4.6L cylinder compression
08-02-2015, 05:32 PM
#3
5th Gear Member
Join Date: Mar 2008
Location: wisconsin
Posts: 2,260
that depends on the compression ratio, but should range right around there. the rule of thumb is that there not be more then 10% difference between the high and low readings.
so base off of your post i would suspect that you have a problem with the cyl that reads 100psi. i suggest adding a squirt of oil to that hole and retesting, if the compression comes up suspect rings, if not i would say you better pull it apart and inspect
so base off of your post i would suspect that you have a problem with the cyl that reads 100psi. i suggest adding a squirt of oil to that hole and retesting, if the compression comes up suspect rings, if not i would say you better pull it apart and inspect
08-02-2015, 06:16 PM
#4
Thread Starter
Join Date: Jul 2015
Location: Texas
Posts: 4
that depends on the compression ratio, but should range right around there. the rule of thumb is that there not be more then 10% difference between the high and low readings.
so base off of your post i would suspect that you have a problem with the cyl that reads 100psi. i suggest adding a squirt of oil to that hole and retesting, if the compression comes up suspect rings, if not i would say you better pull it apart and inspect
so base off of your post i would suspect that you have a problem with the cyl that reads 100psi. i suggest adding a squirt of oil to that hole and retesting, if the compression comes up suspect rings, if not i would say you better pull it apart and inspect
If its the rings I will still have to pull the motor correct? It would be very hard to change rings with the motor in place.
08-03-2015, 05:07 PM
#6
2nd Gear Member
Join Date: Apr 2014
Location: NY
Posts: 478
Check the crankcase ventilation system and the PCV.Even a worn motor shouldn't be putting oil out the air cleaner.Assuming the oil level is proper too.
Has the car sat for a long time? I've known cars that sat for years,had major blow by,and running them,with a few oil changes,freed up stuck rings.
Has the car sat for a long time? I've known cars that sat for years,had major blow by,and running them,with a few oil changes,freed up stuck rings.
08-03-2015, 07:30 PM
#7
5th Gear Member
Join Date: Mar 2008
Location: wisconsin
Posts: 2,260
Check the crankcase ventilation system and the PCV.Even a worn motor shouldn't be putting oil out the air cleaner.Assuming the oil level is proper too.
Has the car sat for a long time? I've known cars that sat for years,had major blow by,and running them,with a few oil changes,freed up stuck rings.
Has the car sat for a long time? I've known cars that sat for years,had major blow by,and running them,with a few oil changes,freed up stuck rings.
08-03-2015, 09:24 PM
#8
Thread Starter
Join Date: Jul 2015
Location: Texas
Posts: 4
I think this I what's going. Can you disable a cylinder and still start the car? If I could unplug the injector wire and spark plug from that cylinder I could tell if the blow by stops.
08-03-2015, 10:18 PM
#9
5th Gear Member
Join Date: Mar 2008
Location: wisconsin
Posts: 2,260
maybe, but the leaking cylinder pressure from compressing the air even without ignition will still cause blowby. trust me, you have a bad hole.... most likely rings, it needs to come apart. anything else is just wasting time and money
08-04-2015, 07:36 AM
#10
Thread Starter
Join Date: Jul 2015
Location: Texas
Posts: 4
Yes agreed, the motor has to come out for repair.