tapping

[caperwing]

Hi all!!! 1981 chev , 305--
My engine was tapping really bad so I took it to a garage and they changed the cam shaft and lifters ( $1200. cdn ).told me it would cure the problem . Now it taps worse than ever on start up in the morning ( really loud ) and although it does quiet down some it does still tap a lot .
It runs like s--T . What is my next option????
thanks John

[TommySS]

Oil pump?

Any specifics on the car: Mileage, maintenance and driving practices, etc, would help a lot.

[caperwing]

Hi!! Don't know much about the history of the car except it was an old guy had it ( even older than me .It was a one owner and the clock says 5000 K .It could be gone around one , two or three times I don't know .
Strange thing though , I changed the plugs the other day and the tips were all really white coloured , not the porcelin part but just the wire tip .I also changed the dis. cap and rotor . I am at a loss right now and that new camshaft really hurt the wallet .
John

[TommySS]

If the tips of the plugs are white-ish, you're running lean.

As far as tapping, it could be a loose rocker arm (or two), and (heaven forbid), a bent pushrod.

I'd perform a cylinder leakdown test and a compression test to make sure things are as they should be. If something is amiss, the mechanics may have missed something during reassembly

[PeteA216]

Mine does that, especially when its cold... Turns out to be a leaky exhaust manufold gasket. Try listening around the engine an see if the sound comes from a specific area of the engine. That could be your problem.

[TommySS]

I like that theory better than mine. It's a much simpler problem that makes sense.

[RageCage]

Sounds like a classic "lifter tick" to me. I had a "lifter tick" on my 85 Caprice two different times. Once I added a pint of Marvel Mystery oil to the oil, and the tick cleared up in about 200 miles. The other time, the tick went away on it's own after a while. If they really did change all the lifters, I guess we can rule out "lifter tick" as a problem, though.
And yes, this "lifter tick" was LOUD.

[TommySS]

When a new cam/lifters are installed, they have to be broken in (start/run at 2000rpm for 20 minutes). When some guys get in a hurry, they tend to cut corners.

Is it a fast tick (like lifters/rockers), or a slower tick (exhaust manifold)?

[HLandin]

Originally Posted by TommySS

If the tips of the plugs are white-ish, you're running lean.

As far as tapping, it could be a loose rocker arm (or two), and (heaven forbid), a bent pushrod.

I'd perform a cylinder leakdown test and a compression test to make sure things are as they should be. If something is amiss, the mechanics may have missed something during reassembly

How difficult is it to perform a leakdown test and a compression test? I also experience a ticking sound, but I'm dumbfounded as to what is causing it. I don't know if its from transmission, rockers, speedo cable, or a bearing somewhere. Any ideas?

[TommySS]

Compression test should be done with the engine warm, all plugs removed.

There are a couple types of compression testers, but you want the kind that screws into the spark plug hole.

Screw it in by hand. Disable the ignition (I usually don't, but you "should"). Hold the throttle wide open and crank the engine over. You'll note the gauge build compression after about 4 cycles of the crankshaft. Write down the reading, go to the next cylinder and repeat.

There should not be more than a 10 percent difference between the highest/lowest readings.

Small block Chevy engines tend to read low on #8

*****
For the leakdown test, you need a tester, and an air compressor.

The test itself isn't complex, but it is more accurate in identifying the source of the leak. Ideally, leakdown should be no more than 25 percent.

My wagon's engine (367k) showed good compression, but some cylinders were leaking at 80 percent. I think my lowest was 30 percent. Typical for a tired engine

[burnM]

Here's a few things that I know of that can cause a tick or tap.

Cracked flywheel
Fuel pump. (I once got an engine for $50 because the guy thought the cam was shot)
Typical small block lifter tap
Typical exhaust manifold leak
It could just be a nasty chunk of carbon that worked its way loose(you did say an old man had it right?)
I just hope that the mechanic didn't nick one of the cam bearings when he reassembled your engine

[caperwing]

Thanks for all the replys
Well I tried all the easy stuff , even changed the fuel pump but the loud ticking is still there . How do I check the push rods to see if one is bent , is it a big job??