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Max Online: 36273 @ 01/23/13 02:34 PM
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#12376167 - 08/07/17 01:15 PM Evinrude 1981 115hp Compression Test Difference
BrazosRiverTom Online   content
Pro Angler

Registered: 12/15/12
Posts: 521
Loc: Mineral Wells, TX
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.

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#12376450 - 08/07/17 05:24 PM Re: Evinrude 1981 115hp Compression Test Difference [Re: BrazosRiverTom]
rb7764 Online   content
Extreme Angler

Registered: 01/08/04
Posts: 2011
Loc: Frisco, TX, USA
Have you checked the starboard side head gasket? You might get lucky.

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#12377065 - 08/08/17 06:40 AM Re: Evinrude 1981 115hp Compression Test Difference [Re: BrazosRiverTom]
Gamblinman Online   content
Extreme Angler

Registered: 11/26/02
Posts: 2625
Loc: Yantis, TX
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.
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#12377410 - 08/08/17 11:34 AM Re: Evinrude 1981 115hp Compression Test Difference [Re: BrazosRiverTom]
PlanoPaul Online   content
Outdoorsman

Registered: 12/16/13
Posts: 202
Loc: Plano, TX
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.

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#12380068 - 08/09/17 10:57 PM Re: Evinrude 1981 115hp Compression Test Difference [Re: BrazosRiverTom]
Alumacraft 14 Offline
Outdoorsman

Registered: 02/24/06
Posts: 67
Loc: Texas
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.

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#12385789 - 08/14/17 03:19 PM Re: Evinrude 1981 115hp Compression Test Difference [Re: BrazosRiverTom]
BrazosRiverTom Online   content
Pro Angler

Registered: 12/15/12
Posts: 521
Loc: Mineral Wells, TX
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

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#12389416 - Yesterday at 07:52 AM Re: Evinrude 1981 115hp Compression Test Difference [Re: BrazosRiverTom]
Gamblinman Online   content
Extreme Angler

Registered: 11/26/02
Posts: 2625
Loc: Yantis, TX
That's a pretty high idle speed...hard on the LU gears when shifting into gear.
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