Stripped bolt heads on distributor rotors: How to remove?? HELP

[gsxr]

Re: Bad bolts on engine rotors , how to take them out ?? HELP

Merged duplicate threads on same topic.

See post #14 from Arnt with information on sourcing different rotor bolt with 4mm hex socket head.

 

[gsxr]

I forgot to post this when I got the rotors last year, but anyway: I finally got my hands on some Beru rotors for M119 (Beru p/n EVL-183). I had to source them from Europe as no US vendor carries them. Photos attached, also on my website here.

As you can see, the box says made in Germany, and the rotor has MB p/n 119-158-02-31 on the face. The top section has the clear lacquer-type coating (Bosch aftermarket does not). I found a tiny double-D logo on the back which is the Doducu logo. Klink confirmed that the OE/dealer rotors are indeed Doduco. So although Bosch supplies distributor caps and insulators to MB, Doduco supplies the rotors.

Interesting side note: The Beru / Doduco rotors have 3mm bolts that fit VERY snugly on a 3mm Allen wrench. By comparison, the Bosch bolts are a very sloppy fit, almost like they were made for SAE, or a 3.5mm, or something... but nothing else fits. Or at least, I could not find any size metric or SAE Allen wrench that was a proper fit in the Bosch rotor bolts.

 

[samiam44]

interesting to see the differences. Looks like the chunkier brass center piece. That's where I've seen high in the bosch parts.

 

[samm]

Hi Dave,

How interesting..Just this past Sunday I installed the brand new Bosch POS rotors. I barely and I mean barely tightened the 3mm bolts and one stripped!!! I just had to remove the old ones by hammering a tiny T20 bit onto 5 of the 6 total 3mm bolts to remove the old ones, and the bloody new ones stripped too! Absolute bullsh8T.

I also thought of getting a SAE size to see what bloody fits. Bearing in mind that I had just put dielectric grease on my insulators to test and see if this helps and I more than likely intended to remove the rotors to install the new insulators (if dielectric didnt help)! Absolutely disappointed with these rubbish Bosch parts. I will look for Beru ones like yours..

 

[gsxr]

I've never had problems with Bosch rotors, except for the ridiculous bolts they use. If you can locate Beru rotors at a decent price, great! Or shell out for the OE Doduco, which are currently $107 list, or $79/ea from Naperville with free shipping (link).

Arnt's solution (in post #14, if you scroll up) is the best low-cost method, just replace the stupid Bosch bolts with aftermarket bolts that have a proper-sized hex socket. Make sure to file down the area under the bolt head so they will "float" properly like the originals.

 

[samm]

yes those Beru are in England. [snip]

ADMIN EDIT: Moved smog pump delete discussion to this thread, see post #16: https://www.500eboard.com/forums/showthread.php?t=199

 

[ricsim]

Re: Rotor Bolt (Stripped)

AlexV,

The joyful "rotor bolt syndrome" lives on as ever.

And here is the solution, post #14 and partially post #16;
https://www.500eboard.com/forums/showthread.php?t=4559

Whatever you end up doing - DO NOT HAMMER ON THE ROTOR BOLT HEADS!! That may induce cracks in the alu.rotor bracket.


-a-


---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----

Just for testing I made additional vent holes on one of the caps on the Limited, the principle is shown on the enclosed image. It works great and shows no sign of entrapped moist due to improved ventilation. I used a cutting disc on the Dreml to make the slots. Something to think about for those living in climates with low and varying dew point during the year.

Hi Arnt
So, what about moisture and ignitions problems with these additionals vent holes in your caps, after These last 3 years.
I'm ready to do the same experience with mine

 

[oaklandw124]

I've never had problems with Bosch rotors, except for the ridiculous bolts they use. If you can locate Beru rotors at a decent price, great! Or shell out for the OE Doduco, which are currently $107 list, or $79/ea from Naperville with free shipping (link).

Arnt's solution (in post #14, if you scroll up) is the best low-cost method, just replace the stupid Bosch bolts with aftermarket bolts that have a proper-sized hex socket. Make sure to file down the area under the bolt head so they will "float" properly like the originals.

I believe I have found a source for the Beru rotors i the USA from NAPA:

https://www.napaonline.com/en/p/ATMEVL183?vehicleAddPDP=true

$57.00 each, but if you have AAA, this month you can get them to $46.00 each. I'm ordering a pair to see if they are the same as GSXR describes.

 

[2phast]

FWIW, this is a common problem, its called galling. Its always best to apply a Moly based grease to the threads of any steel bolt that goes directly into aluminum (Aeroshell 33ms is a good choice). Just make sure you use a Moly grease with no graphite in it.

In some situations when I encounter a stripped bolt like this, if possible, I use a small jewelers file and cut a slot into the top of the bolt so I can use a large flat blade screw driver to remove the bolt. I prefer to use a flat blade bit in a socket and use a socket wrench for better leverage.

