Flathead 6 Air Filter

[meadowbrook]

Hi folks.

I am wondering if anyone here has had this issue with the oil bath air filter.

When I fill mine to the stamped fill line with the prescribed 50 weight oil, the engine sucks it out (big smoke cloud) to a lower level.

Also, the carb always seems to be wet with oil.

Am I missing something?

I am about to cut up the upper portion with the filter media and adapt a paper filter.

Any tips appreciated.

[Don Coatney]

How much oil does it take to fill it when empty?

[randroid]

meadowbrook,

The oil bath filters run a little backwards from what we're used to in that there is a line showing the oil level when it's full of gunk. Methinks perhaps you're putting in oil up to that line, which would cause it to overflow into the carb.

Several threads have been posted about converting the innards into a paper filter and the general consensus seems to be that other than losing the nostalgia effect of retaining the original, it's a good idea . Paper filters will catch smaller particles, are easier to clean, and there is no outward change in appearance.

-Randy

[greg g]

The filter works on the principle of the air changing directions. The air should not actually pass through the oil. Air entering is accelerated toward the oil then forced back up, as it makes the sharp turn, the solids have too much inertia to make the turn and fall out of the air stream to be trapped by the oil. The air movement also causes some of the oil to be aireated into fine droplets which are caught by the screen and fibers in the upper section. So the filter provides two methods of removal of contamanents. When i ran my oil bath, a only put an inch and a half or two inches in the bottom. Oil baths are still use in off road heavy equipment so they must provide a good level or protection.

[TodFitch]

The filter works on the principle of the air changing directions. The air should not actually pass through the oil. Air entering is accelerated toward the oil then forced back up, as it makes the sharp turn, the solids have too much inertia to make the turn and fall out of the air stream to be trapped by the oil. The air movement also causes some of the oil to be aireated into fine droplets which are caught by the screen and fibers in the upper section. So the filter provides two methods of removal of contamanents. When i ran my oil bath, a only put an inch and a half or two inches in the bottom. Oil baths are still use in off road heavy equipment so they must provide a good level or protection.

" Oil baths are still use in off road heavy equipment so they must provide a good level or protection."

I haven't seen any data on effectiveness of a typical OEM paper air filter versus the older oil bath types but I strongly suspect that the big reason for the change was to sell more parts, not to clean the air better.

And, I guess, a bit easier for the mechanic: Pop open the housing, pull the old filter element, drop in a new one. Charge the customer for the same labor as the old style oil bath and add in the (inflated) retail cost of a new disposable filter element.

[Captain Neon]

" Oil baths are still use in off road heavy equipment so they must provide a good level or protection."

I haven't seen any data on effectiveness of a typical OEM paper air filter versus the older oil bath types but I strongly suspect that the big reason for the change was to sell more parts, not to clean the air better.

And, I guess, a bit easier for the mechanic: Pop open the housing, pull the old filter element, drop in a new one. Charge the customer for the same labor as the old style oil bath and add in the (inflated) retail cost of a new disposable filter element.

I'm shocked. Just shocked! A mechanic, overcharging a customer? Shocked! /sarcasm off

[Robert Horne]

The first top I modified by cutting all the metal sections at the base of the upper section, and then pulled the innards out. Real pain in the butt.

Easier way is to cut your way around, down about 2-3", with a cut off wheel. When you put the paper element in and put the top back on that 2-3" section should cover the element so that it does not show that it was modified.

This is how I did an extra Air Filter Case. I used a Fram CA3647 filter.

Size is about 2 & 3/8 by 8 & 3/8. $5.00........

[Robert Horne]

My motor bike came with a foam rubber air filter. The foam rubber did an

excellent job of keeping the carb very clean. Cleaning was easy, with a

little gasoline, squeeze, and then add a few drops of oil, and squeeze again.

The filter lasted 9 years before I replaced it. Some lawn mowers have

a similar filter. Save those sofa cushions guys............

[BobT-47P15]

One fellow used this model air filter to modify his cleaner.

The only problem was, he didn't use the factory top piece.

Made his own.

He then put a metal disc on top of it..........

Then used this aluminum pan lid looking item instead of the original top.

Probably the easy way out rather than cutting the top.

[meadowbrook]

Thanks for all the responses

[Don Coatney]

How much oil does it take to fill it when empty?

Thanks for all the responses

Once again how much oil do you add when it is empty?

[meadowbrook]

I add close to a quart to get to the fill line.

[Don Coatney]

I add close to a quart to get to the fill line.

The only reference I found shows close to a quart is correct. Was the issue actually oil from the air cleaner or leaking fuel from the carburetor?

[meadowbrook]

I have 2 issues.

1- Carb is always wet. I though it was oil leakage from the air cleaner, but now i think it is indeed gas oozing through the actual carb body. Seems to be a problem in old Carter BB's.

2- On the air cleaner, if I fill it to the fill line, the engine 'corrects' the level by sucking out some of the oil until it is at a lower level. I also noticed that the bottom edge of the air cleaner's top half actually is submerged in the oil by maybe 1/8", so the area where the air is supposed to do a 180 degree turn and fling any dirt into the oil is closed, likely forcing the air to bubble through the oil.

[greg g]

Try a pint!!!!!

[Tom Skinner]

I will indeed!