Modern air filter for M38A1

[timjuhl]

Don't beat me up too bad but I came up with a simple modification that allows me to use a modern paper air filter with my M38A1. My reasons for doing so: 1.) Less Mess 2.) Better filtration(?) 3.) More airflow (supposedly).
It is also a lot easier to inspect than the filter media used in the oil bath.

I made my adapter from parts readily available from your local hardware and NAPA Auto store.

1.) I discovered that a NAPA Gold 6188 filter fits perfectly into the existing filter support ring.
2.) To cap the other end, I found that an ordinary paint can lid is a perfect fit as well! Indeed, it has a lip that seals around the bottom edge of the filter like it was designed for the job! The top of the paint can lid is against the filter.
3.) What I did was get a 1/4 inch by 7 inch carriage bolt (threaded full length) and screwed it in from the existing top support bracket.

4.) Drilling a 1/4 inch hole in the paint can lid, I turned a pair of nuts and a washer down the carriage bolt to create a center support just slightly lower than the edge of the filter so as to apply tension on the bottom lid.

5.) Sliding the paint can lid in place I made sure that the lip sealed against the filter.

6.) I secured the filter in position by placing a rubber washer and steel washer over the bolt and securing it with a wing nut.


The nice thing about it is that none of the original components are modified in any way. If you want to restore it to the original oil bath cleaner you can swap them in five minutes.

Tim
_________________
Tim Juhl
1952 M38A1
1946 Aeronca L16A Army Liaison Aircraft

[wilfreeman]

Good job Tim! I was thinking of modding mine a few months back also. The only drawback I can see it's that it wouldn't be as good in a really dusty environment - or would it? I dont know how efficient the oil bath is. I agree that it would be alot less messy and would breath better, so maybe more power? Thanks for the part # also - looks like I have a Jeep project for my days off after all!
_________________
Matt
1953 M38a1
1964 USMC M38a1
'51 USMC M100 trailer, '54 M100 trailer, '90 M101a1 trailer
Http://wilfreeman.wordpress.com (M38a1 build blog)
http://m38a1usmc.wordpress.com (USMC M38a1 rebuild blog)

[G740]

I gotta ask why everyone is $&% bent on changing the filter elements on these old trucks to a paper type unit. I hope you all realize that the only reason they EVER changed away from the more efficient oil bath air cleaners is to SELL you parts. The auto manufacturers wanted to sell more spare parts so they created throw away filter elements.
Just my .02 worth.
John

[frankthecrank58]

if you look at all the after market air filters like K&N or Airaid et al, you'll notice they have an oily feel to them and they sell recharge kits with an oily substance. must be because the oil attracts MORE dust than straight paper. paper is more convenient at the cost of efficiency. i'm sticking (pun intended) with the oil bath.
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Frank 1952 M38 Cdn CAR 52-31812,1952 M38 Cdn F100005, 1967 Jeepster, 1999 XJ, 1999 TJ " rubiCLONE"

[timjuhl]

I knew I was opening a can of worms..... Oil bath, paper, it's up to you. The nice thing about my setup is that no one can tell without opening up the air cleaner can.

According to what I've read, a paper filter should be more effective at filtering out very fine dust particles than the oil bath type. Plus, you can extend it's service life by popping the filter out of the can and blowing it off with compressed air. In normal use a paper filter is supposed to be good for 30,000 miles. Even if I changed it every 6000 miles or so I'd still only need to buy a filter every couple of years.