 

[nocfn]

I have received several nos parts for the w126 local that are MB PARTS sold under the napa altrom label.

 

[gsxr]

I think there is an eBay vendor selling the Beru rotors now in USA at a decent price. Try searching for the MB or Beru part number and see if that turns up anything. I vaguely recall them being <$75/pair...?

 

[oaklandw124]

I think there is an eBay vendor selling the Beru rotors now in USA at a decent price. Try searching for the MB or Beru part number and see if that turns up anything. I vaguely recall them being <$75/pair...?

I think I found it on ebay...$66 for the pair! For Mercedes W119 400E 400SEL 500SEC 500E S500 Ignition Distributor Rotor Beru | eBay

But in the auction listing they are saying a rotor bracket is required? Haven't seen this notice on other MB parts sites.

 

[gsxr]

Nah, the rotor bracket thing is ancient news, for very early build engines only. Assuming the EPC data is accurate, only 12 cars imported to USA (out of 1500+) would have needed the updated bracket, and those probably all had it updated by now.

 

[oaklandw124]

Nah, the rotor bracket thing is ancient news, for very early build engines only. Assuming the EPC data is accurate, only 12 cars imported to USA (out of 1500+) would have needed the updated bracket, and those probably all had it updated by now.

Great, thanks!

 

[JeffSpicoli]

The ebay link for the Beru rotor is still active and good pricing. Additionally, FCP Euro also carries the Beru parts. Distributor cap too.

 

[gsxr]

The ebay link for the Beru rotor is still active and good pricing. Additionally, FCP Euro also carries the Beru parts. Distributor cap too.

That is great news! Previously, eBay was the only source for the Beru (reboxed OE Doduco) rotors.

FCP has them for a few bucks more, $80/pair, but that includes lifetime warranty:

Mercedes Distributor Rotor - Beru 1191580231

Mercedes Distributor Rotor - Beru 1191580231

www.fcpeuro.com

 

[Jlaa]

I forgot to post this when I got the rotors last year, but anyway: I finally got my hands on some Beru rotors for M119 (Beru p/n EVL-183). I had to source them from Europe as no US vendor carries them. Photos attached, also on my website here.

As you can see, the box says made in Germany, and the rotor has MB p/n 119-158-02-31 on the face. The top section has the clear lacquer-type coating (Bosch aftermarket does not). I found a tiny double-D logo on the back which is the Doducu logo. Klink confirmed that the OE/dealer rotors are indeed Doduco. So although Bosch supplies distributor caps and insulators to MB, Doduco supplies the rotors.

Interesting side note: The Beru / Doduco rotors have 3mm bolts that fit VERY snugly on a 3mm Allen wrench. By comparison, the Bosch bolts are a very sloppy fit, almost like they were made for SAE, or a 3.5mm, or something... but nothing else fits. Or at least, I could not find any size metric or SAE Allen wrench that was a proper fit in the Bosch rotor bolts.

This place has 3.5mm allen keys for sale for 87 cents each: Metric Hex Key Wrenches made in Germany from .7 to 36mm sizes

As well, is it possible that the Bosch bolt is a 3mm extended tip bolt that requires an extended tip tool? It is hard to tell from the pictures. If it is, it would require something like this: Extended Pin Hex Key Wrenches for RIBE-IC Cap Screws- From Germany

People were stripping 6mm hex head seat bolts on 90s Porsche 911s for two decades until one guy realized recently that the hex head bolts require a 6mm extended tip tool: FOUND: Cure for FOSYSB (Fear of Stripping Your Seat Bolts) - Rennlist - Porsche Discussion Forums

 

[sheward]

Interesting. I'd seen those wrenches before but had no idea what they were used for. It appears the round peg helps to prevent the wrench from becoming non perpendicular to the fastener.

drew

 

[gsxr]

Jlaa, that is fascinating... I never knew those bolts/keys existed.

Close-up photo of Bosch rotor/bolts below. Doesn't appear they are they special xtra-tip type, still leaving us with a mystery:

 

[gerryvz]

Not sure about the Bremi rotors, but the Beru rotors work PERFECTLY with a standard (non-ball-end) 3mm hex key or socket.

As we know, the Bosch bolts are a slightly larger size.

All the more reason to go with the superior quality Beru rotors, which are reboxed MB OE rotors made by Doduco.

 

[Jlaa]

I feel like one can find bad experiences with Beru, Bosch, and Bremi all over these forums. The only brand I have not read horror-story type experiences with are the OE MB ones.

Stripped bolt heads on distributor rotors: How to remove?? HELP | M119 Engine

Hi guys, I tried to replace my old rotors and could not do it :hammerhead: It is 3 mm hex but it spins inside of a bolt (either bolt was crap or it was too tight) anyway now tree bolts are completely gone:pissed: , they are round inside instead of angular 3mm hex. :fun: So ... any ideas how...

www.500eboard.co

.... Of course I have no experience with my car in a high humidity environment.

