Air Filter Service

[davejones]

Hello guys - would love some input on this!

Since taking ownership of my patrol I have serviced her 3 times - once every 5,000km; that includes oil and oil filter change, 1x diesel filter change, and air filter service.

Now with the after market turbo fitted by Alpine, with it came a "high performance" BMC air filter, including an "air cooling enhancing" CDA (carbon dynamic airbox). See picture below:

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Now 10 months after becoming a 4x4 (let alone patrol) owner for the first time i still know nothing. So back then you can imagine how little i knew. My first service on the patrol was my first service on a car ever!! Anyway, with the assistance of my girlfriends mechanically minded brother, the service was done successfully, no questions asked. Specifically on the air filter, it was disassembled (which is a painstaking job as the whole system connecting to the turbo has to be taken out in order to get the CDA box out in order to get to the actual cone filter), cleaned with K&N cleaner and re-oiled with K&N oil. Then put back into place. Definitely, the filter looks as if it does the job of providing clean air:

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2nd service i did on my own, just before leaving to zim in december last year. That's when I first asked the question... isnt this air filter a little too small?? I mean i have 4.2 engine, BMC website says filters designed for below 1,600cc and above 1,600cc! See comparison to size 10 slop, me thinks I have for 1,600cc:

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Phone alpine developments and ask the question, why this filter? Their answer... Oh! I remember this job, we couldnt find place to fit the original filter (because of second batter) and having searched high and low the only thing they could find was this expensive filter from autostyle (filter = R600, CDA box = R1,800). Hmm... so I think... am i starving my engine of air with this small filter?! To me it feels like it. Then I think, what is impact of long term air starvation for diesel? I dont have answers for these questions, and I find it very difficult to approach mechanic with years experience will my non-experience and tell him i think maybe his solution for air filter not the best one? Frans?

So i do trip to zim (off-topic: Peter C im getting there in terms of the report.. maybe short answer is just go as soon as possible because it is awesome beyond words!) and whole time think this in back of my mind, but watching EGT's and water temp religiously.

so on saturday i planned for service. read lots on aussie forum about air filters etc, lots of options available there. space a general problem for TD42 with turbo and dual battery. Also plenty debate around K&N / BMC type filters and vs factory paper filter. In all honesty, i prefer to follow what will give engine longevity, but recognise challenge for space, and limited knowledge on the subject.

Anyway, back to saturday service, detach air intake pipe and air filter system. Pipe is mild steel, and the section straight after the air filer is showings signs of corrosion.... this doesnt look good to me, metal particles getting sucked straight into turbo?

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Pipe clear of normal dust, so filter working, but this makes me concerned. Should I be? I have been to local supa quick already, its 58mm pipe and they can bend for me in stainless steel. Will just have to weld connection points on pipe (oil breather, I think that its, and then mounting bracket). Is this the best think to do?

Also check all the connection points... seemed to be quite a bit of oil come out of the oil breather pipe when I squeezed it. Also looked at the connection to the actual turbo, the pipe seemed to have a lot of oil around it, also "inspected" turbo, although I have no idea what i'm looking for.

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Then i had also decided in my own mind that I need bigger air filter, aware of space limitations, so i head to autostyle to look for bigger K&N or BMC. Was at autostyle for very long time, debating many things with myself and gf's brother, eventually walked away 2 filters... a bigger BMC (that also manages to connect to the CDA) and then a standalone K&N filter (invoice says for honda s2000, but it was the biggest they had).

This pic shows relative sizes:

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Fitted the K&N first, then ran out of time to fit the other BMC. But feedback on the K&N - definitely more responsive throttle, much louder air intake noise, turbo very eager to spin, freeway performance better, EGT's ,maybe 200deg lower. Air being sucked is very hot being in the engine bay, part of reason didnt get to fit new BMC was that had to wait too long for intake system to cool down. K&N filter can be fitted without undoing whole pipe system!

Long term, I think BMC filter with CDA is good thing if i want to run a snorkel (which I do have thank JG) as it runs a pass-though type system and rubber piping can be connected to the box. Then with overland trips I probably need to have donaldson pre-filter to ensure cleaner air. I dont know?

I also dont know what the typical approach is with both n/a td42s and turboed td42s? Would love if both na td42 and turboed td42 guys maybe show pics of their set up, what filters are being used etc?

Sorry for the long post but this is something that is bugging me as I want what is best for my troll (i dont have kids, but i can imagine what it feels like!!)

thanks

David

[Peter Connan]

Hi Dave
Firstly, I want to make it clear that I am not a mechanic. what I am is a guy who designs control valves.

My feeling is that a relatively small filter not only starves the engine of air, but also the air that does go through is moving at relatively high velocity, which means it is more likely to carry dust particles through the filter. Also the rust in the pipework is definately bad for the long-term life of your engine and turbo.

