K+N Filters - for a Diesel ?? - PeachParts Mercedes-Benz Forum

ISmellDiesel · #1 09-13-2004, 02:27 AM

I used K+N filters in my previous gasser cars and they did a great number on performance and fuel consumption.
anyone have any experience on a Diesel clunker? Would it make sense to shell out the 40-some bucks to get a re-usable filter? I find mine all the time clogged with oil and toss it for a new Hengst Filter

#2 09-13-2004, 11:55 AM

Look here:

K&N air filter on MB diesels

Louis.

boneheaddoctor · #3 09-13-2004, 01:21 PM

Quote:

Originally Posted by mb123mercedes

Look here:

K&N air filter on MB diesels

Louis.

I agree. Also if you don't keep it properly oiled its not going to even do half its job. And I would venture a guess that most are not properly oiled. That thread will give you a lot of info.

vwbuge · #4 09-13-2004, 07:41 PM

There are some people here that will insist that any improvements in air intake, including a K&N filter will do no good on a diesel.
BS...!!!!!!!!!

emissions swap...part one

Old300D · #5 09-13-2004, 07:56 PM

Quote:

Originally Posted by vwbuge

There are some people here that will insist that any improvements in air intake, including a K&N filter will do no good on a diesel.
BS...!!!!!!!!!

emissions swap...part one

I am not going to use a re-useable filter because the test results from the dieselpower site show they pass more dirt. Since my turbo-diesel will be used for commuting, I want clean air, and be damned with a slight restriction. I am, however, opening the exhaust, and when I invest in an EGT gauge, I will be increasing boost and fuel.

whunter · #6 09-13-2004, 08:40 PM

Why do you think that a poor company like K&N knows more than all the OEM's and their race teams?

Fact, K&N passes more grit into any engine.
Fact, diesels need better filtering than gassers.
Fact, The life of any engine running on the road with a K&N filter will be shorter.
Fact, the only time a OEM race team will use K&N is when the total engine life is measured in minutes.
Example = 720 minutes.

If you choose to pit your valves and pistons; it is your choice and right.

Please remember that new members will be seeing your posts, and might think it a good idea, when it is not on a diesel.

There is NO relation between gas and diesel engines, the engineering, duty cycle and service needs are different.
Using something from a gasser on a diesel is a great way to end up with scrap metal.
Ask a few members what overhaul total cost is for a diesel, if that does not scare you into caution.

Gilly · #7 09-13-2004, 09:36 PM

I dislike K&N, but what does this mean:

Quote:

Fact, diesels need better filtering than gassers.

Gilly

psfred · #8 09-13-2004, 10:56 PM

Aftermarket filters often reduce hp and airflow by being an inappropriate design (or more truely, not designed at all, just assembled out of large aluminum tubing). Aerodymanics are as important inside the intake system as they are for airplane wings, any odd bit of pipe won't necessarily work better.

Witness the threads in the vintage forum where an aftermarket intake system serious compromised intake effeciency on a 76 230/8 -- black smoke out the back, no power, etc. Cured by restoring it to factory. Also, a member ran his 280 SE 4.5 on a dyno with and without an air filter while he had the chance - hp was down about 5% without the air filter and housing......

K&N filters are fine for racing on dirt tracks where you end up with half the filter covered in dust, but do not do a good enough job on the street. If you DO gain any hp, it will only be at full throttle/high rpm, and where do you drive like that? Not often, I'd bet!

Peter

whunter · #9 09-13-2004, 11:17 PM

Quote:

Originally Posted by Gilly

I dislike K&N, but what does this mean:
Gilly

Hello Gilly
Diesels are all interference engines.
Just look at the machining specifications for any diesel.
Compare them with a 1970 Chevy 350.
Also please consider the effect of grit: sand blasting the valve and seat, rings and cylinder walls.
Durability testing and common sense shows that a low micron filter = longer engine life.
If the only factor is raw power and low mass, you surrender durability life for it.
If you want long service life and low maintenance, you use the largest surface - lowest micron filter you can afford.
MB did a compromise; they call for a low micron, medium size filter.
If you want greater air flow than this allows, the best thing possible is to install a Heavy truck filter box and plumb it to fit.
The killer is the cost.
I would love to fit one of these to my 300SD.

http://www
.peterbilt.com/index_new_mor.asp?file=1565&archivedate=

psfred · #10 09-13-2004, 11:49 PM

All modern engines are build to much the same spec these days, as were all MB engines that I know of. So are all the Volvo engines I've worked on. Ditto for VW after the flat fours.

