Logo
FULL SITE MENU

SAFE way to solve stuck driveshaft (4HP experience)

M

mf70

Member
Preamble:

About ten years ago I had my '87 Evinrude 4 down to the main bearings. I got it reassembled and running well.

Fast forward to now: Well, says I, after ten years, it's time to replace the impeller. Unfortunately, the driveshaft was stuck in the powerhead. In assembling things ten years before, I had neglected both the O-ring at the top of the driveshaft and the heavy coat of grease on the splines. Trusting the "wisdom of the internet," I set the engine/ driveshaft upside down under a vice and applied an improvised slide hammer to pop it apart. Oops! The shaft slipped in the vice enough to put the vice jaws on a polished band in the way of the lower bearing and the shaft popped into two pieces.

TO get the stub of the driveshaft off the powerhead, I set up an "inverted" gear puller. I placed one heavy plate, bored to press on the crank shaft. I next took another plate and drilled three holes: one for the shaft, and two for jack bolts that would serve to separate the two plates. Finally, I used two cable clamps (plus the vice) to act as a stop. With two grade-8 bolts between the two plates, I was able to wind on the two nuts to pull the stub with no shocks or other drama.

26ba2070-a46d-4ab2-91d9-0ee6ecb9fb96_zpsoqkgyzn1.jpg


The slide hammer trick may work with light rust, but if moderate hammering doesn't work, there is a non-impact way to get things safely apart.
 
Too much pressure on the crank bearings can damage them! I prefer the time and pressure method just hang the motor upside down from the driveshaft and put a pad under the motor for when it falls. Then just dribble WD down the driveshaft and let it soak into the splines. Power steering fluid works good as a liquid wrench and it dont dry out.
 
kimcrwbr1 said:
Too much pressure on the crank bearings can damage them! I prefer the time and pressure method just hang the motor upside down from the driveshaft and put a pad under the motor for when it falls. Then just dribble WD down the driveshaft and let it soak into the splines. Power steering fluid works good as a liquid wrench and it dont dry out.
Click to expand...

A) Your concern for the bearings is well founded. These engines use needle bearings, which are more delicate than the older bronze bearings. In this case, however, the white plate was bored to bear on the crankshaft directly, not on the case, so the bearings weren't stressed.

B) In the case of a decade of rust, how much time should I have given it? I waited a week (with PBlaster soaking the joint) before I got (overly) vigorous with the slide hammer.
 
I thought you were using the crankcase as the stress point. You can allways turn it on its head and put the flywheel on a wood block and then tap down on the driveshaft to break the rust loose so the liquid wrench will soak in better. PB and WD will dry out rather quick so you need to keep adding drops regularly to keep it wet. You can also heat the shaft up just enough the PB starts bubbleing that will also pull the liquid in the void when the shaft expands then contracts. Give power steering fluid a try sometime especially for corrosion just be careful it will wreak havoc on paint.
 
Back
Top