Excessive blow by.
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Cross-Country
Joined: Aug 2006
Posts: 78
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From: Fresno
Excessive blow by.
1994 F250 4x4 Xlt, Long bed, extra cab, 460.
I purchased this truck 3 years ago in as a project. Finally getting around to getting everything for the emissions found and reinstalled. Been driving it last couple of weeks and getting the oil in the airbox. Seems like the more I fix the more it leaks there. After researching on here i pulled the oil fill cap with it running and you can feel the pressure coming out. Can feel it pulse even.
Plugs were just changed for first time since I bought it and cylinder 8 showed oil fouling. Not sure how long these plugs were in, but probably quite a while, as PO did no Maintenace.
Ill do a compression check, and cylinder leak down test, but I feel it probably has either bad rings, a bad cylinder or something. It doesn't miss, no check engine light, (found and fixed all those, Thank you to this forum for that and referring me to a tester that works with this old truck)).
Actually, runs great, other than blowing oil. I have seen comments about possible valve stem seals, but that seems like too much pressure for that.
I have tried seafoam and rislone through the oil and gas to see if it could free up a ring. (So far nothing, although 500 mile oil changes are coming out thin and black.
Currently running some non-detergent 30wt, to see if that has any noticeable effect.
Thoughts? Am I just in denial about the engine rebuild in my future?
Anyone recently purchase an engine kit and have an estimate on shop labor for machine work?
Thanks guys for listening to my rant.
I purchased this truck 3 years ago in as a project. Finally getting around to getting everything for the emissions found and reinstalled. Been driving it last couple of weeks and getting the oil in the airbox. Seems like the more I fix the more it leaks there. After researching on here i pulled the oil fill cap with it running and you can feel the pressure coming out. Can feel it pulse even.
Plugs were just changed for first time since I bought it and cylinder 8 showed oil fouling. Not sure how long these plugs were in, but probably quite a while, as PO did no Maintenace.
Ill do a compression check, and cylinder leak down test, but I feel it probably has either bad rings, a bad cylinder or something. It doesn't miss, no check engine light, (found and fixed all those, Thank you to this forum for that and referring me to a tester that works with this old truck)).
Actually, runs great, other than blowing oil. I have seen comments about possible valve stem seals, but that seems like too much pressure for that.
I have tried seafoam and rislone through the oil and gas to see if it could free up a ring. (So far nothing, although 500 mile oil changes are coming out thin and black.
Currently running some non-detergent 30wt, to see if that has any noticeable effect.
Thoughts? Am I just in denial about the engine rebuild in my future?
Anyone recently purchase an engine kit and have an estimate on shop labor for machine work?
Thanks guys for listening to my rant.
Logistics Pro
Joined: Nov 2013
Posts: 3,928
Likes: 1,198
From: Mojave, Ca
Don't guess about the health of your engine. Do a compression test and find out. If you have a leak-down tester, use that too and get some numbers. Nothing is worse than not-knowing what you're working with.
Hotshot
Joined: Jul 2020
Posts: 10,400
Likes: 2,606
From: Near Salt Lake City
The PCV valve should put enough vacuum in the crankcase to pull a piece of paper down to the other valve cover vent, if it is working properly
If it will not suck a piece of paper to the breather, you do have excessive blowby
So, test that a few times and maybe pull the valve covers to see if the valve cover vents are all plugged up with carbon
I agree with checking the compression too, as that will give you an indicator of overall engine health
If it will not suck a piece of paper to the breather, you do have excessive blowby
So, test that a few times and maybe pull the valve covers to see if the valve cover vents are all plugged up with carbon
I agree with checking the compression too, as that will give you an indicator of overall engine health
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