'81 Evinrude Compression Troubles 115 hp

[dwci97]

I have 120 lbs of compression in the 3 cylinders and the 4th one only has 55 lbs. Head gasket? rings?<br /><br />This wasnt a gradual loss of power it happened all at once. I was idling out and it died. The motor will start at high idle but as soon as I shift it into gear it dies. Any help would be appreciated so I can get going again.

 

[ledgefinder]

Re: '81 Evinrude Compression Troubles 115 hp

You'll have to pull the head to tell. Pulling the head is not that big a deal on those 2stroke V4s. <br /><br />My first guess would be it toasted a piston due to running lean on that cylinder - but it's just a guess. If, instead, the cylinder walls & piston look good, install a new head gasket, torque, and check the compression again. <br /><br />Either way, you'll want to find the source of the problem or it'll just re-occur. If the carbs are dirty/gummed up inside, one or more cylinders may run lean. If the water pump or thermostats are shot, it may have overheated on that bank of cylinders.

 

[Dhadley]

Re: '81 Evinrude Compression Troubles 115 hp

Did this happen on the first run after being in storage?

 

[dwci97]

Re: '81 Evinrude Compression Troubles 115 hp

No, this happened late in the season last year. Out of the blue it just did this. It was running fine and then just gave up. Any help would be appreciated.

 

[Walker]

Re: '81 Evinrude Compression Troubles 115 hp

As has already been suggested, pull the head and do a visual.

 

[dwci97]

Re: '81 Evinrude Compression Troubles 115 hp

pull the head and I will let you know what I find...