Need to rebuild my 1977 55hp Evinrude. Tips please!

[strtbobber]

After having my motor tested by an outboard mechanic, I've learned that I need to rebuild it or scrap it. Compression is good, bleed down test was good, but after he removed the head, there are signs of pieces of rings banging around in the cylinders. The walls are also scored a bit. I'm quite mechanical, so if I decide to rebuild it, I'd do most of it myself. I'm basically throwing this out there to see if I can get a few experienced guys out there to give me any tips/warnings/knowledge etc before I even start shopping for parts.

A few questions I have are:

Do I bore it out and go with over sized pistons? How much over?
I know there are some special tools I'll need. Which tools and can I buy them somewhere, or are there tricks to get around this? One example is, do I NEED to buy the special tool to take the drive shaft nut off in the gear case, or is there a way to do it with a different wrench?


I also need to replace the reverse gear and the clutch dog. Any tips or pointers?

Thanks to all who can offer some sound advice!

 

[Silvertip]

Re: Need to rebuild my 1977 55hp Evinrude. Tips please!

Tip #1: Buy a "Factory" service manual specific to your engine. Don't even start without it.
Tip #2: How much you need to bore an engine depends on how much it has to be bored to remove the damage. .010, .020 and .030 are common oversizes. Only the shop doing the boring can tell you how much is needed. Don't buy pistons and rings ahead of time.
Tip #3: How can compression and leakdown tests be ok if there are bits of rings and cylinder wall scoring going on?
Tip #4: Special tools are listed in the "Factory" service manual which is one of the reasons you need it. Disassembly and assembly instructions will tell you what and how the pinion nut is to be removed as well as how to replace the clutch dogs and gears.
Tip #5: Have you done any research on how much this process is going to cost?
Tip #6: You might look at E-bay or Craigs List for a lower unit. Gears are not cheap nor are special tools. Do it wrong and it costs twice as much.

 

[Haffiman]

Re: Need to rebuild my 1977 55hp Evinrude. Tips please!

The only 'factory' special tool you need is, as mentioned above, the OEM workshop manual. The rest you may use standard tools, provided you have a decent flywheel puller.
If using OEM pistons, you may not have to buy them in advance, however some machine shops demand it. It is a clearance difference between forged and cast pistons to be considered when machining.
Personally I prefer OEM powerhead gasket kits which normally have a better gasket quality. Seal kits for gearcases are just the same.
You may have to add an impeller and carb kits as well to our original budget.

 

[strtbobber]

Re: Need to rebuild my 1977 55hp Evinrude. Tips please!

Tip #1: Buy a "Factory" service manual specific to your engine. Don't even start without it...............Got it.

Tip #2: How much you need to bore an engine depends on how much it has to be bored to remove the damage. .010, .020 and .030 are common oversizes. Only the shop doing the boring can tell you how much is needed. Don't buy pistons and rings ahead of time..............Understood.

Tip #3: How can compression and leakdown tests be ok if there are bits of rings and cylinder wall scoring going on? I wondered the very same thing. Seems kind of fishy to me.

Tip #4: Special tools are listed in the "Factory" service manual which is one of the reasons you need it. Disassembly and assembly instructions will tell you what and how the pinion nut is to be removed as well as how to replace the clutch dogs and gears. I've read how it needs to be removed. I just wondered if there was a way to do it without special tools.

Tip #5: Have you done any research on how much this process is going to cost? I'm researching as we speak.

 

[strtbobber]

Re: Need to rebuild my 1977 55hp Evinrude. Tips please!

Thanks, I already have the manual.