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2008 BMW 528i
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Discussion Starter · #1 ·
All,

For the past few months I have been chasing cylinder 5 misfire. Horrible gas mileage. Around 15-16 mpg.
I only use Shell 93 or Mobil1 93. Once a month I use fuel injector cleaner by techron or similar. ( liqui molly)
Changed spark plugs, coils, injectors and no help.
Changed the valve cover gasket and no difference. ( No leak before and after )
This has been getting worse and worse to the point where if the car idles for a min or so, it starts to ping and goes crazy.
Power is erratic. It comes and goes like extreme jerking. This has destroyed my torque convertor and friction plates inside the transmission.
There is a vacuum leak that just sprung up too.
Oil pan gasket was replaced a while ago and no leaks around the gasket or anywhere but my oil consumption is excessive. A quart for every 500 miles.
No blue or white smoke ( confusing ) at any rpm.
The spark plug on cylinder 5 gets deposited with copious amounts of carbon due to oil burning. Have to clean the spark plug every few days.
Compression is low on cylinder 5. I see excessive vacuum in valve cover. Probable causes - valve stem seal or intake valves full of carbon.
Regardless, since my transmission needs a good servicing, I decided to buy a spare engine and rebuild it. Do the swap and service the transmission in the process.
Will be doing a complete rebuild of the engine and transmission. I will do my best to update with photos and videos.

My car is RWD and finding an engine close to me that is RWD was useless. So I bought a AWD engine, according to REALOEM, the only difference is the oil pan and the engine support brackets. I have visually checked that this is correct. I can swap over the oil pan and engine support brackets and it should be good. ( only time will tell )

As of today the engine is on the hoist. Will be doing the disassembly of the engine except the block which require the timing tools. They should be here this weekend.
I have also decided to hone the cylinders using Sunnen AN-30 paste. I have spoken to a couple of engine builders here in Connecticut and they all recommended AN-30 and the tool by AMTuned. Of course this will be decided on the condition of the cylinders. The machine shop I am using also have experience with n52 engines. So after a good wash and cleaning and blueprinting, will decide whether to hone or not to hone.

All bearings and seals will be replaced.
If anyone has any suggestions on rebuilds, please do comment. I have read posts about N52B25 rebuilds. But no N52B30.

"WHERE CAN I FIND THE CODES FOR THE BEARING COLORS?" I believe this is laser etched on the block. Please someone correct me.
I need to order the correct bearings.

IF SOMEONE KNOWS THE TORQUE SPECS FOR BEARING BOLTS, ROD BOLTS AND HEADBOLTS PLEASE SHARE.

The spare engine as of now:

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It came with a front differential? Wow.

Good luck with your effort. I'd be (very) tempted to NOT pull the pistons and hone the cylinders unless I saw some serious reason to do so. On many high-mile engines, the factory honing marks are still visible, and any time you tear a motor down further, you're taking additional chances something might go wrong. IMHO, YMMV
 

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2008 BMW 528i
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114 Posts
Discussion Starter · #3 ·
It came with a front differential? Wow.

Good luck with your effort. I'd be (very) tempted to NOT pull the pistons and hone the cylinders unless I saw some serious reason to do so. On many high-mile engines, the factory honing marks are still visible, and any time you tear a motor down further, you're taking additional chances something might go wrong. IMHO, YMMV
It did come with a front diff. Unfortunately its useless to me since mine is only RWD.
I am going to throw it away once the project is complete. The only reason I am pulling the pistons is to install new rings. Also the piston needs to come out so the block can be cleaned thoroughly.

Honing will be decided once I can look at the cylinders.
As of now the engine is on the stand and valve cover is out. Internals look clean and I am extremely happy.
Cams look excellent with no scratches at all.
Intake valves look clean with minimal carbon deposit.
Exhaust valves are questionable.
One of the motor support mount holes looks damaged. I am worried about that now.

EXHAUST VALVES. They all look the same.
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INTAKE VALES. All look similar.

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GOOD ENGINE SUPPORT MOUNT HOLE:

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DAMAGED:

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CAMSHAFTS:

Automotive tire Motor vehicle Gas Automotive wheel system Vehicle


I do believe the cylinders to be good. But only time will tell. Also the rod bearings and main bearings will be replaced as well since the motor has some water inside the oil pan from sitting in rain I guess.

