[djtuner13]

Last week i was at the dealer for first time since owning my car to get a melted bag off of my exhaust. Got an oil change also because of the the weather to save some time instead of myself doing it this time. They said the timing chain sounds like it going (chainsaw noises (rubbing i assume he means)). They said well need need to do a full test to make sure. $140. So tomorrow I'm bringing it in to have them review, if so they said could be like 5k they said. But there was no real number to show yet. As I approach my 24k third party powertrain warranty(about 4k away from being out of warranty) I just hit 92k. i sure am glad i got this warranty for $2500 because it looks like its going to pay for it self. Ill keep you posted, figured this would be a good spot to share my story. I put on 20,000 miles in just over a year (amazing how it racks up so fast)

[qualicas]

Got the head off. Just a note about the timing chain. The TIS shows how to splice one together, To replace one in one piece, the front harmonic balancer bolt has to come out. The locking pin from the timing kit is not strong enough. I made a special alum block to hold the starter ring gear. Then I used a 4 ft snipe to loosen the bolt. Also had to make a special brace so I didn't flip the engine stand over. When that bolt is out the whole timing chain and oil pump gears all come out on the crank shaft extension. Surprisingly, they are not keyed in place. Just held by friction of the big bolt. Not the way I would do it!
I pulled the pistons they had a lot of carbon built up. I am soaking them in diesel to loosen everything. Also lots of carbon on the side of the piston to the top ring. Still have to pull the crank shaft girdle to look at the main bearings. Then pull the balance shaft/oil pump apart. I am surprised I have not found any metal from the intake cam sprocket. No damage other than the intake cam bearing caps.

[qualicas]

Engine is completely apart. Main bearings are perfect. I will reuse those. Rod bearings show a bit of wear on the sides where caps meet the rod. I will replace those. I soaked the pistons in Simple Green full strength over night. Then used a toothbrush to remove any remaining carbon. Rinsed them off in water, blew them dry and sprayed them liberally with WD40 so they do not rust. I flushed out the oil pump with varsol and then fresh oil. Could find no metal bits. Today I will check all oil passages, oil filter adapter, oil cooler and oil pan for any metal bits. I find it strange and a bit unsettling that all the sprocket teeth have just disappeared. After doing all this it is time to reassemble.

Just a note on piston cleaning. It can't be done while the pistons are in the block. Lots of carbon on the sides of the pistons above the top ring. Once you start cleaning the tops, stuff will run down the sides of the pistons. That would stay there and score the cylinder walls.
If pistons stay in do not try to clean the tops. Just leave it.

[rjd_F30]

Originally Posted by qualicas

Engine is completely apart. Main bearings are perfect. I will reuse those. Rod bearings show a bit of wear on the sides where caps meet the rod. I will replace those. I soaked the pistons in Simple Green full strength over night. Then used a toothbrush to remove any remaining carbon. Rinsed them off in water, blew them dry and sprayed them liberally with WD40 so they do not rust. I flushed out the oil pump with varsol and then fresh oil. Could find no metal bits. Today I will check all oil passages, oil filter adapter, oil cooler and oil pan for any metal bits. I find it strange and a bit unsettling that all the sprocket teeth have just disappeared. After doing all this it is time to reassemble.

Just a note on piston cleaning. It can't be done while the pistons are in the block. Lots of carbon on the sides of the pistons above the top ring. Once you start cleaning the tops, stuff will run down the sides of the pistons. That would stay there and score the cylinder walls.
If pistons stay in do not try to clean the tops. Just leave it.

Thanks for the update Looking forward to how it turns out when it's all back together.

