R129 distributor caps

[demetrios]

Hi all.
Firstly the search feature won't work, keeps closing dialogue bar when I try to type so had to start new thread.

Right
Haven't driven the 500 for 3 weeks, been starting it, letting it warm up,slight revving then switching off.
Took it for a blast up m6 for a 25 mile round trip, fine UpTo highway on the highway UpTo 80mph then when I got off under 40mph as if cylinders **** off and had 50bhp!!

Quick search brought me to conclusion of moisture in distributor caps,watched a few how to YouTube videos but quick question or two

Do you need to disconnect battery??
If I need to change the rotors stick with Bosch or not.
Found two sites selling with very different prices. Which one is correct??



Then euro car parts has Bosch one for £110!!
[URL="http://www.eurocarparts.com/distributor-cap"]http://www.eurocarparts.com/distributor-cap

Please help

 

[Doodle]

No need to disconnect battery. Bosch/Beru/Bremi are all much of a muchness, I've run all 3 over the years and noticed no appreciable difference.

ECP no longer cheap for these parts and almost zero stock held. Last set I bought (Easter last year) came direct from a supplier in Germany.

Check the fit of the insulator caps (behind the rotor arm mount), change them if they're loose/sloppy on the camshaft.

 

[DSB SL AMG]

I changed all mine in the summer with OEM parts direct from the stealer, was not that bad...

Hi all.
Firstly the search feature won't work, keeps closing dialogue bar when I try to type so had to start new thread.

Right
Haven't driven the 500 for 3 weeks, been starting it, letting it warm up,slight revving then switching off.
Took it for a blast up m6 for a 25 mile round trip, fine UpTo highway on the highway UpTo 80mph then when I got off under 40mph as if cylinders **** off and had 50bhp!!

Quick search brought me to conclusion of moisture in distributor caps,watched a few how to YouTube videos but quick question or two

Do you need to disconnect battery??
If I need to change the rotors stick with Bosch or not.
Found two sites selling with very different prices. Which one is correct??



Then euro car parts has Bosch one for £110!!
[URL="http://www.eurocarparts.com/distributor-cap"]http://www.eurocarparts.com/distributor-cap

Please help

 

[Doodle]

I changed all mine in the summer with OEM parts direct from the stealer, was not that bad...

Have they seen sense now and priced them more reasonably? Last year they were asking around £400.

Also remember the v8 has twin caps and rotors.

 

[demetrios]

Have they seen sense now and priced them more reasonably? Last year they were asking around £400.

Also remember the v8 has twin caps and rotors.

It certainly does have twin caps and rotors as I found out today.

Where is best place to get then from then and what's a Good price?

Also what tools do I need, torque wrench?? Need go buy the tools before I start the job on sunday.
I'm more of a destroyer than a fixer but I'm not willing to pay someone to do it just so it can go into storage next week til april

 

[Doodle]

Hardware will either be hex keys or Torx. No need for torque wrench, just snug them down by hand.

 

[demetrios]

Hardware will either be hex keys or Torx. No need for torque wrench, just snug them down by hand.

Don't look like they are easy to get too with a hex key? What size do I need? Read somewhere people were saying 1/8

 

[Doodle]

It's fairly easy; you just have to poke it between the plug leads, and align the fan for clearance on the driver's side.

IIRC 5mm and 3mm for hex keys (which I think equates to T25 and T10 for Torx), it's certainly not going to be an imperial size. I keep a cheap set of short hex keys in the centre console, I think they were a couple of quid from Tesco of all places!

 

[jaymanek]

3 & 5mm...

I do mine regularly... Every 2-3 years I replace both rotor arm and caps...

I replaced the seals on the backing plate too but they still seem to get damp..

 

[Doodle]

I've seen reports of people using high temp silicone to seal them to the engine block but I'm not convinced that's the best idea.

 

[demetrios]

3 & 5mm...

I do mine regularly... Every 2-3 years I replace both rotor arm and caps...

I replaced the seals on the backing plate too but they still seem to get damp..

How much do you pay for arms and caps then? Do you buy them from Mercedes or elsewhere?

 

[ray_hennig]

How much do you pay for arms and caps then? Do you buy them from Mercedes or elsewhere?