Will update once the block is apart.
:)
 

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You're down the road a bit, so to speak, but as to your much lower mileage: aged O2 sensors will cause significantly decreased mileage, as much as 40% off normal. Aged usually means 80-100Kmiles. Voltages may meter in range, and no codes, but what happens is the switching frequency of the sensor slows over time. Only visible with a scope. Of course, this has nothing to do with your Cyl 5 issues.
 

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Discussion Starter · #5 ·
You're down the road a bit, so to speak, but as to your much lower mileage: aged O2 sensors will cause significantly decreased mileage, as much as 40% off normal. Aged usually means 80-100Kmiles. Voltages may meter in range, and no codes, but what happens is the switching frequency of the sensor slows over time. Only visible with a scope. Of course, this has nothing to do with your Cyl 5 issues.
I will be installing new O2 sensors. But if cylinder 5 was had no oil leak I would definitely try that. But there are so many problems that It needs a rebuild at this point.!
 

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2008 BMW 528i
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Discussion Starter · #7 ·
Just buy my 535i at this point lmao
AFAIK N54 costs more to keep it running with the turbos and HPFP and other issues. N52 is far cheaper to run and maintain. I know more about it and its easier this way since my car has all new suspension including LSD. I know my car has no hidden defects electrical or otherwise. All mechanical components are new including subrfame bushings (OEM).
So putting in a rebuilt engine is anytime better than buying a N54 with unknown condition ( unknown to me).
Also with the 3 stage intake mod and MILVS tune, N52 can make 300+hp which is more than sufficient for my daily.
 

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I'm also a big fan of the N52 option - which is what I chose for my DD / road trip car. It's plenty complicated enough.

And don't forget one more (big!) difference - the N52 is perfectly happy to burn regular fuel, unlike the N54. You do lose about 20 horsepower, but that only matters when your right foot is buried in the carpet, which is almost never for 99% of us (and about 99.99% of my driving).
 

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Discussion Starter · #9 ·
Update:

Need some advice here.
I took the engine apart and the intake camshaft bearings have severe damages.
The bearing caps also have deep scratches. These cannot be replaced since they are made to a particular head like connecting rod end caps.
cylinders have scratches and there is a hole or a pit in two of the cylinders. like something got stuck b/w piston and wall.
connecting rod bearings also have scratches. crankshaft itself has no visible scratches.
I have not taken out the crankshaft since there is no point in rebuilding this anymore. I am exchanging the engine from the place I bought it.

What do you all think ?
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I must have missed it, how many miles on original and replacement engines?
Engine look relatively sludge free. What caused the scored cam journals? Does the original engine have the same issue?
Does the cam ride directly on the aluminum head rather in replaceable bearing inserts?
 

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2008 BMW 528i
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Discussion Starter · #12 ·
I must have missed it, how many miles on original and replacement engines?
Engine look relatively sludge free. What caused the scored cam journals? Does the original engine have the same issue?
Does the cam ride directly on the aluminum head rather in replaceable bearing inserts?
original in my car is still running at 190k+ miles. I am currently experiencing cylinder 5 misfire with low compression and torque convertor failure symptoms. so I bought this used engine with 145k miles and teared it down.
the intake camshaft rides on the head and not replaceable bearings. exhaust cam is good. intake is bad.
even the crank has deep scratches. on cylinder 1,3 and main bearings 1,2,3.
cylinder has pitting that cannot be fixed without boring to oversize. overall the engine is fucked.
I am getting a replacement engine tomorrow. hopefully that will be good.
 

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It could be possible the existing engine has a valve problem on cylinder 5 causing the low compression. Is there a way to determine more definitively what's wrong with cylinder 5? Borescope that cylinder?
 

