PCV Question | Ford Escort Owners Association (FEOA)

PCV Question

Discussion in '2nd Gen 1991-1996 1.9L SOHC' started by JamesGarfield, Dec 7, 2019.

  1. JamesGarfield

    JamesGarfield FEOA Donator

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    1. Talk to me about the PCV valve. I know that all piston engines have some small amount of blow-by, where a tiny bit of combustion gasses get past the rings, and into the crankcase. These gasses build up the air pressure in the crankcase, and if un-vented, this pressure will eventually blow out a gasket or an oil seal, and create an oil leak.
    Back in like the 60's, they just stuck a little elbow pipe in the side of the block, and vented the crankcase straight to the atmosphere. It worked (no EPA regulations back then).

    In the 70's, to take better care of the environment, they started running the vent tube up to the air intake, routing the crankcase gasses back into the engine to be reburned. This worked too, except this method also sucked oil mist into the intake.

    So, enter the PCV valve. This valve, as I understand it, is supposed to block the oil mist, and pass through the gasses? What if I'm seeing my PCV valve always covered with oil-- does this mean my valve is bad, or the hoses not sealing well, or what?
  2. FordMan59

    FordMan59 FEOA Member

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    Most of the time PCV valves will be oily. If it doesn't rattle when you shake it it needs to be replaced. There's still going to be a certain amount of oil get past the PCV valve. I made and put a catch can between the PCV valve and where the gasses are re-introduced into the engine to help prevent oily residue from building up in the system. If you have a healthy engine you'll only get a couple oz. of blow by in several thousand miles.
    denisond3 and zzyzzx like this.
  3. JamesGarfield

    JamesGarfield FEOA Donator

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    FordMan59, thanks for the quick and helpful reply.

    I disassembled and cleaned the whole PCV assembly. Yes, the valve itself was pretty and clean inside, and yes it rattled when shaken.

    So I reassembled everything, using small amounts of Permatex Motoseal Grey gasket sealant. I THINK this will fix the oily seepage problem.

    My reason for this thinking: I HAD been using Permatex Ultra Black for these sort of gasket and sealing repairs, including this very one, 3 or 4 years ago. I'm not sure if I'm doing something wrong with the Ultra Black, because every place I've used it, it starts seeping and leaking oil again in 3 or 4 years (?!?).

    But wherever I've used the Motoseal Grey stuff, the seal has held up well. Your experiences?
  4. denisond3

    denisond3 Moderator Staff Member

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    I have had essentially total success with Ultra Black. There are three caveats; the RTV stuff only bonds well to surfaces free of oil. Then I let it cure overnight at least. And I throw out any tube of ultra black more than one year old.
    The same Ultra Black has held up being leak free on my oil pans for up to ten years. (For the oil pans I lay a bead of Ultra Black around the groove in the lip of the pan for the shaped rubber 'snake' that is the gasket). I also put a drop of ultra black at the four corners where the block meets the main seal casting and the oil pump castings. And I work slow enough that the RTV has cured for a couple of days before it sees any oil mist.

    I know Permatex makes a grey RTV, but I think its meant to be non-flexible, or at least less flexible than their other products.
    I use the Permatex reddish high-temp rtv, to help seal between the outlet of the cat converter and the inlet to the exhaust intermediate pipe. The red stuff holds up well enough, and still pulls apart when I have to open up the exhaust system.
    zzyzzx likes this.

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