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M151 Dry Air Filtration Conversion

Don’t get wet in the “bath” again!

Here is what the installed oil bath filter unit looks like.

Here is what the installed oil bath filter unit looks like.

by Gerald “Jerry” Gardner

In the M151, there was an oil bath air filtration system for all air coming in to the carburetor. This is the same type of system found on the WWII and Korean War-era jeeps and most civilian vehicles of this era and before. I could not understand why the newer model jeeps and trucks (from about 1960-on) did not have the less-messy and probably more-efficient system incorporated.

I have converted my GPW and M38 to the dry-type filtration systems. I decided to convert my M151 over to the dry system. I looked on the internet for a guide and found several different ways to do it. I received many comments and several suggestions on how to do this conversion.

A friend, Bob English, had done this on his M151A2 so I decided to copy his system. I did, but I also made a couple modifications from his as I went along. I did not use the K&N filter element that Bob recommended, because of the cost. I do not drive this M151 to justify the extra cost of that filter. (However, in my everyday driver Ford pick up I have converted it to the K&N system.) On my M151, I used the Fram CA8039 or Puralator A34878 element, because they are less than half the cost and will do a good job.

You have to remove the oil tank out of the filter can and cut part of the cover piece to make room for the filter. You also have to weld a couple pieces to firmly hold the filter in the canister. As far as I can tell, this is going to do a good job of filtering the outside air coming into the carburetor and it will not have the mess of the oil bath.

This conversion keeps the original look of the oil bath filter and no one will know that it has been converted to a dry filter element. The total cost of this conversion was less than $20 with me doing all the labor—it only took a couple hours to do.

How it looks...


Inside oil bath with oil tub installed.


Oil tub removed from oil bath filter unit.


Purolator A34878 filter cartridge.


Oil bath filter unit with filter cartridge installed.


Top of oil bath filter unit cut and plates welded.


Finished oil bath filter unit installed.

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