Eninrude 70hp no compression on number 2

[Philby]

1990 Evinrude 70hp VRO.<br /><br />Took it out for the first time this season and heard a slight rattle. Ran great for 10 minutes than all of a sudden lost power. Struggled back to shore on two cylinders ( about another 10 minutes.<br /><br />I have just tested the compression @ 1=105psi 2=zero 3=105.<br /><br />I would have a guess at either a hole in the piston or a ring gone. Am I right.<br /><br />If I am can I pull out the individual cylinder ? I've got my clymers out and it tells me how to dismantle the powerhead.<br /><br />Preferaby I would rather you tell me that there is a little switch on the side of the engine that I can flick to get me back to full compression.<br /><br />Go on, make my day.

 

[Yepblaze]

Re: Eninrude 70hp no compression on number 2

Yea, the little switch thing, NOT!<br /><br />Don't forget you need to find the cause <br />(fuel, or oil starvation, or timing problem, or ???) <br />or after you get all done, and test ride, it happens all over again.

 

[Philby]

Re: Eninrude 70hp no compression on number 2

Well, the only cause I could think of was fuel starvation. Th4e carb looked ok.<br /><br />It is a VRO but I know that it couldn't be that !!!!!!!

 

[ledgefinder]

Re: Eninrude 70hp no compression on number 2

Check for a leaky exhaust plate, allowing water to enter the cylinder. You'll see the rust on parts, and/or a real clean spark plug on that cylinder. I don't have too much experience with the OMC triples (maybe someone who does would like to comment), but I just pulled apart my second this season with a blown center cyinder due to water leak.

 

[ledgefinder]

Re: Eninrude 70hp no compression on number 2

Actually, your description sounds more like it melted a hole through the piston top, probably due to lean mixture on that cylinder.<br /><br />In any case, full teardown is necessary (sorry).

 

[clanton]

Re: Eninrude 70hp no compression on number 2

There is at least 5 service bulletins for this engine to solve over heating and loss of compression. Try search, if you cant fine them keep bumping to top. My computer is down and I cant check board often. For a start the temp sensor pigtail should be about 7 inches long tan with blue stripe, tattle tale nipple relocated to top of block, main jet increase by 2 sizes and timimg retarded 1 degree from spec on carb cover.

 

[Dhadley]

Re: Eninrude 70hp no compression on number 2

We do know the center cylinder on those motors runs hotter in the mid range. We have had great success following all service bulletins including the new style water pump (as well as those Clanton mentioned) and richening up the mid range jet by 2 to 3 numbers. Also stick with Champion plugs.<br /><br />If you are using last years fuel, that may have something to do with it also.<br /><br />Good luck!

 

[Philby]

Re: Eninrude 70hp no compression on number 2

New fuel.<br /><br />What about this rattle I had. Is it possible this is a broken ring.<br /><br />Tell tale was ok and no overheat warning came on.<br /><br />I really need to find the cause as well as fix the fault.<br /><br />Thanks

 

[Dhadley]

Re: Eninrude 70hp no compression on number 2

What spark plugs?<br /><br />What grade of fuel?<br /><br />Carbs clean?<br /><br />Like I mentioned, we know the center cylinder runs hotter especially in the mid range. <br /><br />Were all the updates that Clanton and I mentioned done?

 

[Cut n' Jump]

Re: Eninrude 70hp no compression on number 2

My old '78 model 70 had a leaky gasket over the exhaust. Piston got a little scored and lost some compression. Don't the later model 70hp have 'integrated' exhaust which can't leak? VRO must be nice if its working but how can anyone have 100% trust in not pre-mixing the fuel with oil?