Catastrophic Failure on 3.0 Mercruiser, Need some advice.

[Siebs]

Was cruising across the lake in my 2004 Larson SEI 180 with a 3.0 Mercruiser and all of a sudden it died. Lots of metal clanking noises. Brought it home, ripped it apart and attached below is what I found.

Here are my options.
1. Local rebuild at a reputable machine shop for at least $1800
2. Summit has a First Mate Marine reman for $2100
3. Rebuild it myself, buy the parts, everything to the machine shop to be worked, and assemble it after. Not sure how much that would cost.
4. Bandaid fix it, replace the valve, bring the head in to get worked, replace the piston and whatever else needs to be, clean the sh*t out of it and slap it back together

Any advice? Looking to get back out this summer. Better places to buy remans or new engines? Any idea why the valve would fail and/or why this happened so that I can hopefully avoid this in the future?

Thanks in advance.
Brandon

 

[Benny67]

Dude...move on...that motor is toast.

Look for a donor boat for a replacement engine if you are looking for a cheap and quick solution.

 

[Benny67]

I 'd be guessing but from the looks of that valve seat on the missing valve you should have noticed a change in performance some time ago

 

[Scott06]

If you want to be on the water this year I'd get a complete engine either used or reman, if money is less of a driver a new complete base engine. It took me less than a week to get my base engine from Michigan motorz you can swap it out in a weekend

 

[Siebs]

This will be the 2nd summer I have had the boat. Haven't seen a change in performance since I have had it. Put it through the rounds over the 4th pulling tube's, motor popped this last weekend.

 

[Bondo]

Ayuh,..... My Guess is,.... Ya detonated it to death, probably from a lean condition,.....

 

[Benny67]

Technically you COULD get a new piston and grind the valve seat and replace the valve and MAYBE be okay for a season or two...

I'm not recomedind doing that....I myself,MIGHT attempt it,depending on a thorough inspection of the whole block and head.

I've brought car engines back from a similar fate with good results..but never a boat motor.

Good luck..

 

[Siebs]

Well, I tore the motor down, removed the pistons and found a little damage but nothing major. 1 minor scratch on the cylinder wall that I can barely catch with my finger nail and a couple scratched on the crank journal for the piston that blew, same thing, barely catch my finger nail on it.

At this point, I know what I have and I don't want to spend the cash on a full rebuild or a reman motor. I found a used 3.0, 1987 model, for cheap from a friend of a friend. Claims it has good compression and ran fine when it came out. I'm trying to figure out if I should spend the 300 on the used motor or do a half rebuild for around 500. Polish the journals, hone the cylinder walls, new pistons, rings, rod bearings, valves, and clean up the head as best as I can along with new gaskets. Both have risks but at this point I want to be back on the lake this summer and if I go the reman way I won't be back on the lake until next year.

Thanks for the help and input.

 

[achris]

Before it blew, what revs were you getting at wide open?

 

[harleyman1975]

Have the crank turned/polished the block bored .010, your head rebuilt/replaced and you have a rebuilt motor. same time and almost same money I bet within $200.

 

[Siebs]

Before it blew, what revs were you getting at wide open?

Full throttle. I see your concern. if it was a lean condition, do I need to look into why? Carb rebuild? Motor ran very well before it decided to let that valve loose.

 

[achris]

Full throttle. I see your concern. if it was a lean condition, do I need to look into why? Carb rebuild? Motor ran very well before it decided to let that valve loose.

No. I'm looking for the revs it was turning at when it was full throttle. It needed to be in the range 4200 to 4600. If it was lower, then that's why it blew.

Chris.

 

[Siebs]

4500, played the RPM game with props earlier this spring to try and get on plane faster. Ended up staying stock and putting smart tabs on. Smart tabs actually worked really well on my boat.

 

[achris]

4500, played the RPM game with props earlier this spring to try and get on plane faster. Ended up staying stock and putting smart tabs on. Smart tabs actually worked really well on my boat.

That's good. You do know you should change down one prop size (2") when playing with tow toys? Unlikely that would have caused your problem, but worth noting.

Chris.....

 

[Siebs]

Update. Motor rebuilt, cylinders honed, within spec, crankshaft journals polished, within spec. Motor in boat and running just as good as before, was out on the lake once with it and found a few small issues and 1 large issue. The lower end of the outdrive is clunking. I used the stethoscope and it is definitely in the lower part of the outdrive. When I had the outdrive off I decided to change the impeller. Shifts in and out of gear just fine but I am having a hard time figuring out this clunking.

I am leaning towards a shift lever/shaft issue. I have read that in reverse, the prop should lock both ways, in forward it should lock forward and "ratchet" the other way, and in neutral it should spin freely. Well at this point reverse and forward both lock the correct way but they also both ratchet the opposite way. When I put the boat in gear and put my hand up by the shift shaft, it's bouncing up and down and it feels like this is where the knocking is coming from.

Any ideas?

PS. wish me luck for the rest of the year on this rebuild......