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2001 325i 80,000 miles
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Discussion Starter · #1 ·
I recently changed my Denso plugs for the proper NGK's, and after only 500-or-so miles on the Denso's, the plug on cyl 5 had some oil on it; when I changed to the Denos from the first lot of NGK's there was a bit of oil on plugs 4, 5 and 6. I've changed up to 5W-40 oil (from 5W-30) to see if this helps, but if it does not, I've been advised to try a "piston soak" at my next oil change because oil control rings are known to stick on the M54. I wanted to see if anybody had done it before.

It was explained to me as follows:

remove plugs and pour 10 ml of some sort of injector cleaner (I've already got some Liqui Moly 1803, so that's the one I would use) into each plug hole,
leave as long as possible, but at least overnight,
disconnect DME and fuel pump and turn the engine over a few times with the plugs out to get the cleaner out of the bores,
change the oil immediately

I have done the CCV test (no vacuum when the oil cap is removed, and air comes out of the filler when I blow into the brake booster hose), and plugs 1-3 were all clean so I must assume the CCV is working correctly.

Is this piston soak safe? If so, has anybody got any data on the results?

Thanks,

M.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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Pouring a cleaning solution into the tops of the pistons works, albeit there's a large issue:
Gravity and the angle that the engine (slant 6 in old school terms) sits at. Within seconds all of the solution will be at
6 O:Clock on the pistons/rings.

I'd think you'd be better served with Liqui Moly engine flush and a couple of rapid (say 1,00 ea.) oil changes with Leichtlauf 5-40.
 

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Discussion Starter · #3 · (Edited)
Pouring a cleaning solution into the tops of the pistons works, albeit there's a large issue:
Gravity and the angle that the engine (slant 6 in old school terms) sits at. Within seconds all of the solution will be at
6 O:Clock on the pistons/rings.

I'd think you'd be better served with Liqui Moly engine flush and a couple of rapid (say 1,00 ea.) oil changes with Leichtlauf 5-40.
Would it be reasonable to completely fill the bores and then suck out all the fluid after the soak? Wouldn't the engine tilt would cause the ring gunk to settle into the 6 o'clock position as well...? :D

The engine flush (Proline version) is very much on the cards for the next oil change - I might even go up to 10W-40 because the next change will be in March, and the UK doesn't get cold enough to warrant 5W from spring to autumn. The last lot of 5W-30 had only around 400-500 miles on it before I changed it, I should add; filter was clean, so I left it in.

(I have also been considering the O2 Pilot mod - is it really as simple as connecting a vacuum hose from one of the plugged ports on the manifold to the plugged port on the CCV catch can? If so, that's less than 10 mins work and £5 cost.)
 

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Neither CCV nor O2 Pilot Mod will work properly if the oil return is obstructed. So start there. Remove the dipstick tube and blow through its oil return to verify it's free flow and there is no partial obstruction. This is not an uncommon problem. Indeed, BMW redesigned dipstick tube if you can't get the current tube completely free flowing. Also check the oil return line back to CCV is clear and open. And replace orings on the dipstick and dipstick tube.

FYI (from ECS website):
Not only a housing for the dipstick but actually a part of oil separator system it is vital to have this piece to be as free flowing as possible

This updated design by BMW will help prevent possible clogging by oil sludge which is common for M54 motors.
 

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Discussion Starter · #7 ·
Neither the CCV nor O2 Pilot Mod will work if the oil return is obstructed. So start there. Remove the dipstick tube and blow through its oil return to verify it has free flow and no partial obstruction. Not an uncommon problem. BMW redesigned the dipstick tube if you can't get the current tube completely free flowing. Also check that the oil return line back to the CCV is clear and open And replace orings on the dipstick and dipstick tube.

Not only a housing for the dipstick but actually a part of oil separator system it is vital to have this piece to be as free flowing as possible.

FYI (from ECS website):
I have planned to pull the tube off and send some brake cleaner and compressed air down the CCV return - is the old tube a double-skin?

I've already got the o-ring ;)
 

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I have planned to pull the tube off and send some brake cleaner and compressed air down the CCV return - is the old tube a double-skin?

I've already got the o-ring ;)
is the old tube a double-skin?

Yes, Double walled.
 

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I have planned to pull the tube off and send some brake cleaner and compressed air down the CCV return - is the old tube a double-skin?

I've already got the o-ring ;)
Yes, double-walled. And damn hard to get completely clean. I couldn't with brake cleaner and steel wire. Finally bought new design and issue solved. Dubious that (if obstructed) this thing can be successfully cleaned short of overnight in parts cleaner and compressed air. Mine had diamond hard bits of black carbon. Followed up with an engine clean using LM Proline engine flush. Now runs fantastic and no oil consumption. GL

P.S. And my thanks to MrMCar
 

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Discussion Starter · #11 · (Edited)
Yes, double-walled. And damn hard to get completely clean. I couldn't with brake cleaner and steel wire. Finally bought new design and issue solved. Dubious that (if obstructed) this thing can be successfully cleaned short of overnight in parts cleaner and compressed air. Mine had diamond hard bits of black carbon. Followed up with an engine clean using LM Proline engine flush. Now runs fantastic and no oil consumption. GL

P.S. And my thanks to MrMCar
I'm prepared to give it a decent soak in hot diesel, and I've seen junior hacksaw blades used to good effect, or a Dremel with a long, thin burr.

