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]

https://www.facebook.com/marketplace/item/867277677895441
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.

 

[SAABologist]

After bolting in the new powerhead, using gasket maker, I used the motor for 5 months about 2-3 times/week in saltwater (Sea of Cortez). The motor runs great. But I noticed salt deposits on the outside of the powerhead in several places. I used my torque wrench and torqued what I could reach and tightened up any other fasteners I could reach. It is running strong, but it does get salt buildup on the outside.

The lesson here for me is that I should have checked and torqued every fastener before I installed the powerhead. It did not occur to me that someone might have pulled off the cylinder head or water jacket cover and replaced them without torquing or new gaskets since it was a salvaged powerhead.

Anyway, I have the old powerhead to re-assemble, and this one that is still running great. Good ol Salty!

 

[wmk0002]

Thanks for the update.