I recently had my 1987 Mariner 115 HP in the shop. While the mechanic was trying to solve the problem,(bad rev limiter) he checked the compression. On the top 3 cylinders he said I have 114. On the bottom cylinder I am at 100. Is that getting low? Should I be worried? Or thinking of selling?
2007-08-11 05:20:43 · 8 answers · asked by erik 1 in Cars & Transportation ➔ Boats & Boating
That's close it might of been dry tested so 25% difference is the most want.Your getting to the end of the life but if you just use it an don't hammer it should last a long time. Has the Eng been sitting a long time?? An did he run it till warm before test? Squat oil in lower cyc an see if it raises the comp. If it comes up a lot than rings or scored cyc.
2007-08-11 14:05:47 · answer #1 · answered by 45 auto 7 · 0⤊ 0⤋
Outboard Compression
2016-12-16 05:51:41 · answer #2 · answered by jeniffer 4 · 0⤊ 0⤋
In my opinion I would be careful on how hard you run the motor.I just had my outboard overhauled due to low compression on one cylinder. The difference was 125 psi on all 5 cylinders and #6 was at 100 psi. I pulled the power head and rebuilt it myself. Rule of thumb is you don't want to see no more than 5 to 10 psi difference between cylinders. Your rings are worn and or the walls on the cylinder wall is scared. You will experience lower horsepower and higher fuel consumption. Eventually you may have a detonation on that cylinder. I hope for your sake this doesn't happen to you. If it does you will know it. My advise is if you like the vessel you have then go ahead and fork out the dollars to have the repair done. This will prevent you from spending a whole lot more down the line. Hope this helps, Good luck
2007-08-11 10:31:54 · answer #3 · answered by Anonymous · 0⤊ 0⤋
It may be OK. But, that my opinion. I would not want to see more than a 20% difference in all cylinders. Really 10% best, but, that one being low and the others close, I would go with it.
I did a little reading. The actual reading is not as important as the differences. A variation of 15 psi between two cylinders indicates a problem with the lower reading cylinder. Worn rings or scored pistons (Oil mix?). You could try running some De-carbon through it and see if it help. I think it "Sea Foam" at most auto parts stores, just read the instructions.
2007-08-11 05:28:50 · answer #4 · answered by Snaglefritz 7 · 1⤊ 0⤋
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i don't think 80# is too low on a stock engine,especially if you didn't warm it up first. i check them every day and they range between 80 to 100 #. the fact that they are even is a good thing.you don't say what year it is, but johnson had a low compression v6 that was about 6to1 compression ratio for a few years. as the other post stated,warm the engine to operating temp, remove all of the plugs, open the throttle to wide open,and be SURE it's in neutral or remove the prop if you want to keep all of your toes. use a remote starter button or a jumper wire, yellow/red to battery + if you don't have a helper to turn the key.
2016-04-10 07:52:38 · answer #5 · answered by ? 4 · 0⤊ 0⤋
ran cold compression on a 1995 Mariner 115 3 cylinders tested at 130 psi the bottom cylinder tested at 125 psi is this good?
2015-02-21 05:11:54 · answer #6 · answered by jeff 1 · 0⤊ 0⤋
maybe a Little, on a 2 stroke Id prefer to see about 130 or better
2007-08-11 07:04:02 · answer #7 · answered by Anonymous · 0⤊ 1⤋
what you want is for the cylinders to fairly close to the same compression. you are ok
2007-08-11 06:21:32 · answer #8 · answered by Anonymous · 0⤊ 0⤋