OM617A broken crankshaft

[John Green]

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[T-Modell]

Great, how did that happen? One of the things that didn’t break in my motor
Thomas

[CraigB]

It’s interesting the face of the break. Do you think it was a fault from the start? Not consistent in surface across break

[Pete49]

Just tig it up, 4" grinder to clean up and good to go.

[Bartman4800]

I am not a metallurgist but my money is on a small crack that started at hardening, and then propagated over the years until it finally snapped...
Must have been a noisy engine?

[John Green]

So, here is the story. This engine was in pieces and in the boot of a 300D I brought about 15 years ago. Back then W123's were not "cool" and I needed the money so I sold it to Tony from west OZ.

https://ozbenz.net/memberlist.php?mode=viewprofile&u=9

He then rebuilt it using parts we supplied to him and put it in his 300D sedan, it was then converted to run on used chip fat. I even went and caught up with him whilst in Perth on business in 2009.

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That's Tony on the left, me in the middle and 70499 (AKA Brad) on the left https://ozbenz.net/memberlist.php?mode= ... file&u=776

Tony then brought a 280CE and swapped the engine over to it, he drove it for some time and then put it up for sale in 2018

https://ozbenz.net/viewtopic.php?f=19&t ... 22#p179722

It was then brought by mathuisella

https://ozbenz.net/memberlist.php?mode= ... le&u=15261

Who shipped it to Brisbane and converted it from Auto to Manual

https://ozbenz.net/viewtopic.php?p=180999#p180999

If you have a read of his thread you will see that he never removed the crank and had it balanced with the manual flywheel. Early MB engines like the OM617 are externally balanced, relying on the external weight of the harmonic balancer and either flex plate or flywheel to counter the weight of the crankshaft. Jamie (mathuisella) had done an auto to manual conversion before and lucked out. He had the old redundant flex plate and flywheel counter balanced, a process that MB even have a process for. BUT, only for replacing a flywheel with a flywheel or a flex plate with a flex plate. An OM617 flywheel is around 15kgs and a flex plate is less than 5kgs. The correct procedure for an auto to manual conversion is to remove the crankshaft and have it balanced as an assembly with the new flywheel and harmonic balancer. For blue printed engines we even bolt on the fan belt pulleys and the clutch/pressure plates to ensure it is all balanced. The M110 engine that I built in the mid 90's was done this way and would rev to 8000rpm.

After the engine failed he put it on the market and I brought it back again!

https://ozbenz.net/viewtopic.php?p=194288#p194288

The damage to the crankshaft and cylinder block is caused by the crankshaft vibrating around and trying to escape as the entire rotating mass was out of balance. The damage is as follows:

- all main bearings have some form of damage
- some may be from swarf that broken off went thought the oil pump and filter (metal cuts though an oil filter when under pressure)
- the third main bearing had grabbed the crank journal at some stage and spun in the block, the block is damaged
- the forth main bearing held in place, but is very flogged out
- the lack of clearance in the third and fourth main bearings has resulted in a loss of oil pressure and there is some very minor damage to all other bearings as a result.
- all the conrod bearings have had some swarf go thought them
- the third conrod bearings is flogged out, worse so on the side of the crack.

Apart form this the remnants of running in on chip fat are still everywhere. I had heard how it seeps out of everything and gums things up, but never really appreciated how bad it can be. It took quite some time with our steam cleaner 2000psi at 120deg C before I started to pull it down to get rid of crap and even then there were still joints that were way harder than they should of been to get apart.

The only other issues I found on tear down were related to to what I would call "home mechanics", something I expected and don't have an issue with, I knew the last two owners were "guys in sheds".

I believe I can recover the block, but it will be complicated. You can close and then line bore the main bearings journals to make up the damage to the third journal, but that has the headache of making the piston crowns closer to the deck of the block which is a problem on a compression ignition engine. tsharky was kind enough to realise I was going to need a crank and is arranging for one to come out from the USofA with some other parts he is importing.

So stay tuned

[John Green]

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[John Green]

The aftermath....

