Missing 450SLC

[maldon]

It's a bit of story but my 450SLC is now running like ab absolute dog - missing and probably running on 5-6 at best.

I had new plug leads fitted a while ago - she was running ok but mechanic who was to look at what I thought was a bit of a wobble on the prop, reckoned she was missing a bit - he removed and cleaned the plugs - two were soorty.

He reckoned it was running perfectly when he took it a couple of miles down the road - but on the way back it started missing.

Any likely causes / what will best way to diagnose the problem? All plug leads and boots are connected properly...

 

[Rasputin]

One of the causes are the fuel injectors particularly if they have not been replaced in the last 30-40K miles. Had the same problem in mine and two of the injectors were blocked. Either replace them together with the seals or take them out and leave them overnight in a jar with celulose thinners then clean the tip of the valve with a needle. It will last you for a while but would recommend replacing them, they are not very expensive.

 

[maldon]

Rasputin - thanks for that - I am quite sure they have not been attended to.

How does one go about removing the injectors / how difficult a job is this?

 

[Rasputin]

Fuel injectors

It is a relatively easy job. They are held by a bracket with a 10mm bolt and the fuel pipe coupling nut 15mm. The difficult one to reach is cylinder 8 by the accelerator spindle as its bracket gets in the way but with a wobling extension on the rachet you can reach it at an angle without having to remove the spindle bracket. If you only intend to clean them at least get a set of new seals, they are inexpensive.

The picture loading facility is not working at this forum for some time, but if you PM me with your email address I can send you pictures of components and step-by-step procedures.

Would suggest to swap two injectors (one the sooted spark plugs) to another cylinder that's working fine. Run the car and check the plugs. This will determine whether the injectors are the culprit.

The injectors valve blockage can get stuck open (sooted spark plugs) or stuck shut (no fuel to cylinder).

 

[maldon]

What a stroke of luck - mechanic suggested call local car electrical firm - spoke to an old boy and explained the problem.

How simple?

Remove the metal spark plug boots. These were required for not causing intereference with German SW (Police?) radio.

Took me 15 mins at the tops.

She is running better than ever - the 'prop wobble' never existed

 

[dawood]

So should we all remove the metal spark plug boots then?

 

[OlafMaxwell]

We used have those same metal boots on motorcycle plug leads......nightmare for trouble and the first thing to do was remove them and then upgrade the leads. They seemed to cause a lot of shorting out.