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Vacuum Problem

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Bill_85

Guest
I have an 85 that is totally stock, with 90,xxx miles. Since I have had it I have had to fix a few minor interior glitches, did an oil and filter change, new plugs, wires etc. The car has always ran good, now all of a sudden it has what could be described as a "howling" noise from the PCV valve.

I have replaced the valve and the hose. Checked for leaks, found none. If I pull the line it reads 17# of vacuum at idle. If I disconnect the line that goes to solenoid for the cannister and read vacuum there it is still 17#, but the howling lessens. It appears to be too much pull at the PCV, but why?, and from where? Any ideas anyone?

Thanks,
Bill
 

mikevochis

Member
Joined
Jun 8, 2002
Messages
20
Location
CT
Corvette
03 50th Convert, 91 & 94 coupes & 96 Collectors
How about an intake manifold leak??? Put the vac guage back on, watch the guage and snap the throttle. If pressure goes down your ok...if it goes up I'd check for a internal leak.
 
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Bill_85

Guest
Here is the latest. I re-checked lines, fittings etc. and still found no problems. Started the car and it puffed a blue haze of smoke out the back for a few seconds and noise was gone. Checked the vacuum and it was at 12#. It does go right about 0 on de-cell also.

What I am thinking is the solenoid right before the cannister is staying closed sometimes and increasing the vac. at the PCV valve.
 
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boblx2a

Guest
This is a shot in the dark, never having worked on this particular system in my '85 (so far!). But what is the condition of your vacuum pump? It appears you have too much vacuum, from your description. Or maybe the line to the Cat has been crimped or something. That would create more vacuum in the rest of the system. Just guessing but at this point I think we will all be guessing. :)
I had some EGR issues with my '86 but have never had a condition where I had too much vacuum. It was usually not enough. But it is a cause for concern it will probably turn out that some part of the system is starving for vacuum. I don't suppose you have any codes set.

Good luck with it............
 

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