Checking Compression
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Freshman User
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Checking Compression
I have a 2012 5.0 with 52K on the odometer.
I plan on checking compression this weekend, and the plan is to get engine up to operating temp, disconnect all the coil wires at the coils, pulling the coils and plugs, removing the fuel pump fuse, bleeding any remaining fuel pressure, connecting a battery charger to the battery to help with the drain/load on the battery.
Finally checking (and documenting) each cylinders pressure.
Am I on track as far as procedure? Am I leaving anything out?
Thanks, KD
I plan on checking compression this weekend, and the plan is to get engine up to operating temp, disconnect all the coil wires at the coils, pulling the coils and plugs, removing the fuel pump fuse, bleeding any remaining fuel pressure, connecting a battery charger to the battery to help with the drain/load on the battery.
Finally checking (and documenting) each cylinders pressure.
Am I on track as far as procedure? Am I leaving anything out?
Thanks, KD
Lead Driver
Joined: Sep 2003
Posts: 7,015
Likes: 208
From: SoCal
You can do that, or leave the key off and use some kind of jumper on the starter relay. Jump between the positive battery terminal and the activation wire from the key switch. Sometimes I use a screwdriver to do this right at the relay.
You might want to wear Nomex gloves to remove the plugs from a hot engine.
You might want to wear Nomex gloves to remove the plugs from a hot engine.
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My thought process is oil analysis (for high wear metal content) and a compression test. Just looking for any red flags. Might even bore scope as well.
Do I have a knock? Not sure...I don't hear anything that says "yes it's a knock". Do I hear what might be a faint knock? Maybe, again, maybe just paranoid, who knows, but would hate to have it turn into a " for sure knock" just after warranty or something like that.
So I figure an hour or two of checking compression might make me sleep better...(or not). Thanks, KD
Thread Starter
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Freshman User
Joined: Aug 2014
Posts: 26
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You can do that, or leave the key off and use some kind of jumper on the starter relay. Jump between the positive battery terminal and the activation wire from the key switch. Sometimes I use a screwdriver to do this right at the relay.
You might want to wear Nomex gloves to remove the plugs from a hot engine.
You might want to wear Nomex gloves to remove the plugs from a hot engine.
Do you mean the starter "S" terminal when you say "activation wire? Thanks, KD
Lead Driver
Joined: Sep 2003
Posts: 7,015
Likes: 208
From: SoCal
The starter solenoid has 2 small posts, one of which is for the wire that comes from the key switch. That's what I meant by "activation wire". There are two large terminals, one of which comes from the battery +terminal. If you short that to the key switch terminal, that should run the starter motor.
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Freshman User
Joined: Aug 2014
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The starter solenoid has 2 small posts, one of which is for the wire that comes from the key switch. That's what I meant by "activation wire". There are two large terminals, one of which comes from the battery +terminal. If you short that to the key switch terminal, that should run the starter motor.
Thanks, I forgot I owned one, it is probably buried in a cabinet in my garage, but will dig it out and dust it off. It should save some time. KD
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