From: MV (MV@dc9.tzo.com)
Date: Wed Oct 26 2005 - 09:10:14 PDT
Caleb,
Normally a leak down test on an engine is done with the cylinder at the
top dead position and both valves are closed.
Then pressure is applied to the cylinder through the spark plug or glow
plug in this case and cylinder leakage is measured via the gauges on the
leak down tester. To find out where it is leaking, you listen at the
crankcase vent, the exhaust pipe, and the intake manifold. That
determines if rings are leaking, the intake valve is leaking, or the
exhaust valve is leaking.
It doesn't sound like this mechanic did this. I don't know why anyone
would tape off the intake or the exhaust. That would not be productive.
Did he pull the valve cover to check the valves? Seems to me that would
be one of the first things to do. A dropped valve, broken valve spring,
etc would make a lot of noise and possibly put a hole in the piston.
I would pull the valve cover and look for problems there first. If
nothing is detected, pressurize the cylinder though the glow plug hole
with the valves closed on that cylinder, and the piston at top dead
center and see where the air goes. Make sure the engine can't move when
the test is being done, as the engine can rotate if not exactly at TDC
from the pressure in the cylinder (assuming that you can build some
pressure in cylinder).
Dave
Caleb Pal wrote:
> Hey guys,
>
> Got an update from the mechanic. He said that the rings were leaking bad
> on #7 hole, and that has no compression. All others in the bank have
> 400+. He said a new engine. They don't rebuild them suposedly. I wasn't
> running it rough or anything, I think I am going to pull the valve cover
> and see whats going on under there. I don't think its the rings.Would a
> head gasket do this? He suposedly did a leak down and it showed that the
> air was going into the crankcase. Is there any way for air from the
> intake to go into the valve cover then into the crankcase. He put tape
> over the intake and exaust, so could air have gone from the intake into
> valve cover, into the crank case and false reading? Anyone else had a
> ring problem with thier truck that cause a ticking noise?
>
> Thanks
>
> Caleb
>
>
>
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