Fuel Filter as Catch Can - Honda Prelude Forum

racinghonda · 06-25-2006, 04:20 PM

Well my Greddy knock off catch can was causing me some problems because it was leaking air somewhere which caused a high idle. So I ran the car without the catch can for a couple of weeks. Today I was rebuilding my throttle body and looked inside the IM, and it was dirty.

It used to look like this:

But it got a little bronzy from oil film. So I went down the Repco store and picked up a fuel filter and a couple of high tensile bolts for my strut brace which I broke . . .

It will do its job until I find time to go to the air compressor shop and get a compressor air/oil seperator.

I saw on a few websites that ppl use fuel filters. It should be able to take the engine bay temperatures and the nasty chemicals. But I will have to keep a close eye on it. Theoretically I should be able to just tip the oil out of it. The filter is directional so I have made sure that the arrow points away from the valve cover.

NotoriouSH · 06-25-2006, 04:26 PM

That's a great idea, I've been wanting an inexpensive catch can for some time now. Can you give me some info on what fuel filter you used? I want to go get the same one and try it out, unless the air/oil seperator is also cheap and more effective.

racinghonda · 06-25-2006, 04:40 PM

Its an aussie brand filter for a Toyota. It doesn't really matter which filter. I just got one that had the inlet and outlets on the top and a resevoir on the bottom. Found the biggest one I could get. There are some with the inlet and outlets on a 90deg angle to each other. In hindsight that may have been better for me as it would have means less hose needed and it would have been a bit neater.

I like the fact that it has a filter in it so it should trap a lot of the gunk.

petern101 · 06-25-2006, 11:20 PM

i use the air/oil seperator

go to home depot. go to the air compressor section. you will find one pretty quickly along with some couplers

it took me a whole of 20 minutes to attach it, cut existing hose, put in.

works great and cost me 10 bux

yohan420 · 06-26-2006, 02:29 PM

petern: do you have a pic of that ?

petern101 · 06-26-2006, 05:00 PM

you can see it near my tower brace.

its really small and picks up what i need.

there may be different types but its all the same. put some wire gauze in there as well.

chester · 06-26-2006, 05:09 PM

How often do you have to empty it, if at all?

racinghonda · 06-26-2006, 05:21 PM

Quote:

Originally Posted by chester

How often do you have to empty it, if at all?

Not sure if that question was for me but here is a pic of the amount that my old catch can caught after 5000kms.

petern101 · 06-26-2006, 05:32 PM

^wow thats alot.

i have probably a tea spoon in mine.

racinghonda · 06-26-2006, 05:36 PM

Yeah, that's what I thought, so I did a compression test and got 215PSI on each cylinder so it must just be the design of the engine. Or maybe I drive it too hard. Seeing that is enough justification for me to go through the trouble of plumbing a catch can on.

chester · 06-26-2006, 05:53 PM

Hmmm...that's quite a bit, even a teaspoon...it adds up.

petern101, do they have different sizes at home depot? I'm thinking this is a worthy modification, even for my sad h23.

petern101 · 06-26-2006, 07:20 PM

^my home depot had like 3 sizes. smallest (the one i used) and the next too were way too big / overkill since they were for bigger machines. i would suggest something around my size.

and the teaspoon is from almost 5k miles of driving so comparatively, its not that much. but i also don't drive my car too hard either.

my friend who did the same modification (i learned it from him) he gets way more oil than i do. but he drives an accord so its a little different

racinghonda · 06-26-2006, 07:24 PM

That was actually a table/dessert spoon in the photo.

racinghonda · 07-20-2006, 06:28 PM

Just an update. I have been thinking and its entirely possible for the crank case fumes to actually go out of the breather pipe and into the intake, through the TB and gumming up things like the idle valve etc. Because when the PCV valve shuts, the crank case pressure has no where to go and the only way out is through the breather (that's probably why its illegal to just vent your breather into the air with just a little breather filter.

So I added an inline fuel filter which cost $5AUD.

This is what the filter looks like

And installed.

And an update on the PCV one. From this pic you can see the oil trapped in it that would have otherwise ended up in the IM.

NotoriouSH · 07-20-2006, 08:24 PM

I've never seen oil residue in any of my intakes, so I don't believe oil is going through the air inlet hose. Your filter should let us know within the next month though!

Update, I went and bought an air/oil seperator made by Husky. It was $11 at Home Depot and has a clear catch basin so I'll be able to see how much oil is in it. The cool part is you can unthread the bottom portion and dump the oil out, then reattach it so in time it will save money over the fuel filter catch can. Right now I have a little oil in the line, but none has collected in the seperator.. I've only driven about 20 miles with it on though (I never drive anywhere) so I won't know if it's working properly for about a year lol.

racinghonda · 08-16-2006, 04:11 AM

Ok, there has been a few kilometres since I did the breather filter mod. And I decided to check it and found a tiny bit of oil in it. This is very strange and I thought that the venting sucks air from the intake pipe. It looks like there must have been occations that the crank case pressure was too great for the PCV to vent?

I have removed both filters now. I tried to blow through both and noticed that there was quite a lot of resistance. And I started to leak oil so I might have experienced an overpressure in the crank case due to the restriction.

yield · 08-17-2006, 05:47 PM

Yeah, normally air does come in through the intake side and goes into the valve cover but sometimes at idle and in some other conditions some blowly will go out into the intake. If you want to eliminate that oil, I'd put just a hollowed out catch can or something similar in between the valve cover and intake. I just have a breather filter on there myself and periodically check it to see if there's much oil contamination and throw it out when it gets wet.