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Crankcase vent tube

mherrcat

Contributing Partner
There was another thread about this a few weeks ago. Here is what I did to reconfigure my filter/vent tube. Similar to what Maine Sail did. I wish I could have used a filter with a rubber top (would have been easier) but all the ones with rubber tops were too big to fit the space. My filter is oriented to the side of the engine (M-18) not the top, so my space is very limited. This filter is almost exactly the same diameter and length as the original metal filter housing. Unfortunately there was not enough space on the bottom of the filter to add the vent tube fitting there. I'll add pictures of it on the engine after this weekend.
 

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rwthomas1

Sustaining Partner
Be very, very sure that the plastic end of that breather fitting that is inside the filter CANNOT come loose! If it does, the result won't be pretty. RT
 

mherrcat

Contributing Partner
I thought about that. The fitting seems to be made of nylon, so I'm not sure what, in terms of a sealant, would stick to it. The inside of the filter has 1/4" of a rubber-like material that bonds the chrome top and the filter element together. The nut on the inside is screwed down against the rubber part very tightly; I don't think it will loosen.

I was thinking I could check it every couple of weeks to see how it is doing, but if anyone has any suggestion for cementing the two parts of the fitting together, I'm listening...
 

mherrcat

Contributing Partner
The filter is K&N part # RC-0170. The vent tube fitting is 85-1120.

http://www.knfilters.com/performance_accessories.htm

Check out the "Universal Filters" and "Air Filter Accessories" sections.

They have lots of different shapes and sizes of filters; the problem was finding one that fit the space I had. I originally chose a larger filter and had an extension fabricated to clamp on the intake that would have moved the filter up and over the top of the engine, but after having the extension made it wouldn't fit on the intake. (Guess I measured wrong!)

Drilling the hole through the thin metal of the top of the filter was a little scary; I did it from the inside of the filter. With a hole that big (9/16) the bit really wants to grab that thin plate when it finally breaks through. Clamping the filter is difficult without crushing the element. (One reason I was hoping to find a filter with a rubber top that would fit...no luck.)

I tried to find the 90-degree vent fitting elsewhere (to avoid paying $11 for it!) but couldn't find one with the NPT threads and nut, so I just got it from K&N.

I did a search on the internet about gluing nylon and it seems this is a very difficult, if not impossible, thing to do. Someone on another forum recommended GOOP adhesive.

Do you really think teflon tape would work? I thought that was more for preventing leaking than actually bonding.
 
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bayhoss

Member III
T tape will not bond

The previous post is completly correct. Teflon tape is used to prevent leaks and makes for a low friction connection. So... anytime you are connecting two threaded fittings and one has t tape on it be careful not to overtighten. But, teflon tape has little or no bonding properties. A good source is a company called Drummond American. They make a host of industrial grade bonding agents. They have a very complete website, its worth a try.
Hope this helps, & good luck!
Frank
"Valinor" E28+
 

newgringo

Member III
Mark,
You are indeed venting the crankcase gases to the right place. I have done something similar on our M25, years ago. My concern with your setup is twofold. 1. If that plastic nut ever comes loose oh wow, you will get to go fishing in the engine (or worse). 2. It appears the nut will partially obstruct the flow of air into the engine. This would only hurt at higher rpms when the air flow is greatest. So if you seem to loose power at full fuel or get misfires or whatever, I would look first at the airflow restriction. Other than that, keep up the good work.
 

mherrcat

Contributing Partner
Below are pics of the orignal air filter setup and the new air filter. I put some contact cement on the vent fitting threads and screwed it down pretty tight, so much so that it deformed the metal top slightly. I don't think it is coming off.

I am also not concerned about impeding the air flow to the engine. The intake opening on the original metal filter housing is only 7/8" x 7/8". (Plus it has always had the vent hose shoved in it!) With the completely open filter I figure I have increased the intake area by at least 1,200%. I don't think the nut is going to block enough air to make any difference.

You can see how little space there is between the filter and the side of the engine compartment. I had to cut a notch in the panel AND take the original filter housing apart to get it off.
 

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mherrcat

Contributing Partner
Unfortunately my intake comes off the starboard side of the engine, not the front like yours. There is only a hair over 2" between the intake and the panel; and that's even after cutting 1/8" off the intake. My intake is also 1.5" OD. I couldn't find a filter with an offset flange that fit the intake and also fit the space between the intake and the panel. But, as you say, it works.

:)
 
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