Compression test

"what is a good average for co

"what is a good average for comprssion on a 1986 mercruiser 14hp four banger. I have one and am going to do a compression test and want to know what kinda numbers I should get



"

"Not much if that huge motor i

"Not much if that huge motor is only "14 hp"! (Sorry, couldn't resist.)

Look for 110 to 140, with consistency between cylinders more important than high readings. While it's out, be sure to replace the water pump belt. And tie wrap a spare belt out of the way but still in place since it's a dog to change.

Jeff"

"Ayuh,......

Above 140 is a

"Ayuh,......

Above 140 is a Good Tight motor,....
Up to 140 is a good runner....
Under 110 is pretty much a Core motor....."

yes jeff its a 140hp heheh and

yes jeff its a 140hp heheh and thank you both

"That looks like my motor from

"That looks like my motor from a Sunbird 17 ft. My motor had 140, 80, 50, and 50. Yes, I do wish I had done the compression test before I bought the boat! If you have to replace all the pistons and head gasket though, this is the motor to do it to. It's not that hard and luckily I have friends that have helped me along the way. If you are looking to buy a used boat, don't even think about not getting it inspected by someone who knows what to look for. I'm only out a couple of hundred instead of a couple of grand or worse yet trashing the whole boat. And to make matters worse, that front motor mount wasn't even bolted down due to the rotten wood under the fiberglass layer. I guess I'll be a fiberglassing expert by the end of this weekend! Wish me luck and see you on the water!"