Factory Air Cleaners

[SilverThing]

One of the things that I like about the 181/Thing is the fact that 181/Thing owners restore and modify their vehicles to suit their needs and tastes. To quote a VW advertisement from the 70’s,” it can be anything.” I personally like my vehicles to reflect how the vehicle left (or could have left) the factory (or dealership) or modifications an owner could have done in period. Much of what I have researched and collected over the last 10+ years reflects that interest. By no means do I intend to imply that this is what others should do with their vehicles.

Having got that out of the way, I thought that folks might enjoy a brief discussion of the air filters that the factory offered for the 181. I apologize in advance for sometimes referencing chassis numbers and other times engine numbers. I will reference whatever I have access to in terms of factory (sometimes German military) documents, which isn’t always consistent in that regard.

181 129 613
Let us begin with part number 181 129 613, which is the first air cleaner supplied by the factory. If you are wondering about the tape on the outlet and warm air inlet of the subsequent pictures (and also the shiny plating on various bits), this particular piece is New Old Stock and is dated January of 1970 (I didn’t photograph the box, unfortunately). What is notable about this air cleaner (at least from the American perspective) is the warm air inlet thermostat, which features a spring loaded wax thermostat instead of the later vacuum operated valve that Americans are probably more familiar with. The wax thermostat is described as opening the preheat flap at 27.5°C. It is unclear to me as a non-native German speaker if that is the temperature at which the flap starts to open or should be fully open. There is a different wax thermostat that was introduced around January of 1971 that begins to open at 45°C, which “improves the driving behavior of the vehicle”. The higher temperature thermostat is listed as a replacement part in a technical bulletin dated April of 1971 and can be retrofitted to earlier vehicles. Other items of note is a small diameter straight down oil breather pipe and no connection pipe for fuel vapor recovery (American emissions equipment for folks in the rest of the world that might not know what I am talking about). This air cleaner was used until engine H 1 277 428 (late January / early February 1971) or AG 0 003 000 (31st of July 1971). In other words, this is until the end of the 1971 model year. The reason for the two different end dates depending on the engine is because in the early part of the 1971 model year the H series 1500 single port engines continued to be produced for military vehicles while the AG series 1600 dual port low compression engines were installed in civilian vehicles. After February of 1971 both military and civilian vehicles got AG series engines.

An overview shot:

Note the part number and date code:

The wax type thermostat is visible on the side of the air inlet:

The small size of the oil breather fitting is easy to discern here:

A close up of the service information on the top:

No fitting for the vapor recovery that the US got:

181 129 613 A
181 129 613 A is not mentioned in the parts books and microfiches that I have. Unfortunately, my parts documentation jumps from a 1970 parts book (with supplements until February of 1971) to a 1978 microfiche. I don’t want to speculate on this part since I don’t have any documentation one way or another. I would love to hear if anyone has one either on their rig or in their collection and what it is like.

181 129 613 B
According to the 1978 microfiche, air cleaner part number 181 129 613 B was introduced on engine AG 0 003 001 and was used until engine AG 0 010 157, which corresponds to August 1971 – July 1972 (chassis 182 2000 001 through 182 3200 000). Interestingly, the “B” air cleaners are skipped in the microfiches dated 1979 and 1982. Unfortunately, I don’t have an example of this air cleaner in my collection so I can’t discuss it in detail. I have opted to not include pictures I have from online as I don’t have the rights to use them. Based on the date range correlations, this air cleaner saw the introduction of the vacuum operated preheat system. One of the advantages of this new thermostat arrangement compared to the previous design is that the air going to the carburetor is prewarmed at idle and part throttle only. This helps the engine warm up better, run smoother, get better economy, and burn fuel cleaner like the earlier thermostats, but at full throttle, manifold vacuum drops off and the flap allows cooler air to be drawn into the filter and on to the carburetor. This cooler air is denser and helps the engine make maximum power, which is presumably what the driver wants when the throttle is opened all the way. There is a note in the German military manual TDv 2310/001-12 that air cleaners with the wax thermostat were installed on vehicles up until chassis number (mistakenly engine number in the 1973 edition) 182 200 007 (note that a digit is missing in that chassis number somewhere). Initially, I was thinking that this was a typo, but I am now second guessing myself. The VW technical bulletins I have regarding the new vacuum thermostat system are dated between August of 1971 and January of 1972 so it may be possible that very early 1972 models may have had wax thermostats, but it also appears that the bulletin dates don’t always correlate with when changes occurred. The owners manual that I have for 1972 models (Printed January 1972) does show the vacuum thermostat on the air cleaner when discussing air cleaner maintenance, but that could have easily been a mid-year revised image. I have seen one example of a “B” air cleaner dated 11/71 on ebay.de that has a wax thermostat. I had assumed at the time I saw it that someone had swapped thermostat housings with an earlier air cleaner (very easy to do), but I am starting to doubt that assumption now. I’d be curious what folks with “B” air cleaners have in terms of the thermostats.

