1993 Ford F-150 rought acceleration/oil in breather

SKIPJACKK1

MEMBER
1993 FORD F-150

Engine Performance problem
1993 Ford F150 6 cyl Four Wheel Drive Automatic 160xxx miles

My 1993 F150 has rough acceleration, like the timing is off and oil is coming through what is like a PCV valve and into the breather case. The timing is hard to check since the distributor is on the driver's side and the timing marks are on the passenger side. There are two timing "gauges" on the engine and the easily seen one on the driver's side is not the right one apparently. At any speed I get the "diesling' sound and the truck shakes. If I jame the gas it would get smoother, but now it doesn't and I have oil spewing out all over. It feels like it's missing. I have recently tuned it up and replaced the MAP, TPS an 02 sensors. None of this helped. Any ideas? 4.9 straight 6. Thanks

7 Replies

DAVE H

MECHANIC
13,383 POSTS

Check the plugs for OIL. It's possible the piston rings are worn and need replacing.? You could also have the cylinders compression tested?

POSITIVE CRANKCASE VENTILATION (PCV)
The PCV system uses intake manifold vacuum to eliminate blow-by gases from crankcase. Manifold vacuum draws gases from crankcase, through PCV hose, into combustion chamber. The PCV valve is positioned in hose through which blow-by gases flow on their way to combustion chamber.
By opening and closing in direct relation to engine vacuum, the PCV valve meters blow-by gas flow to combustion chamber. During periods of high manifold vacuum, such as at idle and deceleration, valve is almost completely closed, limiting flow of gases. During cruise speeds, valve permits greatest flow of gases.
Under conditions in which excessively high amounts of blow-by gases are produced (such as worn cylinders or rings), system allows excess gases to flow back through crankcase vent hose and into intake manifold.

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Sunday, December 28th, 2008 AT 7:55 PM

SKIPJACKK1

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Thanks Dave. I checked the plugs, all were dry except for #5. I also don't see a PCV valve anywhere. What I have on my valve cover is some kind of breather piece, a hose connects that to the breather case where the air filter is. Oil is spewing through this hose and covering the air filter. The breather piece looks similar to a PCV, but it doesn't have any parts inside except a filter. I replaced it with a new one and it does the same thing. I don't know where to look for an actual PCV valve. It feels like so much is wrong at one time. It feels like it's missing and has no power and won't shift right. It's almost like everything is wrong at once. It's pretty strange.

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Sunday, December 28th, 2008 AT 8:36 PM

DAVE H

MECHANIC
13,383 POSTS

Are you saying you have OIL on plug # 5. If so you have a piston rings issue or scored cylinder i'm afraid. There should not be oil in the combustion chamber.

POSITIVE CRANKCASE VENTILATION (PCV)
PCV Valve
Remove PCV valve from rocker cover grommet. Shake valve. If valve does not rattle when shaken, replace valve. Start engine and warm to normal operating temperature.
On 2.3L and 4.9L, remove corrugated hose from oil separator nipple. Place stiff piece of paper over nipple end, and wait 60 seconds. Vacuum should hold paper in place. If vacuum does not hold paper in place, replace valve.
On all models except 2.3L and 4.9L, disconnect hose from remote air cleaner or outlet tube. Place stiff piece of paper over hose end, and wait 60 seconds. Vacuum should hold paper in place. If vacuum does not hold paper in place, replace valve.

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Monday, December 29th, 2008 AT 6:10 AM

SKIPJACKK1

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4 POSTS

Thanks Dave, but there is no PCV valve. Coming out of my valve cover is some sort of breather valve, it is not a PCV. I replaced it already and there is no difference. Plug #5 did have a bit of oil, but not a lot and I have had worse in the past without this problem on other vehicles. Also, I don't know what corrugated hose you mean and I don't know what a separator nipple is. Since I have oil spewing from this valve in my rocker cover, I'm guessing there isn't much vacuum to speak of. I guess I'll have to pay the high shop prices to diagnose the vehicle. I can fix cars easily, it's diagnostics I have trouble with. Thanks

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Monday, December 29th, 2008 AT 6:30 AM

DAVE H

MECHANIC
13,383 POSTS

Is the MIL showing? Most good autoparts stores (autozone)will read the codes for free for you if you can get it there? This will give us a better idea of where the fault lies. It may have codes stored even if the light is not on constantly. Have it read if you can and get back to me with codes if any?