Rod bolt won't torque to spec

[ha9981]

Originally Posted by GearKid

Here's my latest thought that may explain this stripped rod. Let's say a former owner swapped out the bearings at 45k or something like that. New OEM bearings and bolts go in. This rod and maybe the others were significantly over tightened. Maybe instead of 130 degrees they were tightened to 130Nm or ft-lbs. this was not enough to strip the threads initially but after running the motor for 30k miles the threads start to break loose. The rod holds together because the upper threads keep the bolt from pulling out. Everything stays tight until the current shop pulls it all apart and starts to tighten down that rod again. The tech gets only half way to spec when those threads completely fail.
If this is true then we may see similar issues as motors are opened up a second time.

We know eccentricity is impacted by torque. If it really was torqued that high I would assume the bearings would show. It is why the correct torque is so important.

Did they inspect the cylinder for this rod?

[GearKid]

Originally Posted by ha9981

We know eccentricity is impacted by torque. If it really was torqued that high I would assume the bearings would show. It is why the correct torque is so important.

Did they inspect the cylinder for this rod?

Right on. Funny thing is that the rod#8 bearings look normal for this motor. It's rod#7 that had the most wear. The #8 bearings (at first appearance) suggest the rod cap was bolted down correctly.

[Davisca455]

Originally Posted by Helmsman

I would also desperately be looking for a reasonable explanation when being in a tight spot between what seems to be a proper shop and the result. But this can't be that logical answer in my mind. If the bolt was that bad over tightened, it wouldn't make sense that 1) The tech didn't notice, and if he did, just put the engine back together. 2) The thread started to break loose and still kept up fine just to fall apart at second run.
There is a reason to why the rod bolts are extremely strong, holding back the highest load in the engine. If thread where broken I believe the cap would have started to move resulting in significant signs.

I know the situation when debating with people who have plenty more experience and knows better than yourself, while obviously still are quite able to make mistakes. Getting them to admit is...challenging. Have a similar story with a boat yard reg my boat, plain aweful but we can't take the blame for others shit bro.

"You should not win the argument, because you are a superior arguer.
You should win the argument, because your argument is superior."

[Helmsman]

Originally Posted by Davisca455

"You should not win the argument, because you are a superior arguer.
You should win the argument, because your argument is superior."

If the world only could be that simple...

[pbonsalb]

Originally Posted by Davisca455

"You should not win the argument, because you are a superior arguer.
You should win the argument, because your argument is superior."

A lot of lawyers would disagree.

[Scharbag]

Any updates?

[GearKid]

Originally Posted by Scharbag

Any updates?

Waiting on motor at the moment. It'll be awhile before any work is done.

[Helmsman]

Originally Posted by GearKid

Waiting on motor at the moment. It'll be awhile before any work is done.

Crossing fingers blue that it goes fine mate.

[DrFerry]

Any updates?

[kyrix1st]

Sounds like a shop stripped the rod by accident, altered its course of thinking and wanted to charge OP extra $$$ to rebuild the engine!

[///M3Fresh]

Originally Posted by kyrix1st

Sounds like a shop stripped the rod by accident, altered its course of thinking and wanted to charge OP extra $$$ to rebuild the engine!

I agree.

OP regardless of what the shop tells you, its simple, the car was under their care. If it was truly stripped they would have stopped. Not cleaned or went any further, started documenting and taking pics as any legit shop would. But somewhere between taking it off initially, reinstalling to check clearances with a plastigauge and calling you there is too many things missing that someone that isnt at fault would have ready to show.

This isnt a service in for a light bulb scenario and you need to take off air filter to get access and notice the air filter is dirty so while youre there did you want to take care of this? Then yes youd be liable for the cost of the filter. The work you directly paid for to get done to the car was not done correctly and that isnt your fault.

Let us know how it plays out.

Edit: As a shop you are offering a service, if you cant or dont have the know how of doing the work you simply dont do it. In this case the shop took on the work and should be the ones to make you whole. But instead they're beating around the bush.

[Green-Eggs]

Originally Posted by ///M3Fresh

I agree.

OP regardless of what the shop tells you, its simple, the car was under their care. If it was truly stripped they would have stopped. Not cleaned or went any further, started documenting and taking pics as any legit shop would. But somewhere between taking it off initially, reinstalling to check clearances with a plastigauge and calling you there is too many things missing that someone that isnt at fault would have ready to show.

Didn't the OP say this is exactly what the shop did -- stopped, called him, didn't go further? Look at the OP's comments about rod #8...lube still on the bolts because they stopped, called him, and didn't go any further.

Out of curiosity, what are the too many things missing that you mention? I'm not saying they weren't missing...but I don't think any of us know what you mean without an explanation.

Edit: As a shop you are offering a service, if you cant or dont have the know how of doing the work you simply dont do it. In this case the shop took on the work and should be the ones to make you whole. But instead they're beating around the bush.

Let's say the shop pulls off the bottom end, sees the crank damaged beyond repair, calls the OP to tell him. According to the above comment, the shop is now responsible for rebuilding the engine. That's simply not reasonable.

[///M3Fresh]

Originally Posted by Green-Eggs

Didn't the OP say this is exactly what the shop did -- stopped, called him, didn't go further? Look at the OP's comments about rod #8...lube still on the bolts because they stopped, called him, and didn't go any further.

Out of curiosity, what are the too many things missing that you mention? I'm not saying they weren't missing...but I don't think any of us know what you mean without an explanation.



Let's say the shop pulls off the bottom end, sees the crank damaged beyond repair, calls the OP to tell him. According to the above comment, the shop is now responsible for rebuilding the engine. That's simply not reasonable.

