MB GPW Dry Air Filter Conversion Done

1941 - 1945, MB, GPW modifications, sugestions, and ideas, official MWO's and unofficial WWII field mods NO EBAY or COMMERCIAL SALES.
tsmgguy
G-Captain
G-Captain
Posts: 797
Joined: Tue Apr 26, 2005 3:07 pm
Location: West of the Pecos, TX, USA

MB GPW Dry Air Filter Conversion Done

Post by tsmgguy » Sun Mar 11, 2012 6:11 pm

Just a little after action report following my conversion of the MB's oil bath air filter to a dry element. I used this procedure and parts, with the Wix filter listed:

http://1945mb.com/c-80-G503_WWII_Jeep_O ... ilter.aspx" onclick="window.open(this.href);return false;

I'll tell ya, though, it wasn't as easy as one would think when looking at the short article linked above. The foam rubber "doughnuts" from McMaster Carr were both far larger in diameter than the OD of my original later MB air filter housing. They look almost nothing like the rings in the photos above, being far flatter and larger. I suspect that MC shipped me larger seals than ordered, but I'm not certain of this. Anyway, I could barely cram one seal into the oil pan. The other was simply far too large and would not fit into the filter cannister without creasing and bunching up unacceptably. I ended up X-Acto trimming a pie slice out of it, reducing the original diameter by somewhere between 1/6 to 1/8. I rubber cemented the trimmed ends together and the fit was better.

After buttoning everything back up, the old MB started right up, as it always does. It could just be my imagination, but the old girl seems just a little bit more responsive after this mod. At any given speed, the pedal doesn't seem to be as near to the floorboard as it did. Acceleraton seems marginally better. Idle is the same, with the same occasional *chuf*.

Time will tell if this was a worthwhile mod, I suppose!
Last edited by tsmgguy on Mon Mar 12, 2012 6:25 am, edited 3 times in total.
Willys MB 236426, Hood 20336549, DOD 5-20-43
Piper L-4A "Grasshopper", Sn. 10371, USAAF 43-29080, DOD 5-28-43


thidisbogus
G-Major General
G-Major General
Posts: 3180
Joined: Sat Jul 24, 2010 9:49 pm
Location: Magnolia, Texas
Contact:

Re: MB GPW Dry Air Filter Conversion Done

Post by thidisbogus » Sun Mar 11, 2012 10:12 pm

I ran into the exact same problem and had to take an exacto knife and trim those donuts. What I think the issue is in retrospect is the oil pan on the bottom was too shallow. I recently purchased an NOS and it is deeper than the one I had on it.

Schultzd
G-Colonel
G-Colonel
Posts: 1611
Joined: Sun Jun 26, 2005 6:39 pm
Location: Saint Stephen, MN

Re: MB GPW Dry Air Filter Conversion Done

Post by Schultzd » Sun Mar 11, 2012 11:06 pm

Something must have different for you. Mine went exactly as described in the article, took maybe 2 minutes at worst.

Dan
Dan Schultz
Retired USA SFC
GP 9275
GPW 14944 M38 MC70324
M38A1 MD20035
K-38 Lineman Trailer

LetsGo325
G-Sergeant Major
G-Sergeant Major
Posts: 158
Joined: Sun Jun 15, 2008 8:12 pm
Location: Washington State

Re: MB GPW Dry Air Filter Conversion Done

Post by LetsGo325 » Mon Mar 12, 2012 12:40 am

Thanks for the post sir, I was considering it myself and it is nice to hear that you see slight improvements in response or acceleration, immagination or not. I will have to try this conversion soon!
1943 Ford GPW, "Chattanooga ChooChoo"
325GIR, 82ndAB Living History

tsmgguy
G-Captain
G-Captain
Posts: 797
Joined: Tue Apr 26, 2005 3:07 pm
Location: West of the Pecos, TX, USA

