'80 Evinrude E75ERLCSA 75hp Rebuild Question

[BKS72]

Hi, I'm new here and just had a couple of quick questions about a rebuild I'm about to do. I blew the wristpin bearings out of my motor and sucked them up into the combustion chamber, scoring #2 cylinder wall badly and pitting the head.

The block is at the machine shop now waiting to have all cylinders punched .040 over (#1 and #3 have minor scratches as well and I might as well keep them all consistent.)

I've found 2 rebuild kits on line and the only significant difference between them is the center main bearings. One kit has them, and one doesn't. The OMC shop manual (actual OMC manual, not Clymer or Seloc) says if the bearings are in good shape to go ahead and re-use them. Mine look good, but would I be pound foolish to not replace those two bearings (about $100 for both) while I have it tore down? I'm going to replace all other bearings, seals, pistons, the connecting rod that had the bearing failure, and install Boyesen reeds when I build it back up.

Second question is on the head. It's got some pits from the wrist pin bearings and debris banging between the piston and head. The mating surfaces are fine, it's just the flat portion around the combustion chamber that is damaged. Can I dress down the material that's been pushed up around the pits (eliminating any high points) and still use the head or will the small pits left in that surface cause issues with carbon buildup or other problems?

Thanks in advance for your help!

Branden

 

[R.Johnson]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

If the center bearing looks good, I see no reason to not use it. Replacing the bottom ball bearing is a good idea. How did those wrist pin bearings manage to get loose? If you go ahead, and clean up the head, clean off all the high spots. The concern would be more of a pre-ignition problem then carbon build up. Don't try to build up pits with a heli-arc.

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

Thanks for the quick response! I was mystified by the wrist pin bearing failure as well. I'm not a boat mechanic at all, but before I tore it town I was assuming it had been a connecting rod bearing that failed and that the entire lower end (I guess it's still a bottom end on a 2 stroke) would be toast. I was as happy as a person with a blown motor can be to see the crank still in good shape.

I'll clean up the head and post some pictures of the pitting and see what the thoughts are on if it's salvageable or not. It's not a huge amount of money to get a replacement (around $100 for a used one locally) but I'd like to save as much as possible without serious compromises. If I can re-use the middle mains and the head, I can get this whole thing done for around $700 including the machine shop work.

 

[R.Johnson]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

Keep us posted.

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

It's toast. I cleaned it up and it's worse than I thought. Not only pitted but completely uneven. Oh, well, 'nother $100 into my fishing addiction Searched everywhere for the Torrington middle main bearings and of course (like I'm sure hundreds of others before me have found out) the number is not in their catalog - probably proprietary to OMC. I've got the old ones cleaned up and soaking in clean fuel/oil mix, I'll post up pix of them in a bit to see what y'all think. They look/feel good to me, but it's the first set of these I've fooled with. Got everything cleaned and de-greased, just need to clean up all the gasket surfaces and I'm pretty much at a stop until I find out whether my block is salvageable and I get parts in. While I'm getting greasy I may go ahead and pull the LU and check the water pump. I just changed the whole assembly last summer, but there's a lot of sand in the ol' MO river. Speaking of LU's, what's the best kind of solvent to flush them with? I might as well get that done while I'm off the water.

As far as the wrist pin bearing that failed, I got the pin out and there's nothing there - not even a little piece of the cage. Guess that's what happens when something gets crossways at 5200 RPM. Thanks for the help!

 

[Chinewalker]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

If that had the original style caged bearings in there, that could have been the cause as they superceded to non-caged rollers with L-shaped washers on either end. I've had a couple of those cages come out in pieces, usually with other pieces along for the ride...
- Scott

 

[Dhadley]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

I think you pin pointed the problem. 5200 rpm. That's lugging it and if it was on a pontoon it was even worse. The wrist pin was probably pounding first, then the bearing failed.

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

It's on a 20' jon boat - I was running up river at about 3/4 throttle or a little better. I'm going to show my ignorance here, but I don't know what the term "lugging" means. I've heard it before, but don't actually know what it is.

A buddy of mine has a head that's off a 70 or 75 and from what I can tell everything is the same with the exception of the combustion chambers. Mine has round chambers and he says his has a "funky kind of S shaped chamber". Would that one work for my motor? Just curious.

I'm going to go ahead and replace those center mains. I know how I think and if I don't, it will bug me every time I open that motor up. I worry enough as it is (laughing)

 

[Dhadley]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

Lugging the motor means it's working too hard (basicaly). It'll be much "happier" at 5800 or so with a normal load. The combustion temps will be less at 5800 (top rpm) than they are with 5200 as a top rpm. Regardless of what the cruising rpm is. If the wrist pins are dark blue or purple it'll be a sure sign of lugging.

