Rebuild 323i ignition distributor

[agisthos]

I have an E30 323i which has the earlier style M20 pulse mechanical distributor. I wont get any help on E30 forums for this, as the 323i was a rare euro only model. That's why I am here.

I need to get it rebuilt or at least cleaned and serviced. I have heard you cannot just open them up and play with it as the spring is unique for each model, making wrecking yard swaps a gamble.

Is there anyone/company that knows what they are doing with these things? I cannot find anyone in my home town who does.

[uwbuurman]

Hi, where are you based?? Welcome here! Please tell us some more about the car and yourselve. I think we can help you here. What seems to be the problem with this distributor??

[Jeroen]

Welcome here! I sometimes do wonder if an overhaul can be necessary, or at least worth while... never took one apart either so definitely following this!

[e21Keith]

I took one of mine apart as the pulse module had failed, there are videos on Youtube of similar model Bosch distributors.

There are a couple of circlips that can be fiddly to remove but inside it was actually quite simple, there are springs and bobweights like any distributor and the weights will have different numbers stamped on them, presumably because they have a different weight to provide the advance curve characteristics.

The pulse unit is not serviceable and NLA from Bosch but I have found NOS units available online, the unit is not unique to the 323i so one from a 320i would be suitable.

My findings from dismantling my distributor:- Leave it alone unless there is something wrong with it, you can lubricate the bobweights and springs as much as you like, there is a drain hole on the bottom of the casting so any excess will drain out.

As a footnote, way back in 1988 when unleaded fuel made its debut in the UK I had the main dealer retune the engine of my '82 320 for unleaded (back then the advice was to retard the ignition by 4 degrees). They were able to do this by plugging into the diagnostic socket and produced a graph showing that my distributor wasn't advancing to specification. Their advice was that it wasn't significant, they were all like that and even fitting a new distributor may not make an improvement.

[agisthos]

Hi guys I am from Australia.
I am rebuilding the M20B23 engine. L-Jetronic. Its finished finally. The engine builder seems to think the distributor is not good and needs to be fixed. It looks rusty, but also seems stuck and does not spin freely. And it has play when holding the bottom shaft, although I'm not sure if that is normal or not.

Since I am rebuilding and cleaning every other part, it seems like a good time to do the distributor as well.

[e21Keith]

You will no doubt find some lateral play (up and down) in the distributor and this is difficult to improve, I have a total of 4 of these distributors and they all have lateral play, however as the distributor runs on a helical gear when the engine is running it will run in the same position. If you see the ignition timing unstable at idle then I'd worry, otherwise not.

[Jeroen]

My 323i on and off suffers from a high idle, even when warm, defnitely not always. I spent a lot of time investigating and I have ruled out vacuum leaks and I made sure the warm up regulator and aux air valve are functioning as should. Sadly you do not always have measuring equipment on hand when the issue occurs. Car starts and runs fine, does not suffer any lack of power, just this idle that decides to go to 1300-1400 rpm instead of 900rpm. Mind you, at whatever rpm it is, it sits there, not going up and down, and it doesn't go down after a tap on the gas pedal.

Imo I didn't have many other options left than a vacuum advance mechanism that perhaps isn't moving as freely as it should. All 'n all not a huge issue, more of an annoying niggle, but it would be nice to settle this!

[agisthos]

You will no doubt find some lateral play (up and down) in the distributor and this is difficult to improve, I have a total of 4 of these distributors and they all have lateral play, however as the distributor runs on a helical gear when the engine is running it will run in the same position. If you see the ignition timing unstable at idle then I'd worry, otherwise not.

Its not up and down lateral play. When holding the bottom fixed, you can spin the top where the rotor sits back and forth. Not much, only a few mm either way. I'm not sure if this is normal or if the internal spring mechanism is worn. Maybe that's how they are.

I will get onto watching some youtube videos to see how they are torn down.

[e21Keith]

If you mean the rotor at the top moves independently in a clock/anticlockwise direction from the bottom of the shaft that's part of the design, that's the advance/retard mechanism