79 evinrude 35hp overheated won't idle slow

[eastridgebill]

I have a 79 evinrude 35 hp model 35952A which recently overheated. I got it running after it cooled down but it will not stay running at about half throttle or less. It was running perfectly prior to that. No discoloration of head however I did get steam and it stalled coming to my boat landing. Changed plugs with new and still the same. A compression test showed over 75 on both cylinders with about 4lbs difference.Can anyone point me in the right direction?? My son is home from the USNavy and now we're dry docked. Thanks for any help.

 

[tashasdaddy]

Re: 79 evinrude 35hp overheated won't idle slow

your compression is low, try taking it with another guage, to verify. could be blown head gasket, or worse from running hot. have you replace the impeller since it ran hot?

 

[eastridgebill]

Re: 79 evinrude 35hp overheated won't idle slow

Thanks to Tashasdaddy for the reply! I will recheck the compression. I did not replace the impeller because it seems to be fine, good stream of water coming out of the pisser and all.. I believe what happened is we got into the mud and weeds then had a temporary clog. It does seem to turn over faster when starting than it did before the problem occurred.

 

[kenmyfam]

Re: 79 evinrude 35hp overheated won't idle slow

Thanks to Tashasdaddy for the reply! I will recheck the compression. I did not replace the impeller because it seems to be fine, good stream of water coming out of the pisser and all.. I believe what happened is we got into the mud and weeds then had a temporary clog. It does seem to turn over faster when starting than it did before the problem occurred.

Certainly sounds like low compression is a probable reason. It will turn over faster due to less resistance with the lower compression.
Just my 2 cents.

 

[tashasdaddy]

Re: 79 evinrude 35hp overheated won't idle slow

agree. if the impeller has not been changed in the last 2 years, change it, and if the tstat is origingal i would change that also, when you repair the motor, why take a chance to burn it up again.

 

[eastridgebill]

Re: 79 evinrude 35hp overheated won't idle slow

Just an update. I retorqued heads after reading similiar problems and compression went from 75 to 125 runs great again. Need to replace thermostat and impeller. Checked my lower end fluid and it is milky. Should I just buy a water pump kit?