 

[Dhadley]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

The other thing that we see is that if the motor is surging. It's kinda common on pontoon boats. The prop grabs and lets go then grabs again over and over. If it was doing that it'll be pretty hard on the wrist pins.

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

It was running like a top up until it died (no surging, etc) Once I get the 'grunt' work of the rebuild done I'll take it over to my mechanic for a tune up and adjustment. Thanks for all the advice!

 

[jwbmarine]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

i have a few thoughts---5200,..is NOT lugging that eng.....another fellow mentions if bearings look good go w/it...THIS ENGINE,is 28 yrs old....if i was rebuilding this eng,of which,i have been doing for 31 yrs,i would absolutely,repl every brng in it...period...
and,.....040 over....i have never,taken one over 30...where r u getting your pistons.....if it wont go 30,..resleave,..to build a good,dependable,quaility,motor..

 

[R.Johnson]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

JWB: How many outboard engines have you rebuilt? We're not talking auto engine's here! A outboard engine push's every foot of the way, it never coast's.

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

I've found a quite a few places that have .040 over piston and ring sets. It'd cost me over $300 a hole to resleeve, which really isn't worth it to me.

If the block I have can't be saved by boring it, I'll have to think about what I want to do. If I have to put around $350 in a new-to-me block (which still might need some money in machine work), I might just go ahead and buy a rebuilt powerhead. The insurance payment is probably enough to get me close to a rebuilt unit, but if I can save a few bucks and get the enjoyment of learning how to rebuild one by doing it myself I'm all for it. I'm not wanting to do it bad enough to spend the same or more to do it myself than it would cost to buy a rebuilt unit, though.

I'll mic the crank this weekend and see what kind of shape the journals and pins are in. Pix of the bearings and crank are attached. Just wondering if the blueing on the journals and bearing surfaces is normal or a function of lack of lubrication or some other issue. Thanks again, guys, I appreciate all the info.

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

Good news! Crank checked fine and the machine shop called today and they can get the scores out of the cylinders at .030 over. I can get the rebuild 'kit' for the powerhead (pistons, rings, all bearings, seals, and gaskets) for around $600 with shipping and they should be here by Friday if I get them ordered by 3PM tomorrow.

U.S. Boatworks here in town has a head for my motor and probably the connecting rod I need as well, so hopefully Tom and I are bolting it back together on Saturday and breaking it in on Sunday

 

[Dhadley]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

5200 is lugging that motor. The blueing of the crank is just more evidence. Those cranks are so hard it's not unusual to find that it measured good. Very tough pieces. Normally the main bearings should be fine but with all the heat they've seen I think I'd replace them.

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

Manual says full throttle operating range is 5200 - 5800 RPM. Sounds like I need to 1. verify that 5200 is indeed what I'm at WOT and 2. if I'm at 5200, get the WOT RPMs up to the upper end of that range.

What's the easiest way to do that - re-prop? I don't know much about props, but from what I've read it seems like it's a compromise between hole shot and top end. My boat is relatively light and I'd prefer top end over hole shot since I'm just fishing for fun, not tourneys or trying to race anybody.

Does anyone know where to get a test wheel for this motor or a suggestion for an alternative so I can link and synch after the rebuild?

Thanks!

 

[Dhadley]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

We only drop pitch to gain rpm as an absolute last resort on an outboard. That's providing the existing prop is a decent design, in decent shape and is the correct style for the application. Work the set up to gain efficiency. You may find you improve holeshot and top end.

 

[BKS72]

'80 Evinrude E75ERLCSA 75hp Rebuild - Update

'80 Evinrude E75ERLCSA 75hp Rebuild - Update

Got it about 80% back together - tomorrow should just be putting the carbs, linkage, and wiring harness/charging system back together and then I can drop 'er back on the bottom half and see if it'll run

Thanks all you guys for the help and advice. I spent a lot of time searching the forums for questions and found a few things that helped a BUNCH. Probably the coolest was the trick of heating up the lower main bearing. Should have seen my wife's face when she peeked in the oven to see what I was baking at 300 for 15 minutes. Worked like a charm - carried it downstairs to the garage and it slid on slicker'n a whistle.

Pix of how it looks now attached. Turns by hand smooth and no issues going back together. After I get it back on, I'll check the set up and work on getting the rpms up closer to top end of the recommended range after the break-in period.

Thanks again!

Branden

 

[BKS72]

Re: '80 Evinrude E75ERLCSA 75hp Rebuild Question

Got 'er running last night! Linked & synched and timing is set, so I think it's good. I have to fix a small fuel leak and then it's off to the water to see how she does on the water.

Thanks guys for all the help, advice, and great info!!