut off. The vaccum shutoff is on the backside of the IP and should have two brown vaccum lines going to it (one of these brown lines has a blue stripe on it). If you follow them they go to the key switch.

Did you add the ATF before this happened of afterward? If before its likely that you have air in the fuel system and you need to bleed it.

yellit · #4 04-30-2007, 08:03 AM

Pull the Vacuum line off of the round metal can mounted on the very rear of the injection pump and see if it will start with the line disconnected....the little pipe nipple on the can is pointing straight up....my 1980 240D only has one line going to the shutoff can....same on my 1978 300D...

kerry · #5 04-30-2007, 09:26 AM

Are you sure you didn't mess with a fuel line while working on the differential? Seems oddly coincidental that the problem is correlated with that work. If it won't start once you unhook the shut valve, try an alternate fuel source. Fill a soda bottle with fuel and run the input and return lines into the bottle and see if it starts. This eliminates any problems witht he lines or tank.

ajrn · #6 04-30-2007, 11:13 AM

Okay--

On my VW's-- I'd fill the fuel filter (usually with ATF), then had to crank the engine, and crack open the injectors, to get them to prime.. Their IP's have an electric stop solenoid, and they WILL NOT RUN if they don't get their voltage-- so this is why I was worried I had a vac problem..

When I did this-- I wasn't getting any fuel out..

Granted, patience is a virtue, lost on me..

I've got a new starter (mentioned) and decent battery.. Am I not crankin' long enough?? Or is injector line priming not necessary with these beasts??

I didn't realize the vac just shut it off.. That's kind of a relief!!

When I get 'Pearl' started again, they'll be a party in my driveway-- I'd invite you all over, but I think I've only got two beers left in the fridge!

Anything else you can think of, is appreciated..

AJ

Stevo · #7 04-30-2007, 11:27 AM

After you walk down and get some more beer you could crack an injector line at the injector (17mm), and see if your getting fuel up there. do all four. Are your GPs 100% ?, thats the cause of non starting ALLOT of the time.

ajrn · #8 04-30-2007, 06:21 PM

I didn't get anything at the injector, making me think that I was having problems at the IP.. Going to try again later..

AJ

yellit · #9 04-30-2007, 07:04 PM

Have you removed the vacuum line from the shutoff valve on the very rear of the IP ?.....just leave it off until you get the vacuum stuff sorted out...

Stevo · #10 04-30-2007, 08:15 PM

Quote:

Originally Posted by ajrn

I didn't get anything at the injector, making me think that I was having problems at the IP.. Going to try again later..

AJ

Takes about 12 seconds for fuel too get up there, thats a long time, or it seems like a long time when I do it.

ajrn · #11 04-30-2007, 10:04 PM

Okay--

I pulled the (brown/blue) vac line-- cranking, cranking, cranking, and finally had fuel at all but the 1st injector.. It was getting to crank a little slow at that point..

I also took the 'hand pump' out of the circuit, and put a small electric (facet) pump in the feed line.. I'm now convinced, that the handpump leaking was probably pushing as much air as fuel.. I'll get a new handpump, if (WHEN!) I get it running..

After about an hour on the 15amp charger, It'll crank and ATTEMPT to start, maybe run a second or two.. So-- I'm going to let it actually finish charging THEN hit it again..

Anyway-- I hope that the handpump is my actual culprit.. Anyone else had a problem with a failing handpump??

AJ

kerry · #12 04-30-2007, 11:34 PM

Quote:

Originally Posted by ajrn

. Anyone else had a problem with a failing handpump??

AJ

It's a known problem.

mespe · #13 05-01-2007, 12:07 AM

You mention not valve adjustment,,, when was the last time the valves been adjusted?

Judge · #14 05-01-2007, 12:47 AM

Quote:

Originally Posted by ajrn

Okay--

I pulled the (brown/blue) vac line-- cranking, cranking, cranking, and finally had fuel at all but the 1st injector.. It was getting to crank a little slow at that point..

I also took the 'hand pump' out of the circuit, and put a small electric (facet) pump in the feed line.. I'm now convinced, that the handpump leaking was probably pushing as much air as fuel.. I'll get a new handpump, if (WHEN!) I get it running..

AJ

How do you know that it is pushing air as well as fuel?

JimmyL · #15 05-01-2007, 12:52 AM

Quote:

Originally Posted by mespe

You mention not valve adjustment,,, when was the last time the valves been adjusted?

So the valves suddenly became so tight over a day or two that it is now keeping it from starting?
Uh, I think I would stick to the primer pump. I had to replace mine a couple of months ago, and it was the new style!

Apparently they will gush fuel also, so if they are gushing, they are "breathing air" too.