181 129 613 C
181 129 613 C is also absent from the parts documentation I have. Similar to “A”, this one is completely skipped in the microfiches I have. Do you have a “C” on your rig? If so, how does it compare to the other air cleaners?

181 129 613 D
The next air cleaner pictured is 181 129 613 D, which is off my personal 1973. Hence the dents and scratches. It is dated May of 73 (like every other part on the vehicle that has a date). This air cleaner features the vacuum operated preheat/warm air flap that was introduced in the 1972 model year. This air cleaner still features a straight down oil breather pipe, but it has gotten larger and the air cleaner now has a fitting on the front (facing the front of the vehicle) that connects it to the vapor recovery emissions system, which is a US requirement to handle fuel vapors from the gas tank via an activated charcoal canister. I apologize that I didn’t get more pictures of it. I took it off my rig briefly for the photos and it still was full of oil so I was trying not to tip it too much. My 1978 microfiche indicates it is for engines AG 0 010 158 +, AL 0 000 001 +, AM 0 000 001 +, and AF 0 034 770+. That roughly correlates with the 1973 model year. Interestingly, it is not mentioned as being specific for US emissions, which has me wondering if the same air cleaner was used with the rest of the world and if those have the vapor recovery fitting or not.

An overview:

Close up of the part number and date code (not very visible unfortunately):

Close up of the larger oil breather pipe:

The vapor recovery fitting:

A top down view featuring the same service information seen earlier:

181 129 613 E
181 129 613 E is the next variation. Unfortunately, the sticker is covering up the date code on my example, but I have seen examples on ebay.de as early as November of 1972. My microfiches dated 1978, 1979 and 1982 don’t mention it at all. It differs from the “D” air cleaner in that features a 90 degree large diameter oil breather pipe instead of the previous straight version. I assume this was to simplify the oil breather hose and not require a hose with a 90 degree bend. That being said, 1975-1979 US market beetles with L-Jetronic fuel injection use the same 90 degree oil breather hose as the 181 “D” air cleaner so the hose isn’t hard to come by (at least in the US). The vapor recovery fitting is not present on my air cleaner nor on others that I have seen for sale online.

An overview shot:

Close up of the part number (date code covered by the service decal):

Angled oil breather fitting close up:

Side view:

Top view showing lack of vapor recovery fitting:

Overview of the angled oil breather hose mentioned:

Oil breather hose part number close up:

Paper Air Filter
In August of 1974 (the 1975 model year), a paper type air filter became available. The description of servicing the filter in the bulletin implies a different mounting arrangement in the engine compartment from the oil baths, but I don’t know specific details besides a quick release clamp holding the bottom. I have not seen any good pictures of the mount without air cleaner nor have I ever seen the air cleaner on a vehicle in person. Interestingly, the paper filter didn’t show up in owner’s manuals of that year, at least not the Spanish version that I have. Nor does it appear in the January 1976 German language manual. It does appear in the 1979 and 1980 model year manuals (both English and German). Also of interest is its absence from parts microfiches, which makes identifying the correct filter difficult. This NOS example (part number 211 129 607 K) is my best guess based on photographic evidence (primarily those later owner’s manuals). It is different from most type 2 paper filters in that it has a dust collection bowl before the filter element. I don’t know how effective the dust collecting bowl is, but it is an interesting feature. Before I move on, the factory did state that the carburetor idle jet for paper filters changed to 60 (otherwise sized 55 for the oil bath equipped vehicles since November of 1971).

