1988 Evinrude 70 Update: Thermostat issue

[Chinewalker]

Re: 1988 Evinrude 70 Update: Thermostat issue

Thank you. Everything looks like I had it. Not sure what I'm doing wrong, if anything. Might just leave it as is and try it again when I get it on the boat and in the water. I was just running it on the hose when I fired it off on Saturday.

 

[Chinewalker]

Re: 1988 Evinrude 70 Update: Thermostat issue

Finally got the cooling system sorted out. Determined it was due to the mish-mash of parts, with the t-stat not working properly with the head and cap assembly. I installed the head off a recently acquired blown 1989 triple, installed a new vernatherm and now we're warm - not hot, not cold, just warm. As it should be.

 

[bonz_d]

Re: 1988 Evinrude 70 Update: Thermostat issue

Great going Chinewalker! And thanks again for the info yesterday on that driveshaft. Too bad it didn't work out so well for me.
How much time do you have into that rebuild on your 70hp?

 

[Chinewalker]

Re: 1988 Evinrude 70 Update: Thermostat issue

Total, maybe 10-12 hours from start to finish for actual bench time. Lots of fits and spurts as I haven't worked on it consistently. I've done a few of these triples before, although this was my first 56-cuber. The others were all older 49-cuber blocks and there are a few differences along the way, as I discovered. I also re-rigged the boat for the owner and have been water testing it and putting break in time on it for him.

 

[bonz_d]

Re: 1988 Evinrude 70 Update: Thermostat issue

So what year did they make the change in "CID"? May be interesting to know as I still may look for a 70hp to hang back on my Alumacraft. What aside from cid were the major changes?

 

[Willyclay]

Re: 1988 Evinrude 70 Update: Thermostat issue

and have been water testing it and putting break in time on it for him.

Great picture!

 

[Chinewalker]

Re: 1988 Evinrude 70 Update: Thermostat issue

Bonz - the biggest change, aside from cubes, was the block construction. They went to the lost foam casting process, which made for fewer parts involved. Instead of a sandwich of castings for the exhaust side, there's a single cover. Instead of a full cover for the cylinder head, there's a single cap for the thermostat - and fewer head bolts. The new design created a hot spot that resulted in the cooling update needed to properly fill the block with water. Internally, the rods are different - the 56-cuber rods are longer. Cranks are similar, so I suspect they moved the wrist pin location further toward the head on the larger pistons to accommodate the longer rods. They also moved the coils from the cylinder head to a plate on the side of the block.

 

[Chinewalker]

Re: 1988 Evinrude 70 Update: Thermostat issue

Great picture!

Thanks! It was a beautiful evening for a boat ride!

 

[bonz_d]

Re: 1988 Evinrude 70 Update: Thermostat issue

So would you say the 56 incher is a better design other than the temp issue?

 

[Chinewalker]

Re: 1988 Evinrude 70 Update: Thermostat issue

That, I can't say. I've got a 1980 Johnson Stinger 75 that's been an awfully good motor for a very long time. I rebuilt it in the mid 1990s and other than replacing a powerpack and doing a couple waterpump jobs, it hasn't missed a beat. As good? Maybe. Better? The jury's still out on that count...

One thing I do notice about the '88 I rebuilt, it seems quieter than my '80.