40 hp Mariner 2-stroke big problem after I hit a rock...

[SAABologist]

Thanks for any pointers on what to look for when I dive into sorting out what broke in my 1987 Mariner 40EL.

I have an old Mariner 2-stroke 40hp that broke yesterday. I hit a rock and bent the prop. Got that straight enough to run fine with some acceptable vibration considering the prop damage. No problem planing or getting up to speed.

But after 2 or 3 miles, the lower unit started rattling real bad like gears being loose or not meshing or something. It got worse after a couple of miles and now the flywheel appears to be stuck and doesn’t want to move. Ugh.

Do you have any pointers about what I should focus on tomorrow when I start taking it apart to see what I find?

Thanks much,

 

[MrGiggles]

Start with pulling the lower unit and see if the flywheel turns then.

Get it set up in a vice, drain the oil and pull the carrier assembly out. I'd suspect a bent prop shaft or something that caused a major failure.

I'd say a good used lower unit is likely your best choice, if there is any damage to the drive gears, they are a matched set and often quite expensive, and replacing them involves a lengthy shimming process.

 

[SAABologist]

Thanks, will pull that apart tomorrow and report back. I hope I can find a lower unit for it. I am in Baja California Mexico and am hoping some old Mariner motors are still around.

 

[thill]

Pull the lower unit, and the powerhead should be fine. Look for a similar vintage parts motor, then service and swap lowers.

I sold two of them today, but not compatible with yours. The good mariner I have is replacing one that I sold today, sorry. But if you look, you will find one.

 

[lckstckn2smknbrls]

If it's a Yamaha built motor look for Yamaha lower units also.

 

[thill]

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See if you can talk him down. If you don't have power trim, maybe you could add it to yours.

 

[SAABologist]

Thanks, I do believe it is Yamaha built. It would be awesome to get power trim. If I had it, this might not have happened.

 

[SAABologist]

Well, it turns out the top piston is broken. The lower unit is fine. I found a mechanic who is going to take the powerhead apart and we will decide if it's worth fixing. He thinks he can source the parts, so it's a matter of how much it will cost to repair.

Comments welcome!

 

[thill]

OR.... if that parts motor has good cylinders, swap it out, putting your carbs and good stuff on the new one.

 

[RaisedByWolves]

Well, it turns out the top piston is broken. The lower unit is fine. I found a mechanic who is going to take the powerhead apart and we will decide if it's worth fixing. He thinks he can source the parts, so it's a matter of how much it will cost to repair.

Comments welcome!

Man you hit a rock with the top piston….Oof!

I would do as above snd find a used motor with a decent top end.

Should be much cheaper than a rebuild.

 

[SAABologist]

When I took the powerhead off the engine, I discovered a big hole in the crankcase (photos). So I bought a salvaged powerhead from the same group of serial numbers. It has 130/130 compression and cycled with no issues when spun with a starter. So I think this used powerhead will be plug-n-play.

I have a couple of questions:

1. What is a recommended gasket maker (rtv) that I can use to install the powerhead into the platform of the motor?

2. When I bolt on the flywheel, will the engine timing be close to accurate, since I have not adjusted any linkage?

3. Any recommendations about lubrication or other things before starting the motor?

Thanks!

 

[RaisedByWolves]

**** I was right, you did hit a rock with the top piston!!!

Sealant I use gasket eliminator, but it’s a ***** to remove if you need to.

Timing will be fine but you’ll want to do a link n sync.

As far as lube for starting, maybe a bit of double dosed fuel, an ounce or so just to get things wet.

Another half oz in each plug hole and spin it over a bit.

 

[MrGiggles]

Best gasket is a new OEM gasket. Hot exhaust passes through there, not the appropriate application for RTV.

 

[SAABologist]

Thanks MrGiggles, I just posted another question on this, but now see your answer.