1975 70Hp Evinrude: Leaking shift housing

[classiccat]

I brought-home a 1975 70Hp 3cyl 'Rude yesterday (70573B).

During a brief run on muffs at the prior owner's house, I discovered that the water pump wasn't changed in 20 years! I quickly asked in a panic when I didn't see a tell-tale...now i know that this model doesn't have one. Even compression on all-3 cylinders saved the day.

I drained the LU oil and it looked like Dijon mustard.

So I I'm dealing with 2 issues, possibly a disintegrated water pump and a pretty severe leak.

Thankfully after a few tubs of elbow grease, I was able to get the leg off and pull the pump. (have you ever seen so much crud here??)

To my surprise, the impeller was still fully intact!

 

[classiccat]

Re: 1975 70Hp Evinrude: Leaking shift housing

Part 2 of this saga...and the question for you guys...

I had an even pressure loss when turning the drive-shaft & prop-shaft. I didn't observe a leak at these seals when I sprayed with soapy water.

However when I touched the shift rod, the pressure bottomed-out...i could actually hear the air leaving the housing.

Is it possible to reseal this (o-ring & a gasket) without pulling the entire LU apart? This model has hydro-assisted shift.

I did make a high-tech rod-height tool :lol:

 

[classiccat]

Re: 1975 70Hp Evinrude: Leaking shift housing

Well, after sleeping on it, I've come to my senses and decided to do a full reseal.

I'm also concerned about the condition of the internals.

If anyone knows of any common pitfalls/challenges with this LU design (esp the hydraulic assisted shift!), I'm all ears!! Thanks!!

 

[classiccat]

Re: 1975 70Hp Evinrude: Leaking shift housing

Question for you guys, shouldn't this driveshaft bearing carrier slide with minimal persuasion up the driveshaft once the 4 retaining bolts are removed?

I see nothing in the FSM that would indicate that it's fastened beyond those 4 bolts.

I'm thinking that it's simply old adhesive-M or Gasket sealant...and perhaps some capillary force but before I give it some muscle, I wanted to check with the Pros!

otherwise, I need to get new truarcs to pull-out the entire driveshaft as mine won't extend far enough into this bigger housing.

thanks guys!

bearing carrier is out and the needle bearings are in great shape!

 

[classiccat]

Re: 1975 70Hp Evinrude: Leaking shift housing

OK, i answered my own question! (my apologies if I've wasted anyone's time!)

I had an epiphany on the way to bed...apply a shot of heat from my heat-gun to loosen the adhesive(s) and/or reduce the viscosity of any fluids trapped between the metals.

driveshaft bearing carrier popped right up using 2 paint-can openers

pretty goopy in there!

 

[classiccat]

Re: 1975 70Hp Evinrude: Leaking shift housing

How long do you let Quicksilver Perfect Seal cure before doing anything with the LU?

I got the LU to this 70Hp back together this afternoon, put pressure in it and has a slow leak. :mad-new:

Put it in a big tub of water. Bearing carrier, propshaft, driveshaft and Fill/vent seals are solid.

The shift housing gasket was the culprit (in several spots) despite coating both sides of the gasket with quicksilver, torquing to spec and allowing 24hrs to cure.

I re-assembled the shift housing this time allowing the quick silver to stand for 30min before assembling for the 2nd time; I'll retest pressure tomorrow afternoon...or should I wait longer? It's my first time using this stuff beyond bolt threads & water pump gaskets.

 

[classiccat]

Re: 1975 70Hp Evinrude: Leaking shift housing

I finally got this old leg to seal.

I Ditched the old (probably contaminated QS) and I found that somehow split the replacement D/S bearing carrier o-ring (I oilied however didn't seat it with 847).



This time, I sealed the shift housing gasket with BRP gasket sealing compound & seated the D/S bearing carrier O-ring with 3M-847 (and pulled the prop-shaft bearing carrier and seated that O-ring to be on the safe side).

 

[huntxtrm]

Re: 1975 70Hp Evinrude: Leaking shift housing

Great job on this post with the pics. I've got a 74 Johnson, that has some of the same issues. This post is like a guiding light!