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Discussion Starter · #14 ·
It could be possible the existing engine has a valve problem on cylinder 5 causing the low compression. Is there a way to determine more definitively what's wrong with cylinder 5? Borescope that cylinder?
I have ordered a borescope. will do that test soon.
on the other hand, I had problems with engine stalling and struggling to accelerate.
I have narrowed it down to eccentric shaft sensor.
I disconnected it and the engine jerking and stalling problem went away. I am low on power but atleast the car is drivable now.
there is definitely an oil leak in to cylinder 5. I am having to clean that spark plug from cylinder 5 every other day. it gets dangerous amounts of carbon deposit. It is so extreme that there is no gap between the electrodes.
Two possibilities, 1 - oil control ring or damaged cylinder wall, 2 - valve stem seal. I do feel a higher than usual vacuum in the valve cover. funny thing is there is no oil leak anywhere. a few stains on the rear main seal but that's it.
If I have to do a head rebuild on my engine I might as well do a complete rebuild on a spare engine. this is my thinking. not sure how deep the rabbit hole will go.
I have another question. since I have disconnected the eccentric shaft sensor, is it possible to have the valves at max lift all the time? can i manually turn the valvetronic motor to max lift? I know there is a hard stop at the max lift. I do not want the pistons hitting the valves. Any insight on this?

Thank you!
 

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Have a look at the thread below. I recently did a bunch of maintenance, some needed and some just preemptive. Anyway, one repair was a leaking VCG and I discovered the eccentric shaft gear was torn up a bit. I'm guessing lack of lubrication. For the first 14 years I had the car, I didn't drive it much as I worked from home or on the other coast. I've been driving it more consistently the last few years. Anyway, I didn't notice anything wrong with how it behaves before discovering this and I'm just gonna deal with it next year sometime. BTW, I do drive my car pretty aggressively and notice nothing out of the ordinary.

To you question. In researching things, I came across some threads on non-functional VVT and found this one you might be interested in. I have not tried this, but I have it saved in case I need it before I get around to the proper repair:
 

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Discussion Starter · #16 ·
Have a look at the thread below. I recently did a bunch of maintenance, some needed and some just preemptive. Anyway, one repair was a leaking VCG and I discovered the eccentric shaft gear was torn up a bit. I'm guessing lack of lubrication. For the first 14 years I had the car, I didn't drive it much as I worked from home or on the other coast. I've been driving it more consistently the last few years. Anyway, I didn't notice anything wrong with how it behaves before discovering this and I'm just gonna deal with it next year sometime. BTW, I do drive my car pretty aggressively and notice nothing out of the ordinary.

To you question. In researching things, I came across some threads on non-functional VVT and found this one you might be interested in. I have not tried this, but I have it saved in case I need it before I get around to the proper repair:
Hey,

That actually works. I unplugged the sensor and turned on ignition. I heard the VVT motor running. I took an allen key and tried turning the motor manually and it was at a hard stop so fully opened position. that is good. I drove a good 300 miles and did not have any problems with jerking or non responsive throttle. the DME is still adapting and I could feel more power the longer I drive it was more responsive at towards the end of the journey. cylinder 5 did misfire. however not as much as before. not sure what to think about that.

I did manage to get another engine for a rebuild. I will open up the valve cover and intake on my original motor to replace the sensor and I will take a look at the intake valves and stem seals.
Hopefully there is a way I can save this motor.

Thank you!
 

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Discussion Starter · #17 ·
Hey,

That actually works. I unplugged the sensor and turned on ignition. I heard the VVT motor running. I took an allen key and tried turning the motor manually and it was at a hard stop so fully opened position. that is good. I drove a good 300 miles and did not have any problems with jerking or non responsive throttle. the DME is still adapting and I could feel more power the longer I drive it was more responsive at towards the end of the journey. cylinder 5 did misfire. however not as much as before. not sure what to think about that.

I did manage to get another engine for a rebuild. I will open up the valve cover and intake on my original motor to replace the sensor and I will take a look at the intake valves and stem seals.
Hopefully there is a way I can save this motor.

Thank you!
Update :

Got a second spare engine and took it all apart. Cylinder walls look amazing. No scratches at all.
Crankshaft bearings show minimal wear, connecting rod also minimal wear.
The head looks good and the cam shaft bearing caps also look good.

The only bad part is the intake cam shaft. attached are the pictures. Not sure If I should get a different cam shaft or just buy a new one. I cannot feel the scratches on the camshaft bearing. It is smooth to the touch, but has these scratches.
Not sure what to do.