LM Proline Flush is 100% on the cards, but I think I might do all three -

1. LM flush
2. piston soak with periodic hand cranks
3. dipstick removal and soak/blowout

immediately followed by oil/filter change.
 

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I'm prepared to give it a decent soak in hot diesel, and I've seen junior hacksaw blades used to good effect.

LM Proline Flush is 100% on the cards, but I think I might do all three -

1. LM flush
2. piston soak with periodic hand cranks
3. dipstick removal and soak/blowout

immediately followed by oil/filter change.
Bear in mind that if you remove all of the oil from the piston rings you may well impact compression significantly enough to prevent the engine
from starting. This is what happens when you flood your engine. It's called a "dry start" and can seriously damage your engine.
So when you have done all that you want to do you should apply about 10 ml of clean oil to each cylinder aiming to inject it at the top
of the cylinder, because our cylinders are not vertical, and leave it a couple of hours to run down onto the rings. I use a syringe attached
to a length of 3/16" copper brake line with a bend at the end. Turn the engine over, by hand preferably, with the fuel pump fuse removed, to
lube the cylinder walls.

 

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Discussion Starter · #13 ·
Bear in mind that if you remove all of the oil from the piston rings you may well impact compression significantly enough to prevent the engine
from starting. This is what happens when you flood your engine. It's called a "dry start" and can seriously damage your engine.
So when you have done all that you want to do you should apply about 10 ml of clean oil to each cylinder aiming to inject it at the top
of the cylinder, because our cylinders are not vertical, and leave it a couple of hours to run down onto the rings. I use a syringe attached
to a length of 3/16" copper brake line with a bend at the end. Turn the engine over, by hand preferably, with the fuel pump fuse removed, to
lube the cylinder walls.

It is my intention to spray fogging oil into the bores before each hand-crank.

The plan is to soak for a few hours hours, spray some fogging oil in and do a couple of hand-rotations, refill the bores with injector cleaner, and repeat over the course of a couple of days.
I see that Sea Foam spray comes with an applicator tube, so I might get that and aim the spray at the "top" of the bores.
 

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Discussion Starter · #14 ·
I have the opportunity to get the "winter" version of the CCV for no more money than the normal version - worth doing? As I understand it it's just the normal version wrapped in foam, but for no extra cash... :)
 

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I have the opportunity to get the "winter" version of the CCV for no more money than the normal version - worth doing? As I understand it it's just the normal version wrapped in foam, but for no extra cash... :)
Only if you need to. It's a lot bulkier than the non winter version because it's padded with insulation and the non winter
one can be tricky enough to manipulate into place.
 

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Discussion Starter · #16 ·
Only if you need to. It's a lot bulkier than the non winter version because it's padded with insulation and the non winter
one can be tricky enough to manipulate into place.
Good point - I'm going to do it the easy way (unless I discover a vacuum leak at the inlet manifold gaskets), so I don't want to make it any more difficult than it already is!
 

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Discussion Starter · #17 ·
Quick aside: can oil deposition (in the valve cover) affect the camshaft position sensors? I did the ones on my father's old 318 compact and they were doused in oil.

They are insanely cheap, so I might just change them anyway. Just curious because my car sometimes hesitates when coming out of idle, and I can't find any (more) vacuum leaks and the plugs are fresh.
 

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Quick aside: can oil deposition (in the valve cover) affect the camshaft position sensors? I did the ones on my father's old 318 compact and they were doused in oil.

They are insanely cheap, so I might just change them anyway. Just curious because my car sometimes hesitates when coming out of idle, and I can't find any (more) vacuum leaks and the plugs are fresh.
You could just clean them I suppose but while the exhaust camshaft sensor is reasonably simple to get at the intake sensor takes a bit more effort.
On mine I have to remove the air scoop, air box and MAF, oil filter cap (cover it with a cloth) , VANOS intake solenoid and VANOS oil line to get to it. If you're
going to do that I would put a new one in there.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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Quick aside: can oil deposition (in the valve cover) affect the camshaft position sensors? I did the ones on my father's old 318 compact and they were doused in oil.

They are insanely cheap, so I might just change them anyway. Just curious because my car sometimes hesitates when coming out of idle, and I can't find any (more) vacuum leaks and the plugs are fresh.
No.
I've seen some horribly gunked up engines online. Despite all of the goo, the can lobes and sensors usually remain working.
Up until the oil no longer lubricates. Then you have bigger issues.
 

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Discussion Starter · #20 ·
You could just clean them I suppose but while the exhaust camshaft sensor is reasonably simple to get at the intake sensor takes a bit more effort.
On mine I have to remove the air scoop, air box and MAF, oil filter cap (cover it with a cloth) , VANOS intake solenoid and VANOS oil line to get to it. If you're
going to do that I would put a new one in there.
I've seen RHD ones done with just the solenoid unplugged, not sure how left-hookers differ.
 
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