B58 engine oil leak (rear main seal)

[hoohoohama]

The check engine light I was told was due to the computer glitch as it has to convert from liters to gallons. The system flash will fix this when it comes at the end of August. The dealer cleaned the oil around the starter and told me to drive it another week so they can pinpoint where it's coming from. It looks to be a rear main seal weep. We'll see. The problem is no parts availability.

Thank you for the updates, IMO, I doubt if it is actually the rear main seal, as in my case, I was told the same thing and waited for weeks for replacement parts, and then was told it wasn’t the rear main seal and it was from some sort of lubricant being melted after engine got hot.

So the theory is that you will only see this oil drop if the engine is hot, hence if you clean the oil drop near the starter after the engine has cooled down and leave your vehicle overnight, you shouldn’t see it next morning. but it may show up again after you drive the vehicle for a while.

 

[ErnieB]

Thank you for the updates, IMO, I doubt if it is actually the rear main seal, as in my case, I was told the same thing and waited for weeks for replacement parts, and then was told it wasn’t the rear main seal and it was from some sort of lubricant being melted after engine got hot.

So the theory is that you will only see this oil drop if the engine is hot, hence if you clean the oil drop near the starter after the engine has cooled down and leave your vehicle overnight, you shouldn’t see it next morning. but it may show up again after you drive the vehicle for a while.

Thanks for the insight. The dealer cleaned it and told me to drive it for a week. In all honestly, I've been so busy I haven't had the time to crawl under to see if the leak is still there. Dealer called this morning to check on it. I'll look at it some time today.

 

[HereinDaRockies]

TIL smell the liquid that leaks from the grenadier

 

[Salty Overland]

Thanks for the insight. The dealer cleaned it and told me to drive it for a week. In all honestly, I've been so busy I haven't had the time to crawl under to see if the leak is still there. Dealer called this morning to check on it. I'll look at it some time today.

Having the same issue I think. Seeing some small oil leaks on what I think is the base of the transfer case. Also seeing the black cap on the front left under the hood having some small overflow. I’ve read that is intentional, but I am concerned about the apparent oil leaks. 1000 miles on the Trialmaster. The AC condensation drain forward of all of this is also dripping a lot making it hard to understand if that is contributing to what I think is an oil leak near the transfer case. Transfer case temp is fine. Closest dealer is 5 hours away. Any suggestions?

 

[Salty Overland]

Having the same issue I think. Seeing some small oil leaks on what I think is the base of the transfer case. Also seeing the black cap on the front left under the hood having some small overflow. I’ve read that is intentional, but I am concerned about the apparent oil leaks. 1000 miles on the Trialmaster. The AC condensation drain forward of all of this is also dripping a lot making it hard to understand if that is contributing to what I think is an oil leak near the transfer case. Transfer case temp is fine. Closest dealer is 5 hours away. Any suggestions?

Talked to the dealer service and the black cap under the hood is power steering and that’s designed to self vent. The apparent oil leak near the transfer case may actually be the AC condensation drain which he said is known issue for being excessive in the water drain which may be condensation floating back to the transfer case and collecting oil which is appearing to drip. He advised me to wipe it all down and keep an eye on it. If anyone else has experience with this issue let me know.

 

[255/85]

Talked to the dealer service and the black cap under the hood is power steering and that’s designed to self vent. The apparent oil leak near the transfer case may actually be the AC condensation drain which he said is known issue for being excessive in the water drain which may be condensation floating back to the transfer case and collecting oil which is appearing to drip. He advised me to wipe it all down and keep an eye on it. If anyone else has experience with this issue let me know.

Unless you have large puddles on the garage floor I'd follow the service manager's directive. You need to monitor things frequently to discern where the leak is emanating from. Can you tell the difference between different fluids?

 

[las3r]

Not a Grenadier owner but just rebuilt the B58 in my BMW 340i and having the same issue.

This just happened to me so I do not have a resolution yet but I believe the previous posts have pointed me in the right direction.

During the rebuild process, I used assembly lubricant to grease the transmission where it mates to the engine (image attached) this lubricant is designed to melt on startup to blend into the engine oil when used internally.