I paid rather a lot but it was in frustration having thrown away Bremi cap and rotor after 6 months. I replaced them with the 17 year old originals until finally paying loads for MB originals. This is for a 6 cylinder M104 engine but the technology's much the same as yours.

Some people are reporting lower quality from Bosch and that Beru's a better bet. In your shoes I'd be tempted to try Beru but equally tempted to bite the bullet and go to MB.

During my misfiring issues I replaced the cover behind the rotor; another startling price from MB. My line up is now MB original for cap, rear cover and rotor. Beru for coil and HT leads. NGK for spark plugs. All well for the last few years with a car that lives 100% outside, year in year out.

By the way, most vendors seem to imply you can fit Bosch (and maybe others) spark plugs with an 'R' in the part number. Not true. These cars prefer non-resistor plugs and Beru, NGK and Champion seem to be the only suppliers, although Bosch ones from India and other places can be found.

Bonne chance.

RayH

 

[Doodle]

These cars prefer non-resistor plugs and Beru, NGK and Champion seem to be the only suppliers

Or Mercedes themselves, where they are very reasonably priced.

 

[ray_hennig]

Or Mercedes themselves, where they are very reasonably priced.

Yes, I should have mentioned MB for plugs. The reason I didn't is that I have axed my local MB due to insane prices, no discounts and the fact they flogged me the wrong plugs (resistor for €100 for 6!!!) some while back.

The only things I buy from local MB now is batteries and they're good value. Similarly at VW where they're happy to discount.

RayH

 

[DSB SL AMG]

Plenty of posts about using MB OEM ignition parts only for the M103/104 engine, aftermarket seem to fail pretty quickly...i also replaced the suppressor (insulator) cap behind the rotor in the summer on my R129, MB part only, think it was around £20 for a piece of plastic...it gets forgotten and can cause misfire issues with stray arcing (my old one attached pic after 24 years).
Non resistor type plugs as you stated are a must...

Useful M103 / M104 Ignition info

What to do when my M103 is giving me trouble: A beginners guide ~ Artisan

https://starfest2016.mbca.org/star-...tting-technical-ignition-misfiring-1990s-m-bs

I paid rather a lot but it was in frustration having thrown away Bremi cap and rotor after 6 months. I replaced them with the 17 year old originals until finally paying loads for MB originals. This is for a 6 cylinder M104 engine but the technology's much the same as yours.

Some people are reporting lower quality from Bosch and that Beru's a better bet. In your shoes I'd be tempted to try Beru but equally tempted to bite the bullet and go to MB.

During my misfiring issues I replaced the cover behind the rotor; another startling price from MB. My line up is now MB original for cap, rear cover and rotor. Beru for coil and HT leads. NGK for spark plugs. All well for the last few years with a car that lives 100% outside, year in year out.

By the way, most vendors seem to imply you can fit Bosch (and maybe others) spark plugs with an 'R' in the part number. Not true. These cars prefer non-resistor plugs and Beru, NGK and Champion seem to be the only suppliers, although Bosch ones from India and other places can be found.

Bonne chance.

RayH

 

[Doodle]

Those parts were NLA for the V8 a couple of years ago, although still available from Bosch. They're flippin' expensive, circa £40ea, and of course you need a pair.

Bosch p/n is 1230500240

 

[demetrios]

So I'm gonna tackle the rotors in the morning but can you spray a moisture repellent spray or something? A guy came in and said on his old cars he sprays them with that stuff, buys it from halfords or something iirc

 

[demetrios]

So I've got the right side apart, looks like hasn't been taken apart but then the part says beru on it so must if been changed at some point in its 24 yr and 78000 mile life.

I can't get the bolt out the steel rotor though and I'm a strong guy. Any advice??

 

[demetrios]

Left side off, bolts much much easier to get off but left seems like has more particles than right
Also more moisture on outside of orange cap by the seal. More pics after
Oh and left side is a bremi

 

[RichardF]

So I'm gonna tackle the rotors in the morning but can you spray a moisture repellent spray or something? A guy came in and said on his old cars he sprays them with that stuff, buys it from halfords or something iirc

Probably WD40 (WD stands for water displacement)