Unusual power problem

Dammit man!

Timing chain!!!!

Greetings,
Mr. HW. So, NOT the cockroach eh? Hmmm...Too much fuel is being injected and/or not enough air is getting to the cylinder(s) for complete combustion.

Don't tell yet but another hint perhaps?

twistedtree said:

Tell us, tell us, tell us.

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Alrighty then...
It wasn't the port engines fault at all!
The starboard transmission was slipping! The Starboard engine reved up to WOT but the prop didn't. The boss looked at the stbd shaft and said it ought to be turning alot faster for that RPM.
The Port engine was overloaded trying to pull the whole boat up to speed because the stbd was slacking off, hense the black smoke.

Well heck. At least I got my post count up!

Though, why wouldn't the port engine "come up to cruise" RPMs as per your OP?

I would have thought it would in this case?

The stbd engine was not pushing much at all. Had the owner tried to power the boat from the starboard engine alone, the fault would have been obvious. But he always pushed up both throttles together.

Wow, that's a good one.

High Wire said:

The stbd engine was not pushing much at all. Had the owner tried to power the boat from the starboard engine alone, the fault would have been obvious. But he always pushed up both throttles together.

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But given that the port engine would have behaved normally and got to normal RPM for that throttle position, and the boat would have turned to starboard, hence indicating an weakness issue with the starboard engine? No?

Now that is doozie!! Nice catch! You don't ever forget those.


1983 Present 42 Sundeck
Twin Lehman 135's

menzies said:

But given that the port engine would have behaved normally and got to normal RPM for that throttle position, and the boat would have turned to starboard, hence indicating an weakness issue with the starboard engine? No?

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Yes, very possible, but the volvos take a long time to push the boat up to plane. Long enough for the owner to compensate with the hydraulic steering. In his mind, the port eng would only get to 2600 rpm with heavy smoke and the stbd ran right up to 3800+ with no smoke. He came to the conclusion right there that the port eng was the problem. The mechanics came aboard to troubleshoot why the port engine would not rev up and was smoking.

Didn't they ever try to throttle it up out of gear?

That was fun! Well - entertaining anyways... at least for those of us NOT paying the mechanics! Tuck that away in the mental file!

No rudder position indicator? It would be an early indicator of a problem with asymetric power.

I hope he got a big refund for them replacing everything but the block on the port engine!

When I last talked to the owner, they were trying to find a rebuilt Volvo HS-1 tranny. So its not over yet!

THD said:

I hope he got a big refund for them replacing everything but the block on the port engine!

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Let me know when you find any mechanical repair shop that will do that......

Some will knock off labor if they have made a big mistake...obviously not expensive parts that you didn't need but they probably won't eat those.

Have seen them eat the cost of some bulk fluids like winterizing antifreeze when the tech obviously wasted way too much.

I think it really depends....this misdiagnosis was pretty egregious for replacing parts, filters, etc...but was one of those that if the young guys were working it...I can see the incorrect path they followed. Yet it is a path too many shops follow.

twistedtree said:

Let me know when you find any mechanical repair shop that will do that......

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Happened to me and the result was a total repower. Both engines removed and rebuilt, new transmissions, etc. etc. for my cost of 16K. Yard were very quick to put their hand up and say it was down to them.

I'll tell that story one of these days.

menzies said:

Happened to me and the result was a total repower. Both engines removed and rebuilt, new transmissions, etc. etc. for my cost of 16K. Yard were very quick to put their hand up and say it was down to them.

I'll tell that story one of these days.

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Sounds like one heck of a story... please, do tell.

Have had several lazy engine experiences caused by different things. Determining which engine was at fault was easy. Powering up each individually quickly showed which was not doing the job

There's one of the upsides to a single engine.

Was the transmission fluid darkened or smelling funny? Often a pre cruise day dip stick check can note a clutch pack problem.

As mentioned, the next steps will be interesting. Is he using the same guys to repair tranny as "fixed" the engines? Knowing who the right guys are is never easy.