There seems to be a rattling coming from my PCV valve. The car is a 67 327-350 hp L79. The PCV is an AC type CV-726C. I took it off, and when I shake it in my hand it rattles. Is it supposed to rattle? Thank you.
Mario
Mario
-
-
Re: PCV Valve
Yes, the rattle indicates the valve is not stuck. The "shake test" is an easy way to see if the valve has become stuck due to crud -
Re: PCV Valve
Yes, the rattle indicates the valve is not stuck. The "shake test" is an easy way to see if the valve has become stuck due to crudComment
-
Re: PCV Valve
Should it make a rattling sound when the car is running -- is that normal?Comment
-
Re: PCV Valve
Should it make a rattling sound when the car is running -- is that normal?Comment
-
Re: PCV Valve
Mario----
I agree with Bill. Also, if the valve rattles when the engine is running, that MAY be an indication of a low vacuum condition. Actually, though, an L-79 engine will run less vacuum than lower performance engines due to the overlap of the cam. So, the 726C might be a little marginal from the get-go when used with the L-79. However, for 1967 this was the only valve ever originally used with small block engines.
Starting with the 1968 model year, the AC 736C was used for most engines, but another valve was used for low vacuum engine applications (68-69 L-88/ZL-1 and 70-72 LT-1). This valve was the AC 746C. However, due to its different configuration, the AC-746C cannot be used for any pre-68 small block. It can be used for 66-67 big blocks, though, if PCV valve rattle is a problem.In Appreciation of John HinckleyComment
-
Re: PCV Valve
Mario----
I agree with Bill. Also, if the valve rattles when the engine is running, that MAY be an indication of a low vacuum condition. Actually, though, an L-79 engine will run less vacuum than lower performance engines due to the overlap of the cam. So, the 726C might be a little marginal from the get-go when used with the L-79. However, for 1967 this was the only valve ever originally used with small block engines.
Starting with the 1968 model year, the AC 736C was used for most engines, but another valve was used for low vacuum engine applications (68-69 L-88/ZL-1 and 70-72 LT-1). This valve was the AC 746C. However, due to its different configuration, the AC-746C cannot be used for any pre-68 small block. It can be used for 66-67 big blocks, though, if PCV valve rattle is a problem.In Appreciation of John HinckleyComment
-
Re: PCV Valve
Like Joe said, if the valve "dithers" at idle it is a sign that there's not
enough vacuum to keep it pulled all the way in. You can probably cure this
by raising your idle speed 50 to 100 revs. It should pull about 14" at about 850 to 900, which should eliminate the dithering assuming you don't have some other problem with the engine that is causing low idle vacuum.
DukeComment
-
Re: PCV Valve
Like Joe said, if the valve "dithers" at idle it is a sign that there's not
enough vacuum to keep it pulled all the way in. You can probably cure this
by raising your idle speed 50 to 100 revs. It should pull about 14" at about 850 to 900, which should eliminate the dithering assuming you don't have some other problem with the engine that is causing low idle vacuum.
DukeComment
-
re: PCV Valve
Thanks guys...I seem to be idling slightly low. I'll bump it up a bit and see what happens. The rattling is only during idle.Comment
-
re: PCV Valve
Thanks guys...I seem to be idling slightly low. I'll bump it up a bit and see what happens. The rattling is only during idle.Comment
Comment