1975 75HP Evinrude Engine spurts

So I finally put the boat in the water a few hours ago and she was runing fine until I hit a tree stump. Didn't do anything to the prop or anything, but it wouldn't go high speed anymore and it's very hard if at all to keep it running. Someone said, I might have sheared a "timing pin" in flywheel. Is that possible? I'll change the sparks plugs to the type you suggested just to make sure, but what else could it be. I mean it ran fine before hitting the stump!

I can't even locate such a part in iboat or anything to do with flywheel. How do I get the pin and what is it called?

Thanks
Munawar

Re: 1975 75HP Evinrude Engine spurts

what lake, and whereabouts on the lake were you? (makes no difference, I'm just curious).

What plugs you running? If they're in good condition, changing 'em won't help.

Hit it at high speed? no prop damage...did the motor kick up, or just suddenly stop running? I'm wondering was it a prop strike, or did it just hit the lower unit?

It's a "flywheel key", #13 in the diagram below. (www.shop.evinrude.com click on "electronic parts catalogues", drill down to your year/hp/model.)

Spark timing is controlled by sensors in the flywheel, so it has to maintain its orientation to the crankshaft. If the key shears, flywheel spins on the crank, the timing gets screwed.

It's a likely candidate, but before ya go yanking the flywheel off, check the compression first, it might reveal whether the engine suffered any internal damage. Do a spark test, too. If you got good spark on all three, makes a timing problem seem more likely.

you'll need a gear puller, torque wrench, inductive timing light, and a shop manual (highly recommend the factory shop manual).

Not the kind of puller that grips it by the edge (flywheel will break), it needs to have three bolts that screw into the threaded holes in the flywheel. Believe those are 1/4-20 but check first to be sure. You can use those same holes to bolt a piece of wood or bar stock or something to hold the flywheel while you remove/reinstall the flywheel nut. It must be torqued to spec (100 ft lbs) else the key will shear again.

Afterward you have to reset the TDC pointer and set the timing. When you get ready to set the WOT timing, go to the "engine FAQ" section and look for the Joe Reeves thread on Setting WOT Timing at Cranking Speed. You won't find that information in any manual.

factory manuals available at www.kencook.com or www.marineengine.com little pieces parts like that (gaskets/orings/hardware, chemicals like OMC Gasket Sealant, etc. not available on iboats), you can order from BRP at that evinrude website, or I use www.ishopmarine.com sometimes...lower prices but higher shipping & handling.

Keep us posted.

Re: 1975 75HP Evinrude Engine spurts

Wow sounds like more technical than an engineer can handle, but I'll try. That's why I bought cheaper boat to learn on. I was as Cedar Creek Lake in Garland, Texas.

It much have just hit the lower unit, because prop doesn't have even a scratch from it. Neither the engine kicked up nor it stopped running. It just wouldn't pick up speed any more. By the time we got back to the ramp and messed around a bit it wouldn't even stay running.

The spark plugs are over 10 years old, but the boat has been sitting that long on dry dock. Plugs are cheap so I though changing them wouldn't be bad. I have a compression gauge so I'll check compression as well.

As old of engine it is and as much learning I'll have to do, I think I'll order the manual.

I'll definitely keep you posted as I check things out.

Thank you so much for your help.
Kind Regards
Munawar

Re: 1975 75HP Evinrude Engine spurts

PS: Where do I find the exact engine model number. I have to pick from 75542B or 75543B for flywheel key and in the manuals it even has couple of more choices.

Thanks
Munawar

Re: 1975 75HP Evinrude Engine spurts

It's not that complicated, but I tend to avoid flywheel removal whenever possible, just a personal preference.

Might've knocked a float or something out of whack in 1 or more of the carbs, or a wire came loose (spark test will tell), something like that.

You'll find your model number on the port side engine mounting bracket.

