Crankcase pressure - FSB Forums
Register Home Forums Active Topics Photo Gallery All Albums Mark Forums Read Auto EscrowInsurance FSB Store
FullsizeBronco.com is the premier Ford Bronco Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools Display Modes
Old 11-02-2012, 11:25 PM   #1
tylerb
Registered User
 
Join Date: Nov 2012
Location: Wisconsin
Posts: 11
iTrader: (0)
Bronco Info: 1978 BRONCO xlt 400cI 4" lift 33" tires
Crankcase pressure

Engine was rebuilt then sat for 2 years. The engine is now in the truck with about 2000 miles on it. I've noticed a mist of oil on the valve cover next to the breather. I currently have a breather on one side and a fill cap on the other. I was wondering how to tell if i have to much blow by or bad valve seals or if that's just normal. Was thinking about adding a tube from the oil fill cap to the air cleaner but want to make sure I dnt have a bigger problem. Took a compression test and had 150 psi +/- 5 psi on all 8 cylinders
tylerb is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 11-03-2012, 12:39 AM   #2
Steve83
Registered User
 
Steve83's Avatar
 
Join Date: Jul 2003
Location: Memphis, TN
Posts: 34,875
iTrader: (100)
Bronco Info: '83 VIN & title on '93 frame/body w/'95 4.9L & EB paint
Quote:
Originally Posted by tylerb View Post
I currently have a breather on one side and a fill cap on the other.
Well, THERE's your problem. This diagram is for EFIs, but the caption describes the system as it applies to all engines:

Quote:
Originally Posted by tylerb View Post
I was wondering how to tell if i have to much blow by or bad valve seals...
A compression test:

Quote:
Originally Posted by tylerb View Post
...or if that's just normal.
No.
Quote:
Originally Posted by tylerb View Post
Was thinking about adding a tube from the oil fill cap to the air cleaner...
Don't halfass it - do it right.
Quote:
Originally Posted by tylerb View Post
...but want to make sure I dnt have a bigger problem.
If you keep driving without the PCV system, you WILL.
Quote:
Originally Posted by tylerb View Post
Took a compression test and had 150 psi +/- 5 psi on all 8 cylinders
That's not how a compression test is done or evaluated - read that caption above.
__________________
Walk softly & carry a BIG SIX ! ! !

. .
Steve83 is offline   Reply With Quote
Old 11-03-2012, 11:27 AM   #3
tylerb
Registered User
 
Join Date: Nov 2012
Location: Wisconsin
Posts: 11
iTrader: (0)
Bronco Info: 1978 BRONCO xlt 400cI 4" lift 33" tires
So you are saying I just have to add a pcv and my problem will go away? Is there a way to tell how much crankcase pressure is to much? I can feel air coming out of valve cover when it's revved. how did I do the compression test wrong? I took out all plugs and held the throttle in while testing each cylinder. 3 cylinders went from 60-90-120-150 psi and 5 cylinders went from 90-120-150 psi. I was watching the gauge as the engine was cranked and recorded the jumps at each crank. Did this twice on all cylinders and came up with the same results
tylerb is offline   Reply With Quote
Old 11-03-2012, 12:06 PM   #4
Steve83
Registered User
 
Steve83's Avatar
 
Join Date: Jul 2003
Location: Memphis, TN
Posts: 34,875
iTrader: (100)
Bronco Info: '83 VIN & title on '93 frame/body w/'95 4.9L & EB paint
You need a PCV system; not just a PCV valve. The engine originally had one, so just buy the direct-replacement parts and install them. Read the caption above for the compression test procedure.
__________________
Walk softly & carry a BIG SIX ! ! !

. .
Steve83 is offline   Reply With Quote
Old 11-03-2012, 01:48 PM   #5
pete64
Registered User
 
Join Date: Oct 2012
Location: AZ
Posts: 27
iTrader: (0)
Bronco Info: 1995 XLT 5.8 E4OD
The only thing "wrong" with the compression test is you did not induce some oil to see if the readings came up. That said, compression tests of this nature are highly dependent on cam timing and the state of the lifters. Your readings seem ok but you should do the ring check steve's link outlines to be sure.

