1989 twin mariner 200 cxl compression?

kahuna · #1 June 24th, 2003, 06:40 PM

I have twin 1989 mariner 200 hp. When I bought the boat last year, the surveyor said the compression results were 130 to 135 psi on five cylinders on both engines but the sixth cylinder on the engines were 115 and 110. Do I have a problem and if so what should I do? Also the engines run rough between 1500 and 2000 rpms.

dakk1 · #2 June 24th, 2003, 07:24 PM

Kahuna

Strange that both motors would have one cylinder a little low. Not too bad though. Could rings be sticking a little on those cylinders? I had a ring sticking on my Merc 150 and a decarb worked wonders. I used Mercs Powertune. Good Luck!

kahuna · #3 June 25th, 2003, 07:21 PM

Thanks dakk1. It is strange that the 6th cylinder is low on both, It's even stranger because the port engine has a new power head (less than two years old.) Could the sticking ring be the cause of the rough vibration at 1500rpm to 2000 rpm? By the way they are smoking alot also.

dakk1 · #4 June 25th, 2003, 07:32 PM

kahuna

I would do a decarb. This is just my opinion. Some believe in it some don't. It worked for me. It has been suggested to me that it should be done every 50 hrs or so and I think that is reasonable. If you think its been that long or longer give it a try. Since your compression is real close to tolerable it may bring those cylinders that are a little low up. Might help the smoking too. You'll need new plugs after. Good Luck!

gss036 · #5 June 25th, 2003, 08:51 PM

Do a SEARCH for DECARB and read the results. You may find a good answer is you search under member # 727 (DUNK), he post a lot and has a lot of wisdom on the subject.