Oily air filter
Thread Starter
|
Senior User
Joined: Sep 2003
Posts: 254
Likes: 0
From: Colorado
Oily air filter
My air filter is incredibly black and oily on the backside. It's coming from the crankcase breather vent that goes into the back of the airbox. The breather filter itself is soaked with oil also. What is causing so much oil to come out this vent? I would like to try and fix this before I go to a K&N filter. It's an 88 351w EFI. Thanks.
Elder User
Joined: Mar 2003
Posts: 522
Likes: 0
From: Warren, MI
EKK!
This is a common problem among us 302'ers but I didnt know you 351'ers got it bad too.
Its bad rings.. or a single cracked ring. What is happeneing is when the sparks lights and the gas explodes and shoves the piston down, some of that pressure is leaking past the rings and putting pressure (hot hot hot air) down into the oil which then makes some hot oily air shoot into the crankcase and you get what is called "Blow-by"
When I installed my so called "ram-air" I got a longer piece of hose, connected it to the oil thingie on the crankcase, then looped it over the compressor and down and then back up to the side of the air box and put one of those "ricer" breathers on it.
The reason I did this was when I bought that part (the 460 air tube), I was in horror how bad my air filter was soiled and just reaked. So I cleaned it really good 2 times, plugged that hole on the back of the stock airbox where the old beather used to go with a rubber cap (3/4 i think?). That way there was no air leaking and no oil going into my filter.
Ohh and I forgot to add, the reason I looped that hose down was to hopefully catch any oil before it made it up, and I will drain it every month or so.
Good luck.
This is a common problem among us 302'ers but I didnt know you 351'ers got it bad too.
Its bad rings.. or a single cracked ring. What is happeneing is when the sparks lights and the gas explodes and shoves the piston down, some of that pressure is leaking past the rings and putting pressure (hot hot hot air) down into the oil which then makes some hot oily air shoot into the crankcase and you get what is called "Blow-by"
When I installed my so called "ram-air" I got a longer piece of hose, connected it to the oil thingie on the crankcase, then looped it over the compressor and down and then back up to the side of the air box and put one of those "ricer" breathers on it.
The reason I did this was when I bought that part (the 460 air tube), I was in horror how bad my air filter was soiled and just reaked. So I cleaned it really good 2 times, plugged that hole on the back of the stock airbox where the old beather used to go with a rubber cap (3/4 i think?). That way there was no air leaking and no oil going into my filter.
Ohh and I forgot to add, the reason I looped that hose down was to hopefully catch any oil before it made it up, and I will drain it every month or so.
Good luck.
Senior User
Joined: Jun 2003
Posts: 159
Likes: 0
From: CA
It could also be a bad pcv valve...usually when this question comes up people will ask how many miles are on the engine...if it's a lower mileage engine or an older engine that has been properly cared for then it's is less likely to be your rings and blow-by. You should try replacing your pcv valve first as it's fairly inexpensive and may be all you need. Hope this helps and that others can confirm this...a search will bring up a bunch of topics on oil in air filters.
explination of what PCV valve is and does - https://www.ford-trucks.com/forums/s...ght=pvc+valve+
Threads on oil in the air filter box - https://www.ford-trucks.com/forums/s...d.php?t=121095
https://www.ford-trucks.com/forums/s...ad.php?t=58564
explination of what PCV valve is and does - https://www.ford-trucks.com/forums/s...ght=pvc+valve+
Threads on oil in the air filter box - https://www.ford-trucks.com/forums/s...d.php?t=121095
https://www.ford-trucks.com/forums/s...ad.php?t=58564
Thread Starter
|
Senior User
Joined: Sep 2003
Posts: 254
Likes: 0
From: Colorado
Well, my assumptions were the same as yours. My girlfreind's bronco (302) had broken rings in the 8th cylinder due to that PCV problem. However, on mine I have 135-140 compression on all my cylinders, and I have replaced the PCV valve twice in the last year, so I'm a bit at a loss as to why this is happening.
Senior User
Joined: Mar 2003
Posts: 306
Likes: 0
From: Mobile, ALABAMA
I had the same prob with mine...although i knew what the prob was...oil leaks pretty bad on the back cyclinder, causing the spark plug to be covered in oil, causing me to change it every 3k miles....i put on a cold air intake,(crome tube) k&n air fliter...most of them have a what some would call a nipple on the crome tube, just get a hose run it from there to the valve cover...seemed to work fine for me...before then it was messy...ohhh boy was it ever.....
Elder User
Joined: Mar 2003
Posts: 522
Likes: 0
From: Warren, MI
Originally Posted by siphor84
Ayoungblood,
So is your "ricer" filter and tube going to the inside the airbox like stock, or just attached to the outside of it?
So is your "ricer" filter and tube going to the inside the airbox like stock, or just attached to the outside of it?
Good luck!
Thread
Thread Starter
Forum
Replies
Last Post
hooler1
Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W)
1
Apr 16, 2011 11:00 PM
Spydycarnge
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
4
Jan 21, 2010 08:48 PM
bullofthewoods
1987 - 1996 F150 & Larger F-Series Trucks
5
Mar 14, 2005 11:30 PM
Deadblow
Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460)
1
Apr 21, 2002 09:17 PM