[qualicas]

So a final recap on the engine failure. I pulled the intake cam out. Three of the bearings were badly scored. So much so that with only one of the scored caps still on I could not turn the cam with a wrench. So why did they score? (The first bearing actually has a groove 360 degrees in the cam so that is well oiled.) Oiling for the other 4 bearings consists of a single 1/8" hole to the flat alum bearing which is not really a bearing as much as just a part of the machined head. As well that hole is on the side with no load on it. The load is on the caps. That isn't unusual. The oil supply to the cam is via that 1/8" hole but on the way there is a T which allows the oil to run out to lube the valve lifter mechanism. So when there is low oil pressure most of the oil will run out the T line and very little will go to the cam.
So when you go for long oil changes and only drive in town, the oil sludges up. When the oil pick up is the size of a quarter it sludges up easily. Oil pump can't get good oil supply so oil pressure goes down. Low oil pressure means oil runs out the lines to the valve lift mechanism and not any pressurized oil to the cam bearings. Cam bearings run dry and score. Cam gets harder to turn and eventually seizes and chain rounds off the intake cam sprocket. Engine is now out of time and stops. The end of another engine!
I am on the hunt for a used head.

[rjd_F30]

Originally Posted by qualicas

So a final recap on the engine failure. I pulled the intake cam out. Three of the bearings were badly scored. So much so that with only one of the scored caps still on I could not turn the cam with a wrench. So why did they score? (The first bearing actually has a groove 360 degrees in the cam so that is well oiled.) Oiling for the other 4 bearings consists of a single 1/8" hole to the flat alum bearing which is not really a bearing as much as just a part of the machined head. As well that hole is on the side with no load on it. The load is on the caps. That isn't unusual. The oil supply to the cam is via that 1/8" hole but on the way there is a T which allows the oil to run out to lube the valve lifter mechanism. So when there is low oil pressure most of the oil will run out the T line and very little will go to the cam.
So when you go for long oil changes and only drive in town, the oil sludges up. When the oil pick up is the size of a quarter it sludges up easily. Oil pump can't get good oil supply so oil pressure goes down. Low oil pressure means oil runs out the lines to the valve lift mechanism and not any pressurized oil to the cam bearings. Cam bearings run dry and score. Cam gets harder to turn and eventually seizes and chain rounds off the intake cam sprocket. Engine is now out of time and stops. The end of another engine!
I am on the hunt for a used head.

Very informative and interesting (and mildly scary)! I'm glad you came on here to share your experience rebuilding this engine.

This goes to show again how important it is on these engines to get everything up to temp before revving it out at all, and doing oil changes every 5k consistently. Kind of surprising BMW built this engine with such low tolerances/clearances too, it's not like this is an S series engine...

[kobluna]

Originally Posted by rjdnyy224

Very informative and interesting (and mildly scary)! I'm glad you came on here to share your experience rebuilding this engine.

This goes to show again how important it is on these engines to get everything up to temp before revving it out at all, and doing oil changes every 5k consistently. Kind of surprising BMW built this engine with such low tolerances/clearances too, it's not like this is an S series engine...

This also makes me wonder if atleast some of the failing timing chains are caused by this. When scored cam is harder to turn the chain will eventually fail. A new chain would still be capable of turning the cam but for how long?

This theory requires that mild scoring in cam would only cause mild increase in needed force, I mean kind of linear response. So if the scoring is not bad enough for actually preventing cam from turning but is bad enough to cause additional stress on the chain then we might finally got some insight on what causes the timing chain to fail in some of the N20's.

I will atleast keep changing my engine oils more often than what BMW suggest. In Finland the oil change interval is actually 30000km (~19000miles) or 2 years. That is quite a lot and I have followed the 15000km/1 year interval. Maybe that is too much as well, I don't know?

What comes to tight tolerances, I guess one reason is to keep fuel consumption as low as possible. So it's easier for oil pump to pump oil in small volumes for small diameter oil channels. In the other hand, it's harder to get oil to flow in narrow channels, so I don't know if my theory actually flies.

[rjd_F30]

Originally Posted by kobluna

This also makes me wonder if atleast some of the failing timing chains are caused by this. When scored cam is harder to turn the chain will eventually fail. A new chain would still be capable of turning the cam but for how long?

