Drivetrain what compression levels does a motor need a rebuild?
You have a 23% difference in compression between cylinders 1/4, and 2/3 which is above what is normally acceptable. Besides that, your 100psi value on cylinders 1/4 is on the very low side. As long as the compression check was done properly, it sounds like this short block is in need of a rebuild.
Take a look at some of these links. They describe what may cause low compression and how to diagnose the differences. Unless the cam was ground incorrectly where it allowed too much of the compression to blow off prior to the valves completing closing, I would suspect you have a problem with a burnt valve(s), a bad head gasket, or a problem with the rings or pistons.
A car with low compression due to poor rings will idle fine and won't throw any CELs, however it will simply be down on power and you may not even realize it. I can't remember for sure, but I think I had compression numbers from 125 to 175 on my motor prior to rebuilding it. Mine had a blown head gasket, and it simply was time to rebuild since it had 140K on it at the time.
http://www.aa1car.com/library/compression.htm
http://www.search-autoparts.com/sear...l.jsp?id=16170
Here's a video (kinda long) on how to do a compression check. If you look at the side of the screen there are alot of videos showing how to do a check and how to diagnose the cause of low compression. http://www.youtube.com/watch?v=9U8iNb21arw
A car with low compression due to poor rings will idle fine and won't throw any CELs, however it will simply be down on power and you may not even realize it. I can't remember for sure, but I think I had compression numbers from 125 to 175 on my motor prior to rebuilding it. Mine had a blown head gasket, and it simply was time to rebuild since it had 140K on it at the time.
http://www.aa1car.com/library/compression.htm
http://www.search-autoparts.com/sear...l.jsp?id=16170
Here's a video (kinda long) on how to do a compression check. If you look at the side of the screen there are alot of videos showing how to do a check and how to diagnose the cause of low compression. http://www.youtube.com/watch?v=9U8iNb21arw
If it runs fine... Drive it...f you have problems..rebuild it.
Are you sure it is not the valves that are leaking?!
Generaly IMO, if a motor is happy, why are you digging for stuff to fix if it idles fine, has no codes, etc? If you are trying to make big hp, then things are a bit different.
Any idea about how clean the motor is? The rings could be stuck...caused by carbon/varnish....
Are you sure it is not the valves that are leaking?!
Generaly IMO, if a motor is happy, why are you digging for stuff to fix if it idles fine, has no codes, etc? If you are trying to make big hp, then things are a bit different.
Any idea about how clean the motor is? The rings could be stuck...caused by carbon/varnish....
that's what i think it could be or something minimal.
runs fine. i had other mini owners tell me they didn't notice any issue.
yes. no codes, good idle, good driveability, with no apparent issues.
thanks a bunch
runs fine. i had other mini owners tell me they didn't notice any issue.
yes. no codes, good idle, good driveability, with no apparent issues.
thanks a bunch
If it runs fine... Drive it...f you have problems..rebuild it.
Are you sure it is not the valves that are leaking?!
Generaly IMO, if a motor is happy, why are you digging for stuff to fix if it idles fine, has no codes, etc? If you are trying to make big hp, then things are a bit different.
Any idea about how clean the motor is? The rings could be stuck...caused by carbon/varnish....
Are you sure it is not the valves that are leaking?!
Generaly IMO, if a motor is happy, why are you digging for stuff to fix if it idles fine, has no codes, etc? If you are trying to make big hp, then things are a bit different.
Any idea about how clean the motor is? The rings could be stuck...caused by carbon/varnish....
thank you very much for the links!!!
Take a look at some of these links. They describe what may cause low compression and how to diagnose the differences. Unless the cam was ground incorrectly where it allowed too much of the compression to blow off prior to the valves completing closing, I would suspect you have a problem with a burnt valve(s), a bad head gasket, or a problem with the rings or pistons.
A car with low compression due to poor rings will idle fine and won't throw any CELs, however it will simply be down on power and you may not even realize it. I can't remember for sure, but I think I had compression numbers from 125 to 175 on my motor prior to rebuilding it. Mine had a blown head gasket, and it simply was time to rebuild since it had 140K on it at the time.
http://www.aa1car.com/library/compression.htm
http://www.search-autoparts.com/sear...l.jsp?id=16170
Here's a video (kinda long) on how to do a compression check. If you look at the side of the screen there are alot of videos showing how to do a check and how to diagnose the cause of low compression. http://www.youtube.com/watch?v=9U8iNb21arw
A car with low compression due to poor rings will idle fine and won't throw any CELs, however it will simply be down on power and you may not even realize it. I can't remember for sure, but I think I had compression numbers from 125 to 175 on my motor prior to rebuilding it. Mine had a blown head gasket, and it simply was time to rebuild since it had 140K on it at the time.
http://www.aa1car.com/library/compression.htm
http://www.search-autoparts.com/sear...l.jsp?id=16170
Here's a video (kinda long) on how to do a compression check. If you look at the side of the screen there are alot of videos showing how to do a check and how to diagnose the cause of low compression. http://www.youtube.com/watch?v=9U8iNb21arw
Thread
Thread Starter
Forum
Replies
Last Post
SneedSpeed
Vendor Announcements
0
Sep 10, 2015 07:22 AM