Therefore I would definately replace that pipe, and Stainless is probably the best bet. In fact what I would be tempted to do is to put the snorkel on, connected directly to a new pipe leading to the turbo, and then bolt a ruddy great big Donaldson filter to the front of the roof rack, connected to the snorkel pipe.

While the blow-by oil is definately not an advantage, I doubt whether it is something you really need to worry about, but guys like Frans and Johndough can give you better advice here.

Cheers
Peter

[davejones]

Thanks Peter

I forgot to add a picture of the current set up since the service.

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I like your idea, but its really not practical! In terms of donaldson I was think a pre-filter on the snorkel would be a better solution, at least it doesnt require the roofrack to be on my patrol 24/7

[tour de frans]

Hello David.
You ask the right questions,and I know it not always possible to make the right answers work for certain aplications.But you are on the right track for your Patrol's breathing/Aircleaner.
I have a concern and would like to share it with you.(sorry for if I sound like someone looking for the wrong,I am not, but their is only one right.)
Stay away from freeflow airfilters.No matter what their name or how good they are.They are not designed for offroad.
In my language.( freeflow filter hou die bakstene uit en laat klippe deur.)
Allso in my case I dont care what they say on the box,in practice it do not fit our vehicles.
Second,if you could open the filter(cut the paper cardridge) and lay the paper flat.It will cover a smaller area than a normal paper filter.Even if they were se same size cardridges before you cut them.Paper filter better.
A open airfilter like in your picture are wrong.All the heat under the bonnet will push the intake air temp trough the roof.
The first filter in your car,where to small and a freeflow,but was better than a open filter.
I know it not always possible to have a big filter fitted,but you have to try.It will make a huge diffarance in the long run.
Look in the diy section,my turbo convertion.See the filter I manage to fit with the radiator overflow bottle still in place.Allso with the snorkel with its pipe linked on the filter drum.The drum were a 4.5 petrol efi model with its braket.You will have to move the 2nd battery.
I hope this help and I did not mess up your project.
Rdgs
Frans

[G-MAN]

Any performance filter is a no no on a 4x4!
Fine dust will get past the filter, a paper filter is best.

[Russ Kellermann]

Agree with all the above.

guys, will dave not have to have the fuel pump re calibrated / tuned, once the bigger factory spec airbox and filter is in place ? As i was under the impression that Diesel vehicles suck 100% of its available air all the time (unlike a petrol that increases its intake in proportion to throttle?) , therefore, with this smaller airbox currently in use, the pump would have been set to work with less air than it will get once the bigger factory spec unit goes back in, upsetting the balance between air-to-fuel , or am i off the track completely ?

IMO - i would rather have the motor sucking the right air than having a second battery in the bay, if need be, relocate the battery to the rear drawer system....?

[tour de frans]

Russ,the only ajustment will be Dave's right foot.If his filter system work,he will find less throttle for the same work.Yes,he can tune the pump,but the only tune he will find is more fuel,because with the better air the egt will cooldown and allow for more fuel to perform better.
That is the main secret,if you can keep the air cool and enough,you can add feul.
For example: 1bar boost and the fuel set @ 650deg egt.Now you up the boost,The only thing you did was to add air ,so the mixture will become weaker.The boost is higher but the engine safer,because the egt came down.If your engine and plumbing can handle the higher boost,you can up the fuel.
So on 1bar you had 650deg on a certain fuel setting.After the higher boost the egt came down to 550deg.With that same boost you up the fuel back to 650deg.And you will not beleave the diffirance in the more power. That is why a turbo diesel break when it leak boost or the airfilter is blocked,if the engine cannot breath after your more fuel setting for more power and you do not know,that is what killing a turbo diesel.The air got less,so the mixture go stronger.Sorry I got carried away,I can tell much more. This work only for a turbo diesel.
Cheers

[Russ Kellermann]

Yes this makes sense, shot Frans. I thought it would be the pump that would need adjustment to add more fuel, not his right pedal as you have described.Also, your description of leaking hoses and connections = overfuel/too rich , make sense.

Definitely agree with your explanation of - More Air + more fuel = bigger power at same EGT as little air and little fuel.

I have learnt again. nice one!

Dave you are in good hands here mate!

[Ross]

Ja, agreed...performance filters and off-road don`t mix, due to the poor filtration performance of fine dust.

I run K&N for my daily commuting and for the long haul tar portion of overland trips (I find my EGT`s run lower with the K&N installed, as effectively the increased flow means a leaner mixture), but I carry a normal paper filter that I use for trails or as soon as I hit the gravel roads.

[ricster]

Hmmmm... I got one of those #^$&#@ foam filters in my Maiden. I need to relook at getting a decent size paper filter in the box ( not sure if it is a standard Nissan airbox).... I'll take a photo and pose here too