problems getting my car started - PeachParts Mercedes-Benz Forum

#1 03-03-2003, 11:10 AM

Hi,
I have a 1971 280SE (with fuel injection) and I have problems starting the engine - the starter turns seemingly well but it takes a long time until the engine actually starts running on its own. Once it started, it usually runs fine, sometimes I have to pump the gas pedal a couple of times.I do not drive the car very often, and if I drive it, its usually just for a few miles. As a consequence, because starting takes so much juice, the battery is empty after just a few weeks!
I noticed that the battery cable gets hot during me trying to start the car - actually, I noticed that when the battery camp on the + contact melted (litteraly!! I had drops of metal on the battery!!), so I replaced that cable and the others that are connected to the starter.
The sparc plugs are relatively new (2 months),
the alternator is working fine and no current flows when the car is off.
Does anyone have an idea where the problem could be? Does it make sense to replace the starter itself (could it be that it turns to slowly or is not strong enough)?
Thanks,
Andreas

ctaylor738 · #2 03-03-2003, 12:53 PM

This sounds like fuel delivery to me - fuel pump, filter, trigger points. If it only does it when the engine is cold, I would suspect the cold start valve.

#3 03-03-2003, 01:43 PM

I'm in California, so it does not get really cold...

but the car actually starts better when the engine has been running for a while - so maybe i'll try the cold start valve.
Would I notice a badly working fuel pump when the engine is running? (Fuel filter has been replaced a week ago, did not make a difference at all).

Also: is there any vacuum needed during start-up? Because I know that the vacuum is leaking somewhere, the power lock only works within less than a minute after turning off the engine!

Thanks,
Andreas

#4 03-03-2003, 03:41 PM

I would first make sure the ignition is in order, and then go into the fuel system of the car. With the ignition switch on, check under the car at the fuel tank and make certain the fuel pump is running. You should be able to hear it as well as feel it running. Next check for fuel delivery at the cold start valve on the air intake horn. There is a small plug (7mm) I believe that you can just loosen while the pump is running, you should get some fuel from this plug. Next take a jumper wire from the hot side of the battery and energize the wire on the cold start valve by just touching the wire intermittantly and listning. You should be able to hear the valve click. If you can see fuel from the afore mentioned plug, and can hear the valve work, go ahead and try just clicking the valve a couple of times. Now try and start the engine. If it fires right up you are on the right track. Try this first before going further into problem. And by the way cold start valves in good operating condition are necessary in California.

Trrbo 240

#5 03-03-2003, 06:55 PM

this might be a stupid question: if I can drive (once the car got started), does that tell me that the fuel pump and injection work fine? I would not expect the engine to pull the fuel all by itself, is that correct?

Thanks for your suggestions, I will try them as soon as possible!
Andreas

#6 03-03-2003, 07:22 PM

Me too.
Car was running fine. Weather got cold. No start.

Why would a 'cold-start' valve go bad when it gets cold? Isn't helping to start in the cold the whole point of that part? I mean, not to sound too stupid, but what would go wrong on that part to make it not function in cold weather?

Of course I understand that this is a machine and anything can go wrong any time, but it seems odd that the part would fail just when it's needed. Oh well.

How about just replacing that valve? Is it difficult? It looks like it's just a few nuts.

Can I wait for warmer weather and let it heal itself?

All advise welcome.

Bill

Larry Delor · #7 03-03-2003, 08:07 PM

Stick your finger in the exhaust (when its cold-before you start it).
If your finger comes out with soot all over it, you most likely have a rich condition. Before you start taking stuff apart, I would take it out on the freeway, and blow the dust off/out. Then try and start it the next day, and see what you get.
The reason I say to try this, is because you say you only start it every now and then, and when you do, you only drive it for a few miles around town. I am willing to bet it could use a good freeway run, so it can clear its throat a bit.
btw, be sure and use premium fuel.

-Larry

cbdo · #8 03-03-2003, 08:58 PM

Don't have a specific fix for your immediate problem, but I do know that the mechanical FI pump and system in the 280SE engines gum up and don't do well when they're not driven regularly, and strenuously enough to warm up thoroughly. Think of your car as an athlete that needs to work out to stay in shape, and you'll be on the right track. I've seen a number of posts on 113 Pagoda sites (with engines similar to yours) from owners whose cars run well when run often, but not otherwise.