Tim
_________________
Tim Juhl
1952 M38A1
1946 Aeronca L16A Army Liaison Aircraft

[JeffreyE]

I did just about the same thing for my running jeep.
Basically have 2 jeeps cj2a for running around m38 for making perfect.
I think its important to have that running jeep... what is the point of all the work if you cant play?
Good work and cheers

[skyjeep50]

Great post! Thanks!
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1951 M38

[RICKG]

http://willysmjeeps.com/v2/modules.php?name=Forums&file=viewtopic&t=4451&start=0&postdays=0&postorder=asc&highlight=bath
I did a similar conversion on my M-38 2 yrs ago and was met with the
Pro and Con discussion as should be. After 2 yrs i'm still satisfied with
the conversion and knowing it's not a permanent mod. The important
thing is i'm up and runnin and not lookin back!!
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keep 'em rollin'
RICKG MC 51986 DOD 01-52, '50 CJ3a

[wesk]

The pro's and con's are always fun to read but the effort put into a mod or update should always be rewarded. It is the result of our labors that is a great part of the satisfaction we get with this hobby.

With that said the impetus involved with the industry switch to throwaway paper element filters is really the ease of maintenance and the benefit to the parts manufacturers. Very little has to do with volume metric efficiency or improvements in particulate restriction in induction systems.

The tons of data out there are mostly biased opinions as with any product defense. Bottom line is the oil bath aircleaner is still in production and use in heavy industrial applications and it works very well.

It is obvious if you read enough hype and fact that the paper element in extreme dusty conditions is not adequate and must be augmented with sticky films to control the dust entry whereas the flow dynamics of the oil bath unit is more then adequate to keep this fine dust out of the engine.

So some of the valid reasons for conversions to paper elements are:
1-Ease of maintenance
2-Not messy to deal with
3-Will work in jeeps not used off road a lot in extreme dusty conditions.

Some valid reasons not to convert are:
1-You want a truly stock jeep.
2-You intend to operate in extreme dusty conditions.
3-You enjoy not only ownership of a classic jeep from a classic period in automotive history but the experience of maintaining and operating one under identical conditions.


_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

[wilfreeman]

That's all I needed to read - the pros and cons. I was not sure whether the oil bath was as efficient as a paper filter. I knew that they were prone to clog in alot of dust (4 wheeler experience). I do not drive my Jeep daily ( only 5-6 times a month), so the maintenance is not really an issue either since I will only be cleaning it a couple of times a year or so.

I gues I'll have to find something else to do with her this week off then - maybe I'll adjust her timing and just put some more miles on her, becaude it looks like another nice(high 60s) weekend!
_________________
Matt
1953 M38a1
1964 USMC M38a1
'51 USMC M100 trailer, '54 M100 trailer, '90 M101a1 trailer
Http://wilfreeman.wordpress.com (M38a1 build blog)
http://m38a1usmc.wordpress.com (USMC M38a1 rebuild blog)

[timjuhl]

Time to stir the pot again I've been testing my modified air filter and so far am pleased with the results. I have come up with a couple of potential modifications and thought I'd throw them out there for those that are thinking of doing something like I did. I have driven the Jeep with both mods and found no change in performance. In normal driving I am not using the sleeve but I am using the deflector described below.

1.) Since the air enters the filter can through a small opening, I thought I'd adapt one feature of the oil bath filter and see what happened. Oil bath filters rely on the air taking a number of sharp turns so that inertia will throw the heavier particles into the oil cup at the bottom. I installed a deflector made from 0.025 aluminum on the side of the filter that is placed by the opening. The air is forced to take a sharp turn, either right, left, or down. My hope is that it will prevent one part of the filter from being packed with dust as well as direct some of the heavier particles into the bottom of the can. Note, you should remove the oil cup at the bottom of the can so there is a open path for the dust particles to fall. In my Dodge Sprinter I always have sand collect in the bottom of the filter box. Since I drive mostly paved roads that seems a bit strange but better in the box than in the engine. I'll tell you what happens with the Jeep after I've used the filter for awhile.


2.) For those concerned about operating in really dusty environments, a simple foam sleeve can be adapted from readily available foam elements designed for shop vacs. Trim one inch off the bottom, treat with filter oil from an auto parts store and install. The foam can be removed and cleaned with dish soap and water and reused if desired.


Remember, I'm not suggesting what you should do, only sharing what I've done.
Tim
_________________
Tim Juhl
1952 M38A1
1946 Aeronca L16A Army Liaison Aircraft