Now the fun begins - replacing crank shaft on OM603
 

The crank shaft arrives today from Germany for my OM603 engine. Need some hand holding on the how to replace the crank in the most efficient manner. Basically, the crank shaft broke near cylinder 1 and it is the only problem. I drove for 20 miles to get home and the car was parked ever since. The engine was noisy and leaking oil from the front seal ( the broken shaft moved in and out a bit ), apart from that it drove fine. So the engine is sound. Question, what are the rough steps to replace the crank? Please list the steps and any pitfalls, if any. I have never done this kind of engine work. Thanks.

Step 1) - Remove engine from car.

Step 2) - Take engine and new shaft to competent engine repair shop.

Step 3) - When new shaft has been installed, replace engine in car.

:)

Well, that is can't go wrong advice.

Do you know why the crank broke? I've never heard of a mb crank breaking before.

To do it correctly you will have to remove the cam chain as a minimum. At that point it makes sense to replace all the cam chain guides. Removing the crank without removing the head will be very tricky to say the least but it might be possible. I'd think going through the engine and replacing whatever is deficient would be a good idea.

Did you try to find a known good used engine?

Shall I take the car to the shop as well. Why bother to remove engine myself?

Truly, the better solution.

Prior to this the oil chain snapped and engine seized. The #1 piston journal of the crank was oval'ed by the rod bearings. I rehab'ed the engine but I did not machine the journal. I drove the car for another 15K and then the crank snapped near the oval'ed journal. I am pretty sure that was the reason and there is nothing wrong with the rest of the engine. I could replace the engine but I give myself a more challenging task :). Basically I do not know what I am getting into but I will give it a shot. The worst is to replace the engine later, nothing to lose but my time.

Seems like there is a good possibility of a lot more damage than just the crank.

Now the fun begins - replacing crank shaft on OM603
 

How did it stay running? Did it break in front of the timing gears. Or did a rod let go.


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I could have laughed at '( the broken shaft moved in and out a bit ), apart from that it drove fine. So the engine is sound.' but the impact of reading a tragedy never amused me.

It broke after the timing gears. It did run after the crank snapped. It broke near the 1st piston but all timing gear still turns. It was pointed out to me that the engine sounded very noisy and oil dripped out. I did not even notice it myself, I was doing 70 mph on the freeway to get home. The guy who noticed it told me try not to stop on the way home. The reason of the oil leak is the front seal is not sealing the 'vibrating' crank. I removed the oil pan and 1st rod bearing. I looked very very hard around the front of the crank before I saw the hairline crack . I was thinking about welding it back and mickey mouse the job until I saw a crank shaft for sale on eBay for cheap. So I decide to do a 'better' job. I may change the timing chain and a few plastic guides along the way but that is about it.

The car has been sitting for a few months and I schedule a year to put it back together. The car is rust free CA car so it is worth fixing. If the worst come to the worst then I can source an engine or just donating it. No sarcastic comments please. Anyone has any idea/good steps to offer for an engine novice? I just want some rough steps on replacing the crank with the engine removed. Some dos and don'ts and the minimum parts removal to access the crank and do the job. btw: I have the OM603 engine FSM.

I don't have any tips but whenever I tackle a big job I follow the factory service manual step by step. Or try to find a good online tutorial. Most people, if pulling the motor for a crank would probably just go through the whole engine.

Thankfully I just avoided this kind of repair.

Why not do "the best" job?

Fix it once.
Fix it right.
Drive More.
Worry less.

This isn't sarcasm... I honestly want to understand the logic.

Add me to this list. If the journal was ovalled due to oil pump failure and crank seizure, it seems like there would be more collateral damage to the engine than just ONE area. Since it ran that way for 15K afterwards and then ran at highway speeds on a return trip home with a broken crank :eek: I'd expect there to be other hidden goodies waiting to ruin your day once the new crank goes in.

I'd be personally drawing the line on this engine and sourcing a good 2nd hand one. If the engine were truly special, it'd be sent off to an engine rebuilder and gone through since it's being taken down that far, but 603's aren't really anything special all things considered.