-
Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.
89 4.0 blow by
- Thread starter grous33
- Start date
RTicUL8
NAXJA Forum User
- Location
- Rocky Mountain High... Colorado!
Welcome to 
. :wave:
The bad news:
The oil is blowing by the piston rings due to wear and/or breakage. There is no permanent fix, other than a tear down and fix/machine/or replace the broken/worn parts.
The good news:
There are lots of temp fixes which sometimes work - temporarily.
Do a search for "blow by" and you'll stay busy for the rest of the day with reading.
. :wave: The bad news:
The oil is blowing by the piston rings due to wear and/or breakage. There is no permanent fix, other than a tear down and fix/machine/or replace the broken/worn parts.
The good news:
There are lots of temp fixes which sometimes work - temporarily.
Do a search for "blow by" and you'll stay busy for the rest of the day with reading.
8Mud
NAXJA Forum User
- Location
- Central Germany
Mine hasn´t spit much oil into the air cleaner, since I cleaned out the vacuum line from the rear of the valve cover to the intake manifold. I also blew some solvent down the orifice in the top of the valve cover.
The small line sucks mostly, with the throttle closed, the large one to the valve cover, does most of the scavenging of crankcase pressure, with the throttle open. When the throttle slams shut and the small line is plugged, often blowby will force some oil out the larger hose, into the air cleaner.
If the blowby is bad enough, nothing is really gonna help it much. But if it´s marginal (in the beginning stages), cleaning the small vacuum line to the valve cover helps.
The small line sucks mostly, with the throttle closed, the large one to the valve cover, does most of the scavenging of crankcase pressure, with the throttle open. When the throttle slams shut and the small line is plugged, often blowby will force some oil out the larger hose, into the air cleaner.
If the blowby is bad enough, nothing is really gonna help it much. But if it´s marginal (in the beginning stages), cleaning the small vacuum line to the valve cover helps.
Bradlybob
NAXJA Forum User
- Location
- Lancaster, CA
My vac line was completely clogged back in the day as well. So much so that I had to replace the whole shebang. The replacement line I used was 1/4" I think. I used an old spark plug boot at the valve cover fitting, a short piece of the original hard plastic line coming out of the boot over which I slid the new rubber vacuum hose. A couple of inches up the line I installed one of those clear plastic fuel filters to catch any crud and oil coming down the vacuum line. It looks pretty nasty after 5-6000 miles so I just change it every other oil change. When I first discovered the problem I removed the valve cover and cleaned all of the yuck and deposits that were clogging the line where it attaches to the valve cover. Since then I've not had any oil in my air filter.
karter74
NAXJA Forum User
- Location
- Longview, TX
we ghetto rigged my 87. we just disconnected the tube that goes to the air box and ran it to an empty quart of oil bottle situated next to it. had to empty it every so often, but it worked!
BIGSLVRXJ
NAXJA Forum User
- Location
- Des Moines, Iowa
karter74 said:
It was actually suggested a couple days ago that I do the same thing. Is it okay to do?
red91
NAXJA Forum User
- Location
- exact location unknown
CollinM said:
Collin,
Ive seen guys that run the line into a small catcher can.
Yeah...its ok Buddy.
black89xj
NAXJA Forum User
- Location
- Sleeping near Seattle
Mine is also an '89 with 300,000 miles on it. I've had the same problem for the last few hundred thou.
Lets put it this way....at least you dont have to buy a K&N air filter!!!!
;-)
--Karl
Lets put it this way....at least you dont have to buy a K&N air filter!!!!
;-)
--Karl
Yucca-Man
NAXJA Member # 683
- Location
- Castle Rock, CO
WobblesXJ
NAXJA Forum User
- Location
- South Carolina
Took my valve cover off cleaned all the crazy crap out of it, put it back on got new grommets and a vacuum line. Replaced the rear line that goes to the manifold from the valve cover. Then put a separate breather on the front grommet. Worked great.
WobblesXJ
NAXJA Forum User
- Location
- South Carolina
Yeah the biggest thing I noticed was the vacuum lines would become loose and wouldn't suck out of the valve cover as they should. Took some zip ties and tightened them around the vacuum hose on each end. You can hear it suck now. Not a problem yet.
BIGSLVRXJ
NAXJA Forum User
- Location
- Des Moines, Iowa
red91inWA said:
Thanks Red.