bosch fuel distributor quiz

[Stringer]

right, fingers on buzzers, your starter for 5 points. What should a skint brit in Lebanon do if his fuel distribtor on an old 300E is packing up, according to his mechanic who says this is the achiless heal for this model. Is it
1) look for a used one from a UK breakers?
2)get a repair kit on line sent
3)buy a 'reconditioned' one from the various companies
4) try and fix the existing one
5)none of the bove


desperate, but thanks anyway
mj in beirut

 

[martyz]

If I was him,I would be going route 1,plenty to be found,and probably cheapest sure fix,if it is the problem.It might be an idea to post the symptoms.

 

[tintinmt]

My suggestion would be 2 or 3, although 3 is probably favourite if the reconditioning company has a good reputation.

 

[Dieselman]

There isn't much to a fuel distributor.
The most common faults are seals leaking fuel, the bottom half joint leaking air, the metering needle sticking, the EHA giving up.

I wouldn't do anything until ascertaining what is wrong with the existing one.

 

[E270 Owner]

There isn't much to a fuel distributor.
The most common faults are seals leaking fuel, the bottom half joint leaking air, the metering needle sticking, the EHA giving up.

I wouldn't do anything until ascertaining what is wrong with the existing one.

Definitely +1

 

[carat 3.6]

according to his mechanic who says this is the Achilles heal for this model.

Never heard anyone say that before, vacuum leaks and distributor caps are the weak points of the m103.

 

[LTD]

Surely invading Israel and repatriating another one must be a considered option ?

Seriously though, as Dieselman says, these are simple units and faults involve simple problems and simple solutions.

I'd overhaul the entire unit to give you total piece of mind for a long time. Fixing one thing this time might mean you fix another in a few months .....

 

[Vlad]

I've had to replace two fuel distributors on ex 300E's that I've owned. The first after I ran some injector cleaner through the system....all the crud ended up in the fuel distributor. The second 300E had a rough idle and a stutter from pull away. Replaced the distributor cap+ rotor, then injectors only to still have a rough idle. Then replaced the fuel distributor and rough idle was history.

I may have a good used fuel distributor somewhere, as I took one of the replacement distributors off one of the 300E's after it got written off.

 

[Stringer]

have a dig about. If you 're ok about all the flaffing around involved in posting it, then i'd happily buy it off you - after the inspection tomorrow with my merc mechanic who has all gadgets for blowing through the distributor and jets and detecting where the fault is. He mentioned to me today that it might just be air, but i have a feeling he might tell me the bad news tomorrow that the FD is buggered. Reading eh? Lived there most of my youth. Small world.
MJ in Beirut

 

[Stringer]

still struggling to work out if my fuel distributor is the problem or not as my mechanic fiddled with a HT lead on piston number 2 and then it fired up again on all six.
HOWEVER, this didnt last long as in town today (it's hot here), it went back to 5 cylinders again. I floored it once on a long drag and it cleared for a while, but then went back to running on 5
Is this a fuel issue?
thanks
MJ

 

[carat 3.6]

still struggling to work out if my fuel distributor is the problem or not as my mechanic fiddled with a HT lead on piston number 2 and then it fired up again on all six.
HOWEVER, this didnt last long as in town today (it's hot here), it went back to 5 cylinders again. I floored it once on a long drag and it cleared for a while, but then went back to running on 5
Is this a fuel issue?
thanks
MJ

If your mechanic cant tell if the fault is fuel or ignition related, you need another mechanic!

You have an ignition fault, can you remind me which ignition parts you changed last time?

 

[Stringer]

i changed all the plugs and just cleaned the distributor cap. that's all.
thanks
MJ

 

[carat 3.6]

Going by the fact that it ran on all 6 after the ht leads were moved, I would think they need replacing.

Seriously, your mechanic should be able to tell if there is a spark getting to all cylinders. With the engine running on 5 cylinders, pull the ht lead off from the cylinder you think is not getting a spark. If it runs worse, put the lead back on and try another cylinder. When you pull off a ht lead and the engine runs the same, there is no spark at that cylinder.

Get your mechanic to do the above test, the shock from the ht current might wake him up a bit.

 

[Stringer]

he doesn't need to do it. i did it myself and couldn't identify a non-runner pot. However, i noticed that when i connected a spark plug and let it earth on the exhuast manifold, that a couple of the cyclinders had a weak spark which occassionally missed. would this indicate leads/distributor cap?
You've got the mechanic all wrong. On many occassions he didn't even see the car, it was just his opinion when speaking about it to me in person. He did say one thing though which i think was wise: the after market spark plug leads which must be at least 10 years old tend to start to pack up and underperform.

but how can you know that it's not the fuel distributor not delivering to some of the pots...which in turn makes the plugs oil up (cos there is some seapage - it's an old engine)? What's the deal breaker?

 

[Dieselman]

The fuel distributor isn't a rotary distributor, it just delivers to each of the outlet ports together, hence it is called CIS...Continuous Injection System.

It is possible you have low HT voltage.

 

[stwat]

New cap and rotor needed. As mentioned, the M103 need regular cap and rotor changes. They eat them for breakfast.
They may look alright but will have internal cracks.

 

[Stringer]

whats the easiest way of testing that?
thanks
M

 

[carat 3.6]

he doesn't need to do it. i did it myself and couldn't identify a non-runner pot. However, i noticed that when i connected a spark plug and let it earth on the exhuast manifold, that a couple of the cyclinders had a weak spark which occassionally missed. would this indicate leads/distributor cap?
You've got the mechanic all wrong. On many occassions he didn't even see the car, it was just his opinion when speaking about it to me in person. He did say one thing though which i think was wise: the after market spark plug leads which must be at least 10 years old tend to start to pack up and underperform.

but how can you know that it's not the fuel distributor not delivering to some of the pots...which in turn makes the plugs oil up (cos there is some seapage - it's an old engine)? What's the deal breaker?

If you've got a weak spark at some plugs, but a good spark at others, you have an ignition fault. You can exclude the ignition coil, coil to cap ht lead, and the rotor arm, as if any of these were at fault you would have a weak spark at all cylinders.

This leaves the ht leads, or the distributor cap. Now if the ht leads are 10 years old they will need replacing anyway, the same can be said of the distributor cap.

You could test the ht leads by swapping the lead from from a known good cylinder to a bad one, although make sure you swap it at both ends. (the leads to cylinders 5 and 6 are normally long enough to swap with each other) If the weak spark moves with the ht lead it will need replacing, if it stays on that cylinder you can assume the distributor cap is at fault.

Take a look inside the distributor cap, if you see any green like oxidization on the terminals, or any hairline cracks in the casing, the cap will need replacing.

I can rule out a fault with the fuel distributor because your fault is intermittent, a dirty blocked port or leaking seal issue would be a permanent fault. You could carry out a fuel delivery test of the injection system if you wanted to waste half a day, but your fault is definitely ignition related.

 

[Stringer]

thanks a lot. great advice, as always
best
M in Beirut

 

[johnsco]

Check all your ignition components before you spend any time or money on the fuel distributor.
Distributor caps, rotor arms and HT leads are most-likely villains.
Be careful when sourcing spares.
It's worth buying these parts from MB, as some of the alternative parts are not up to much.