Evinrude or Johnson ??

[F_R]

You asked why. Because it has a thermostat-controlled recirculating cooling system. Water goes up one tube, through the powerhead, and is then presented to the thermostat. If the 'stat says it is not warm enough, the water goes back to the pump via the second tube for recirculation until warm enough. Single tube systems do not have the recirculating feature.

 

[Teacher48]

That’s really interesting. I now understand the system. I thought maybe cooling separate sides, but that made no sense when I looked at pump itself. When I started the engine the first time I had the lower unit off and put water to both tubes, little pressure but some. Engine ran fine and never really got remotely hot, just slightly warm. Hopefully I didn’t screw something up with water going the wrong way.

 

[racerone]

Sounds like a 135 HP powerhead was swapped out on the 115 HP.----Likely the model # and serial # of block are different from midsection.

 

[F_R]

That’s really interesting. I now understand the system. I thought maybe cooling separate sides, but that made no sense when I looked at pump itself. When I started the engine the first time I had the lower unit off and put water to both tubes, little pressure but some. Engine ran fine and never really got remotely hot, just slightly warm. Hopefully I didn’t screw something up with water going the wrong way.

Water can't go the wrong way, as long as nobody has stripped all the innards out of the thermostat box..

 

[Teacher48]

Did some more looking. Removed coil plate and found circle where #s should be I think. Port side looks like soft plug. No #s!! Not surprised. Did however find part # on starboard side cylinder head. (319943). Looked that up and found fits 1970s 135 Johnson. Then checked out model # for Evinrude on the engine mount and that cylinder head is not the same. So as of right now I do think it’s a135 on top of a 115 as was suggested. My logic is if the 2 engines are almost the same then pistons must be slighter different then cylinder heads must be different but I’m not a trained mechanic. Not that it matters at all, as also suggested it may be junk, but between NYS winter, Covid, no restaurants, no casinos, no vacations, no family get togethers and my arm in a sling for 6 weeks it’s been a great diversion, Thanks everyone for your input!

 

[F_R]

Yes, 135 and 115 motors are different bore size. Among some other items.

 

[racerone]

???----As far as I know pistons are the same for the 3.500" bore crossflow from 1974 to 1998 models.----Be it an 85 / 100 / 115 / 135 / 140 HP model.----The 115 and 135 have the same bore , stroke and displacement !!

 

[ct1762@gmail.com]

come on atleast change the impeller while your in there after that work. those gearcases are heavy when doing by yourself! i like piece of mind, personally. plus you are up in clean freshwater country... probably wont have to do another one for 5 years

 

[F_R]

'???----As far as I know pistons are the same for the 3.500" bore crossflow from 1974 to 1998 models.----Be it an 85 / 100 / 115 / 135 / 140 HP model.----The 115 and 135 have the same bore , stroke and displacement !!

I stand corrected---sort of. The 85 was smaller bore at 3.375", but 115 and 135 were 3.500". At least in 1974.

 

[Teacher48]

Ok so here is my logic ( means nothing). So bore is the same for 115 and 135, 20 hp needs to come from somewhere but nor displacement. Either fuel jets, air intake or exhaust ports, the info I have found is that the cylinder heads have different numbers. I believe that they contain both intake and exhaust ports. Just maybe thats where the extra 20hp comes from.
As far as impeller replacement goes I agree but I’m not putting any $s into this Frankenstein until I’m sure it’s a solid engine. I’m learning a ton, thanks everyone.

 

[racerone]

There are no ports in the cylinder heads at all !!

 

[Teacher48]

So much for that thought. Who knows doesn’t really matter ,going to get to

 

[Teacher48]

messed that up. Going to try and get her started in the spring and check it out completely before I do anything with it. Just a fun project until I found another one. Always messing with something.

 

[F_R]

I can't (won't) sit here and research all the differences. But compression ratio (cylinder heads) can make a significant difference in horsepower. Also can exhaust tuning (that bulging exhaust cover is part of it). Lots of other possibilities. Let's just say it all has to work together.