Diesel Struggles Under Load

[Kenomac]

One more very important bit to consider that nobody's mentioned. If you clear something from the prop like rope or growth, you can't test your engine for higher revs while it's tethered to the dock, you'll need to take it out into open water. Tied to the dock, your engine will only rev part way due to increased resistance. The boat needs to travel through the water in order to rev the engine higher under load. Tied to the dock, it will struggle like it's trying to move the dock... which is exactly what it's trying to do.

Good luck.

[bobofthenorth]

I vote for the governor. It's load related which for me rules out exhaust. If there's no fuel or air restrictions then the governor is the next likely culprit.

R.J.(Bob) Evans
www.travellingwithgeorge.blogspot.com

[CptLawrence]

When cleaning the prop did it turn easy in neutral?

[strqaightv8]

Kenomac, it's a good thought but even just a quick rev before the slack got taken out still showed limited revs .

The prop spun fairly easily by hand after cleaning, unfortunately I don't have anything to baseline it off of

It sounds like I'm going to get into the governor today after work and see what the guts look like


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[HappyMdRSailor]

Originally Posted by strqaightv8

I did not run two lines, I just put the suction line in and let the return run to the stock tank, didn't think it would make much difference. I can bypass the first filter but not the second, they have some specialty hoses and fittings from my primary pump all the way through the injector pump.

It's not a terrible job to unbolt the shaft, I've got pretty good access, and it shouldn't be too stuck, I just replaced the coupler about 7 months ago. I like the idea though, I hadn't thought of it. At the very least it would confirm it's nothing to do with prop.

And I bought a 30 year old boat, of course I like fun

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I'd redo yer bucket with the return plumbed to it... Good news on the coupler... 30 min job instead of a 3 day swearfest... Whew!

Oh man... Ain't they all... Age just increases the fun factor...

[strqaightv8]

Originally Posted by HappyMdRSailor

I'd redo yer bucket with the return plumbed to it... Good news on the coupler... 30 min job instead of a 3 day swearfest... Whew!

Oh man... Ain't they all... Age just increases the fun factor...

I'll give it a shot, just out of curiosity, what's switching the return line over going to do?

3 days my stern, sawzall takes care of that in about 5 minutes, but I'm appreciative of the fact I don't have to buy a new coupler again....

Hey, if we didn't love it, we wouldn't do it


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[HappyMdRSailor]

Originally Posted by strqaightv8

I'll give it a shot, just out of curiosity, what's switching the return line over going to do?

3 days my stern, sawzall takes care of that in about 5 minutes, but I'm appreciative of the fact I don't have to buy a new coupler again....

Hey, if we didn't love it, we wouldn't do it


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Restricted or blocked return raises the pressure inside the IP, changing all of the designed pressure parameters... Can mess with governer output etc...

One thing we haven't touched on is revving up in neutral... What do we get doing that?

Not all couplers are treated alike! Mine has 2 different couplers, BOTH have recessed cap screws.... No sawzallability whatsoever...

We're a tolerant bunch to be sure!

[sailorchic34]

--full range of revs in neutral, around 4k top end, when I put it into gear it bogs down slightly and limits revs to 2-2.5k. It reaches this level where it should, around halfway up my control lever's throw, but the last half of the throw sees no additional increase. And it's not the linkage either here, I've adjusted my screws and worked it manually, no change. I do remember reading about someone with a similar problem and it was the spring that caused it, it's worth looking into, I'll see what I can do with it later today

AH, so we're at either a clogged discharge elbow or injector limiter setscrew or spring. Either of these would cause this condition.

FYI on the Yanmar GM engines if the injector limiter is set wrong, you get the same reaction as above..... Normally set at factory and forgotten about it. Unless some blonde chick, removes it when disassembling her engine, Doh.

But as the engine runs to high rpm without issue in neutral, we can say that the discharge elbow is fine, or fine enough.

BTW Westerbeke calls the injector limiter, High Speed set. located next to the idle speed adjust.

Play with that. if you get smoke at the exhaust, back it out a 1/4 at a time. (only 1/4 turn at a time) otherwise turn it in 1/4 turn at a time till throttle response improves. If it's missing the seal, somebody messed with it. Normally it is never adjusted, factory set.

[strqaightv8]

Welp, diagnosis almost complete. Unbolted the transmission coupler and gave her a go, my problem magically disappeared. I'm still cautious to call it finished, the shaft and prop are going to add some kind of resistance which could translate into a struggle earlier down the line somewhere, but it seems pretty definite to me. Time to take another swim.

Anyone have an idea of what might be causing this? I'm going to look for bent blades and the like

As for everything else, didn't test the return line yet, coupler was the first thing I did. I checked the exhaust elbow already and it was clean. Set screws are fine, I fiddled with them first and while it changed my neutral range did nothing for my in gear progress


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[JPA Cate]

strqaightv8,

Sounds like fish line got wrapped around your prop shaft, maybe even sucked up into the cutlass bearing.

Ann

[strqaightv8]

Originally Posted by Ann T. Cate

strqaightv8,

Sounds like fish line got wrapped around your prop shaft, maybe even sucked up into the cutlass bearing.

Ann

That's a good idea, I didn't think about that. I didn't get a chance to dive under today, and won't be back until Monday, but I'll check it then

My thoughts are either something's muffed up in the cutlass bearing or stuffing box, or I ran into something underwater and bent a prop fin or the shaft


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[jimbunyard]

When you had the transmission uncoupled, how hard was it to turn the prop shaft?
Was there a certain spot that felt like it was binding? The shaft should turn easily all the way around. Do you have a packing-type stuffing box? Is it adjusted correctly?

[HappyMdRSailor]

Originally Posted by sailorchic34

--
FYI on the Yanmar GM engines if the injector limiter is set wrong, you get the same reaction as above..... Normally set at factory and forgotten about it. Unless some blonde chick, removes it when disassembling her engine, Doh.

You could make a killing sneekin' a "curious looksee" on peoples boats while ya were visitin' for sudowners and the like...

Then ya drive around the marina in a white panel van with the words:

LIMITER SETTING SERVICE

Boldly emblazoned on the side of the van... In the back you keep your custom gold plated, pink handled screwdriver in a velvet box...

[HappyMdRSailor]

OK man!

Any progress is good progress... Now why did we replace the coupler a few months back??? Did we replace the packing at the same time???

Still not convinced we don't have a load/fuel requirement problem, but again... we have more info... Waiting for your dive info with the rest of us!

[strqaightv8]

Originally Posted by HappyMdRSailor

OK man!

Any progress is good progress... Now why did we replace the coupler a few months back??? Did we replace the packing at the same time???

Still not convinced we don't have a load/fuel requirement problem, but again... we have more info... Waiting for your dive info with the rest of us!

Did it when I bought the boat in February, my stuffing box hose was shredded, so I replaced that, repacked it at the same time, have it a good cleaning, and changed the cutlass bearing. The old coupler was rusted to **** so I changed that as well


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