Walnut blast intake valves on n55: when?

wheela

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What are people's thoughts/experiences on when to walnut blast intake valves on n55? I know they don't build up carbon as fast as n54, but from my searches it still builds up. I'm at 61k miles, if there's a good chance they're caked up I don't mind getting it done, but would rather put it off longer if they'd still be practically clean at this point. I bought the car at 30k miles CPO, and its been mostly 5 minute highway commutes since 2017 when I bought it. Any thoughts🤷‍♂️
 

Torgus

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What are people's thoughts/experiences on when to walnut blast intake valves on n55? I know they don't build up carbon as fast as n54, but from my searches it still builds up. I'm at 61k miles, if there's a good chance they're caked up I don't mind getting it done, but would rather put it off longer if they'd still be practically clean at this point. I bought the car at 30k miles CPO, and its been mostly 5 minute highway commutes since 2017 when I bought it. Any tInstagram.

No 1st hand experience on an n55 but you could try and get a scope to look at them, but probably a hassle. You can walnut blast and be done in 3 hours if you diy. Faster if you know what you are doing. If you are willing to diy it just take the IM off and look. 1-2 hour job give or take.

If you have to pay...I would wait.
 
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wheela

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No 1st hand experience on an n55 but you could try and get a scope to look at them, but probably a hassle. You can walnut blast and be done in 3 hours if you diy. Faster if you know what you are doing. If you are willing to diy it just take the IM off and look. 1-2 hour job give or take.

If you have to pay...I would wait.
Thanks for responding. With n55, the intake mani is an extra pain since the DME is mounted on its underside, so there's all those harnesses to deal with. I've never had it off so maybe it's not that bad, but probably more than I'd want to chew off just to take a look. If I look myself, I'd probably pick up a cheap boroscope and try to go through the throttlebody take take a look. I'll most likely be paying, as I'm super slow on first-time DIY's, and I just can't see making the time to do this in the near future.
 

fmorelli

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BMW's longstanding Idea that it should attach crap to the bottom of the intake manifolds making work on engines a general pain in the ass. Only reasonably modern motor I didn't mind working on was an N52, which at least front mounted the wiring junction box. It's an N55 - I'd just drive it.
 
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SlowE93

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BMW's longstanding Idea that it should attach crap to the bottom of the intake manifolds making work on engines a general pain in the ass. Only reasonably modern motor I didn't mind working on was an N52, which at least front mounted the wiring junction box. It's an N55 - I'd just drive it.
I'd just junk it.
 

fmorelli

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I'd just junk it.
N55 / 8HP is a great daily driver. A toaster - put bread in, push lever, wait 60 seconds, out comes toast. It is what I recommend to normies when I get questions on BMW's to buy. I've gotten two friends into N55/8HP X5's, my oldest son just got an N55/8HP X3, my middle son in an N55/8HP F10, my youngest son is the smartest, in an N52 E90 (German Honda) as a daily driver.

How reliable are they? At least in the USA they race the M235ir in AER and it's a change the oil activity. Some great software for the 8HP as well.

I wouldn't want it as a pet project car, personally, but for daily driver next best thing to an M57 :).
 
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RuskiRacer

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I've added port injection to motors that I've never walnut blasted and checked back on them in 5k-10k miles and they look super nice. So my biggest recommendation is adding port injection not only for added power capabilities but also keeping the intake valves clean. N55 is so much more difficult to remove the intake manifold as opposed to the n54 just because of the dme being there.
 
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fmorelli

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I've added port injection to motors that I've never walnut blasted and checked back on them in 5k-10k miles and they look super nice. So my biggest recommendation is adding port injection not only for added power capabilities but also keeping the intake valves clean. N55 is so much more difficult to remove the intake manifold as opposed to the n54 just because of the dme being there.
Frankly for a driver, that's not bad advice - pay once to have the intake off/blasted, spend the next walnut blast's money on port injection ... double win ... never go back in again.
 
