'08 M3/4 spun bearing - crank damage pics - need input

[RoofusM3]

Long story short, spun a bearing and tech sent over pictures of the resulting grooves cut into the crank. Said one channel was enough to sink his fingernail into. He thinks they can polish it down to some degree and get it back together, but said that may also leave me at risk for future failure if the measurements are then slightly off when installing new bearings.

Pics below. Thoughts? Options? Jump off my balcony?

[tbuck]

For me it would be new/used crank time, or getting another engine all together. Replacing the crank might seem cheaper at the outset, but later may begin to be less of a value. In either case engine has to come out, and if you are paying a shop for all that labor, well, quickly adds up to big money. Engines come up on here now and then, and then there is always totaled cars that you could get the engine out of and sell off the rest to mitigate some of the cost. Either way, I definitely feel your pain. Not a pretty picture.

I would not try and fix that as it is, that is some serious damage, and the only way to make that clean enough where I would trust it in an 8400 rpm engine is to take it out and have it properly machined. Still, big money, and another engine would be better all around.

[GORDON.M3]

Germany lottery, sorry to hear... I wouldn't trust a repair/polishing or machining job. I would potentially look for a donor crank if the block is still good and the mains are not shot. But when you start adding up labor it's probably cheaper to just find a donor motor and swap it in completely. Make sure you do the rod bearings before swapping the new motor in. Sucks to be in this situation...

[atopa2002]

https://www.m3post.com/forums/showthread.php?t=1565421

[Davisca455]

Originally Posted by atopa2002

https://www.m3post.com/forums/showthread.php?t=1565421

^
I thought of this thread as well.

But even if the mechanic can get the journal cleaned up, I'd still be concerned about metal debris that may have migrated into other areas of the engine.

I'm so sorry this happened.
If this happened to me, I'd be on Suicide Watch.

[omgzirra_exe]

is there any more info on this engine as to why you had this failure?? i would start to source a new block.. the cylinder walls on the S65 are stupid sensitive. i would check those before going any further.

[roastbeef]

I'm no expert but there's no such thing as polishing the crank.

[omgzirra_exe]

Originally Posted by roastbeef

I'm no expert but there's no such thing as polishing the crank.

it's definitely a thing

[Green-Eggs]

Depending on the damage, the crank can be fixed, and fixed very reliably. Many very high-end race shops use hard chrome plating; in fact some race shops will send brand new crankshafts out for hard chrome plating. The new surface should be harder than factory. But they can only fix so much. This is the shop that we use, and is used by many other shops in our area and other parts of the country.

https://www.ecgrinding.com/

[Johal E32]

Originally Posted by roastbeef

I'm no expert but there's no such thing as polishing the crank.

Any competent engine/machine shop can polish a crank

[roastbeef]

Ok, I stand corrected.

[RoofusM3]

Originally Posted by Green-Eggs

Depending on the damage, the crank can be fixed, and fixed very reliably. Many very high-end race shops use hard chrome plating; in fact some race shops will send brand new crankshafts out for hard chrome plating. The new surface should be harder than factory. But they can only fix so much. This is the shop that we use, and is used by many other shops in our area and other parts of the country.

https://www.ecgrinding.com/

Thanks, Green-Eggs. From the research I’ve done the cost of a new crank is negligible to repairing the existing crank. And I would risk changing the measurements.

At this point I’m having the shop get me a quote on a rebuild with ACL bearings as well as a sourced motor installed with ACL bearings. I’ll price that against selling the car as is with a warning or parting it out.

The car was purchased for $18,500 ($22k out the door) so there is a point where this is no longer valuable and it might be a better idea to sell it to someone who wants to part it and just get something else. We’ll see what they come back with. The shop I’m at has done many of these and is a respected race shop in the area so I expect to receive pretty good guidance.

[Green-Eggs]

Originally Posted by RoofusM3

Thanks, Green-Eggs. From the research I’ve done the cost of a new crank is negligible to repairing the existing crank. And I would risk changing the measurements.

At this point I’m having the shop get me a quote on a rebuild with ACL bearings as well as a sourced motor installed with ACL bearings. I’ll price that against selling the car as is with a warning or parting it out.

The car was purchased for $18,500 ($22k out the door) so there is a point where this is no longer valuable and it might be a better idea to sell it to someone who wants to part it and just get something else. We’ll see what they come back with. The shop I’m at has done many of these and is a respected race shop in the area so I expect to receive pretty good guidance.

There is no risk for changing the measurements of the crankshaft during repair if you know give them the proper measurements (found on the BE Bearings wiki page). There's more risk to installing unmeasured and unfitted bearings than fixing the crank to the proper dimensions. This is why we only use BE Bearings which are each hand-measured and created as perfectly matched sets. They have much stronger backing material than any others also and withstand more load without deformation.

In our experience, the price of sourcing a used crankshaft here in the USA is about 5x the price of fixing the old one, and the price of sourcing a new crankshaft would be about 8x the price of fixing the old one. But crankshafts are heavy, and the cost of round-trip shipping could easily be the same price of fixing the crankshaft -- which is usually about $250 per journal.

[RoofusM3]

Originally Posted by Green-Eggs

There is no risk for changing the measurements of the crankshaft during repair if you know give them the proper measurements (found on the BE Bearings wiki page). There's more risk to installing unmeasured and unfitted bearings than fixing the crank to the proper dimensions. This is why we only use BE Bearings which are each hand-measured and created as perfectly matched sets. They have much stronger backing material than any others also and withstand more load without deformation.

