[M.a.r.k.u.s]

I'm at 47k and wondering if this is something I should start considering. I haven't seen anyone post that they had it done on their N55. If anyone has before and after pics, please post them. I'm curious how much build up there is on these. I know it's less than N54's but don't know how much.

Thanks!

[Knobi]

Interested in this too

[CombatNinja]

Non-issue on N55s.

[Bavarian Tech]

No point, completely different beast.

[jwzimm]

Originally Posted by CombatNinja

Non-issue on N55s.

Originally Posted by Bavarian Tech

No point, completely different beast.

I would be curious to know your logic in this. While the N55 does have notable differences from the N54 I am not aware of one that makes the N55 immune to this issue. We still have a PCV system which allows crankcase air and oil into the intake tract. We are still direct injected which prevents any washing of the ports.

I think it would be interesting to have someone run a bore-scope to the intake ports to see what they look like on an older N55. I will bet we do see a fair amount of carbon buildup.

[M.a.r.k.u.s]

Originally Posted by jwzimm

I would be curious to know your logic in this. While the N55 does have notable differences from the N54 I am not aware of one that makes the N55 immune to this issue. We still have a PCV system which allows crankcase air and oil into the intake tract. We are still direct injected which prevents any washing of the ports.

I think it would be interesting to have someone run a bore-scope to the intake ports to see what they look like on an older N55. I will bet we do see a fair amount of carbon buildup.

I agree. They do sell Oil catch cans for this car and I know they collect a decent amount of oil. Maybe not as much as N54's but still enough to get everything pretty gunked up in there

[JETmn]

From the pictures I have seen they still need it, but it takes about twice as long to get to the same point as an N54.

[turbo_chris]

Originally Posted by jwzimm

I would be curious to know your logic in this. While the N55 does have notable differences from the N54 I am not aware of one that makes the N55 immune to this issue. We still have a PCV system which allows crankcase air and oil into the intake tract. We are still direct injected which prevents any washing of the ports.

I think it would be interesting to have someone run a bore-scope to the intake ports to see what they look like on an older N55. I will bet we do see a fair amount of carbon buildup.

Without getting into too much detail, Valvetronic is what keeps the N55 inlet valves clean.

[MNick]

Originally Posted by M.a.r.k.u.s

I agree. They do sell Oil catch cans for this car and I know they collect a decent amount of oil. Maybe not as much as N54's but still enough to get everything pretty gunked up in there

I've installed the OCC, and after 3 months of use it was nearly dry. Probably won't need to change it for another 24 months. On a side note for others with an OCC, be careful not to let it hit your headlight wires...

[jwzimm]

Originally Posted by turbo_chris

Without getting into too much detail, Valvetronic is what keeps the N55 inlet valves clean.

Umm...please do get into details. Valvetronic only varies the lift of the valves to regulate airflow and control engine speed. I do not see any way that this would have a cleaning effect on the intake valves or ports.

[CrustyNoodle]

Originally Posted by turbo_chris

Without getting into too much detail, Valvetronic is what keeps the N55 inlet valves clean.

Come on, try us with the details, I'm interested in your theory (and I must admit, somewhat sceptical).

[CombatNinja]

There have been multiple forum members here who have run oil catch cans for varying lengths of time on these cars (including me). There was not a drop of oil in mine after 7000+ miles. Same mileage in an N54 would produce several ounces of oil accumulation. It is simply not an issue on these cars. Every car on the planet will have trace amounts of oil residue in the PCV system to varying degrees, esp. as they age. But as far as it being a 'thing' like it is with the N54, nope.

[M.a.r.k.u.s]

posted this on N54 tech as well and this is the answer I got from someone there:

"I have cleaned quite a few N55's. I normally recommend them to be cleaned at around your mileage where I have received positive reviews after the clean.
The shape of the carbon is not so bad to the eye and it looks like there is much less carbon. The issue is if you look at it with the valves open a crust forms around the valve seat which creates a type of negative venturi that I would imagine bounces the flow straight into the valve.
The first one I opened I thought I shouldn't even bother and did it anyway. The client called me when he got home and was ecstatic. I guess if I owned a N55 I would look at doing it around 60,000miles or so but its all relative to the smoothness of the motor and if you realize things are go a miss."

[wwc310]

sub'd

[JETmn]

Darknight had one, sold it and bought another one. He thinks it needs it. I put my chargepipe on and took it off 5 days later to make sure it was sealed correctly and I had a nice film of oil in it already. I think the N55 still needs an OCC as I have not seen any DI cars that don't have a buildup issue unless they have the extra injector in the intake somewhere like the VW's do.

I have one and will be installing it here sometime, maybe this weekend.

[Dark_Knight_335]

We also have a much improved Vanos and oil distribution system over the N54 - one of its biggest Achilles heels.

[Dark_Knight_335]

Originally Posted by JETmn

Darknight had one, sold it and bought another one. He thinks it needs it. I put my chargepipe on and took it off 5 days later to make sure it was sealed correctly and I had a nice film of oil in it already. I think the N55 still needs an OCC as I have not seen any DI cars that don't have a buildup issue unless they have the extra injector in the intake somewhere like the VW's do.

I have one and will be installing it here sometime, maybe this weekend.

Yep, I sure did...and now I feel kind of guilty for doing so

On my last change of my second OCC I realized it didn't catch much of anything, except what appeared to be gas and water vapor.

I didn't see all that much oil in there to be honest, not enough to justify keeping the thing pressed up against my head light ballast anyway.

I'm sure it catches something, as it was filled about a quarter of the way, but I'm just not sure what without paying for a relatively expensive chemical analysis I'm sure

I do know this much- the N54 benefits far more from an OCC than the N55 does.

After you install it, check it after six months and let us know your findings- it seems to be just a bit different with everyone.

I imagine with a more aggressive setup and tune there would be more gunk and oil in the oil catch can, but that's just a guess.

[Andrewe92]

me and a friend actually had a small argument about this, I didn't really have much to back it up tho. at any rate I'm sure the n55 needs it and it might vary engine to engine.

[Jdub679]

If anyone has any access to using one of those bore scope cameras, please snap a photo and post mileage. I don't expect the valves to be clean, but it would just be nice to have some idea.

[Aaron_N55]

I asked the same but came across no pictures. Some say there is none because of Valvetronic & others say it still prone to it.

[elinstylez]

I had it done last year as preventative maintenance at LTMW. I was told that due to the age and miles on the car (40K) there wasn't really much of a difference from the blasting. On a side note, they said that the n55 is much more difficult to do compared to the n54 due to the wiring setup/access to the shell.

[Unklejoe]

My guess is that the Valvetronic increases the velocity of the air going by the valves at low loads when compared to a motor where the valves are operated at full lift all the time.

Maybe this has the effect of preventing shit from sticking to the valve?