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wheela

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I've added port injection to motors that I've never walnut blasted and checked back on them in 5k-10k miles and they look super nice. So my biggest recommendation is adding port injection not only for added power capabilities but also keeping the intake valves clean. N55 is so much more difficult to remove the intake manifold as opposed to the n54 just because of the dme being there.
Yeah, that is a huge upside to port injection. Just not crazy about the extra parts and controller. If I ever went this route, I think this would be the reason why.

What have you seen as far as carbon build up on n55's you've torn into? I've seen some people comment they walnut blasted at 60k and the valves looked totally fine when they got in there and didn't need it. Most comments seem to be from people getting it done only to discover they didn't need it yet. There are exceptions that look pretty bad already at that point, but from my searching those cars seem more rare🤷‍♂️ I almost wonder if those cars had some undiagnosed mechanical issue going on contributing to the excess build up?
 

wheela

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BMW's longstanding Idea that it should attach crap to the bottom of the intake manifolds making work on engines a general pain in the ass. Only reasonably modern motor I didn't mind working on was an N52, which at least front mounted the wiring junction box. It's an N55 - I'd just drive it.
Even the concept of cooling the DME with charge air... I guess that works well for stock (obviously that's what they designed for) and as long as the charge air temp isn't above any DME component operating temp all the flow through the intake will still pull alot of heat out. Heat will shorten any components life, but this strategy doesn't seem to cause any problems for n55.
 

RuskiRacer

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Yeah, that is a huge upside to port injection. Just not crazy about the extra parts and controller. If I ever went this route, I think this would be the reason why.

What have you seen as far as carbon build up on n55's you've torn into? I've seen some people comment they walnut blasted at 60k and the valves looked totally fine when they got in there and didn't need it. Most comments seem to be from people getting it done only to discover they didn't need it yet. There are exceptions that look pretty bad already at that point, but from my searching those cars seem more rare🤷‍♂️ I almost wonder if those cars had some undiagnosed mechanical issue going on contributing to the excess build up?
The n55s I've blasted were around the 100k mark . And they didn't look to bad but they did have some buildup that the blasting removed. I know a couple people running port injection on their n55s and there intake runners and valves look brand new
 
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CalvinNismo

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This is a cylinder 6 before and after of an N55 135i (not mine) with roughly 70,000 miles on the clock.

BjfP1JY.jpg


Not too bad really.
 
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wheela

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Well, I decided to go ahead and get it blasted at just over 60k miles, as I'm planning on upgrading the turbo, and want to feel confident it's starting out with a clean slate.

I had the shop take before and after pics. The before pic is poorly lit, I can't really tell if it was very bad or not. You can see on the after they look pretty good. Probably didn't need it, but i'm glad to know they're clean, and my motor isn't accumulating too badly after 60k. I can't tell any difference driving (I didn't expect to), only thing is I think the shop put her back together with a leak, as my ltft was around 10% at idle before, and now it's idling around 15 - 17%😐 I'm going to have to make some time poke around a bit and see what's going on.

Before and after pics:
 

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RuskiRacer

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Dang thats no good that there's a new leak 😕. How much did they charge for a n55 blast ?
 

wheela

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Dang thats no good that there's a new leak 😕. How much did they charge for a n55 blast ?
Yeah, I'm annoyed with that... It was $800 for the blast. Kinda high, but i've seen some people post they've been quoted up to $1000 so it could have been worse. I originally made the appointment to refresh my transmission fluid/pan/mechatronic sleeve for preventative maintenance, so I decided to do the blast as well to save a trip.
 

wheela

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Well, guessing the high ltft is due to not getting the purge valve and/or related plumbing connected back properly after reinstalling the intake manifold, as today the dash said my fuel cap was open, and it threw the 321C code for fuel tank ventilation system. I'm guessing that's where the extra air is coming from. I'll poke around for something obvioulsy disconnected there when I get a chance, but if I don't find anything at least I have a code that popped after their work, so I can take it back and let them fix it.
 

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