During the first startup of the engine, no leaks were observed from the starter motor until the engine was ran for 15 min. Upon seeing the leak, the oil was removed with a rag and brake cleaner, and the car sat overnight with no leaks present in the morning.

Second startup, no leaks present until 15 min into running and then the leak appears in the same location. Working with the information the previous posts have provided and the reasoning of the dealership, this must be an issue that occurs when the assembly lubricant reaches the temperature it was designed to melt and combine with the engine oil at.

Due to the location of the leak, it does present as a rear main seal issue, so to do my due diligence I will be removing the starter to confirm our working theory.

Thank you all for your contributions and I will post again with an update after I have had time to remove the starter and get a scope camera up near the rear main seal.

IMAGES: leak location, assembly lube front and back, transmission location where lube is applied during engine assembly.

**UPDATE:

In my case, it seems the rear main seal is the issue. I folded the lip in during installation due to inexperience.

Trying to diagnose this issue without knowledge of how the lip seal was installed would be pretty difficult. Even with the starter removed and a scope camera the transmission butts right up against where the rear main seal is and identifying if oil is leaking or assembly lube is next to impossible without in mixing UV oil dye into the engine oil.

Luckily in my case, I am using engine break-in oil which has a high zinc content. I could see the zinc present in the oil around the main seal meaning that it was the engine oil leaking and not the assembly lube.

I also tried heating up the assembly lube with a heat gun to try and replicate the melting process with no success. It could be I couldn’t get it hot enough or the dealership uses a different lube so that could very well still be the issue for some people.

Looks like I am pulling the transmission and redoing the rear main seal!

IMAGES: Starter, assembly fluid melting attempt, rear main seal general area.

 

[Salty Overland]

Update: took my rig to INEOS Sewell (Dallas, TX). Travis, the service manager, was super helpful. After further investigation it was a leak on the coolant lines that connect to the transmission and not a transfer case seal issue. All of the oil that I saw at the base of the transfer case was just fluid that traveled back while driving and was pooling in the frame and then dripping off the transfer case and through the holes in the frame.

Here are some pictures to help. Hopefully this helps others.
1st pic: oil dripping from the rear transfer case but not the source of the leak
2nd pic: actual source of the leak. 2 lines that run to transmission. Replaced these lines and the thermostats.
3rd pic: oil was pooling in the frame and dripping out the holes and also collecting around the base of the transfer case.

 

[NQ94]

Update: took my rig to INEOS Sewell (Dallas, TX). Travis, the service manager, was super helpful. After further investigation it was a leak on the coolant lines that connect to the transmission and not a transfer case seal issue. All of the oil that I saw at the base of the transfer case was just fluid that traveled back while driving and was pooling in the frame and then dripping off the transfer case and through the holes in the frame.

Here are some pictures to help. Hopefully this helps others.
1st pic: oil dripping from the rear transfer case but not the source of the leak
2nd pic: actual source of the leak. 2 lines that run to transmission. Replaced these lines and the thermostats.
3rd pic: oil was pooling in the frame and dripping out the holes and also collecting around the base of the transfer case.

Having that other cable loosely cable tied to the transmission cooler line wouldn't help. Those plastic hose connectors really don't like supporting extra weight that can move or vibrate.

 

[Dus10R]

I just changed the oil on mine at 5500 miles in preparation for a road trip. Has never leaked anything up to this point. I drove it from Reno to Vegas and then back over the holiday weekend around 900 miles round trip. Today I noticed a single drop of what appears to be new oil. I crawl underneath and see this. Fluid all around that black rubber cap and on the edge where the motor meets the transmission. Not a lot. Just a small area around that black plug. I wiped it off and then drove to the gym. Checked it again when I got home and the fluid is back. Still not bad but back. Has anyone come up with a definitive? Saw the post on the coolant lines Ill have to check those. seems awfully early in age to have a RMS leak.

