CHEVY VACCUUM HOLES DIAGRAM & TAPPING NOISE

1986 Chevrolet Truck

Tiny

sheeptender

July, 29, 2010 AT 7:10 PM

Engine Mechanical problem
1986 Chevy Truck V8 Two Wheel Drive Automatic 89k miles

2 Questions My 86 Custom Deluxe has a Carb and I need a diagram of the vacuum hoses for the 305 eng. I want to make sure I redo them right. Also I took the passenger side value cover off because of a pretty hard tap that would be heard at idle some of the time. I thought I had a bent push rod. But the noise stopped for now and all the rods spin freely at idle and even when I idle it up some. Could it be the fuel pump or maybe a rod that is a little bent. It's a noticeable tapping when it does it. But now that the cover is off it's not doing it.
Thanks

FOUND 409 RELATED QUESTIONS

3 Answers

Tiny

obxautomedic

July, 29, 2010 AT 9:42 PM

Hello,

Ok, on the Vacuum Diagram need to know if canister is on driver or passenger side.

Now the tapping. Since it seems to only be present with valve cover on. Look for damage to valve cover,

Measure from lip of head to top of rocker arms at valve closed. Then measure inside of valve cover.

You also may be able to just inside of valve cover for signs of the rocker arm hit it.

Another possibility is a lifter starting to fail.

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Tiny

sheeptender

July, 29, 2010 AT 10:24 PM

The canister is on the driver's side.
I will check the inside of the cover for rocker arm damage to see if it is hitting it. What would make it start hitting the cover?
Thanks

Tiny

obxautomedic

July, 31, 2010 AT 5:24 PM

I say check the inside of valve cover for damage because after you took it off the tapping was gone. Inside the valve cover on some models there is a plate that prevents oil from spraying out the oil fill and the PCV Valve. If the plate has been damaged or has broken loose could be cause of tapping.

Here is the Vaccum Diagram...


http://www.2carpros.com/forum/automotive_pictures/188069_86chevy305vacuum_1.jpg



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