1975 Ev. 70 HP Lower Unit Bolt Torque?

[KilroyJC]

Hello - <br /><br />I have a 1975 Evinrude 70 HP Model 70573 (mechanical shift) that has a waterpump problem. This is my first boat & motor (it is on a '76 Starcraft 18' runabout), so I bought the SELOC manual. Having played with cars & aluminum before, I know about stripping out threads...<br /><br />ANYWAY - The manual does not list torque specs for the 6 bolts attaching the lower unit to the exhaust housing. The manual says to go to the appendix for specs, but it only lists specs for all the powerhead bolts - nothing below. I searched the forums for about an hour (Honest!) & found a bunch of good info on my motor, but not that info. Any help with torque specs? Before I put it together and create more problems than when I started?<br /><br /><br />While I'm at it - My friends who got me into boating - and let me keep my boat in their driveway - have a 16'Boston Whaler with 1 '91 70HP Evinrude on it. It has a tell-tale (the things you learn by reading through the forums), but mine apparently does not. Am I correct in assuming this? The '91 has a fitting with tubing from the top cyl. head that goes to the spout, while mine does not. Just want to make sure I'm not missing something.<br /><br />Thanks for any info that anyone can provide, 'specially since the nice weather is finally here and my new/old toy is not running.

 

[KilroyJC]

Re: 1975 Ev. 70 HP Lower Unit Bolt Torque?

Hello again -<br /><br />Just refreshing the post, in case it slid by you all unnoticed. . .

 

[KilroyJC]

Re: 1975 Ev. 70 HP Lower Unit Bolt Torque?

Well, just found the answer to my own question about the tell-tale...<br /><br /><br />Why do I feel like I'm in one of those Virgin Atlantic Airways commercials from a couple years ago:<br /><br />WHERE IS EVERYBODY?

 

[Cricket Too]

Re: 1975 Ev. 70 HP Lower Unit Bolt Torque?

I have the factory manual for that engine, I will take a look and see if I can find something for you. And you are correct about the tell-tale, I think they started putting those in around 79 or 80.

 

[CATransplant]

Re: 1975 Ev. 70 HP Lower Unit Bolt Torque?

If they don't list a torque spec, there probably isn't one. So, the appropriate tightness is just a matter of feel.<br /><br />For an experienced mechanic, that feel just comes naturally. A 1/4" bolt gets tightened to one feel. A 5/16" bolt has another feel. If it's going into aluminum, it's another feel.<br /><br />How to translate that into more precise terms isn't a simple question.<br /><br />Here's what I think:<br /><br />If you take a set of common box end wrenches, you'll find that they're all different lengths. That's intentional. If you draw a bolt or nut to be "tight" with one of these box end wrenches, you're going to be close to the right torque. It should feel "tight" when you're using the wrench.<br /><br />Same with screwdrivers. The smaller the head, the smaller the handle. You "feel" when it's "tight."<br /><br />I know that doesn't give you a precise answer, but it's about the best I can do. You won't see a mechanic pulling out the torque wrench for those lower end fasteners. It's not needed. They just need to be "tight."

 

[KilroyJC]

Re: 1975 Ev. 70 HP Lower Unit Bolt Torque?

Thanks for the info - <br /><br />I landed up taking out the in/lb torque wrench, and an old Audel's Guide for Mechanics, and guesstimated from the charts in there. Nothing broke, and nothing leaks (except from where it should...) I changed out the thermostat as well. WHile in the thermostat housing, I cleaned out a load of sand from two plastic valves also in the thermostat housing (which don't seem to be present on my friend's "91"), and now water is shooting out all the vents like it should.