From the shop:
I did it in this order. (Example: One rod/cap at a time, to make sure I didn't accidently swap caps) I didnt see this posted.
I visually inspected each bolt/bearing/cap (I find it hard to believe that the stripped bolt had 0 metal/thread on it that it wasnt till the re-use of that bolt, to varify spacing on the new bearings, that they noticed it was stripped. They are usually covered in oil. Something would be on the OE bolts)


Some of the things going thru my head if I was going thru the steps to swap bearings that I thought was missing from the shop. OP mentioned by the time they told him the bolt has no metal. Even after the 2nd time going back in??

As to your other comment, yes, they are. This is something so precise that a pre-existing issue of a stripped rod bolt was the cause?? Come on. I would lawyer as soon as I heard that. If the shop worked on your car and then took it for a test drive to validate the issue is resolved and spins out into a curb because your tires are bald, would you pay or split the bill on the damages with the shop?

[Green-Eggs]

Originally Posted by ///M3Fresh

From the shop:
I did it in this order. (Example: One rod/cap at a time, to make sure I didn't accidently swap caps) I didnt see this posted.
I visually inspected each bolt/bearing/cap (I find it hard to believe that the stripped bolt had 0 metal/thread on it that it wasnt till the re-use of that bolt, to varify spacing on the new bearings, that they noticed it was stripped. They are usually covered in oil. Something would be on the OE bolts)


Some of the things going thru my head if I was going thru the steps to swap bearings that I thought was missing from the shop. OP mentioned by the time they told him the bolt has no metal. Even after the 2nd time going back in??

As to your other comment, yes, they are. This is something so precise that a pre-existing issue of a stripped rod bolt was the cause?? Come on. I would lawyer as soon as I heard that. If the shop worked on your car and then took it for a test drive to validate the issue is resolved and spins out into a curb because your tires are bald, would you pay or split the bill on the damages with the shop?

The shop's theory is that the previous owner started to change the bearings, caused the problem, knew about the problem, then put the car back together and sold it before it went kaboom. There is a a piece of evidence that might help prove that -- or at least would hint in that direction: the motor mounts. If the motor mounts had been changed but the rod bearings were still original, that would be a very strong sign that the previous owner also had fiddled with the rod bearings at the same time. Those two jobs go hand-in-hand more often than not. Maybe the OP can comment whether or not the shop noticed the motor mounts were changed by the previous owner. I have a very strong feeling that they were.

[Scharbag]

I still wanna know how the shit you strip a rod... that has to be tough to do!!!

[///M3Fresh]

Originally Posted by Green-Eggs

The shop's theory is that the previous owner started to change the bearings, caused the problem, knew about the problem, then put the car back together and sold it before it went kaboom. There is a a piece of evidence that might help prove that -- or at least would hint in that direction: the motor mounts. If the motor mounts had been changed but the rod bearings were still original, that would be a very strong sign that the previous owner also had fiddled with the rod bearings at the same time. Those two jobs go hand-in-hand more often than not. Maybe the OP can comment whether or not the shop noticed the motor mounts were changed by the previous owner. I have a very strong feeling that they were.

Possibly. If intent was to replace the engine mounts I certainly wouldn't be thinking about bearings too. Maybe the other way around it would make more sense. I don't recall if OP stated if the shop noticed any signs of the oil pan and everything internally showed signs of tampering or being touched.

[pbonsalb]

Either the mechanic at the current shop screwed up or a prior mechanic or owner who was replacing bearings screwed up, tried to hide the screw up by not actually replacing any bearings and putting the rod back together (and swapping back any new bearings replaced before the faulty work), and the owner sold the car to an unsuspecting buyer.

The OP has not provided any history on the car, but even if he did, the prior mechanic/owner theory would be hard to prove.

[///M3Fresh]

^ for sure anything is possible. I just don't buy the latter. If someone messed up and stripped a con rod to the point where it won't torque down to spec, knowing what we know about S65 bearings, that car wouldn't have made it 500 or so miles like the OP said it had between purchase and current shop touching it.

[Davisca455]

Read the very first post carefully.
He said the shop claimed they couldn't achieve the torque, but that didn't even matter because the adjacent rod journal was out of round by 1.4mm, so he needed a new engine anyway.
Ya right.
Very, very smelly...

[tbuck]

Just read this post, and agree something very smelly.
I build engines for a living as a QA tech (diesels, but same principles apply) and have seen hundreds if not thousands of stripped bolts. Absolutely ZERO chance that there would be no debris to be seen after pulling threads out of a rod, nor would a rod with only half the original threads be able to take the loads to drive 500 miles or even 5 miles. Not possible. I have seen enough ventilated blocks from rod issues. Rod bolts are the third strongest in the engine, but stretch style (OE BMW bolts) do tend to snap rather than pull threads. Also it is rather easy to "over torque" stretch bolts as once they begin to stretch the force required to turn them does not increase much at all. It is the elastic properties of those bolts that hold things together. But still, they generally snap prior to removing threads.
My bet here the shop somehow damaged the threads, cleaned it all up and then made the call. There had to have been some debris as a result of the failed "20nm" attempt somewhere. If you could not get beyond that small level of torque then the bolt kept turning and as a result would have removed even more material from the threads. Yet none was to be seen when the OP came to the shop. That is pure BS right there.
My heart goes out to OP in this case, but the shop should bear some level of responsibility for the damage. They have insurance to cover such things after all. I would have been on the phone with a lawyer right after visiting the shop. The retainer would be far cheaper than replacing the engine.

[ha9981]

Just going to say that you have to be advocating for the devil to defend the shop here.

It's wreaks of foul play. No way in hell is it prior damage. The story makes no sense.

Let's say the shop is innocent, forsake of argument, they should cover this on goodwill given how it seems suspicious as hell.

If they intend to stay in business...