blew the port engine while offshore

lime4x4 · Sep 1, 2014

While offshore on Saturday i blew the port engine. It's 1987 yamaha 150. Cylinder #3 failed looking at the pics below what type of failure was it? No oil or did that cylinder run lean? Now just to find a complete outbaord of that vintage. I broke 2 head bolts and all the bolts that hold the power head on are gonna snap. Plus i'm not even sure if it's gonna seperate from the mid section. I was hoping just to rebore that cylinder. Repowering aint an option since i'm only planning on having the boat another 2 to 3 years then upgrading to something bigger. Anyone have a cheaper fix???

Doc Stressor · Sep 1, 2014

You usually burn a hole in the piston from running lean. You likely had either a broken ring or wrist pin. You won't know for sure unless you pull the piston. But the pattern on the head looks like a piece of ring was banging around in there. Many things can cause a ring to eventually fail such as overheating or carbon build up that prevents proper lubrication.

Replacing a single piston doesn't work out too well on an old engine. You would have to remove a lot of metal in order to properly re-hone the bad cylinder and use over sized rings if you can find them big enough. The result would likely be an unbalanced engine that won't hold up for very long long.

You best solution would be to find a used 150txr 2-stroke. They made an awful lot of those engines and were still selling them until just a few years ago. They might be the most reliable outboard Yamaha ever built. The older ones are only worth a few thousand. Sometimes you can find one with a blown lower unit for not much money. Look for one with even compression in all 6 cylinders.

lime4x4 · Sep 1, 2014

If i go with a newer 150 2 stroke don't i also have to replace the starboard engine as well?

Doc Stressor · Sep 1, 2014

Don't see why you'd need to do that. The engine hasn't changed much since they first came out in the 80's. The weight is the same.

billyttpd · Sep 1, 2014

Links Outboards in Newark Delaware may be able to help you out. They rebuild older outboards. If your going to do the work yourself they may be able to help you find the parts. I have never dealt with them but have seen their advertisements in boat shopper and the like. Putting it out there for you it might be worth a phone call.

suzukidave · Sep 2, 2014

sorry for your loss. at least it picked the right point in the season. is the survivor a counter rotation motor?

you might do better buying a pair of old 2 strokes motors off someone repowering and then selling your remaining 150 and parting out the dead one, especially if the survivor is normal rotation.

lime4x4 · Sep 2, 2014

It was my counter roatating engine that failed. I'm currently in the process of tearing the powerhead off. If i can get the powerhead off in one peice i'm thinking i'll get it rebored and install over size pistons. If not i'll be spending the winter searching for another engine or a pair

family affair · Sep 3, 2014

If you rebuild, you need to determine what made that cylinder fry or history will repeat itself.

lime4x4 · Sep 3, 2014

It's hard to tell I think it ran lean for some reason or a ring broke. Seeing how no other cylinders are damaged I'm thinking the oil pump didn't fail. Both engines have 572 hours on them. Engine never smoked while running

family affair · Sep 3, 2014

Let me first say I'm no expert on engine failure but I do know running water through an engine does a heck if a job removing carbon. Considering how clean the piston and head are for that cylinder, I can't help but wonder if you were sucking in water. How did the head gasket look?

lime4x4 · Sep 3, 2014

Head gasket appeared to be intact yet. I'm thinking the top of the piston is clean cause of the peices from the broken ring bouncing around. If it's rebuildable yet i'm gonna have the machine shop check it for cracks and flatness. Also gonna rebuild the carbs as well. Also when i removed the intake and exhaust cover there was no traces of water

lime4x4 · Sep 20, 2014

How to remove alum from cylinder sleeve? I called 10 machine shops in a 100 mile radius of where i live and none of them work on outboards. After looking at it more closely i think the cylinder might be usable yet. It looks like a ring broke.