Close up of the part number sticker:

Showing the various fittings:

Top down view:

Side view showing the dust bowl:

Dual Air Cleaners
Lastly, and probably of most interest to folks is the dual air cleaner system. As far as I have seen documentation for, the dual air cleaner system was first mentioned as an option (M 153) for the 181 in a technical bulletin dated June of 1971 specifically for “dusty countries”. The filters themselves carry the part numbers 211 129 611E and 211 129 612E. In the picture, the driver side example is NOS and the passenger is used. Of note, both air cleaners lack preheating unlike all the previous 181 air cleaners discussed. Presumably dusty countries are also hot, at least in the minds of VW, and didn’t require preheating. Based on the wax thermostat temperatures, I wonder if VW assumed an ambient temperature in dusty countries of at least 27.5°C. I would love to know which countries VW considered to be “dusty”. Interestingly, vehicles built before the introduction of the dual air cleaner option appear to have been anticipating it. While the mounting bracket for the driver side air cleaner is not present on those early vehicles, the lower panel on the driver side of the engine compartment has clearance for the oil bowl that could eventually go there. It doesn’t appear to be related, but at the same time as dual air cleaners were introduced (and in the same bulletin), the 31 PICT 3 carburetor for civilian models was changed from part number 181 129 027 A to 181 129 027 C. The jetting appears unchanged. The distributor paired with the civilian carburetor changed from 113 905 205 AJ to 113 905 205 AL at the same time so the carburetor change is likely related to changing from Dual Vacuum Dual Advance (DVDA) distributors to Single Vacuum Dual Advance (SVDA) distributors. The military (M 63) carburetor 181 129 027 B and distributor 181 905 205 remained unchanged at that time. Only a few months later in November of 1971, the civilian “C” carburetor would get revised jetting and the military carburetor would change to 181 129 027 D also with the same revised jetting. Nothing is mentioned about the dual air cleaners in the carburetor revision so the carburetor changes are likely unrelated in my mind.

Overview:

Showing the pieces separately:

Driver side air cleaner (NOS):

Close up of driver side part number:

Passenger side air cleaner (used):

Close up of passenger side part number

Close up of the passenger air inlet showing oil breather and preheating:

Underside of the dual air cleaner elbow:

Close up of the dual air cleaner elbow part number:

Follow Up Thoughts
For a while I ran a dual air cleaner system that consisted of the rare center elbow depicted above, my stock “D” air cleaner and a modified stock air cleaner for the driver side. The modified air cleaner consisted of cutting out and moving the outlet to the other side along with removing the oil breather and flap from the inlet. The city where I was living at the time is in a semi-arid high desert. It gets both hot in the summer and downright cold in the winter and my thinking was just because it may get dusty doesn’t mean it doesn’t get cold, hence dual air filtration while retaining carburetor pre-heating. I never got the driver side preheat setup the way that I wanted so that air cleaner was often blocked off during the winter. One thing that I did notice while running that setup is that the driver side air cleaner was getting almost all the air flow (when it wasn’t blocked off in the cold of winter) and unsurprisingly, the oil bowl was trapping more dirt than the other side. I think the weighted flap for the oil breather on the unmodified passenger air cleaner was preventing air flow except at higher engine speeds and loads. I’d be curious if other people have similar experiences since most dual air cleaner set ups I have seen retain the stock air cleaner on the passenger side.

Overview of the modified air cleaner before paint:

Photo showing brazing down to modify air cleaner:

I’m sure I will get a bunch of private messages asking me if any of the air cleaners are for sale. They are not at this time.

