Oil Filler Cap
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From: N Richland Hills, TX
Oil Filler Cap
1965 F100 352
What is the correct oil filler cap for my truck? I currently have a cap with a hole in the top, maybe for a PCV? There is currently nothing in the hole (in the cap!) I am gettting a lot of blow-by around the intake and I was wondering if this could be part of the problem. Thanks,
James
What is the correct oil filler cap for my truck? I currently have a cap with a hole in the top, maybe for a PCV? There is currently nothing in the hole (in the cap!) I am gettting a lot of blow-by around the intake and I was wondering if this could be part of the problem. Thanks,
James
Hotshot
Joined: Mar 2001
Posts: 13,552
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From: Manhattan, KS
Others may have a better answer, but, I have a 64Tbird and it has nipple on the cap that connects to a short hose that attaches to the aircleaner. Trucks probably had something similar. I can't answer the the blow by, but wouldn't think it was related unless there is no other way for pressure to escape from the block.
Posting Guru
Joined: Jul 2003
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From: East Central Florida
I'm gonna say YES. 65 & up engines are not the same as 64 or earlier. There is no road vent tube. Crankcases after 64 all vent by PCV system. 
Because the PCV "floats" open when there is sufficient vacuum but drops shut when there is no sufficient vacuum, PCV doesn't draw from acceleration up to full throttle, until vacuum rebuilds itself. If engine internals are getting along in age/ mileage they produce more crankcase pressure that when fresh.
The PCV hose should run from PCV Valve in oil filler cap to a plate under the carburetor, on top of intake manifold. The port belongs out front, pointing towards thermostat housing to front of it.
If you use another vacuum port you risk fouling plugs in cylinders an intake runner goes to. IOW it's OK to tap vacuum off a runner for power brakes or such, but not to injest fumes from a crankcase scrubber system into. . . . . By using a dispersion plate under your throttle plates, your engine can usually mix and burn off fumes (blow by) unless its' getting bad.
Also, I run heavier oil like 20W -50 multigrade, especially when my engines get weary.
Your other rocker/valve cover should not have a cap or vent.
FBp
Because the PCV "floats" open when there is sufficient vacuum but drops shut when there is no sufficient vacuum, PCV doesn't draw from acceleration up to full throttle, until vacuum rebuilds itself. If engine internals are getting along in age/ mileage they produce more crankcase pressure that when fresh.
The PCV hose should run from PCV Valve in oil filler cap to a plate under the carburetor, on top of intake manifold. The port belongs out front, pointing towards thermostat housing to front of it.
If you use another vacuum port you risk fouling plugs in cylinders an intake runner goes to. IOW it's OK to tap vacuum off a runner for power brakes or such, but not to injest fumes from a crankcase scrubber system into. . . . . By using a dispersion plate under your throttle plates, your engine can usually mix and burn off fumes (blow by) unless its' getting bad.
Also, I run heavier oil like 20W -50 multigrade, especially when my engines get weary.
Your other rocker/valve cover should not have a cap or vent.
FBp
Last edited by FordBoypete; Jul 9, 2005 at 10:02 PM.
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From: Elizabethtown, PA
My unmodified '65 has a oil cap/breather on the pass side v/c with PCV valve...the hose runs to the carb baseplate on the manifold (but it's at the rear). The driver's side v/c just has a filler cap/breather with no other attachments.
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Joined: Apr 2005
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From: Burkburnett, Texas
Well now I understand why my truck ran like crap when I got it. It seems it was just vented to the wrong port! However, I bought a breather cap for it instead of using a PCV valve and hooking it back up to the carb. It's ran fine, with no noticable problems. Should I actually hook it back up to the carb, or just leave it?
vernon
vernon
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From: East Central Florida
My personal feeling is crankcase fumes burn off better when mixed evenly throughout an entire intake routing system to all cylinders so they mix evenly in the gasoline flow. That's why FoMoCo went to a baseplate set up in 65 in the first place.
Sometimes on older engines, baseplates foul reducing their ability to draw fumes from engine. If that happens, remove it and clean it out in carburetor dip or a cleaning vat. I suppose it could be hand cleaned, but chemical cleaning does a better job IMHO.
FWIW, if/ when crankcase ventialting systems stop all together, it's quite possible to generate enough internal pressure to blow engine oil past seals in timing cover and/or a rear main, as well as from under the valve covers.
Also when blow by is excesive in an older engine, even with PCV systems, it's a good idea to go up a step or two in spark plug heat range to aid in burning all those extra hydrocarbons in crankcase fume loads.
I've upped plug heat ranges and also gone to CDI or Breakerless [electronic] Ignitions in order to get worn engines to comply with emissions standards. It's a sort of trial & error deal but it does work when ya get 'er right.
FBp
Sometimes on older engines, baseplates foul reducing their ability to draw fumes from engine. If that happens, remove it and clean it out in carburetor dip or a cleaning vat. I suppose it could be hand cleaned, but chemical cleaning does a better job IMHO.
FWIW, if/ when crankcase ventialting systems stop all together, it's quite possible to generate enough internal pressure to blow engine oil past seals in timing cover and/or a rear main, as well as from under the valve covers.
Also when blow by is excesive in an older engine, even with PCV systems, it's a good idea to go up a step or two in spark plug heat range to aid in burning all those extra hydrocarbons in crankcase fume loads.
I've upped plug heat ranges and also gone to CDI or Breakerless [electronic] Ignitions in order to get worn engines to comply with emissions standards. It's a sort of trial & error deal but it does work when ya get 'er right.
FBp
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