This Motor Sounds Broken . . .

[tpenfield]

The extended family fleet includes a 2010 Grady-White 305 with twin Yamaha 350 4-stroke V8's. Yesterday, one of the engines starting doing this after cruising for about 15 minutes while slowing down to anchor near shore (so coming off of planing speeds as far as I understand it). Not sure of any further specifics.

​To me it sounds like a valve lifter or perhaps an exhaust gasket leak. Just wondering if anyone has some additional thoughts. :noidea:

This is my brother's new-to-him boat of about 1 month's time, and so far it has been putting up a fight with repairs, etc. Survey and sea trial went flawlessly :facepalm:

​This is the port side engine . . . he motored back to the marina on the starboard engine only (once the cooler was empty, I assume)

 

[Scott Danforth]

sounds like a V5 vs a V8. something is amiss literally.

 

[tpenfield]

I just hope it is not too bad, the boat is costing a fortune to keep operational.

I'm thinking if it were multiple cylinders- it would probably not even idle.

 

[Scott Danforth]

I just hope it is not too bad, the boat is costing a fortune to keep operational.

I'm thinking if it were multiple cylinders- it would probably not even idle.

a v8 will idle on 4 cylinders. heck the V6 in my drag car back in the 90's would drive around town on 3 (forgot to reconnect them once)

 

[tpenfield]

The boat is coming out of the water in the next few days. . . second time coming out this month. We shall see what the shop has to say.

 

[tpenfield]

Well Scott Danforth you were right about something really being amiss . . .

The engine had a failure of some sort that was caused by a crack or deterioration in the exhaust manifold which then led to water in the cylinders and a hydro-lock situation. At this point something broke loose (or bent) in the powerhead preventing the engine from turning freely. The shop has sent some pictures and the valves on one side of the engine have seen salt water.

So, it is looking like a new/rebuilt powerhead at this point. :facepalm: :faint2:

 

[99yam40]

I have read some of those big motors being so heavy and sit so low, that stopping quickly or backing down can get water up the exhaust and into cylinders

 

[tpenfield]

There is a somewhat known issue with the early day big V8 Yammy's with the exhaust manifold corroding and allowing water to get into the exhaust passage up near the valves. So, that is more likely the issue, but who knows for sure. The engines are from that vintage where the problems were known to have occurred. Later models have an improved manifold (supposedly).

The warranty ran out in 2015 . . . but I think it is worth pushing the issue, since it is a known defect.

 

[Scott Danforth]

people wonder why I dont like outboards (especially todays outboards with the crank in the wrong direction). Ted, talk the family into a pair of 7 marine 627's. I can get Rick and Erik to sign them

 

[tpenfield]

people wonder why I dont like outboards (especially todays outboards with the crank in the wrong direction). Ted, talk the family into a pair of 7 marine 627's. I can get Rick and Erik to sign them

Yea sure . . ., the quoted cost to fix is about 2/3 the price of a new engine . . . boating season might be over for them. Also, this experience, even though I'm in the cheering section on this one, is making me re-think having outboards.

 

[tpenfield]

Quick update:

No love from the folks at Yamaha as far as fixing the engine. The exhaust manifolds on the starboard engine are going to be replaced as a precaution to hopefully avoid the same issue with that engine.

 

[tpenfield]

Update:

​The motor(s) are supposed to be fixed by next weekend . . . so about 3 weeks to get repaired. New powerhead is being shipped and supposed to arrive this week. . . It has to go by truck since it is wicked heavy.

​I got a better description of the problem/situation that caused this mess. The engine was idling fine and then my brother felt something like a bump and the engine had stalled. When he started it back up it was making the noise in the video. So, my guess is the hydro-lock stopped the engine and probably bent a connecting rod or two. The shop could not get the engine to turn freely; it would hit a hard stop before making one revolution.

 

[tpenfield]

Update:

$24K later the boat is back in the water :faint2:

I'm sure glad it is not my boat :facepalm:

There was still an exhaust manifold on back order to replace the original one on the other engine, but the shop pressure tested the original one and said it was OK. Not sure I'd roll the dice though, but not my decision.

Yamaha has stopped covering these issues, but were covering them, even out of warranty, up to a couple of years ago. I told my brother he needs to find a different place to do repair work. . . everything seemed way pricey.

I'm thinking I'll stick with I/O engines, after seeing this nightmare.

 

[99yam40]

lots of I/Os went south do to exhaust manifolds dumping water into motors also.
just saying

 

[tpenfield]

lots of I/Os went south do to exhaust manifolds dumping water into motors also.
just saying

​Absolutely, been there, done that with a previous boat. It just seems that fixing the I/O engines is an order of magnitude less $$$$