I hope you found this informative! Feel free to correct me if I made a mistake and please share any information or photos you may have of air cleaners that I glossed over or missed. Please let me know if you would like to see more posts like this in the future.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy

[Olli from NJ]

Wow! What a fantastic and well detailed post. Thank you. This should be a stickie.

Your post clarified something for me. A friend of mine came over to see the Thing that I had just acquired and when we were looking inside the engine compartment he asked why there was a curvature in the body on the driver's side exactly like there is on the passenger side where the air filter housing sits. I said that maybe VW made a dual air filter setup for the military. So it looks like my guess of a dual system was correct.

Thanks again.

Olli

[Wildthings]

Interesting that they went to a 90° PCV fitting as I have thought that would help by giving a bit more slope to the PCV hose so that it doesn't clog up with engine snot so badly if driven in cold weather. This was a major problem for me decades ago when a Thing was my daily driver and the hose would fill, block the flow of crankcase gases and then the oil would spew out of the engine everywhere. Had to clean that hose out frequently to keep the vehicle driveable.

Not a problem for the light summer use my present Thing gets.

[SilverThing]

I haven't ever had my breather hose clog, but I have gotten the engine snot as you call it. I don't think I ever correlated it with the cold weather, but it makes sense. I drive both of my VWs any time of year.

The snot makes quite the mess of the inside of the throttle body on my '75 l-jet fuel injected bug. At least in the Thing those vapors are getting mostly caught in the oil bath.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy

[Wildthings]

[SilverThing]

That's interesting. I have read about folks introducing filtered air into the rocker boxes (either via fittings in the valve cover or using type 3 style fittings in the head). I am forgetting if they were doing it to address engine snot or for some other reason.

250k miles is doing pretty good by any measure. My bug is just over 150k on the original engine. I replaced what appears to be the original clutch not too long ago (very faint VW logo in pinkish paint). I felt pretty good about that given that over 100k of the miles on the car are mine.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy

[Wildthings]

On my first Thing I added a fitting to the left rocker box IIRC. I read an article about doing this in one of the VW magazines that was available 50ish years ago.

At some point in the early 80's when I was in Alaska, I talked to a guy who drove his Beetle as his primary driver during the winter. No clue how many miles he was driving, but he said he had to change his oil every two weeks during the winter as so much water built up in his oil that it would slush up/freeze and the starter couldn't budge the engine.

[SilverThing]

Since my initial post, it has occurred to me that I didn’t do a good job of citing my sources. Ideally, I would have included scans of relevant bulletins and manual pages. Unfortunately, all my dealer binders and manuals are boxed up and aren’t readily accessible at the moment. The next best thing is Michael Knappmann’s webpage, which has many of the documents I referenced. http://www.michaelknappmann.de/bulli/michaelk/vw_bus_d/reparat0.htm#T1lokal They are, however, all in German and I find that pages occasionally have difficulty loading.

Bulletins I referenced in my previous post are: K-8 (Januar 1970), K-27 (Dezember 1970), K-40 (April 1971), K-45 (Juni 1971), K-59 (November 1971), K-60 (Januar 1972), K-87 (April 1973), K-98 (August 1973), and K-113 (August 1974). The numbering is on the German bulletins and not the English ones for some unknown reason. At least that is the case in the US and Canada service binders.

181 129 613 B revisited
Through the generous help of one of our other members (who wishes to remain anonymous), I now have an example of air cleaner part number 181 129 613 B. It is dated 10/71 so it is an early example based on the date ranges in my first post. Also of note is the thermostat, which is the vacuum operated type. This confirms what official VW documents have to say. Closer inspection of the example I saw on ebay.de (item number 314895673963) reveals the vacuum thermostat control fitted in the air cleaner outlet, which I had missed earlier. My apologies for any confusion this may have caused anyone. Below are pictures of my example

Side overview:

Opposite side overview:

Close up of the part number and date code:

Front side (note no vapor fitting):

Top down overview:

_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy

[bnam]

My first post in the Thing forum. Great post on these airfilters. There are at least a couple of Beetles here with option m153 “double oil bath air filter with serial cyclone filter”. One belongs to a friend and is parked in my garage. He’s missing the left side filter which he is trying to track down.