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[brycedunn]

Interesting stuff. From reading this, I am assuming the turbo block must be different from the NA block, or you wouldn't go through all this trouble of re-using it. Would assume there are better NA blocks here in OZ, but not turbo ones. I take it this is worth it because any engine you import from the states probably has 200,000miles on it so would need to be gone over anyway?

Bryce

[John Green]

Interesting stuff. From reading this, I am assuming the turbo block must be different from the NA block, or you wouldn't go through all this trouble of re-using it. Would assume there are better NA blocks here in OZ, but not turbo ones. I take it this is worth it because any engine you import from the states probably has 200,000miles on it so would need to be gone over anyway?
Bryce

Yes, yes and yes. The turbo block is very differant.

[W123 300D]

Is the power difference from a non turbo to turbo engine much different?

Is it worth all the stuffing around to do the swap?

[John Green]

Is the power difference from a non turbo to turbo engine much different?
Is it worth all the stuffing around to do the swap?

Your engine is 59kw (80hp), the turbo version is 92kw (125hp). Which would you prefer?

[W123 300D]

Is the power difference from a non turbo to turbo engine much different?
Is it worth all the stuffing around to do the swap?

Your engine is 59kw (80hp), the turbo version is 92kw (125hp). Which would you prefer?

wellllllllllll I've heard people on the internet say the turbo engines are more prone to overheating and are more complicated to work on......I realise people on the internet say a lot though.
If they survived in California and Florida and places like that, they would survive here

Would bow to your knowledge on the subject though?

have toyed with the idea of importing at LHD 300 turbo diesel though

[tsharkey]

As someone who has driven both types of diesels and who owns a couple of OM617A, the turbo makes the diesel a very nice car to drive.

The stress heating / issues you mention is generally when someone fits a Turbo to the Normally Aspirated block / head. John's broken crank aside, the OM617A properly maintained is as reliable as it's NA counterpart properly maintained. Aside from considering a Turbo and the ALDA on the IP, the rest is pretty much as straight forward as it's NA sibling.

[300TDT]

What a story!!
Thanks for putting it all together.
I can't help wondering how the engine ended up in the boot of the 300D originally....

As someone who has driven both types of diesels and who owns a couple of OM617A, the turbo makes the diesel a very nice car to drive.

I agree with tsharkey.
Very different driving experience.
125hp + turbo can really throw you back in your seat - especially from idle in 2nd - kicks-down to 1st and then really powers through 2nd

[300TDT]

the ALDA on the IP

As you no doubt know, the ALDA is NLA.
Here's an interesting old post re getting rid of it altogether.
See posts by Zedd.

https://www.benzworld.org/threads/alda- ... s.1315380/

[Christo C]

These guys will sort you out
https://fb.watch/9YRKJ5RNif/

[Bartman4800]

These guys will sort you out
https://fb.watch/9YRKJ5RNif/

For the tools they have, these guys are expert craftsmen.

Still does not give me a warm fuzzy feeling...and I wonder who's 3-cylinder crankshafts they are manufacturing


Regards, Bart

[math]

:D

Mathuisella here > now just math :)

wow, that picture of the broken crankshaft damn :O

Yeah, it doesn't really make sense to me how it broke.

It wasn't an oil thing as that would lead me to believe a journal would be the point of break, but on the webbing between seems really strange. I think i'm with Bartman on it being a half dodgy one that made it through quality control back in the day and a tiny little fracture was overlooked :'( and it just grew bigger over the last 40 years ?

the vege oil, yeah i found it to be very sticky stuff and a pain to remove :'(
I like these engines due to their lack of computers and how forgiving they are of bad quality fuel, where in the future when mad max comes to pass, we'll all be using some kind of alternate fuel haha.

