PCV system reversing
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Joined: Jan 2001
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PCV system reversing
1992 F-150, 5.0 litre engine. My emissions hose from the air filter box to the oil filler cap is putting crankcase mist into the air filter box after a few miles of driving instead of sucking the air into the crankcase. I disconnected the hose at the air box and ran the engine. The hose now sucks properly with engine rpm. Is this a bad design (throttle body volume maybe sucking more air than the pcv system can override)? Any aftermarket solutions re: new airbox location and pcv routing??
Thanks.
Thanks.
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From: NorCal
PCV system reversing
I was curios about the same thing. I have to replace the crankcase breather filter every oil change because it basically falls apart from all the oil. I'll try to remove it from the box and see if it helps.
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PCV system reversing
Hi, the pcv system is designed to suck fumes and vapor out of the engine and into the intake to reburn them so the oil should be there just not alot of it. if there is a lot of oil present you probably have blowby which is more than likely a high mile engine with bad rings. John
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From: Linwood, N.J. USA!
PCV system reversing
Fatforty is corect. I have had trucks do this in the past. It can make the air breather a big mess. I wound up leaving the hose off of the air breather and extending it down to the frame rail. This would allow the mist to blow out of the engine and not mess the air breather.
Jakegypsum // Ford fleet, soup to nuts.
Jakegypsum // Ford fleet, soup to nuts.
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PCV system reversing
Of course, venting the PCV to atmosphere is illegal, so we don't want to do that.
You may want to make sure the valve is operating properly. I'd just replace it all together.
My best recommendation for you is to add a catch-can to the PCV system to reduce the amount of solid (non-vapor) oil you are getting in the box. You can buy them from Jegs or Summit and you need a baffled oil catch can and you want to put it in series with the PCV line.
This will allow you to not break the law, reduce the amount of oil into the engine (good for mileage and misses), and keep things clean in the box. Just remember to drain the catch can every oil change.
Randy
BTW-I don't have this on my truck, but every turbo vehicle I have converted from NA I have used this method. It is the best compromise I have seen to maintaining the tree-hugger design and reducing the amount of oil vapor in the combustion charge.
You may want to make sure the valve is operating properly. I'd just replace it all together.
My best recommendation for you is to add a catch-can to the PCV system to reduce the amount of solid (non-vapor) oil you are getting in the box. You can buy them from Jegs or Summit and you need a baffled oil catch can and you want to put it in series with the PCV line.
This will allow you to not break the law, reduce the amount of oil into the engine (good for mileage and misses), and keep things clean in the box. Just remember to drain the catch can every oil change.
Randy
BTW-I don't have this on my truck, but every turbo vehicle I have converted from NA I have used this method. It is the best compromise I have seen to maintaining the tree-hugger design and reducing the amount of oil vapor in the combustion charge.
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PCV system reversing
Appreciate the info. On my 5.0 litre engine the pcv valve does suck crankcase vapours into the upper intake manifold at the back end of the engine. The fresh air supply for this is from the air breather box and the emissions hose to the oil filler cap so the airflow should be into the crankcase from here. Like I said, it works fine away from the air filter box, at different rpms. The engine seems to run smooth and I get good gas mileage. Other than weak piston rings could a head gasket be leaking??
92 F-150 XLT ExtraCab Shortbox Flareside. 5.0 engine, E4OD tranny, 3.55 posi., Accel Supercoil & 8.8mm wires, NGK plugs, K&N Filter.
92 F-150 XLT ExtraCab Shortbox Flareside. 5.0 engine, E4OD tranny, 3.55 posi., Accel Supercoil & 8.8mm wires, NGK plugs, K&N Filter.
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PCV system reversing
Head gasket is a possiblity, but you would be losing either coolant or oil at a an alarming rate. And the color of the smoke out the tailpipe would tell the tale.
It may be possible that you have heavy sludge buildup in the driver's side valve cover which is impeding the air-flow into the crankcase. Then the pressure builds up in the valve cover and the intake sucks it in.
It may be worth pulling the valve cover to see if there is any sludge buildup. As for the headgasket, do a compression check and inspect the oil and coolant for mixing.
Good luck,
Randy
It may be possible that you have heavy sludge buildup in the driver's side valve cover which is impeding the air-flow into the crankcase. Then the pressure builds up in the valve cover and the intake sucks it in.
It may be worth pulling the valve cover to see if there is any sludge buildup. As for the headgasket, do a compression check and inspect the oil and coolant for mixing.
Good luck,
Randy
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PCV system reversing
I think there's something to how soaked the breather is and where it takes the air from. Since the hose leads from the oil filler on the valve cover, then the air coming thorugh that pipe must be from the valve covers. This area is filled (not literally, but it's on every surface) with oil. So any air, regardless of ring failure, going through that spot would become saturated with oil. plus, if there is little blowby and less pressure to vent than vacuum from the engine, the intake would then act like a vacumm sucking in oil, right? Basically, I'm saying that It's hard to see this as a problem since the oil is kinda built into the design. correct me if I'm wrong, but It seems logical (my idea, not the design).
1989 F-150 : 5.0, shorty headers, Flowmaster cat-back, K&N filtercharger intake, March pulleys, MSD-6T, soon to be Mass-Air...doesn't know she's not a Mustang
1989 F-150 : 5.0, shorty headers, Flowmaster cat-back, K&N filtercharger intake, March pulleys, MSD-6T, soon to be Mass-Air...doesn't know she's not a Mustang
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PCV system reversing
Hotrodmex, You are basically correct. The problem here sounds more like stronger than normal blowby. To me at least, (if it is not a head gasket problem.) If the pressure being passed by the cylinder rings is stronger than the PVC vacuum, the oil vapor mist needs to pass through an alternative exit since the system can't handle it. Normally, the next route that the excess pressure is to take is the air filter vent tube, thus gumming up the air filter.
Jakegypsum // Ford fleet, soup to nuts.
Jakegypsum // Ford fleet, soup to nuts.
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Joined: Sep 2000
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From: Linwood, N.J. USA!
PCV system reversing
RAGZ, Oil catch-cans? I have never seen them. Do newer trucks come with anything like this set up or is this strictly an after market type of thing? I wish I new of this several years ago. We did make something like it on our 83' F-100 out of a coffee can and steel wool. It worked for a while but then became a nasty mess after time. I do realize that extending the hose off of the valve cover and not capturing the mist is illegal. NJ inspection will not allow it. We have done this in the past as basically a quick fix just to be able to use the truck without having any on the road problems. Normally the engine would need attention within reasonable time.
Jakegypsum // Ford fleet, soup to nuts.
Jakegypsum // Ford fleet, soup to nuts.
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