In our experience, the price of sourcing a used crankshaft here in the USA is about 5x the price of fixing the old one, and the price of sourcing a new crankshaft would be about 8x the price of fixing the old one. But crankshafts are heavy, and the cost of round-trip shipping could easily be the same price of fixing the crankshaft -- which is usually about $250 per journal.

I was quoted $275 for a new crank. Can you share your recommendation for a shop experienced at crank repairs? And can you comment on the potential issue of losing the crank coating by grinding it down or if it can be recoated?

[Green-Eggs]

Originally Posted by RoofusM3

I was quoted $275 for a new crank. Can you share your recommendation for a shop experienced at crank repairs? And can you comment on the potential issue of losing the crank coating by grinding it down or if it can be recoated?

The price of a new crankshaft is approximately $3,800 USD. Here's a discounted price for $3,300.
https://www.ecstuning.com/b-genuine-...s/11217841460/

The prices for used crankshafts vary quite a bit. I've seen them as low as $1,200, and as high as $2,500.

There isn't a "crank coating" as you think. There is a surface on the bearing journal that has been heat treated and nitrided. Hard chrome plating is stronger. I gave you a link above for the company we use. Here it is again for your convenience.
https://www.ecgrinding.com/

Where did you find a new crankshaft for $275?

[RoofusM3]

Originally Posted by Green-Eggs

The price of a new crankshaft is approximately $3,800 USD. Here's a discounted price for $3,300.
https://www.ecstuning.com/b-genuine-...s/11217841460/

The prices for used crankshafts vary quite a bit. I've seen them as low as $1,200, and as high as $2,500.

There isn't a "crank coating" as you think. There is a surface on the bearing journal that has been heat treated and nitrided. Hard chrome plating is stronger. I gave you a link above for the company we use. Here it is again for your convenience.
https://www.ecgrinding.com/

Where did you find a new crankshaft for $275?

Thank you so much! That's the price I recall him telling me on the phone. I'll verify once I'm sent a quote. But from your link it sounds like I didn't hear right or he thought I was asking him something else.

Okay, so if I understand you correctly if we resurface the damaged journal, we then would just need to check the wiki you linked for the correct sized bearings?

Also, would it be a good idea to have all the journals chrome plated for uniformity? And if so, would that cause any issues with bearing fitment?

[Scharbag]

Originally Posted by Mog-10

If your on the edge of just unloading it because of this just let him polish it. It may not sit well with others because of its crudeness but at least you can enjoy the car a little longer you're already going to have to pay the tax for what he has done. you're not going to let him just not put it back together before you offload it, so might as well let him do his thing. Enjoy to the fullest knowing what you know. In some cases you might be able to claim it on your insurance if you have full coverage as catastrophic failure. Your primary insurance company will probably not cover it but if your finance company has an umbrella coverage and that is where you can seek retribution do the fact that the car is inoperable and considered a total loss to do is value being diminished because an engine replacement is too costly.

Worst advice ever.

1) after spinning a bearing, the engine needs a tear down to get the swarf out of the block. That basically means engine out.

2) recommending that the owner let the car self destruct to require the financier to pay for the issue is just wrong. Give your head a shake.

[RoofusM3]

Originally Posted by Scharbag

Worst advice ever.

1) after spinning a bearing, the engine needs a tear down to get the swarf out of the block. That basically means engine out.

2) recommending that the owner let the car self destruct to require the financier to pay for the issue is just wrong. Give your head a shake.

Yeah, not super great advice. Grew up with a dad that owned a small business and know the pain of someone trying to pawn off their responsibilities on you.
Luckily, however, knowing of the issues with the E90, I paid for coverage on my loan for catastrophic failure. I'm meeting with my credit union today to go over details to see if that would be the better exit strategy. If so I'll duck out and just try to find a later model E90 or early F80. The only problem there is it took me four months to find a good condition black on black 4-door manual last time and in the current economy, the used car market for these cars is horrendous.

[Scharbag]

Originally Posted by RoofusM3

Yeah, not super great advice. Grew up with a dad that owned a small business and know the pain of someone trying to pawn off their responsibilities on you.
Luckily, however, knowing of the issues with the E90, I paid for coverage on my loan for catastrophic failure. I'm meeting with my credit union today to go over details to see if that would be the better exit strategy. If so I'll duck out and just try to find a later model E90 or early F80. The only problem there is it took me four months to find a good condition black on black 4-door manual last time and in the current economy, the used car market for these cars is horrendous.

If you paid for the coverage, you are entitled to use it!! Absolutely a huge PITA for you as it is hard to find exactly what you want again.

Good luck!

[PETE914]

Thanks for the photos. How did it go with the Credit Union?

I'm a new black e90 DCT owner. 108k on the clock. Original bearings

We would all be interested to hear about when the failure happened. Miles on engine and service history would be great for better understanding.

Either way if you can get insurance on the engine that's pretty awesome.

[Redd]

After looking at this failure I'm thinking to do my mains during my next rod bearing change. Can the mains be accessed from below like the RBs or is it an engine out job?

[redline9001]

Originally Posted by Redd

After looking at this failure I'm thinking to do my mains during my next rod bearing change. Can the mains be accessed from below like the RBs or is it an engine out job?

Engine out