This theory requires that mild scoring in cam would only cause mild increase in needed force, I mean kind of linear response. So if the scoring is not bad enough for actually preventing cam from turning but is bad enough to cause additional stress on the chain then we might finally got some insight on what causes the timing chain to fail in some of the N20's.

I will atleast keep changing my engine oils more often than what BMW suggest. In Finland the oil change interval is actually 30000km (~19000miles) or 2 years. That is quite a lot and I have followed the 15000km/1 year interval. Maybe that is too much as well, I don't know?

What comes to tight tolerances, I guess one reason is to keep fuel consumption as low as possible. So it's easier for oil pump to pump oil in small volumes for small diameter oil channels. In the other hand, it's harder to get oil to flow in narrow channels, so I don't know if my theory actually flies.

Could be. That's what's so hard about this particular issue, the timing chain, that it's near impossible to trace it back to exactly what happened. But fortunately for us qualicas did exactly that. Now we know for sure that low oil pressure or too thick of an oil due to sludging and long intervals can cause a bearing to score which can introduce more resistance into the chain mechanism and can cause it to fail.

This makes me think even more adamantly that no more than 5k miles should be done between oil changes, so I would of course recommend that you do the same.

[uncleruckus]

Originally Posted by kobluna

I will atleast keep changing my engine oils more often than what BMW suggest. In Finland the oil change interval is actually 30000km (~19000miles) or 2 years. That is quite a lot and I have followed the 15000km/1 year interval. Maybe that is too much as well, I don't know?

I personally get my oil changed between 8-10k KM (I believe the interval on my iDrive is 16 or 18k KM between oil changes). This equates to about 5-6k MILES. Not exactly much help to you, but I personally wouldn't go past 12k KMs between oil changes (I want to stress that this is what I personally do, doesn't mean its the best or even "recommended")

Wondering if oil viscosity and the ambient air temperature affects this as well.... would be interesting to see if there is any correlation between geographic location (and therefore temperature) and chain failures. Granted I doubt we will ever get this data.

[rjd_F30]

Originally Posted by uncleruckus

I personally get my oil changed between 8-10k KM (I believe the interval on my iDrive is 16 or 18k KM between oil changes). This equates to about 5-6k MILES. Not exactly much help to you, but I personally wouldn't go past 12k KMs between oil changes (I want to stress that this is what I personally do, doesn't mean its the best or even "recommended")

Wondering if oil viscosity and the ambient air temperature affects this as well.... would be interesting to see if there is any correlation between geographic location (and therefore temperature) and chain failures. Granted I doubt we will ever get this data.

Oil viscosity almost certainly has something to do with it, not sure that temperature would though. A thicker oil won't help with cold start lubrication either. I use, like many people, 0W-40.

[meltbox]

Originally Posted by rjdnyy224

Oil viscosity almost certainly has something to do with it, not sure that temperature would though. A thicker oil won't help with cold start lubrication either. I use, like many people, 0W-40.

What oil do you use? I bought up a couple change supply of the castrol 0w-40 ll01 oil but it seems like production stopped.... Don't know what I will do after I run out.

I think I literally bought out every Walmart within a reasonable distance of me haha.

[rjd_F30]

Originally Posted by meltbox

What oil do you use? I bought up a couple change supply of the castrol 0w-40 ll01 oil but it seems like production stopped.... Don't know what I will do after I run out.

I think I literally bought out every Walmart within a reasonable distance of me haha.

I use BMW branded 0W-40. Pretty sure it's just Castrol or Mobil oil branded as BMW, but I get it straight from a dealer.

[Billfitz]

Originally Posted by meltbox

What oil do you use? I bought up a couple change supply of the castrol 0w-40 ll01 oil but it seems like production stopped..

What stopped is Castrol paying BMW a royalty to use the LL01 designation, as that's a BMW trademark. I believe Pennzoil is the current BMW oil provider, but it changes literally from year to year, depending on who gives BMW the best deal. LL01 isn't all that special. I now use Molygen, and it works better for me than LL01-FE did.