When that engine was in my hands, i ran about 80-90% diesel through it, a few times when i was broke as @!#$% there was a guy near me who made proper biodiesel, and i also got more biodiesel from a fellow member here in sydney that has since sold his w123 ( sad days )

Once i ran out of fuel due to a bad fuel sender/gauge and put in some ATF which got me to the servo haha. ( brand new in bottle, saving me a loong walk and buying a jerry can i would only use once, so it was worth it )

any ways, i look forward to seeing how you go with the engine now that it's in your hands :) I wanted to get a crankshaft, new bearings and do it myself, but i just don't have a workshop's tools or space :'( I bought a new set of bearings for it, which have since arrived but now sit on the shelf gathering dust. I wonder if they are the same as the NA motor's bearings so they'll be useful to me in the future 'shrugs' .


So yeah, strange/odd times, but i do hope it goes well.

the turbo om617A vs the om617 NA both with manual transmission, in t he same car i can honestly say, there is a big difference. the Turbo engine handles all the hills ect: without having to shift down a gear, or having to sit in left lane as you lose speed/momentum.


Having the turbo on the engine is like the difference between manual and auto transmission, in terms of power loss.

A friend of mine who has now gone to w124's, we compared his cars vs mine in different configurations ( I've had 5 w123's :O )

Auto + NA engine = slowest

Auto + turbo engine = Manual + NA engine = Middle of the range in acceleration, manual + NA was more fuel efficient by about 2.5 litres per 100km The auto box really sucks the power bonus of the turbo out of there.

Manual + Turbo Engine = fastest and uses less fuel than with auto transmission.

[300TDT]

I wonder why Mercedes never produced that combination? Maybe too much stress on the drivetrain?

Manual + Turbo Engine = fastest and uses less fuel than with auto transmission.

[T-Modell]

Afaik they didn’t habe a gearbox for that torque….
Thomas

[tsharkey]

Afaik they didn’t habe a gearbox for that torque….
Thomas

The M110 got the same gearbox, and it has a fraction more torque than the OM617A .....

[T-Modell]

More torque than the turbo-diesel? Surprised ...

Edit: The max. torque for the M110 I found is 240NM; the turbo had 230NM and after 1982 250NM ... so should have been possible.

[math]

The diesel om617 was put into the w123 for USA shipping to meet their emissions and fuel economy regulations for the w123 series. So as a whole series the w123 got better fuel economy.

The US people were not happy with the slow acceleration of the om617, so they quickly brought out the turbo version


California had emissions and more stringent mpg coming in during the early to mid 80's and the w123 300D turbo cars for 1985 year only for a lower ratio differential so better MPG as the engine isn't spinning as fast for the same speed. 2.88 new diff ratio for 1985, where as the turbo diesel for all other years got a 3.06 ( or 3.07) ratio. the naturally aspirated engines don't have quite as much grunt down low, so they got a 3.46 differential.

the american market is crap though as they drive on the incorrect side of the road. most people are naturally right handed, and thus are more suited to steering with their dominant right hand, just like a guitar the infinite varied movements that need to be precise are done with the dominant hand. The static position movements are done with the non dominant hand, just like the frets on a guitar, suitable for shifting gears.

also humans are right eye dominant, which is better in the elderly population as in countries that drive on the left, with RHD have less head on collisions between vehicles per capita in older age brackets as peoples' eye sight fades.

[Bartman4800]

the american market is crap though as they drive on the incorrect side of the road. most people are naturally right handed, and thus are more suited to steering with their dominant right hand, just like a guitar the infinite varied movements that need to be precise are done with the dominant hand. The static position movements are done with the non dominant hand, just like the frets on a guitar, suitable for shifting gears.

also humans are right eye dominant, which is better in the elderly population as in countries that drive on the left, with RHD have less head on collisions between vehicles per capita in older age brackets as peoples' eye sight fades.

I agree with the first bit about the diff ratios etc, because it is based on facts. It is on point with the rest of the thread.

The dross you wrote above on the other hand is coming straight out of your thumb and is not based on any research (and nothing to do with the thread anyway). The majority of the world has the steering wheel on the left side of the car, not just the US. The position of the steering wheel has no effect on which hand you use on the steering wheel (you have been taught to use both hands anyway). Most people are right hand dominant and would be able to shift better with their right hand, were it not that young people prefer the auto box.
The bit about the right hand dominance of the eye makes no sense to me.

Please stick to the facts instead of your bias.

Regards, Bart