McMaster PCV check valve - restrictive ?
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From: San Diego, CA
McMaster PCV check valve - restrictive ? I got the McMaster Carr check valve (P/N# 7775k52) and am about to install it inline in between my PCV valve and my catchcan to prevent the boost from positively pressurizing the crank case via the PCV line.
Here's the thing - when I try to blow through it (the way it flows, heh) it has quite a bit of resistance (obviously no flow at all the other direction). Seems like it would take a considerable amount of crankcase pressure to open it, a lot more pressure than the factory PCV valve takes. I'd prefer it to be easier to open so there's less resistance - I'm thinking intake idle vacuum may not even open it at all, which means no positive crankcase venting and it would require a good amount of pressure to build inside the crankcase to open the valve and release it - bad...
Will this release crankcase pressure OK ? Should I install a breather ?
Also if anyone is running this check valve, had any problems with it (or as a result of using it ?). I have always been leery of putting too much restriction in that line (i.e. paint filters, fuel filters etc. to catch oil vapor, etc). The Greddy catch can has been working great to pull out moisture and oil vapor without restricting flow.
Cheers,
Bad30th
Here's the thing - when I try to blow through it (the way it flows, heh) it has quite a bit of resistance (obviously no flow at all the other direction). Seems like it would take a considerable amount of crankcase pressure to open it, a lot more pressure than the factory PCV valve takes. I'd prefer it to be easier to open so there's less resistance - I'm thinking intake idle vacuum may not even open it at all, which means no positive crankcase venting and it would require a good amount of pressure to build inside the crankcase to open the valve and release it - bad...
Will this release crankcase pressure OK ? Should I install a breather ?
Also if anyone is running this check valve, had any problems with it (or as a result of using it ?). I have always been leery of putting too much restriction in that line (i.e. paint filters, fuel filters etc. to catch oil vapor, etc). The Greddy catch can has been working great to pull out moisture and oil vapor without restricting flow.
Cheers,
Bad30th
Thread Starter
12 Second Club
iTrader: (13)
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From: San Diego, CA
.3 PSI sounds pretty low, grabbed this from their website :
• Maximum Pressure:
Viton: 1000 psi @ 400° F
• Cracking Pressure: 0.3 psi
• Temperature Range:
Viton: -20° to +400° F
Male x Male
Engineered for an extra-low cracking pressure of just 0.3 psi. Valves have a brass piston, 300 series stainless steel spring, and your choice of Buna-N or Viton seats.
Connections: NPTF (Dryseal).
I'll probably give it a try since the benefit of not pressurizing the crank case with boost via the PCV probably outweighs any negative effects of building .3psi inside the crankcase before it can vent...
Thanks for the opinions everyone. Keep 'em coming.
BTW, haven't had any problems with this yet (i.e. oil dipstick popping out, etc) - just trying to head off any problems before they occur.
Thanks,
Rob (Bad30th)
• Maximum Pressure:
Viton: 1000 psi @ 400° F
• Cracking Pressure: 0.3 psi
• Temperature Range:
Viton: -20° to +400° F
Male x Male
Engineered for an extra-low cracking pressure of just 0.3 psi. Valves have a brass piston, 300 series stainless steel spring, and your choice of Buna-N or Viton seats.
Connections: NPTF (Dryseal).
I'll probably give it a try since the benefit of not pressurizing the crank case with boost via the PCV probably outweighs any negative effects of building .3psi inside the crankcase before it can vent...
Thanks for the opinions everyone. Keep 'em coming.
BTW, haven't had any problems with this yet (i.e. oil dipstick popping out, etc) - just trying to head off any problems before they occur.
Thanks,
Rob (Bad30th)
Last edited by Bad30th; Apr 27, 2005 at 01:05 PM.
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