[rjd_F30]

Originally Posted by Billfitz

What stopped is Castrol paying BMW a royalty to use the LL01 designation, as that's a BMW trademark. I believe Pennzoil is the current BMW oil provider, but it changes literally from year to year, depending on who gives BMW the best deal. LL01 isn't all that special. I now use Molygen, and it works better for me than LL01-FE did.

How did you determine that it works better?

[TankTouring]

I’m collecting my 2013 f31 328 tomorrow. A disintegrating N20 is the stuff of nightmares, but how many people has it actually happened to? Are there any concrete figures?

I don’t want to dread driving the car for fear of it blowing up! Some of the posts in here are pretty concerning.

[rjd_F30]

Originally Posted by TankTouring

I’m collecting my 2013 f31 328 tomorrow. A disintegrating N20 is the stuff of nightmares, but how many people has it actually happened to? Are there any concrete figures?

I don’t want to dread driving the car for fear of it blowing up! Some of the posts in here are pretty concerning.

I don't have exact numbers for you, but the failure rate is low, and the odds of your engine just blowing up are slim. Just know that people come on here to discuss issues, and there are thousands of N20 owners that have no problems, so they don't come on to talk about how their car runs fine.

[TankTouring]

Originally Posted by rjdnyy224

I don't have exact numbers for you, but the failure rate is low, and the odds of your engine just blowing up are slim. Just know that people come on here to discuss issues, and there are thousands of N20 owners that have no problems, so they don't come on to talk about how their car runs fine.

Thank you. Fingers crossed and regular oil changes seems to be the recommended course of action.

[rjd_F30]

Originally Posted by TankTouring

Thank you. Fingers crossed and regular oil changes seems to be the recommended course of action.

Pretty much And as you can see from reading this thread, oil passage ways seem very tight, at least in some places, so it's very very important to let the oil get to full operating temperature before revving it too high. I keep it below 3.5k until everything is all warmed up.

[qualicas]

Got another head the other day. I pulled it apart to do a valve job. I found that the 3 intake cam caps that were really scored on my head show signs of scoring already. This head was from a running engine. Looks like my theory holds water.
ie Long oil changes cause sludge, sludge causes lack of oil to the oil pump, resulting low oil pressure staves the intake cam bearing caps. The caps score making the intake cam harder to turn. When really hard to turn chain stretches and rides up on sprocket teeth breaking the chain guides. Replacing the chain with a stronger chain does not eliminate the problem.
If you have one of these engines, my advice would be to change oil often and make sure it gets a long highway drive often so sludge does not build up, And if you have the stop and go engine, turn that feature OFF! As sooner than later it will stop and not go any longer.
This my humble opinion.

[meltbox]

Originally Posted by qualicas

Got another head the other day. I pulled it apart to do a valve job. I found that the 3 intake cam caps that were really scored on my head show signs of scoring already. This head was from a running engine. Looks like my theory holds water.
ie Long oil changes cause sludge, sludge causes lack of oil to the oil pump, resulting low oil pressure staves the intake cam bearing caps. The caps score making the intake cam harder to turn. When really hard to turn chain stretches and rides up on sprocket teeth breaking the chain guides. Replacing the chain with a stronger chain does not eliminate the problem.
If you have one of these engines, my advice would be to change oil often and make sure it gets a long highway drive often so sludge does not build up, And if you have the stop and go engine, turn that feature OFF! As sooner than later it will stop and not go any longer.
This my humble opinion.

This is super encouraging should your theory indeed be the cause. I guess it means this should disproportionately affect those with short commutes if they change at a set and long interval.

I feel like the computer is pretty good at shortening intervals if you do that though. hmm.

Could it depend on software version? Maybe older software revisions weren't very aggressive about shortening oil change intervals based on environmental factors and driving distance?