They won't pass emissions requirements otherwise.

A 1970 Chevy 350 isn't a very good comparison, they were about the worst engine in production at the time -- crankpins up to 0.030" off center (in all directions!), lifter bores as much at 0.100" off center and up to 6 degrees out of line, piston clearance of 0.005" and higher, etc. Very sloppy from worn out production equipment, then nearly 20 years old (some of it older).

Peter

RLD · #11 09-14-2004, 03:26 AM

One little thing that everyone seems to overlook about using low restriction air filters on old diesels , is that when you lower the restriction to the outside air, you reduce what little vacuum there is in the intake system. This has one nasty little side effect on old diesels in that it reduces the scavanging effect on the crancase breather. When this happens, blowby gasses arent removed from the crancase as well, causing crancase pressure to rise, which in turm can cause oil to start belching through the breather and get sucked into the intake increasing oil consumption. it can also lead to oil leaks in other places.

And they do let more dirt through which has to go somewhere. much of it winds up in your oil and not all of it will be caught by the oil filter so oil quality will suffer.

That said, I've been thinking of trying a K& N on my 300sd...Hey , at least I know what I'm in for

CHAPP · #12 09-14-2004, 05:03 AM

Well...I put a K & N on my 84 300SD and after 30K it started smoking like crazy. Head & valves were fine but compression was shot in a couple of the cylinders. I don't know if I can blame the filter, the engine had 320K on it, but it makes sense now. I read a couple of K & N threads here and got enough nerve to run the K & N on my 83 300SD for a about a thousand miles, and then switched to the stock filter. No difference in power or mileage I could detect, but it sounded more powerful with the K & N. I like the idea of a re-useable filter, but will not donate another engine.

How about a foam pre-filter on the outside of the K & N filter...I have seen these on some high performence air filter systems?

BobK · #13 09-14-2004, 06:41 AM

I change my air filter probably twice as often as recommended. Change oil and filter pretty often and use Mobil1 to boot. Probably cost me $100 extra per year per car. .......and engines cost how much? Plus I'm getting too blasted lazy to do many engine swaps anymore. (gotta do one on an all wheel drive Eclipse this week...arrrgh!)

TonyFromWestOz · #14 09-14-2004, 08:59 AM

Quote:

Originally Posted by RLD

One little thing that everyone seems to overlook about using low restriction air filters on old diesels , is that when you lower the restriction to the outside air, you reduce what little vacuum there is in the intake system. This has one nasty little side effect on old diesels in that it reduces the scavanging effect on the crancase breather. When this happens, blowby gasses arent removed from the crancase as well, causing crancase pressure to rise, which in turm can cause oil to start belching through the breather and get sucked into the intake increasing oil consumption. it can also lead to oil leaks in other places.
SNIP

Isn't this a contradiction?
If the crankcase pressure isn't lowered (see below), then the blowby gases will lead to an increase in crankcase pressure, which WILL then flow to the inlet manifold thru the breather.
There should be no liquid oil belching thru the breather. The oil separator in the valve cover, or an external one, should prevent any such event.
The crankcase pressure would not be likely to increase more than one or two PSI above ambient
By the same token, the vacuum in the inlet should NEVER increase beyond one ot two PSI (2 or 4 "Hg). If it does, your engine is suffocating and the air cleaner should be replaced.
Would that difference in pressure cause oil to "belch"?
I don't think so.

quiettype · #15 09-14-2004, 09:58 AM

Greetings! I added the air filter and oil separator kit on my 1984 300d. It works fine.It draws outside air which can't hurt. Gets rid of the OEM air cleaner, oil separator etc. which makes me happy.It seems to require oiling and frequent checking.No problem there. Yes,the turbo spools up quickly with no lag.The turbo intake stays very clean.I think I'll keep it.
The last couple of posts are interesting in that they refer to blowback gases and pressure changes inside the valve cover. After my installation I noticed an oily area around the elbow connection to the valve cover.Gases were escaping.I removed the 1/2" "kit" hose,from the elbow to the new oil separator and replaced it with four feet of 3/4" heater hose.Since then no more oily signs of gas escaping under pressure.
What do you think would be the long term effects of excessive back pressure inside the valve cover? Not enough pressure to stall the motor.Would it damage the head gasket?Thanks