To your question, India is one of the countries which were considered dusty. Other specs for counties like India include m240 - “engine with dished pistons for low octane fuel”, m103 - “heavy duty shock absorbers”, m105 - “harder rubber bonded metal mount for gearbox suspension”, and m006 - “frame supported on front axle with heavy duty rear torsion bars”

Byas
_________________
1971 1302LS Convertible (RHD) owned since '74
Click to view image
1965 Karmann Ghia Coupe - under restoration
1966 Fiat 1500 Cabrio (with 1600 Twin cam)
1952 Citroen TA 11BL

[SilverThing]

Thanks for your post bnam and welcome to the Thing forum!

That is good to know that India is one of the countries where the M153 option is commonly seen (at least on beetles). I assume that the 181/182 is rare in India, but maybe I am mistaken.

The heavy duty suspension parts is interesting. M105 exists in the 181 option code list as well, but appears to have only been used up until the end of the 1972 model year. I have thought that it was a strange option for the 181 because I would have assumed the 181 would have come with heavier duty rubber mounts as standard given that it is an off-road intended vehicle. I'm not aware of M006 or M103 as being 181 options.

What octane fuels were available in India back in the day? The M240 engines typically were rated for 83 research octane (ROZ or RON) vs the 91 research octane of "normal" engines. Unfortunately, I haven't seen any published motor octane (MOZ or MON) ratings for VW engines. I've been curious if lower octane rated engines was actually necessary or not back in the day.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy

[bnam]

[SilverThing]

At least on the 181, M105 was both the front and rear mounts. Type 181 M105 rear mounts are part number 111.301.263B and the front is 311.301.265C.

M006 would not be needed on the type 181 as all 181 had front beam reinforcements. The shock towers were reinforced (compared to ball joint beetles) and there were braces from the beam ends to the chassis. That is on top of the heavier duty ball joints and unique spindles.

Regarding M103: there are two part numbers listed for the front shock absorbers of 181. The early 181 had 181.413.031B. Mid-73 and later had 181.413.031D except for M63 (military) vehicles, which continued to use the early shocks. The rears consist of 181.513.031 for early vehicles. Mid-73 and later had 181.513.031E except for M63 vehicles, which had 181.513.031B. The M63 option code doesn't specifically mention heavier duty shock absorbers, but it is implied in microfiches by them having different shocks.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy

[bnam]

Thanks! I was not aware of the standard reinforced beam/shockmount on the Typ18s. Makes sense. The beetle m105 parts are the same as the ones you've listed.

The m103 shocks in the Typ1 parts manual are listed as heavy duty. Different part numbers though.
113 513 031 M - upto 70 (and for 70-on swing axles)
113 513 035 - from 70 on.

Sorry to derail the airfilter thread.

Are there any sites where we could find the stock left airfilter that is missing on the car we have?
_________________
1971 1302LS Convertible (RHD) owned since '74
Click to view image
1965 Karmann Ghia Coupe - under restoration
1966 Fiat 1500 Cabrio (with 1600 Twin cam)
1952 Citroen TA 11BL

[Wildthings]

This is a filter for an industrial engine that cold be made to work.

It's a bit larger than the T181 filter.

[SilverThing]

Bnam, do you have a part number for the existing air cleaner? The dual air cleaner sets I have often seen in the parts books will be nearly identical numbers except for the last number. For example, in my first post the air cleaners ended in 611E and 612E. I'm not familiar with the air cleaner options on beetles to know how many variations there might be.
_________________
"I like how everyone likes talking about Zeke's Thing yet he's the only one that's ever seen it." - Katie
"I've seen pictures..." - Jeremy