Re: MB GPW Dry Air Filter Conversion Done

Post by tsmgguy » Mon Mar 12, 2012 7:42 am

I was struck by how clean the oil in the air filter pan appeared before I disposed of it. This was always the case, even though I live in the dusty desert Southwest. I was tempted to just pour the oil into the engine sump, but didn't as there's probably contamination that can't be easily seen. That old wet air filter worked! Also, it never leaked, even though there's no gasket.
Willys MB 236426, Hood 20336549, DOD 5-20-43
Piper L-4A "Grasshopper", Sn. 10371, USAAF 43-29080, DOD 5-28-43

LetsGo325
G-Sergeant Major
G-Sergeant Major
Posts: 158
Joined: Sun Jun 15, 2008 8:12 pm
Location: Washington State

Re: MB GPW Dry Air Filter Conversion Done

Post by LetsGo325 » Mon Mar 12, 2012 10:48 am

Being new to the hobby of jeep restoration five years ago, I had never heard of that type of oil bath air filter when I was putting an original 4 cyl. back in the jeep (my jeep came with a 6 cyl flathead and a pancake air filter). My dad (in his 50's) of course knew the type and told me all about it, It was really cool to put it back together how it was supposed to be, and I've never had a leak or any trouble with the oil bath but I still feel if I can get that dry filter and possibly improve at all in how it runs and accelerates I'm all over it!
1943 Ford GPW, "Chattanooga ChooChoo"
325GIR, 82ndAB Living History

User avatar
Nikko
G-Brigadier General
G-Brigadier General
Posts: 2171
Joined: Thu Jan 06, 2005 3:01 am
Location: Oslo Norway
Contact:

Re: MB GPW Dry Air Filter Conversion Done

Post by Nikko » Mon Mar 12, 2012 12:28 pm

Hi Folks
http://www.richardmilitaryparts.com.au/FGPW.html" onclick="window.open(this.href);return false;

look att the picture it is a urethane/plastic spacer 2 stk.and 1large O-ring
,I have one kit inn my air cleaner 5.min innstall
the engine gets better air flow/breathing and a bit more throttle/accelration response is also a bit better :D
no more messy oil change for me

Cheers From The North
Nikko
1943 GPW 135099
1949 Spen 1/4 t trailer S/N 158
and a lot of nuts and bolts :-)

User avatar
Tim52
Sergeant Major of the Gee
Sergeant Major of the Gee
Posts: 265
Joined: Sat Mar 06, 2010 2:45 pm
Location: Rocklin CA (Northern CA)

Re: MB GPW Dry Air Filter Conversion Done

Post by Tim52 » Mon Mar 12, 2012 10:36 pm

I did the same conversion with the McMaster Carr rings and things fit perfectly in my original filter. No trimming was required.
CDR USN (RET)
Patrol Squadron 46 "Grey Knights"
Naval Flight Officer
Gulf War Veteran

45 GPW 271750
frame/engine match no data plates (DoD est. July 5 '45)

tsmgguy
G-Captain
G-Captain
Posts: 797
Joined: Tue Apr 26, 2005 3:07 pm
Location: West of the Pecos, TX, USA

Re: MB GPW Dry Air Filter Conversion Done

Post by tsmgguy » Wed Mar 14, 2012 10:45 am

Tim52 wrote:I did the same conversion with the McMaster Carr rings and things fit perfectly in my original filter. No trimming was required.
Interesting! Beside being too large, the rings MC sent me had a pair of holes in each flange. These don't show up in the conversion photos linked above. I've contacted MC about this, and frankly, would like for the correct rings to be furnished, as ordered.
Willys MB 236426, Hood 20336549, DOD 5-20-43
Piper L-4A "Grasshopper", Sn. 10371, USAAF 43-29080, DOD 5-28-43

mrbill
G-Second Lieutenant
G-Second Lieutenant
Posts: 573
Joined: Mon Jan 24, 2005 2:52 pm
Location: Pittsburgh, PA

Re: MB GPW Dry Air Filter Conversion Done

Post by mrbill » Wed Mar 28, 2012 1:31 pm

tsmgguy wrote:
Tim52 wrote:I did the same conversion with the McMaster Carr rings and things fit perfectly in my original filter. No trimming was required.
Interesting! Beside being too large, the rings MC sent me had a pair of holes in each flange. These don't show up in the conversion photos linked above. I've contacted MC about this, and frankly, would like for the correct rings to be furnished, as ordered.
Howard, did you ever get an answer from McMaster-Carr? I just received what looks to be the same gaskets that you got.