 

[C-Mack]

I just changed the oil on mine at 5500 miles in preparation for a road trip. Has never leaked anything up to this point. I drove it from Reno to Vegas and then back over the holiday weekend around 900 miles round trip. Today I noticed a single drop of what appears to be new oil. I crawl underneath and see this. Fluid all around that black rubber cap and on the edge where the motor meets the transmission. Not a lot. Just a small area around that black plug. I wiped it off and then drove to the gym. Checked it again when I got home and the fluid is back. Still not bad but back. Has anyone come up with a definitive? Saw the post on the coolant lines Ill have to check those. seems awfully early in age to have a RMS leak.

I doubt it is the rear main seal that is the culprit… on the B58 engines I believe the timing chains are on the back of the engine or transmission facing side. Could be a seal on one of the chain housing cover plates that could be weeping perhaps but I’d be more inclined to look for oil spilled or dripped down from your oil change especially if oil turned up soon after. Fingers crossed for you it isn’t more serious than that as getting to the backside of the engine for repairs would be a transmission out job.

 

[Dus10R]

I doubt it is the rear main seal that is the culprit… on the B58 engines I believe the timing chains are on the back of the engine or transmission facing side. Could be a seal on one of the chain housing cover plates that could be weeping perhaps but I’d be more inclined to look for oil spilled or dripped down from your oil change especially if oil turned up soon after. Fingers crossed for you it isn’t more serious than that as getting to the backside of the engine for repairs would be a transmission out job.

Will keep an eye on it for a few days and see if it persists.

 

[hoohoohama]

Will keep an eye on it for a few days and see if it persists.

I still have the same issue today, but don’t think it is the lubricant anymore. a small drop of oil showing up near starter after driving. No leaks if engine is turned off.

I also run engine oil checks every 1000 miles, had to add about 200ml recently to pass the off-road engine oil checks. (On road check was fine) But it is hard to tell if the oil loss is caused by this leak or just oil being burnt by the engine. I guess only time will tell.

I do plan to bring it to a dealership again, hopefully this time to a dealership that has more experience with BMW engines.

 

[ForceV4]

Transmission removed for a rear main seal repair.

 

[hoohoohama]

Transmission removed for a rear main seal repair.

How long did you have to wait for parts?

 

[ForceV4]

How long did you have to wait for parts?

It wasn’t my truck - I saw it at the dealership.

 

[Dus10R]

Update: Im thinking mine might have been the melting grease issue some have mentioned. I wiped it all down and cleaned it all up and it hasn’t leaked since. Yay me. Ill continue to monitor it for awhile just to be safe.

 

[Lemon35]

Posting here since transfer case leaks were mentioned and evaluated against rear main seal failures.

On August 22nd, my dealer repaired a small leak at the Transfer Case Input Shaft. I was told this was a known issue by INEOS Automotive to the point they were preparing kits. Mine is a 6xxx VIN produced in AUG2023. All items serviced under warranty.

Parts list:
1 GRA-5C12-034180 S910 Transfer Box Seal Kit
1 GRA-5C12-034540 S910 Output Shaft Seal
8 GRA-5D00-019750 S910 Propshaft Fixing Kit

"Transfer case input seal failed. Removed/replaced transfer case seal, output shaft seal, replaced 1 time use bolts via prop shaft fixing kit. Tested, No leaks at this time."

I'd like to see IA share more data on known issues, VIN ranges, and kits such as these. I only found out about this because my door seals were being swapped.

 

[255/85]

Posting here since transfer case leaks were mentioned and evaluated against rear main seal failures.

On August 22nd, my dealer repaired a small leak at the Transfer Case Input Shaft. I was told this was a known issue by INEOS Automotive to the point they were preparing kits. Mine is a 6xxx VIN produced in AUG2023. All items serviced under warranty.

Parts list:
1 GRA-5C12-034180 S910 Transfer Box Seal Kit
1 GRA-5C12-034540 S910 Output Shaft Seal
8 GRA-5D00-019750 S910 Propshaft Fixing Kit

"Transfer case input seal failed. Removed/replaced transfer case seal, output shaft seal, replaced 1 time use bolts via prop shaft fixing kit. Tested, No leaks at this time."

I'd like to see IA share more data on known issues, VIN ranges, and kits such as these. I only found out about this because my door seals were being swapped.

Paging @Rok_Dr

 

[Rok_Dr]

Paging @Rok_Dr

Thanks. Will add to the part number list in the next edition.