High oil consumption and alusil cylinder liners

High oil consumption and alusil cylinder liners

Author
Discussion

k20erham

372 posts

125 months

Thursday 7th April 2016
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Hi I'm reasonable sure your efforts whilst thorough will not cure your oil consumption issues, unless you have a major breather issue which I think you will have investigated before tare-down. your ring bore seal has been compromised and will not rectify it's self, true your worn exhaust guides could pass oil but that is not your issue here.
True your injectors could have caused bore wash and replacing the faulty ones addresses one issue, it will not fix the ring/bore issue, this has been done and it will not correct itself. It's been debated much for years piston ring bore seal is critical and the window of getting it right is very small, once out of that window it rarely corrects itself.
Once an oil burner always an oil burner until you address the cause and replace the rings/bore finish accordingly. At least your head rework will not be in vane should you decide/ need to pull the motor to correct the bore issues, which I suspect you have had in the back of your mind anyway.

Pumaracing

2,089 posts

206 months

Thursday 7th April 2016
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The bore wear measurements you gave were not very helpful. Rather than relative taper and ovality what we need is absolute measurements versus nominal in both planes and at three positions, top, middle and bottom. However with pistons in you can only really give top and middle. Also on the thrust plane (90 degrees to crank axis) whether there is any measureable wear ridge from just above where the top ring comes to which will be unworn and then just below that.

bmwmike

6,918 posts

107 months

Sunday 10th April 2016
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2010 model year injectors and they are junk, wow I had hoped / thought they sorted that out long ago.

bmwmike

6,918 posts

107 months

Thursday 21st April 2016
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Presumably the bearings will be shot too because of fuel contaminating the oil?


SoupAnxiety

299 posts

109 months

Wednesday 27th April 2016
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I'm adding 1 litre of oil every ~2,000 miles to my 148k N53 330i.
Very worried after reading this thread. I've got an ongoing cold start misfire issue throwing combustion misfire codes ( http://www.pistonheads.com/gassing/topic.asp?h=0&a...).

Brilliant write up, good luck with your fix. I will watch for updates.

viperbluecerb

Original Poster:

69 posts

130 months

Wednesday 27th April 2016
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Got everything reassembled and running last night. With new injectors coded up and refreshed head it's running super smooth. It's going to be a couple of hundred miles before I know if there has been any significant impact to oil consumption, I'll report back as soon as I have some more info to share.

helix402

7,832 posts

181 months

Wednesday 27th April 2016
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Good job.

bmwmike

6,918 posts

107 months

Wednesday 27th April 2016
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Cool!

What did you do about the oval cylinders? Or were they not that bad?

Any chance of a vid of it idling? Am sad like that tongue out

Cheers

viperbluecerb

Original Poster:

69 posts

130 months

Thursday 28th April 2016
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bmwmike said:
Cool!

What did you do about the oval cylinders? Or were they not that bad?

Any chance of a vid of it idling? Am sad like that tongue out

Cheers
I didn't touch the bottom end, and the measurements I took didn't indicate that there was any major distortion, as best as I could tell. Surfaces also didn't show any signs of scoring or abnormal wear.

Video of cold start idle at the bottom especially for you bmwmike :-)

Edited by viperbluecerb on Monday 30th May 10:26

bmwmike

6,918 posts

107 months

Thursday 28th April 2016
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Thanks.. sounds great, much more stable than my 40k n53. I wonder how much the coked up inlets affect that. I know DI engines are super sensitive to airflow.

Were yours coked up much?

Nice write up, looking forward to your next installment but hope it's not your n53 smile

helix402

7,832 posts

181 months

Thursday 28th April 2016
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Top job, whenever I do a head gasket or other major engine I work I run the engine up to temp then change the oil and filter. However careful you are there will always be small bits or dirt from the rebuild.

viperbluecerb

Original Poster:

69 posts

130 months

Friday 29th April 2016
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bmwmike said:
Were yours coked up much?
They weren't really bad compared to some of the pictures I have seen, but they weren't good either, with fairly thick layers of carbon on the back of the valves and stems.

If I hadn't had the cylinder head off and I just wanted to de-coke, I would probably walnut blast the intake ports. From what I have read it seems the only good way to do it while the engine is still assembled.

http://blog.modbargains.com/get-nuts-feed-bmw-n55-...

viperbluecerb

Original Poster:

69 posts

130 months

Monday 2nd May 2016
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500 miles and no drop in oil level on the electronic dipstick... before it would have consumed over a litre by now so things look promising!

stevesingo

4,848 posts

221 months

Monday 2nd May 2016
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Good news!

Andy RV

303 posts

129 months

Friday 6th May 2016
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Interesting thread!... But can you explain to me why changing the injectors may have solved the oil consumption issues?

viperbluecerb

Original Poster:

69 posts

130 months

Friday 6th May 2016
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My theory is bore wash through oil dilution causing oil that would normally be kept as a film on the bore surface to be partially consumed as part of the combustion process.

viperbluecerb

Original Poster:

69 posts

130 months

Friday 6th May 2016
quotequote all
After 1K miles, it is unfortunate but not unsurprising that I must report that the oil consumption continues. It was always a strong possibility that the issue was ring/bore related and after all the work that I have undertaken, this has proven to be the case. Slightly overfilling led to a longer that expected time for the oil level gauge to report a drop in oil level and then it continued at the previous rate. Generally running very well with a stable idle and no visible smoke under any observed conditions.

The next step would be to completely pull the engine and rebuild/replace the bottom end. While my pockets run reasonably deep, I am not sure that for this problem they run that deep. Realistically it is another 4K+ to completely rebuild the rest of the motor with a new block and pistons and everything else that will be done should I choose to do so.

Hope the thread helps others in any way they choose to draw from it.

Edited by viperbluecerb on Sunday 29th May 11:50


Edited by viperbluecerb on Monday 30th May 10:28

anonymous-user

53 months

Sunday 8th May 2016
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This is probably one of the most helpful threads I have come across on BMW oil consumption. Thank you for taking the time and money to look into it!

Here is my issue: http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Reading online a few forums have also stated that the oil rings are thin and become carbonised quickly. Anyhow I am trying out Liqui Moly Cera Tec. My theory is that it will address any micro imperfections in cylinder walls if it is the case. It's hard to tell just yet. I added it to existing oil. I had fresh oil in January and it's done 2147 miles since then - at which point it requested a litre top up.

Last year I was on the cusp of the tolerance and the warranty claim was denied which was frustrating. Mine has the oil separator built in so it is not a standalone serviceable part. I stsrted to change oil more regularly and it improved the consumption.

My compression checks out, leak down tests and oil analysis did not present any concerns.

viperbluecerb

Original Poster:

69 posts

130 months

Sunday 8th May 2016
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Thanks. I am currently running 5w30 and have some 5w40 Liqui Moly sitting at home, LL04 approved. This coming week I will change the oil and filter for this, just in the interest of seeing if in my case it has any noticeable affect and report back any finding.

PumaRacing2

4 posts

94 months

Wednesday 11th May 2016
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It's shame you didn't get a happier outcome. I really can't see why a light reconditioning of the bores and a new set of rings wouldn't resolve this.

http://www.sunnen.com/NewsDetails.aspx?NewsID=11