Not hitting the prop is lucky. I hit something hard at full throttle a few years ago, the motor kicked up (power tilt has a safety release valve), cracked the fiberglass in the splashwell, actually shifted the motor a tiny bit on the transom, but had no mechanical effect on the motor at all. Didn't even leave a mark on the lower unit. Or else there's so many marks there already, one more wasn't noticeable.

You said Cedar Creek in Garland? The CC I know of is down around Kaufman & Henderson counties, love the lake but haven't been there since the price of gas got so high couple years ago. Ray Hubbard is in Garland, I was there last Friday. I'll be chasing sandbass & hybrids around Lake Lewisville tomorrow.

Re: 1975 75HP Evinrude Engine spurts

I am just afraid of getting in too deep without any safety net, like someone I can talk with or take the boat to if I get in trouble.

I'll check the spark test and compression today after work. What will I see in the Spark Test that will tell if the Carburetor float or wire is the problem. Also, once I change the plugs or whatever I have to do, do I have to put in back in water to test or is there someway I can test the engine at home? I do woodwork so if I have to I can put together a wooden box for water and drop the engine in it. Will that work?

My bad, the lake was actually Ray Hubbard at the ramp opposite from Bass Pro Shop. I was supposed to take the kids out to Cedar Creek lake on Saturday if I hadn't messed up the engine, so that's why I had CC in mind.

I can't tell you how much I appreciate all your advise.

Regards,
Munawar

Re: 1975 75HP Evinrude Engine spurts

PS: Where can I go in Garland / Plano area to buy a flywheel puller and the timing light?

Re: 1975 75HP Evinrude Engine spurts

Any car parts store. maybe even walmart. bought my timing light on ebay.

If you got good spark on all three, it says all the ignition components are good.

How will you know if a carb got knocked out of adjustment? I guess if the flywheel key is intact, that would be the next place to look.........

When you get the manual, whatever is unclear can be answered right here. I have no formal mechanical training, and yet have never had to put my '79 vintage rude in the shop and don't plan to either. You can do it.

Water level on LRH is down several feet. I usually use the Robertson Park ramp on the north side of I-30. There's room to beach the boat and its more protected from wind/wakes. With the water level down like this you have to step in the mud, though.

Re: 1975 75HP Evinrude Engine spurts

Thanks for everything. I'll keep you posted.

Re: 1975 75HP Evinrude Engine spurts

Here's the update:
We went to Cedar Creek lake this morning and had a blast. Absolutely no issues with the engines all day. I even pulled kids on a tube, ran the boat full throttle and came to complete stop and the carb didn't even flood! Overall excellent day, except at the end. I discovered the fuel hose connection at the engine side doesn't lock the fuel hose so the boat stopped when we were going back to the ramp; this might have been the problem all along. Would a loose, not completely off, hose connection cause engine not to run? Today when that happened, the brand new hose/bulb felt the same way as it did when I hit the tree stump. Well, that wasn't the end of it! I forgot to trim up the engine before pulling the vehicle off the ramp and dragged the bottom, boke the impeller.

I am still very happy though, because other than my mistakes, the engine and boat was great. I also had a trouble with the trim/tilt going up, but that's for another thread.

I truly appreciate all the great help I got on this forum, couldn't have possibly tackled flywheel business on my own. And here are the lessons I learned for someone trying to learn:

You have to use block of wood with hammer or a soft face mallete to tap the flywheel down snug on the crank shaft before you torque the nut. Don't use impact wrench on the nut because you don't know how tight that is. I did that with first key I replaced and watched the nut come off and the flywheel was about to fly! Shattered the new key and took an hour to get that out. Put a new key tapped it down and hand torqued the nut. You can borrow a torque wrench from Autozone for free! Book calls for 100 to 105 ft-lb torque which isn't much so you really don't need heave tool to hold the flywheel; hand would do. When first pulling the flywheel you may have to wiggle it with a long screwdriver wedge at the bottom in addition to the flywheel puller otherwise all the force on the puller won't do; at least it didn't for me.

Best regards,
May winds be on your back
Munawar