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The head at block are at a machine shop for cleaning and resurfacing.

I need to figure out which bearings to buy. If someone can help me with that it would be awesome.

Crank shaft markings - 2122222
Block Markings - BBBBBBB

Position Upper Shell Lower Shell
1 - green green
2 - green yellow
3 - green green
4 - green green
5 - green green
6 - green green
7 - green green

I can buy the OEM bearings from FCP euro but they cost a fortune. I can either buy King bearings or Mahle but I am not sure which one to buy since I do not know what the tolerances are for the color coded bearings.
I can find King bearings for standard size ( part # MB7776SI )
I can find KOLBENSCHMIDT: 77947600 standard size.
These are the only two options that I can afford and get it in under 2 weeks.
Not sure If I can use these. So I am guessing I have to measure my crankshaft and then order the bearings.
If someone can help me out here that would be much appreciated.

Thank you!
 

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I can't contribute much to this thread, just following as I am glad of the efforts you are making to save the engine. I have a N52B30 with just under 210k original miles with hardly any major issues.

[I have only replaced the major gaskets (VGC, oil cooler, valvetronic/eccentric shaft, intake manifold, etc.) in addition to spark plugs, coolant hoses, expansion tank, starter, fuel filter/fuel pump, and other minor components].

I did have a cyl 5 misfire that turned out to be a bad fuel injector. doesn't sound like you have a fuel problem however. Good luck and please continue providing updates. I fell this will help those us that have N52B30 engines!
 

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Discussion Starter · #19 ·
Update:

I did figure out the bearing size:

The process is simple. Look at the markings on your crankshaft:

Rectangle Font Screenshot Circle Parallel


In the above picture, numbers in group 3 denotes the OEM bearing colors and group 4 indicates your crankshaft size. If nothing in present in group 4 it is standard size. If you have any data in group 4, refer to the table and you will get the size. i.e, over or undersized bearings from the factory.

If the crankshaft has never been touched then this will be sufficient to determine what bearings to use.
For me it is standard bearings. I have ordered the King bearings.

Now comes the important bit.
***Do not throw away the old bolts for the bed plate. You will need them to check clearances.
1 - Clean the bearing locations on the engine block, bed plate and crankshaft of any oil residue.
2 - Install the new bearings with a plastigauge to determine clearances ( or as BMW calls it radial play ).
* Installation torque for bed plate - 100NM + 360 degrees*
3 - Remove the bed plate and check for clearances.
Acceptable clearances - 0.025 - 0.061mm or 0.00098" - 0.0024"
4 - If you have everything in spec, all is well, if not then you need to figure out what bearings you need from BMW.

BMW has color coded bearings for standard sizes. N52 has only three colors.
The engine block has letters for each bearing position that corresponds to a color. This is the upper shell of the bearing.
The Crankshaft has numbers that corresponds to a color. These are for lower shell. ( the bearings installed on the bedplate. )

*** If you have any bearing out of spec, too tight or too loose, you need to go to your local BMW tell them you need a lower shell or upper shell that will bring your clearances to spec. I am not sure which color is what. I am yet to do the test. I just figured out the method.

If your old crankshaft bearings were good when you removed them, chances are you do not have to go through the process of getting bearings from BMW. Not only they are expensive, but you would need to understand clearances and size to be able to explain what you need. This is not a simple remove old and install new job.


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For the connecting rod bearings, the markings are on the side of the engine block. Same place as markings for main bearings. They should be standard as that is the only option available. I am going with OEM bearings for this since, none of the other bearings are in stock.

As far as my damaged camshaft, I am having is polished. The camshafts do not need such tight tolerances, so it should be fine.

Sorry I could not post videos of the disassembly. I am working alone in a tight space. So no place to take a video.
However, I plan to make a video or detailed pictures of assembly process. There are videos on YouTube, but it assumes you know about engine rebuilding and what it takes to do a successful rebuild.

Also N52 from AWD and RWD only difference is oil pan and engine mounts. everything else remains the same.
So you could salvage an engine from AWD or RWD and use it rebuild any N52 car. Even X series cars.

Hope this helps.!
 
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