That said what you are seeing is normal on a system with no PCV.

A basic carbureted system is a PCV valve installed in one valve cover and hooked up to manifold vacuum source. The other valve cover is connected to a filter in the air cleaner to filter the air that is drawn in by the PCV. You can just as easily use a filter at the valve cover but, as anyone who has done a tuneup on a stock carbureted car knows, you will still get oil out of the breather since during acceleration there is no vacuum to the PCV system.

You won't do any damage to the motor running it without a PCV as long as the valve covers are vented but you should use one if you can. Also before you hook this up make sure there is a baffle of some sort in the valve cover so you don't suck oil into the PCV.
pete64 is offline   Reply With Quote
Old 11-05-2012, 07:56 PM   #6
tylerb
Registered User
 
Join Date: Nov 2012
Location: Wisconsin
Posts: 11
iTrader: (0)
Bronco Info: 1978 BRONCO xlt 400cI 4" lift 33" tires
I just redid the compression test with oil and my readings came out 10 psi higher. Is that to much of an increase or am I ok
tylerb is offline   Reply With Quote
Old 11-05-2012, 08:07 PM   #7
pete64
Registered User
 
Join Date: Oct 2012
Location: AZ
Posts: 27
iTrader: (0)
Bronco Info: 1995 XLT 5.8 E4OD
yes that is fine.
pete64 is offline   Reply With Quote
Old 11-05-2012, 08:11 PM   #8
tylerb
Registered User
 
Join Date: Nov 2012
Location: Wisconsin
Posts: 11
iTrader: (0)
Bronco Info: 1978 BRONCO xlt 400cI 4" lift 33" tires
Alright thanks for the help
tylerb is offline   Reply With Quote
Old 11-19-2012, 06:02 PM   #9
streethawk
Registered User
 
streethawk's Avatar
 
Join Date: Aug 2012
Location: EL MONTE Ca
Posts: 113
iTrader: (0)
Bronco Info: dana 60 kingpin/sterling 10.25/ 4:10 gears/38.5 tsl. minor engine upgrades
I put cap on the breather tube coming,from the oil fill cap...is that bad...i capped it cus it was sucking in dirt...
__________________
JESUS MIGHT HAVE BEEN A CARPENTER.....BUT PLUMBING IS GODS WORK
streethawk is offline   Reply With Quote
Old 11-19-2012, 08:06 PM   #10
pete64
Registered User
 
Join Date: Oct 2012
Location: AZ
Posts: 27
iTrader: (0)
Bronco Info: 1995 XLT 5.8 E4OD
Quote:
Originally Posted by streethawk View Post
I put cap on the breather tube coming,from the oil fill cap...is that bad...i capped it cus it was sucking in dirt...

yes that is bad. You need some sort of filter there. Either get a filtered breather cap or a cap with a hose that runs up to the air cleaner.
pete64 is offline   Reply With Quote
Old 11-19-2012, 10:19 PM   #11
streethawk
Registered User
 
streethawk's Avatar
 
Join Date: Aug 2012
Location: EL MONTE Ca
Posts: 113
iTrader: (0)
Bronco Info: dana 60 kingpin/sterling 10.25/ 4:10 gears/38.5 tsl. minor engine upgrades
Ok 10 4 im gona get a brether filter from auto zone for 10 bucks...its only been like that for a day and havent drove much
__________________
JESUS MIGHT HAVE BEEN A CARPENTER.....BUT PLUMBING IS GODS WORK
streethawk is offline   Reply With Quote
Old 11-20-2012, 04:11 PM   #12
85turdburger
Registered User
 
Join Date: Sep 2010
Location: lynchburg, va
Posts: 86
iTrader: (0)
Bronco Info: 85 Bronco, 300 straight 6, early carb and dist conversion, 33X10.50 4inch rough country lift
I'm going to agree on steve with this one, A pcv system is very important on these old girls. I had the same problem with mine before I installed my pcv system. Even using filters on the breathers they were getting oil soaked without the pcv.
85turdburger is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  FSB Forums > Bronco Discussions > Noobie Bronco Tech Questions. Flame free zone!


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 02:41 AM.


2003-2009 FullSizeBronco.com. All rights reserved