1988 Evinrude 70 Update: Thermostat issue

[Chinewalker]

I am rebuilding a 1988 Evinrude 70 - new pistons, etc. The pistons I removed had two tiny pinholes on the skirt (see photo, not mine, but same holes). They are not found on the replacement aftermarket pistons I bought for the motor, and I've never seen them on any other pistons I've removed from other motors. Anyone know their purpose?

 

[boobie]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

My first guess would be lubrication.

 

[nwcove]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

interesting.....are the holes in the other piston in the same spot?

 

[Chinewalker]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

The holes are on all three pistons I took out. The pistons were .030 oversize OEM replacements from a previous rebuild. I don't have pics of mine at the moment, the pic above is same style.

 

[woody66912]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Are they on the exhaust side or intake side?. And who's pistons are they.

 

[Faztbullet]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

They are there to add extra lube to the exhaust bridge and keep it cool. Thats one of the problems with the this engine( and 120/140/200 225hp of same years) as if it gets the slightest bit overheated or lugged the bridge will expand and scuff exhaust side of piston. This is one of the mods I do to these blocks as I sand the bridge down about .001...

 

[Willyclay]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

This is one of the mods I do to these blocks as I sand the bridge down about .001...

Is this mod for "race" motors or all flavors?

 

[Faztbullet]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

For all motors with bridged port exhaust (1986-93 yrs 60/70hp) and (1985-91 120/140hp) and( 2.7L 200/225) as the later motors have a 3 port oval exhaust

 

[Willyclay]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Great info, thanks!

 

[Chinewalker]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

It's a cruddy photo, but here are the pistons I took out. This motor was "rebuilt" in 2002 (or more recently, the piston crowns are dated from 2002). I use the term loosely, as it had a lot of questionable things done to it. Missing bolts, no thermostat, no cooling system/telltale update, generous use of orange RTV all over the place, etc. The middle piston was burned (rightmost in photo), as could be expected with these motors, particularly when the updates haven't been done...

 

[boobie]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

The #2 cyl was usually the one that went on those mtrs. Check your water pump and if it's still got the 3 blade impeller in it, get rid of it and put in the 6 blade kit.

 

[Chinewalker]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Already on that. I'm getting the OEM kit with the update for the telltale switcheroo....
Thanks!

 

[Chinewalker]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Got the beastie almost all together. Ran into some confusion with the thermostat. The waterpump kit came with the new spring, etc. to update the thermostat. Problem is, there was no thermostat in this head when I got the motor! No problem, I had a blown 120 from the same era that the parts book says uses the same t-stat. But it won't fit! Not even close! $*@&&^*!!

Sooo, a beer is called upon to lube the brain cells a bit. I recall that the motor had been rebuilt previously and the head was bare aluminum, while the block was black. Possibly a different cylinder head? Checking the casting numbers confirms that it is off a late 1990s Johnson triple, and the parts listings do indeed show a different t-stat assembly for the later head. Now I can order up the correct parts and get this thing outta my shop!

Can anyone think of a reason why the '99 head wouldn't work with the block I've got? The replacement block I bought off eBay was early 1990s...

 

[Faztbullet]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Can anyone think of a reason why the '99 head wouldn't work with the block I've got?

As long as its a foam cast block it will be fine...

 

[Chinewalker]

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Re: 1988 Evinrude 70: Anyone Know What The Pinholes in Piston Skirt Are For?

Thanks - yeah it's all 56 cuber stuff. Just wasn't sure if they changed dome or cooling pattern in some way that would make the hot spot tendency worse if mismatched...

 

[Chinewalker]

Re: 1988 Evinrude 70: UPDATED Running Motor! But....

Re: 1988 Evinrude 70: UPDATED Running Motor! But....

Okay, I fired up the motor for the first time today. Fired right off, but found a small fuel leak at one of the T's. Found another T and no more leak. Ran it for several minutes, found that the cylinder head was very hot - head bolts sizzle a bit when spritzed. Rest of block was nicely warm, no more than that.

My question is, is there any trick to assembling the thermostat? As noted above, I have a head from a much later motor and the thermostat coverage in my '88 manual is quite different. By the '99 parts listings, I have everything in the right order, but I wasn't sure if there was anything I was missing. Anyone have a manual for the '99/'00 era 56-cubers that they could scan the thermostat page for me?

For grins & giggles, I removed the t-stat just to verify flow and the head gets lukewarm and that's it, so it's definitely a thermostat flow issue.

Here's a pic of the parts I have - all for the '99 head.

 

[itsaboattime]

Re: 1988 Evinrude 70: Running Motor! But....

Re: 1988 Evinrude 70: Running Motor! But....

At the risk of sounding like a wise-guy, I'm thinking that's why there wasn't one in it when you took it apart. It gets HOT!!! lol.

Would a 110 horse be included in those motors that had issues?

 

[Chinewalker]

Re: 1988 Evinrude 70: Running Motor! But....

Re: 1988 Evinrude 70: Running Motor! But....

The 110 was a crossflow V4. I'm not aware of any inherent cooling issue with those...

 

[Chinewalker]

Re: 1988 Evinrude 70: Thermostat issue

Re: 1988 Evinrude 70: Thermostat issue

Just to confirm, I put the brass thermostat bit in hot water and the pin extended as it should. I think I have the concept of how it works down - just not sure why it isn't letting water through.

 

[Faztbullet]

Re: 1988 Evinrude 70 Update: Thermostat issue

Here ya go ..should open with PDF reader
View attachment IMG.pdf