mercruiser 5.0 alpha one compression test

[lukeskywalker]

hi, i bought 21 beachcraft recently, it has m/c alpha 1 inboard engine. i think i got a pretty deal. i did a compression test. here is the rezult, 150;140;120;120;120;125;120;125. is it still runnable? should i try some seafoam or miracle?

thanks

 

[achris]

Hello Luke, and :welcome: to iboats. May the 4th be with you.

It's always more helpful to add things like the year of the engine (boat year and engine year are not always the same, and knowing the boat doesn't have any bearing on the engine), and the engine serial number when you're posting.

Those results aren't wonderful, but yes, the engine should run with them. I do have to ask, what procedure did you use to conduct the compression test? Engine warm? All spark plugs removed? Throttle set to wide open?

Chris.......

 

[tpenfield]

Use the force . . .

What Chris said, and I would make sure to have a good battery and keep a charger on it during the testing. Also if you re-test, label the results with the cylinder number.

You can also do a cylinder leak test, which may help diagnose some of the low cylinders.

 

[lukeskywalker]

Thanks Chris and Ted! It is 79 beachcraft. The guy told me the engine has about 500 hrs. And some technicians at a marina did the test. It was winterized and dry stored for at least 2 years. I was told the motor running rough.