how to compression test

[dppham]

i seen on youtube where they would use a jumpstart cables to do a compression test
where do they plug it up to
is it safe?
will it burn anything up?

 

[gordwa]

Re: how to compression test

when you do a compression test you have to hook up a gage to one cylinder at a time at the spark plug hole.Then crank over the motor several turns.Usually at wot and a warm motor.Then record the reading for each cylinder.If its with in 10 ten pounds is good more than that a ring job is close at hand.You can buy a satisfactory compression kit a harbor freight.I dont understand what you mean by jumpstart.

 

[RogersJetboat454]

Re: how to compression test

i seen on youtube where they would use a jumpstart cables to do a compression test
where do they plug it up to
is it safe?
will it burn anything up?

Hard to say with out seeing the actual video. But if I were to guess,
they are most likely bypassing the key by applying power directly to the starter solenoid.

This would be a no-no on an engine in a contained area (bilge) as the arcs that could be produced by doing this could ignite latent fuel vapor. The safer alternative would be to use a starter button, which most auto parts stores carry.

Don't know what your working on for an engine, so I can't say whether or not it would cause any damage.

 

[cr2k]

Re: how to compression test

You can buy a handheld "Remote Starter Switch" at any auto parts. It is hooked up to the solenoids big + term and the "S" term (Usually brown or yellow/red stripe) depending on engine, but not to the BLACK or Ground.

Kill the ignition (key off or lanyard pulled) and block throttle wide open. All cylinders should be within 10 PERCENT of each other.

 

[444]

Re: how to compression test

All spark plugs out, throttle wide open and hit the key. Turn it over long enough for about 3 complete revolutions of the engine. It will stop building pressure by then anyway. You want to do each cylinder and record the readings.

 

[aussieflash]

Re: how to compression test

Most important thing to do to avoid damage is ground your plugs to block or pull the lanyard/kill switch.I run my motor then pull lanyard,then motor dies,i know it works and im good to go.....oh and dont smoke while your testing.