Thanks Dennis.

The Gowesty vacuum type throttle switch was disconnected because the
wires were slightly in the way of the AFM-filter housing. In
hindsight, a hasty thing to do. The ignition coil lead was
disconnected from coil, throttle body valve held open during test.

It's occurred to me that the lifters may be at play here. The engine
sat for some time unused. I ran it before the compression test, heard
zero lifter noise so I assumed the lifters were fully pumped up. If I
recall, it took several cycles of the starter motor to bring each
cylinder up to its' maximum pressure.

Looking at my notes, when purchased, this is what the mechanics test
showed for engine compression:

130 120
140 140

I had wondered about doing a leak down test. An air compressor
purchase may be in my future!

Neil.

On 5/5/17, Dennis Haynes <d23haynes57@hotmail.com> wrote:
> A compression test is not complete without also doing a leak down test.
> Also, when doing a compression test you want to disable the fuel pump and
> ignition coil or at least center the center coil wire to ground. Throttle
> should be held open. What did you expect to accomplish by disconnecting the
> throttle switch?
>
> As an extension of a leak down test when you get a cylinder with a low
> reading you can bypass the gauge set and put full available air pressure in
> the cylinder. Be sure the crankshaft is secured for this. For the ultimate
> extension of this test you can remove the rocker arms so you can test the
> piston-rings at both the top and bottom of the cylinder. During these tests
> remove the pressure cap and have the coolant topped off all the way to the
> brim. Major internal leaks will quickly be obvious with the coolant pushing
> up or bubbling. Very small leaks or leaks that open under heat or pressure
> may still hide.
>
> I discovered this anomaly on Fun Bus around 200K. I have also seen it on
> other engines. Since Fun Bus does not have any coolant issues and the leak
> down test is good I am still driving it and it is now over 313K
>
> Dennis
>
>
--
Neil n

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