Blown engine...Need some advice

[Nashvegas]

I bought a 2010 AR240 last fall. The engines have around 200ish hours and my right engine is apparently done according to the mechanic I took it too.


Some details:

I was surfing behind the boat when the engine cut off and a friend was pulling me out (around 7000 rpms).

The oil was fresh and full.

No problems leading up to this incident.

I thought it had to be something simple so I took it to the local mechanic/shop at my marina to find out it blew a spark plug and apparently the engine.

Questions:

Seems like low time to have to replace an engine. Any idea what would cause this to happen?

Any chance of a misdiagnoses?

The mechanic is "working up a quote". Any idea what I should expect to put a new engine in? (engine plus maintenance costs total)

Should I take it to a certified Yamaha mechanic since it's not something simple? If so, does anyone have a link to certified Yamaha marine mechanics? My initial yahoo search was confusing at best.

Thanks,

Greg

 

[Matt Phillips]

The first clue to an anomaly here is that the 1.8 engines usually top out on RPM about 7500. Surfing is typically done about 11-12 MPH and that seems like an unusually high speed for that engine to be turning at that gps speed.

As a comparison, the MR1s in my 2009 only turn about 6500 at 10-11MPH and they limit out at 10,250 rpm.

 

[Nashvegas]

I was just being pulled up along with about 2600lbs of ballast on the boat. The boat had not planed off yet. So it would not have continued to run that high.

 

[waterboy]

There are some posts on the board about limited timing chain failures in 1.8 motors, much more so in the 1.8 supercharged motors. Search that and see what comes up. Sounds like you had a catastrophic failure and a timing chain fail would certainly show itself that way.

I don;t have that motor so will not claim to know much more about the issue. May be worth checking with Yamaha about warranty coverage too, although I see you have a 2010...

 

[Gym]

@Nashvegas. The 2010s have a known issue with the #3 oil cooler bolt breaking causing an oil leak. You said, "the oil was fresh and full." Was that the case after the failure? The other thing you said was, "it blew a plug." Are we talking about a spark plug? Did it blow a spark plug out of the head?

Regardless of what your mechanic finds I would still get a second opinion on an expensive repair just to keep everybody honest. You want to make sure you at least get the same diagnosis. A Yamaha dealer may have more parts in stock or may be able to get what they need faster.

 

[Jebinok]

I would pull all the spark plugs and have a buddy try to rotate the engine by hand while i was looking for piston movement. If you cant rotate by hand or only part way, equals something bad, If all the pistons move up and down, no broke crank or broken rods. then a compression test. If all that is good, look for stripped threads on the blown plug. it the threads look good, it might be something as simple as the plug loosening up and the compression popped it out. My 2 cent. goodl luck

 

[ar240owner]

I would try to get more
Detailes from the "mechanic"

 

[Scottintexas]

what does " blew a spark plug mean" ?

how many hours have you used it since you bought it?

I agree more details are needed as this is very unusual,

 

[Nashvegas]

@Gym

Yes, the oil was the first thing I checked and it was fine. And yes it was a "blown spark plug" according to the mechanic. That's all the info I have on the spark plug.

 

[Bennie]

I'm with everyone else on this. If you "blew a (spark) plug" the engine would run like crap, but still run. First thing I'd do is check the oil. Then as stated above turn the engine, if possible preform a compassion test.

With twin 1.8 in my boat I'm very interested in what happens!

 

[Gym]

@Gym

Yes, the oil was the first thing I checked and it was fine. And yes it was a "blown spark plug" according to the mechanic. That's all the info I have on the spark plug.

I find that very strange also. Do you suspect the spark plug was not threaded in all the way. It would be impossible for it to work its way out due to the firm grip the coil boot has on it. The only other possibility is some sort of catastrophic event occurring in that cylinder such as an explosion (rather than a controlled fuel burn) or a wrist pin or piston breaking sending the piston to the top of the head. This is sounding more like a timing chain event but keep us in the loop.

 

[Noko]

If the plug was blown and not grounded, so it wasn't sparking, could the ECU detect that and thus shut the engine down?

 

[bronze_10]

Sounds lIke a trip to a 2nd mechanic is in order..... blew a plug... need new motor... doesn't sound like enough information to me!

 

[Nashvegas]

Thanks for all the advice guys! I'm not mechanical in the least so this has given me some things to talk to the mechanic about and will probably get a second opinion.
I was pretty sure it was not very common just from reading this forum the last few weeks.

 

[ruztew]

If you can find a good PWC mechanic to look at it, that'd be a good option...it's basically a Waverunner engine

 

[Ronnie]

Get a second opinion from a Yamaha dealer or established PWC shop. They should be able to give you a lot more detail before stating you need a new engine, like what the compression is in each cylinder, possible causes of the failure, what parts need to be replaced, etc. sound like your mechanic knows that you are not technically inclined and is taking advantage of it.

 

[Bennie]

@Thor - I would also reach out to your local boaters. Check out our user map and send a few PM messages. Someone close may be able to help.

I looked for your location on your profile page but didn't see it. Just giving a very general location can help in times like these.

 

[jcyamaharider]

The first clue to an anomaly here is that the 1.8 engines usually top out on RPM about 7500. Surfing is typically done about 11-12 MPH and that seems like an unusually high speed for that engine to be turning at that gps speed.

As a comparison, the MR1s in my 2009 only turn about 6500 at 10-11MPH and they limit out at 10,250 rpm.

When fully weighted my SURF rpm is 8900-9200 rpms @ 10.7 mph....You have to factor in the weight.



To the OP, get a second opinion, sometimes people just want to make a mountain out of a mole hill.

 

[Nashvegas]

Hey guys, taking it to a certified yamaha dealer this afternoon for a second opinion. I'll post more info when I get it. I'll also post a pic of my bad spark plug when i get a chance. Mechanic says he removed all the plugs and shaft wouldnt turn.

IF I need a new engine, does anyone have a ballpark figure on that cost?

Just my luck... got the wake wedge and boat broke down before I could even try it out.

 

[jcyamaharider]

Hey guys, taking it to a certified yamaha dealer this afternoon for a second opinion. I'll post more info when I get it. I'll also post a pic of my bad spark plug when i get a chance. Mechanic says he removed all the plugs and shaft wouldnt turn.

IF I need a new engine, does anyone have a ballpark figure on that cost?

Just my luck... got the wake wedge and boat broke down before I could even try it out.

It might be cheaper to find a used 1.8l ski and just do a swap?