Regards,

Bill
1945 Ford GPW 268739 from the Dallas, TX plant.

User avatar
tamnalan
G-Lieutenant General
G-Lieutenant General
Posts: 6309
Joined: Sat Feb 02, 2008 9:58 am
Location: SW Oregon
Contact:

Re: MB GPW Dry Air Filter Conversion Done

Post by tamnalan » Wed Mar 28, 2012 5:57 pm

You all are using the McMaster Carr 2793K81 rubber rings?

They dropped right in for me too. No trimming at all. I'm also using the Napa 2036 filter. The rings looked just like the ones shown in the photo. I did this mod about 3 years ago. Perhaps McMaster Carr changed the specs on that number since then.
Alan W. Johnson
_______________
MB, 201453, "Lt Bob"
MB, 1942, not stock
M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939

mrbill
G-Second Lieutenant
G-Second Lieutenant
Posts: 573
Joined: Mon Jan 24, 2005 2:52 pm
Location: Pittsburgh, PA

Re: MB GPW Dry Air Filter Conversion Done

Post by mrbill » Thu Mar 29, 2012 1:27 pm

tamnalan wrote:You all are using the McMaster Carr 2793K81 rubber rings?

They dropped right in for me too. No trimming at all. I'm also using the Napa 2036 filter. The rings looked just like the ones shown in the photo. I did this mod about 3 years ago. Perhaps McMaster Carr changed the specs on that number since then.
Yup. Just checked the packing slip and it says 2793K81 with a description of Toilet Bowl-to-Outlet Sealing Ring for 3" & 4" Waste Pipe, 3/4" Thick Sponge Rubber. Diameter appears to be 6 3/4 inches.

Bill
1945 Ford GPW 268739 from the Dallas, TX plant.

User avatar
WILLYS45
G-Master Sergeant
G-Master Sergeant
Posts: 113
Joined: Mon Feb 06, 2012 3:05 pm
Location: Big Sky Country

Re: MB GPW Dry Air Filter Conversion Done

Post by WILLYS45 » Mon Apr 23, 2012 12:55 pm

I am skeptical of chopping up the rubber seal rings to hodge podge this thing back together.
Last edited by WILLYS45 on Wed Feb 15, 2017 6:54 pm, edited 1 time in total.
MVPA Member #34754
MMVCC Member
VFW Life Member
AFSA Life Member
1945 Willys MB
Body/Frame #440438
Engine # MB487286

thidisbogus
G-Major General
G-Major General
Posts: 3180
Joined: Sat Jul 24, 2010 9:49 pm
Location: Magnolia, Texas
Contact:

Re: MB GPW Dry Air Filter Conversion Done

Post by thidisbogus » Mon Apr 23, 2012 6:24 pm

I know what it is for sure....there are two different bottom pans available. One is shallower than the other. I know this, because I had to chop mine down, then sourced a better NOS pan and it is deeper so now I have to source the rings again and will not have to chop them.

User avatar
WILLYS45
G-Master Sergeant
G-Master Sergeant
Posts: 113
Joined: Mon Feb 06, 2012 3:05 pm
Location: Big Sky Country

Re: MB GPW Dry Air Filter Conversion Done

Post by WILLYS45 » Tue Apr 24, 2012 1:00 pm

The bottom fits fine enough, almost perfectly actually, it is the top part of the housing. The housing has an inner liner that is about 5 & 1/2 inches wide and the ring is about 7 inches without cutting it. If the inner lining was not in the can, I think I could make it work, but the liner looks like it is not removable in anyway.
MVPA Member #34754
MMVCC Member
VFW Life Member
AFSA Life Member
1945 Willys MB
Body/Frame #440438
Engine # MB487286


Post Reply

Return to “MB GPW Modifications”

Who is online

Users browsing this forum: No registered users and 12 guests