[kobluna]

Originally Posted by qualicas

Got another head the other day. I pulled it apart to do a valve job. I found that the 3 intake cam caps that were really scored on my head show signs of scoring already. This head was from a running engine. Looks like my theory holds water.
ie Long oil changes cause sludge, sludge causes lack of oil to the oil pump, resulting low oil pressure staves the intake cam bearing caps. The caps score making the intake cam harder to turn. When really hard to turn chain stretches and rides up on sprocket teeth breaking the chain guides. Replacing the chain with a stronger chain does not eliminate the problem.
If you have one of these engines, my advice would be to change oil often and make sure it gets a long highway drive often so sludge does not build up, And if you have the stop and go engine, turn that feature OFF! As sooner than later it will stop and not go any longer.
This my humble opinion.

Yep, that theory actually seems like the best explanation for the timing chain issues that I have read so far. I'm glad that my car has been, and still is, driven mainly on highways / motorways and only occasionally in city. Of course there is some city driving every day but anyway the engine gots to warm up properly almost every day.

Now I'm wondering if it would be advisable to drop the oil pan every let's say 100k miles and clean up oil pickup thoroughly. I don't know if there is some sludge that wont self clean up even if oil is changed. So even if the car is driven usually for long distances can there still be some sludge there? It would be also nice if there would be some upgrade available to oil pan that would have improved oil pickup. What I have understood the oil pump has hard time to get oil during heavy breaking and heavy cornering. If the car is tracked it might be a problem.

I'm also wondering if it would make any difference if I would do ceramic coating treatment to the engine? Something like this: https://www.rvs.fi/en/technology/
That product is claimed to help to reduce the friction between moving parts and at least some user reports says that the engine runs "smoother" after the treatment. Hard to say really if it works or not? Anyway I haven't seen any reports of the BMW users, let alone N20 users, if that kind of treatment is helpful or not.

Edit. Actually that RVS company has tested the product on E90 328i and the dyno results improved which means that internal engine friction is reduced. Of course the result must be taken with a grain of salt as the result is provided by the company selling the product. https://www.rvs.fi/wp-content/upload...estimonial.pdf

[rjd_F30]

Originally Posted by kobluna

Yep, that theory actually seems like the best explanation for the timing chain issues that I have read so far. I'm glad that my car has been, and still is, driven mainly on highways / motorways and only occasionally in city. Of course there is some city driving every day but anyway the engine gots to warm up properly almost every day.

Now I'm wondering if it would be advisable to drop the oil pan every let's say 100k miles and clean up oil pickup thoroughly. I don't know if there is some sludge that wont self clean up even if oil is changed. So even if the car is driven usually for long distances can there still be some sludge there? It would be also nice if there would be some upgrade available to oil pan that would have improved oil pickup. What I have understood the oil pump has hard time to get oil during heavy breaking and heavy cornering. If the car is tracked it might be a problem.

I'm also wondering if it would make any difference if I would do ceramic coating treatment to the engine? Something like this: https://www.rvs.fi/en/technology/
That product is claimed to help to reduce the friction between moving parts and at least some user reports says that the engine runs "smoother" after the treatment. Hard to say really if it works or not? Anyway I haven't seen any reports of the BMW users, let alone N20 users, if that kind of treatment is helpful or not.

Edit. Actually that RVS company has tested the product on E90 328i and the dyno results improved which means that internal engine friction is reduced. Of course the result must be taken with a grain of salt as the result is provided by the company selling the product. https://www.rvs.fi/wp-content/upload...estimonial.pdf

I don't think you should have much of a sludge problem if you do get the car up to full operating temp every day or so like you said. I wish I could say the same but when I'm at school, 90% of my driving are 2 mile trips to the grocery store, so at least once a week I make it a point to hit some backroads and give her a full cycle, just for this reason.

I also wouldn't consider any oil additives as real helpers the any of the issues discussed in this thread. If an oil additive could reduce friction enough to prevent a timing chain issue or cam scoring, you had too much friction happening in the first place, if that makes any sense lol.