Posted By: BrazosRiverTom
Evinrude 1981 115hp Compression Test Difference - 08/07/17 06:15 PM
I just did a compression test and I got the following readings:
Cylinders 2 & 4 Port Side 108 psi
Cylinders 1 & 3 Starboard side 82 psi
The engine runs good most of the time. If I keep it at 4000 RPM's and under
how much longer can I expect to motor to last?
I cannot afford a rebuild this year.
Appreciate any help.
Posted By: rb7764
Re: Evinrude 1981 115hp Compression Test Difference - 08/07/17 10:24 PM
Have you checked the starboard side head gasket? You might get lucky.
Posted By: Gamblinman
Re: Evinrude 1981 115hp Compression Test Difference - 08/08/17 11:40 AM
As suggested, check to make sure its not the head gasket. After that, its a crapshoot how long it will last. All depends on what is causing the low compression on that bank of cylinders.
Posted By: PlanoPaul
Re: Evinrude 1981 115hp Compression Test Difference - 08/08/17 04:34 PM
I'd crack it open, hone and re-ring. Not very costly at all, and actually a pretty ease job. Clean carbs after to make sure you are getting proper fuel to the cylinders. Might end up getting quite a few more years out of her.
Posted By: Alumacraft 14
Re: Evinrude 1981 115hp Compression Test Difference - 08/10/17 03:57 AM
Shoot some wd40 in the cylinders with low compression, then do a test. If it raises the compression then it's not a head gasket.
If it stays the say then inspect hear gasket.
Posted By: BrazosRiverTom
Re: Evinrude 1981 115hp Compression Test Difference - 08/14/17 08:19 PM
Okay just redid compression test and these are the new results
Cylinders 2 & 4 Port Side 108 psi
Cylinders 1 & 3 Starboard side 88 psi (up from 82 psi from previous test)
Did what Alumacraft 14 suggested and the Starboard side came up 4 points to
92 psi on both cylinders.
Do not know what else I can do cheaply till I can afford to start replacing things on it.
I did install a water/fuel separator. Idling much higher now (after I made some adjustments) like 1100 in neutral and 700 in gear. But still cuts back once in a while to 300 rpm and then dies. Always starts right back up easily.
PanoPaul thanks for your suggestion but that is out of my expertise and I am sure I do not have the right tools to do a job like that.
Appreciate everyone's input. Thanks
Posted By: Gamblinman
Re: Evinrude 1981 115hp Compression Test Difference - 08/17/17 12:52 PM
That's a pretty high idle speed...hard on the LU gears when shifting into gear.