 

[DarkStar]

Just doing caps and rotors this weekend. I used a 1/4" Milwaukee impact with a 3mm or 5mm hex bit to remove. The shock tends to break them loose, think mine have been on the car at least 10 years and 5k miles but the screws were stuck. I wish the rotors came with 4mm hex heads as the 3mm is bit too small. They also seem kind of soft. My old parts are Bosch but bought some Beru from FCP and will never buy another cap or rotor again.

 

[500AMM]

This place has 3.5mm allen keys for sale for 87 cents each: Metric Hex Key Wrenches made in Germany from .7 to 36mm sizes

As well, is it possible that the Bosch bolt is a 3mm extended tip bolt that requires an extended tip tool? It is hard to tell from the pictures. If it is, it would require something like this: Extended Pin Hex Key Wrenches for RIBE-IC Cap Screws- From Germany

People were stripping 6mm hex head seat bolts on 90s Porsche 911s for two decades until one guy realized recently that the hex head bolts require a 6mm extended tip tool: FOUND: Cure for FOSYSB (Fear of Stripping Your Seat Bolts) - Rennlist - Porsche Discussion Forums

View attachment 110233

Socket head bolt with guide point and low head is DIN 6912 and the tool for it is DIN 6911. The bolts on the valve covers were this type as well until they were superseded with regular DIN 912 and DIN 911 tool.

 

[500AMM]

Just doing caps and rotors this weekend. I used a 1/4" Milwaukee impact with a 3mm or 5mm hex bit to remove. The shock tends to break them loose, think mine have been on the car at least 10 years and 5k miles but the screws were stuck. I wish the rotors came with 4mm hex heads as the 3mm is bit too small. They also seem kind of soft. My old parts are Bosch but bought some Beru from FCP and will never buy another cap or rotor again.

The bolts on the rotor is DIN 7984, which is a low socket head with reduced key grip i.e. smaller key size. In this case it is a 3 mm key grip vs. 4 mm on a regular M5 DIN 912 bolt. So with a reduced key size and a lower bolt head giving a shallower grip, it's no surprise to get problems after sitting for a certain time. And the Chinese low cost market fucks up everything by overflowing the suppliers with mediocre quality products, which next is sold at a premium price level to us.
\end of rant\

I solved this for myself several years ago, described in post #14 in this thread. It's really a cheap & easy fix and recommended for those living in similar climate conditions as I do.

 

[TX Benz Driver]

One trick I've learned is that if you have to drill out a bolt that has stripped is to use reverse (left hand) drill bits when drilling. More often than not about 1/2 way done drilling the vibration breaks the bolt free and it simply backs out.

Something like this: https://www.amazon.com/Tools-Hanson...ords=reverse+drill+bits&qid=1597748857&sr=8-7

 

[robm.UK]

... Just for testing I made additional vent holes on one of the caps on the Limited, the principle is shown on the enclosed image. It works great and shows no sign of entrapped moist due to improved ventilation. I used a cutting disc on the Dreml to make the slots. Something to think about for those living in climates with low and varying dew point during the year.

I was recently directed to your thread by Gerry.

Round about the same time I was testing the same mod and was posting in the R129 forum over in Benzworld but feedback and uptake was slow to zero.

Either ppl had been going about the modification and not reporting back, or more likely, faced with the thought of modifying a $90 part, they held back.

So, to provide ppl (including myself) with more assurance that the effort would not be wasted, I did some research / DIY testing and wrote up a report which can be download HERE, or from the link in this thread: -

Post in thread 'M119 Ignition issues when warm'
M119 Ignition issues when warm | M119 Engine

I submitted a previous version of the report (without testing) in Nov 2014 to Bosch R&D in Germany and didn’t hear back, but I wasn’t surprised about that.

2 months ago I received some positive feedback from BW member John Coin: -

“Well robm.UK I cut the distributors just like you did and, IT WORKED . Its rained a few times and no problems.
Thank you very much for the info I was about to sell this car because of this problem . Thanks to you i will keep it.
Thanks
John”

Gerry said you had some positive results. Did you get any feedback from other members?

 

[500AMM]

WOW - a 81 page research report on the topic, that's impressing!
I haven't read the report and the discussion in the other thread yet, but I'll do as soon I've get time, I have to absorb all details in it.

As for my simple test, I never came to the point recording any figures because the car went into storage for years and it is now sold. But I did notice that the moisture problems never occured after the mods, even during autumn with rainy & cold nights which is a killer low dew point period here in northern Europe.
Many thanks for sharing that report, really interesting stuff!

I didn't get much feedback here about this mods. I think just one member did the mods and got the same positive experience as I did.