Lovely day blighted

jonthetourist

Active Member
Joined
Feb 2, 2011
Messages
174
Location
Glos
Car
SL 300-24
Well yesterday was a decent day for drying out my 129 hood prior to putting the hard top on. Tarp over it overnight to keep the damp off and another sunny day today. All that remained was a little run out and a session on the drive with the heater going full blast. That was the plan anyway.

The car hasn't been out for 3 weeks as my other half has broken her arm so I have been driving hers, which is easier for her to get in and out of. But the engine sprang into life first turn of the key and we ran beautifully for 4.5 miles, at which point it cut out. I pulled over and restarted it twice, but in each case it ran rough for a couple of seconds then cut out. So fuel, thinks I, calling the breakdown service.

He tried listening for the fuel pump while I turned it over, then we checked fuses and took out the MAS box and reseated it (not sure what else you can do with it). Meanwhile, with the car back on the drive and out of range of his jump leads, we discovered those leads hadn't been connected properly and I had flattened my battery. So my plans to swap the roof bit the dust too.

It will go on the star machine tomorrow. I have read elsewhere it could be expensive, but I am just posting to share my pain. It was going to be such a nice day . . .

Jon
 

Dieselman

Banned
Joined
Jul 13, 2003
Messages
34,206
Car
Peugeot 403 Convertible
The car starts with water in the distributor but as the engine warms it evaporates and then condenses in the cap.
I was once asked to look at a Rover that would start from cold no problem but would cut out at a junction about 3 minutes into the journey, regular as clockwork.
The problem was the thermostat was leaving the engine too cold so not drying out the condensation in the dizzy.

Check the cap rotor arm and plastic backplate.
 
OP
OP
J

jonthetourist

Active Member
Joined
Feb 2, 2011
Messages
174
Location
Glos
Car
SL 300-24
The car starts with water in the distributor but as the engine warms it evaporates and then condenses in the cap.
I was once asked to look at a Rover that would start from cold no problem but would cut out at a junction about 3 minutes into the journey, regular as clockwork.
The problem was the thermostat was leaving the engine too cold so not drying out the condensation in the dizzy.

Check the cap rotor arm and plastic backplate.
Thanks for clarifying DM.

Logic tells me it shouldn't be binary - the first bit of condensation should generate a misfire which I din't get. Anyone else have an opinion on this?

Jon

PS Nothing to lose by getting a dry cloth to work of course :)
 

Dieselman

Banned
Joined
Jul 13, 2003
Messages
34,206
Car
Peugeot 403 Convertible
Thanks for clarifying DM.

Logic tells me it shouldn't be binary - the first bit of condensation should generate a misfire which I din't get. Anyone else have an opinion on this?
Nope, just a dead cut, depends on where the 'lectricity tracks, one track and that's it, game over.
 

grober

MB Master
Joined
Jun 22, 2003
Messages
28,357
Location
Perth, Scotland
Car
W204 C200CDI Estate
Dieselman is almost certainly correct. Remove as many distributor innards as you can rotor arm? plastic shield? and use your other half 's hairdrier to dry out the internals Have a close look at the inside of the distributor cap and check for tracking marks or worn /corroded contacts- give them a clean up with a small file if they are burned. Wash out with WD40 and dry off with some kitchen roll - sorted. If the cap is badly damaged or cracked --- replacement is the real answer. Only get a Bosch [OEM] or genuine MB replacement.
 

Howard

MB Club Veteran
Joined
Apr 23, 2004
Messages
18,624
Location
Toad Hall
Car
CLS 500 / A 150
When you are checking the cap , be especially vigilant as you tighten it up again.

On my old w124 i had a terrible misfire , the cap looked ok when i had it out and examined it , but as you tightened it down , it opened a hairline crack in the cap.
 

clever dicky

Active Member
Joined
Nov 27, 2010
Messages
421
Car
Jag
Just try and start / turn it over in the dark. You'll soon see if its tracking anywhere.
Mind you, as its that old, does it have points? or a spark suppressor ( capacitor ) in the distributor? They dont last long and can dry out.
 
OP
OP
J

jonthetourist

Active Member
Joined
Feb 2, 2011
Messages
174
Location
Glos
Car
SL 300-24
So can you actually hear the pump prime?
I was the man turning the key. The breakdown man said he couldn't hear anything from the fuel pump.

Thanks for all the feedback folks. I will be putting the battery on charge tomorrow and investigating.

Jon
 

murray motors

Active Member
Joined
Aug 18, 2010
Messages
81
Location
belfast
Car
129 sl 500 and sprinter
CHECK cap and arm mine need done every time you take it out after leaving it for a few weeks then it runs like a dream
 

jaymanek

Authorised Forum Sponsor
SUPPORTER
Joined
Nov 29, 2002
Messages
16,415
Location
Nuneaton Warwickshire
Car
Lots of Mercedes!
You just need to turn the key to ignition on and the fuel pump will prime for a second or two. If its not priming then you need look at your fuel or OVP relay.
Dont need to actually turn the car over...
 

grober

MB Master
Joined
Jun 22, 2003
Messages
28,357
Location
Perth, Scotland
Car
W204 C200CDI Estate
As usual in an attempt to be helpful we have all piled in with detailed advice on the most likely cause of your problem-- the distributor cap. But as JAY rightly points out --- " other problems are available" ;)
 
OP
OP
J

jonthetourist

Active Member
Joined
Feb 2, 2011
Messages
174
Location
Glos
Car
SL 300-24
Just a quick update. My theory was that if it is the distributor cap then the car would start today. I would leave it running and it would cut out as it warmed up and started to evaporate.

Thwarted by the battery being so flat the trickle charger couldn't get it to the point of turning the engine over. :-(

Many thanks to all contributors. My local indie (who lives nearby) is going to bring a battery pack and code reader home.

Jon
 
OP
OP
J

jonthetourist

Active Member
Joined
Feb 2, 2011
Messages
174
Location
Glos
Car
SL 300-24
code reader will be useless.... good old fashioned investigation needed here.
And old-fashioned investigation reveals that Dieselman was almost certainly correct. (applause)

The inside of the cap was damp, plus the spring-loaded bit in the middle (you can tell my level of mechanical ability here) appears to have lost its spring.

New cap and rotor arm on order.

Thanks again for all contributions.

Cheers

Jon
 
OP
OP
J

jonthetourist

Active Member
Joined
Feb 2, 2011
Messages
174
Location
Glos
Car
SL 300-24
There is a rubber seal that goes around the cap, I would replace that too... mine was as flat as a pancake.
Good point, thank you.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom