regaining some compression ?

[buddyholly]

is there any thing that can be done short of a rebuild to bring back some compression? '75 115 crossflow. I am thinking that i have a low cylinder, at idle it it stumbles but at half to full throttle it runs good. I pulled each plug wire off when running andlower left piston wasn't firing. swapped coils and nothing changed. when i say not firing i mean it didn't change the sound of the motor. also changed plugs,nothing. i havn't looked in the plug hole to see if there was a hole in the piston yet. If there is any other trouble shooting that I can do I will. But you guys will have to tell me what.

 

[BoatBuoy]

Re: regaining some compression ?

Don't know much about those, but all cylinders must have the magic trio - fuel, spark, compression. If it were mine, I would first like to know if it had spark at that cylinder.

 

[buddyholly]

Re: regaining some compression ?

yes it does have spark and the plug has gas on it. i am thinking that i have a really weak cylinder, compression wise.

 

[jfm1]

Re: regaining some compression ?

you should do a spark and a compression test

 

[buddyholly]

Re: regaining some compression ?

when removing the boot from the plug i can hear the spark jumping inside the boot. like i said i swapped coils and plugs from other cylinders and nothing changes. the coils work and i am getting spark and fuel but for some reason the motor idle doesn't change when removing the plug wire from that plug

 

[Solittle]

Re: regaining some compression ?

You will just be guessing until you get the compression readings.