240 Ed · #9 03-03-2003, 09:20 PM

I would NOT replace the cold start valve!

These usually last 12 lifetimes or more!
BUT, they get their directions to work from a cold start sensor, and this is usually the cause.
I have never worked on this car, but if it works like other Bosch systems, the fuel pump won't work in the "ignition on" position.
The pump and cold start valve usually work only in the "start" position. ...and your pump obviously works.

Oh, and have some pity on your poor starter! If you are cranking that long to heat upp the battery to that condition, your starter can't be far behind! Let it cool down between "takes".

As a experiment, you can try a shot of starting fluid into the intake/air cleaner. If it starts right up, then I feel confident your thermo/time switch or cold sensor is bad.

Larry Delor · #10 03-03-2003, 11:19 PM

Quote:

I have never worked on this car, but if it works like other Bosch systems, the fuel pump won't work in the "ignition on" position.

Mine does. I found out the hard way. After forgetting to turn the ignition all the way off, the pump had run down the battery, and I had to get a jump.

-Larry

ctaylor738 · #11 03-04-2003, 07:33 AM

Sorry - when I said "cold start valve" I was was referring to the whole chain of stuff that makes it work. But I did have a valve fail on my 280E.

#12 03-04-2003, 03:51 PM

Fuel pumps on 71 280 SE models certainly do run with just the ignition being on, they also after many years and thousands of miles have a tendency to be intermittant in operation. Try what I suggested in my earlier reply and you may be surprised at the results. I speak with 22 years experience as a Mercedes Benz registered technician.

Turbo 240

psfred · #13 03-04-2003, 09:44 PM

These cars tend to run VERY rich cold, and you can foul the plugs if you don't run them long enough to get them good and clean.

How old is the fuel? If you have been driving for six months on the same tank, get some Redline injector cleaner and dump the whole bottle in, then drive to the nearest gas station and fill up with good clean fuel. Drive the whole tank out in the next few days -- this should get all the crud out of the pump and lift pump.

chances are the cold start valve isn't working -- depending on the model, there are several relays and temp switches involved, and if it doesn't spray fuel, you won't start.

Peter

#14 03-05-2003, 03:49 AM

Thanks for all your help!
I have now recharged my battery - I think I forgot to say that my car generally starts reasonably well with a full battery - and I will drive somewhere far away one of these days.
The fuel is relatively old, maybe two month's (which tells you how much I drive the car...), and it is not premium; possibly, these things sum up to me doing just about everything possible wrong.

One more thing: when I manage to get my car started, during the first 30 seconds or so I hear something under the hood clicking very actively. Is this the cold start valve? And, why are cold start valves so extremely expensive?

So I will try to drive my tank and engine clean and see if that improves the situation. I would not be surprised, as everything worked fine when I got the car (six month's ago) and during the first couple of weeks, when I drove more than now.
I'll let you know what is going on.

Thanks again,
Andreas

#15 03-07-2003, 12:30 AM

So... I have driven my car a bit yesterday, about half a tank, so that I could refill with fresh premium fuel... as usual, the car was running ok, apart from occasional loss of gear when I pushed the kick-switch (does this hint to serious transmission problems coming up?).
But the main problem is now that it does not start at all when the engine is hot - I could barely get it to restart yesterday when I stopped in front of my house before parking it, and today the same happened, just that it would not start anymore at all.
I checked the battery (which was freshly charged yesterday afternoon) and it is down to ca. 60%, after a number of starting-attempts.
It sounds as if the starter tries to get the engine turning but the pistons get stuck and can hardly be pushed/pulled. I reckon that this is a common symptom for a weak battery but I don't see why 60% should not be enough.
Also, I see that there might actually be a problem with the alternator - or does it seem reasonable to assume that a couple of attempts to start a car take almost half of the battery charge?

Thanks,
Andreas

p.S.: I guess my comment about expensive cold-start valves must seem strange - I was referring to the price that I had seen on www.thebenzbin.com: $670!