vacuum boost leak at fuel pressure regulator?

[Allen fong]

anyone ever come across this? so i fixed this leak and it seem to help hold at 20 psi but then i went out and it dropped to 0 so i check everything again and now i have air escaping from my catch can? bad PCV?

[Allen fong]

Can i bad pcv valve cause lean idle?

[Lowell Foo]

Typical low quality Aeromotive regulator.  Mine does the same thing, and also leaks fuel pressure after shutoff.

PCV valve leaks are common and will blow boost pressure into the crankcase where you don't want it.  If you really must keep the PCV, consider putting a proper check valve in the line.

[Allen fong]

thanks Lowell

I just noticed I did put a check valve inline before the PCV but still have air coming out of the cover, maybe my engine is just tired

[Ricky Grewal]

http://www.dsmtalk.com/forums/showthread.php?t=202057
someone else with same issue, removed the adjustment screw and teflon taped it to fix leak.

[Brett Haviland]

Yeah the "chinese" aeromotive knock off regilator in my buddies turbo colt does the same thing...  I just used teflon tape and wrapped a good amount on the adjustment bolt and it was good to go after that...  I'd imagine if you are constantly adjusting that screw tho, it might leak again tho...  But all you could do it re-wrap it in teflon tape again.

[Allen fong]

yup teflon tape did the trick, now the only leak is from the valve cover?? and i have a check valve before the PCV!

[daniel Dee]

Yeah the "chinese" aeromotive knock off regilator in my buddies turbo colt does the same thing...  I just used teflon tape and wrapped a good amount on the adjustment bolt and it was good to go after that...  I'd imagine if you are constantly adjusting that screw tho, it might leak again tho...  But all you could do it re-wrap it in teflon tape again.

x2
It is normal to have boost leak coming out of the valve cover...
Normally good compression results are adequate indicator.
You could do a leak down test to see how much air is escaping from the cylinders into the crankcase (then out through the valve cover).
I would say up to 15% is acceptable on a older motor.
I have seen drag cars with 30% leak down and still have great results.

[John Hartman]

that and unless you pull your cams for your boost leak test, some valves are open allowing air into the chambers.

even on the best engines, some pressure is going to leak past the rings.  They don't seal perfectly.

The teflon tape thing has been covered and yes, check valve.  I should do one on the Talon I know, I have one on the Merkur and it works well.  I should look at the Mazdaspeed too just for shits and giggles.  Cheap valves, easy to install.

[John Hartman]

oh and the pcv if actually faulty will cause a rich at idle, not lean as it will be sucking crankcase vent fumes(fuel and oil) into the manifold, actually richening it up.

You can actually watch the CO (and HC/NOx) change by pinching the PCV valve line on older worn engine cars when they are hooked up to the 5 gas analyser