Just want to know more about compression. I did a bit of research on the web and said that if you have bad compression in the one cyclinder, then it normally means bad exhaust valve. Is this true?

I'm thinking of buying my friends car who has a low compression on one of the cyclinders its out by 15. I was told anymore than that and I am looking at getting new pistons, rings, valves etc which is costly. If that was the case what am I better of doing?


The readings are 162, 160, 165, 164, 150, 162

The mechanic that tested it for me said it's nothing to worry about as long as it doesn't drop below 150 for cylinder number 5, but I just want to see my options and other opinions I guess.

I was also told that cylinder 5 is normally lower in a GTR since more air gets dumped into that cylinder.?

Thanks.

 

ur rings could be going or u could have a valve leak or very worse case scenario u could have a damaged cylinder