Starting Problem

[eyelight]

Have W124 E220 that has sometimes won't start. Battery is fairly new, and engine turns over fine, but nothing happens. Other times it starts just fine.
Anyone any ideas what the problem could be / Or is this too general a question.

 

[andrewwhamond]

no solution yet

I have had this problem for six months same car 124 E220 I posted my question and the reply was change the Over Voltage Protection Relay,my garage didnt think it was this so I didnt.
I have been driven to distraction by this intermittent problem and am going to change the OVP next week.
I hope others have a solution for you,I will let you know

 

[eyelight]

Thanks Andrew for your info. Our starting problem here has now changed to a permenent problem, not intermittent anymore.
Having checked the car further today I've narrowed it down to an electrical fault. Tried several times to start it but it just turns over and won't go. Battery is fairly new so it shouldn't be that.
Pulled a plug wire and cranking engine produced a spark and the engine almost started, ironically the one time there was a plug out.

Tried again and no spark after that one time. I'm hoping it's something fairly simple like a coil, but wouldn't the coil go bad and stay that way and not build up to this intermittently. When car is running it's great, it's just this starting problem driving us crazy.

Any help or info greatly appriciated.

 

[mike65]

When it was intermittent, did the starting get worse with particular cirucmstances, like hot/cold weather, or hot/cold engine?

Mike.

 

[eyelight]

We've only had the car a short time so weather has been pretty hot.
talked to my cousin this evening who used to work at a Mercedes dealer, and just getting it described to him over the phone, he's saying the things to check are the fuel pump relay, and also the overvoltage protection relay. says the coils are generally good on these engines.

 

[mike65]

I'd go for a new fuel relay before the OVP (the OVP is thing everyone blames if they can't think of anything else!).

Mike.

 

[andrewwhamond]

new fuel relay

This wasnt my posting but if I may ask Mike? If it was the fuel relay would there normally be a spark at the plug,mine was tested when it wouldnt start and there was no power to the plugs,the starter motor worked etc.
Thanks and hope this helps
andrew

 

[eyelight]

Thanks for the tips Mike. This is my girlfriend's car and is currently stuck in the car park at her office. She's getting the RAC to have a look at it today, and apparantly there's a Mercedes specialist in the area (near Aylesbury, Bucks) so she might get it towed there. She just bought this car recently (after me talking about how reliable W124s are supposed to be) so hopefully this isn't an expensive introduction to Mercedes ownership.

 

[mike65]

This wasnt my posting but if I may ask Mike?

Sorry I was being slightly flip, I've read no end of posts on about 5 different Merc boards over the last few years where as an offered solution someone will mention the OVP when its actually most unlikely to be that innocent looking relay. I think its gets mentioned so often simply cos its easy to check the fuse (is it blown? Nope. Okay OVPs fine then...etc).

Mike.

 

[eyelight]

RAC checked the car this morning and the fuel pump and fuel pump relay are fine. Car has been towed to a local garage - (not sure how expert they are with Mercedes but fingers crossed).

Talked again with my cousin and he'd been talking to a Mercedes Dealer mechanic he knows. This mechanic had worked on a W124 last week with a similar starting problem and it was the OVP Relay at fault.

RAC guy claimed not to be able to find the OVP Relay and was talking about some camshaft sensor ??? I wasn't there and am only hearing this secondhand.

From looking round the internet in the past 24 hours yes it does seem like the OVP Relay gets the blame for everything, but I hope it's the culprit in this case, as it's not too expensive.

 

[andrewwhamond]

To Mike 65,
Mike would there be a spark to the plugs if the camshaft sensor was at fault or if it was the fuel pump relay?
A recovery man tested mine when it wouldnt start and there was no power to the plugs.does this point the finger at anything?
thanks
andrew

 

[mike65]

Its nothing to do with fuel relay dunno about cam sensor.

I'm no expert (as you can tell) but if the plugs are getting no power to spark then you have to trace back the power route, plugs - leads- distributor - coil.

Do you know if all the plugs were checked? Its unlikly you'd have a complete set of "wasted" leads so that leads us (sorry) to the distributor, I had a bad 'un which was replaced and improved things no end.

The coil can give up the ghost eventually, as a wire breaks up the starting can become hit and miss before total failure.

Mike.

 

[eyelight]

Bad coil was my first idea whe this first happened. Talking to my cousin (ex chief mechanic at a large Merc dealer in Dublin) he said this 16v engine in the E220 operates on something called a Wasted Spark. There's no coil in the conventional sense and no distributor, but 2 coils on the engine block that give out constant spark. Makes little sense to me at this time of night without seeing a manual, but I'll believe him.

When I did a quick check of the car yesterday there was a spark once and no spark most of the time. RAC guy has said fuel pump working fine so it narrows it down to an ignition problem. Can't figure out how he could't find OVP relay. Not like W124 Merc is a rare car. The fact that a mechanic friend of my cousin had a similar problem with a similar car last week, leads me to favour the OVP relay solution.

This is my girlfriends new car and I was the one saying W124 Mercs were supposed to be very reliable, so I'd love it if it was just a relay.

 

[mike65]

I did'nt even notice it was the 16v engine (i tend to forget the w124 had that engine option late on)! Disregard everything I said about coils and dizzy...!

Mike.

 

[eyelight]

Currently the car has been towed to a garage near my girlfriend's office. I called them this morning, and she called them about lunchtime and they've had someone do some diagnostic check on it, but he's left and won't be back till later !!! They were saying they think it's the fuel pump, but yesterday the RAC guy who checked it said fuel pump was working fine. I tried to give my info about the OVP relay, but I think it was falling on deaf ears. I know people don't like to be told how to do their jobs, but I was just suggesting it as something to check. Anyway, it seems to me that any competent mechanic could test whether a fuel pump is working or not in a matter of minutes with a 12 volt tester.

They don't seem to be experienced in Mercedes however, and if they don't come up with a solution by tomorrow morning, I think we should get the car towed elsewhere, or back home.

All money though.

 

[996jimbo]

Whilst OVP relays are (apparently) Mercedes favourite fault, cam sensors are the favourite diagnosis of AA/RAC. That's not to say it isn't either - it's just amusing to hear that one again, and again and again.

 

[andrewwhamond]

ovp

I had mine replaced this morning 1994 E220,it just got to the point where something had to be tried,my garage who are excellent thought the camshaft relay was unlikely ,also the fuel pump was unlikely as I didnt have the full range of symptoms that go with it,they couldnt rule them out though.
Its difficult to know short term whether it cured the problem,the car starts ok at the moment!!!!

 

[eyelight]

Thanks for that info Andrew. I'm betting that the OVP is the problem on our car too, but the garage where it's stuck is still talking about the fuel pump last I heard.
They've had car since yesterday evening and have not come up with anything !!!

 

[andrewwhamond]

I had a very good garage recommended to me near the M4 ,George Frazier 02087951055,my neighbour uses him and we live on the south coast!
He is a very nice chap,helpful specialises in older Mercedes,has complementary cars etc,ex mercedes mechanic,might be worth a try.

 

[eyelight]

Thanks Andrew,
George Fraser seems to be highly recommended when I did a Google search.
I'm out in Henley, and our nearest Merc specialist seems to be Star Motors in Caversham, who were recommended on this forum. Talked to them this afternoon and they seemed grand. Car however is currently stuck up near Aylesbury. Currently thinking I might just go by a dealer, pick up a OVP Relay and just show up and try it on the car tomorrow.
Star Motor incidently were saying OVP would cost about £50 and £10 - £15 to install.