[GDT]

I drive a 2010 BMW 335xi 147000 miles. regular maintenance. Car has slight modifications and runs of MHD flash tune stage 2. Has DP, Charge pipe, Precisions Racework coils.

I recently had my AC compressor blow up on a road trip. During the trip I had some of oil and coolant leak onto the belt not realizing until the AC Comp started literally rattling out of position. We didn't know if the fluid caused the AC comp to break because the rod inside the AC comp was completely shattered so we couldn't conclude what happened first the AC comp breaking of the fluids leaking on the belt. After having the AC compressor replaced as well as a bunch of other hoses and the belt of course and OFHG. The car shut off a quarter mile into a test drive. Prior to this it was running perfectly fine in the shop, I had even been there when they pulled it out to test drive it and I heard nothing out of the ordinary.

After the car shut off the owner (BMW Mater mech) and another worker drove to where the car was shut down and thought it might have been electrical. After they ran all there test and tried to get the car to turn back on they came to the conclusion it was another issue.

When the car made it back to the shop they wound up hand cranking the motor and realizing there was some resistance toward the top of the turn cycle. After putting a bore scope in the top of the motor and seeing now scoring of any marks at all, the conclusion was it could possibly be the bottom end of the motor like maybe a barring. From there I made the decision to get another car and leave that car at there shop until I could get someone to bring it home. (after later talking to the owner of the shop he said it could also possibly be a transmission issue)

I am trying to see if anyone has had an similar issue, or if anyone has an idea as to what it could be? The owner at the shop said he's never seen a bottom end on one of these motors go(without pushing over 500+ Horsepower). If anyone could help with this issue it would be much appreciated as I am in what some would call a pickle.

[Serf27]

Take the belt off and spin the engine by hand.

[GDT]

When turning the engine by hand there is resistance toward the top of the stroke. Thats why a possible barring or rod problem was a possibility.

[F31B48]

Seems to be a bit of an issue for n54 n55 engines. Change ofhg then engine shits itself. Pretty rare but does seem to happen https://www.e90post.com/forums/showthread.php?t=1554479
https://www.e90post.com/forums/showthread.php?t=1587427

[Biginboca]

When your belt broke did it wrap around the main crank pulley where the front crank seal could ingest some of it?

Unfortunately this is a very common issue on these engines is a serpentine belt breaks, gets wrapped around the front crank and bits of it enter the crank seal. Then these bits find their way down into the oil pan and get sucked into the oil pickup, thereby blocking the pick up and starving the engine for oil. Subsequently the rod bearings (lower end bearings) get starved for oil and fail.

Anytime a belt breaks there is a decent chance of this happening and it’s been repeated many times on this forum. Sometimes shady owners knowing this just sell the car after a belt break knowing the ticking time bomb that will be the new owners problem. The engine will run fine for a short while before it’s totaled.

The aftermarket has you well covered with many options to provide protection from this happening although it might be too late in your case…

https://vargasturbo.com/product/vtt-...nk-seal-guard/

https://www.maloindustries.com/produ...ection-plate-1

https://www.kiesmotorsports.com/prod...82-f83-e92-etc

https://store.vacmotorsports.com/vac...s55-p4964.aspx

https://www.ecstuning.com/b-ecs-part.../005771la01~b/

https://www.ebay.com/itm/254984169174

[GDT]

I thought about this to, but there is no signs around the front crank seal that anything protruded past/through it. I have heard that is something that was a possibility.