DennisG01 · Sep 20, 2014

That looks pretty much identical to the issue with my "spare" engine. Same thing with the aluminum embedded into the cylinder. After some discussion on this forum, it was obvious that a ring broke based on the little dents and such on the piston top and head - but I don't know if the cause was a simple ring failure or injector problem, etc. There's a shop here in Allentown that said he 'might' work on it - "Beav's machine shop". It would have to be bored out and then an oversized cylinder put in. If my memory serves, a Yamaha piston can be found for about a $100. The question is, how far will it have to be bored out to get rid of the aluminum... in other words, how far did that aluminum melt into the wall?

For now, I've relegated the engine to be my 'spare parts bin' since it's an exact match for the one currently on the boat. But if you want to be the guinea pig and let me know how it turns out?!?!

lime4x4 · Sep 20, 2014

I'm gonna try hydrochloric acid to desolve the alum. Then hone out the cylinder and c what i have.. I've found over size pistons also found a company that makes the sleeves as well. But the machine shops in are area don't work on outboards. I might try and call some of the machine shops in Delaware along the coast.

DennisG01 · Sep 20, 2014

When I had talked with Beav's, I got the impression that as long as I tore it down (further than what you have there, so that he can pass all the way through the cylinder w/o the crank in the way), he could do it.

I was curious, too, about just honing. I was just worried that the aluminum would be embedded too far into the wall and it would have just been a waste of time.

lime4x4 · Sep 20, 2014

The few shops i spoke with said that they don't have the necc jigs to bore or replace a sleeve in an outboard engine. Monday at work i'll get the pistons and crank out and go from there. If i can hone out that cylinder i'll just put in a new piston and rings in that cylinder only. Probably should do them all but the engines only have 572 hours on them. Plus if i'm gonna chance only honing that cylinder don't really want to have alot of money tied up in it.

seasick · Sep 21, 2014

It definitely broke a ring in my opinion. The cause of ring breakage can be many things but one common cause is carbon buildup in the ring groove. Of course lack of oil can cause ring damage also. The fact that the there was no smoke doesn't tell me that the oil pump is good. In fact it could mean the pump is bad. These motors generally smoke a lot and no smoke could mean no oil.
If the rings in the bad cylinder were gummed up with carbon, the rings in the other cylinders could be also. I don't think that re-boring one cylinder is a good plan. The motor is pretty old and had a long life. I would look for a similar used motor. Since the counter rotating LU is OK, you don't have to look for a CCW motor.
For curiosity sake, did you use Ring Free or similar treatments regularly?
Good luck with the project

lime4x4 · Sep 21, 2014

I've owned the boat for 2 years now. Never used ring free or other additives. I thought 2 strokes should smoke as well. But mine never really smoked. The only times they smoked was when they were first stated after sitting awhile or coming off a hgh speed run they would smoke slightly for a minute or so. When idling there never was any visible smoke but u could smell it was a 2 stroke. The first thing i did was check the oil injection system as per the yamaha service manual and both pumps are within specs. The other cylinders in the blown engine don't show any signs of lubrication issues. I've priced reman power heads and there 3 to 4k. I've found a few used 150 yamaha outboards in the 1500 to 2500 range. If i do a complete rebuild on this motor replacing all pistons and rings with aftermarket ones i'm around 600 bucks for parts and what the machine shop will charge for installing a new sleeve. Below is a short video of the engines running earlier this year..

https://plus.google.com/photos/111440106210552481200/albums/6061542638158158305/6061542635763656754

DennisG01 · Sep 21, 2014

Can you still make out the cross-hatching on the cylinder wall? Even with the smooshed aluminum, I can still very easily see the cross-hatching and there is no other type of scratches. Engine building/diagnosis is certainly not my forte. But to my untrained eye, that seems to indicate that fuel/oil was not the cause in my case.

lime4x4 · Sep 21, 2014

I have no cross hatch marks in any of the cylinders. My engines are older then yours. Also the yamaha service manual makes no mention of honing the cylinders just rebore and/or replace

blew the port engine while offshore

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