1 GM power problems

Brian H · Post by **Brian H** » Jun 13th, '09, 18:42

Hello,

The last several times I've been out, I' ve had problems with no thrust being delivered by the propeller on a regular basis. When leaving the mooring, the engine/transmission seem to operate fine.
I only run the engine about ten minutes.

However; when returning to the mooring [ usually three to six hours later] the propeller does not deliver thrust at all times [ most of the time]. It would appear that it's cavitating , but I'm sure that's not the problem.

It happens at any rpms, but mostly when turning to starboard, but even when motoring dead ahead? There are no strange noises or smells. Oil levels are fine and were changed this Spring.

Does this appear to be a loose propeller, transmission, or clutch problem?

Thanks,
Brian

Ed Haley · Post by **Ed Haley** » Jun 14th, '09, 08:22

Think simple things first. Best guess is that your prop may have picked up some weeds while sailing. Turning the prop when you started the engine wrapped the weeds around the prop and shaft interfering with propulsion. Visual inspection may confirm this.

Joe Myerson · Post by **Joe Myerson** » Jun 14th, '09, 11:55

Brian,

There's a good chance that Ed is right (you should hope so).

When I bought my 25D, the PO warned me that the I would think that my transmission was going bad sometime in August. He said it was because of crud growing on the prop.

That was certainly the case in years past. Last year, when I did nothing in the way of prop anti-fouling, I had to dive down and whack at the barnacles in mid-July.

Check your prop first, then worry about more serious problems.

Best of luck,

--Joe

John Vigor · Post by **John Vigor** » Jun 14th, '09, 19:26

Brian, this is a most intriguing problem. But first, we need more information.

It's very unlikely to be a loose propeller, but not totally impossible, I guess. The way your prop is attached to the shaft, with a key in two slots, and two large nuts to keep it in place, would tend to ensure that your prop is either correctly in place or gone altogether. But it obviously isn't gone altogether, from what you say.

It's more possible that your transmission might be faulty. There might just be something loose in the gearbox that slips out of place occasionally, and then slips back in by happenstance.

It's also possible that your dog clutch might be playing up, possibly because the control wire to the little lever on the transmission that controls it is somehow working loose or misbehaving. Check out the connection between the control wire and the lever, and watch it while someone works the gear lever up in the cockpit. It might also need adjustment. It might be just on the edge of a correct adjustment, and slip out of whack occasionally. Make sure the lever travels through the full range from astern to ahead, and can't slip into neutral of its own accord.

As for the fact that your problem occurs mostly when you're turning to starboard -- well, that sounds rather like some witch has cast a spell on your boat. Nothing much you can do about that, except hire a more powerful witch.

The first thing you need to do is look at your prop shaft from inside the boat when you lose thrust. Is the propshaft turning or not? That alone will tell you a lot. If it's not turning, suspect the transmission or lever adjustment.

And does the engine speed up or slow down when you lose thrust?

And when you say you lose thrust, do you lose all thrust, or just some of it? Does the boat come to an absolute halt in the water with the engine running at normal revs, or does it just slow down--and if so, does it slow down a lot or a little?

Finally, are you sure that when you put the tiller over to port, (to turn to starboard) nothing catches on the gear lever in the cockpit to kick it into neutral? Sounds silly, I know, but strange things happen on boats.

Cheers,

John V.

Dean Abramson · Post by **Dean Abramson** » Jun 14th, '09, 19:29

Are you sure that the transmission is going into gear? Check the cable to the tranny. Watch the transmission's control arm while you put it into Forward and Reverse.

With the single-lever throttle/tranny control, you might not feel any difference if it is not engaging.

Dean

Brian H · Post by **Brian H** » Jun 26th, '09, 13:00

Thanks for the feedback and advice given. I've followed through with it, but unfortunately; the problem persists.

A diver checked out the prop and found nothing fouled, the key in place and the prop nut tight. The propeller will not turn when the shaft is held tight.

The propeller shaft turns when the engine is put into gear [ both forward and astern] and speeds up when the rpms are increased.
However; only a maximum of 1.5 knots can be obtained and at times no headway can be obtained at all even thought the shaft is spinning and appears normal.

There are no stange noises or smells.

Is it possible for the propeller and shaft to rotate at normal rpm, but not deliver any thrust or torque because of transmission or clutch problems?

Other than putting the transmission into forward, astern, and nuetral, what does that lever at the transmission actuate? How would the engine/transmission react if it wasn't going through it's full range?

The boat operates fine when under sail, obtaing a little over five knots.

I feel like there's a simple solution here but I'm missing it.

Thanks again,
Brian

Jim Davis · Post by **Jim Davis** » Jun 26th, '09, 13:18

When you said you could rotate it in reverse this got me thinking. Check the set screws in the shaft flange.

shavdog · Post by **shavdog** » Jun 26th, '09, 13:33

since i operate my cd 22 with a minnkota elec trolling motor dont know how much help i can be but you might looking up torreson marine in michigan..these people are yanmar specialists with message boards and a phone number....if yours is a yanmar...i'd try calling the experts also..

John Vigor · Post by **John Vigor** » Jun 26th, '09, 16:59

Brian, it almost certainly must be the propeller. If the shaft is turning at a reasonable speed, and the propeller is also turning at the same speed, you must get forward thrust.

Is this a folding or feathering propeller, by any chance? What kind of propeller do you have? Fixed three-blade, two blade? Can you give us the diameter and pitch? Perhaps there is some truth in what you say about cavitation. Has the propeller been changed recently? Could the pitch be so wrong (so oversized) that it cavitates at high revs but will give some thrust at low revs?

John V.

John Vigor · Post by **John Vigor** » Jun 26th, '09, 18:28

Jim Davis wrote:When you said you could rotate it in reverse this got me thinking. Check the set screws in the shaft flange.

Jim, I can't find where he said he could rotate it in reverse. Where did he say that?

Cheers,

John V.

Brian H · Post by **Brian H** » Jun 26th, '09, 18:40

John,

I believe the propeller is the original 11 x 13 RH two bladed propeller. It's operated fine the first two years I've owned the boat.

Each Spring I put a coat of anhydrous lanolin on it which eliminates all barnacles and has never compromised the performance of the propeller.

Now; I'm reduced to wondering if the lanolin applied this year has created a too slippery surface on the prop where it cannot grab hold and deliver thrust? I know I'm grasping at straws at this point.

However; after launch this Spring, I motored the four miles to my mooring with no problems.

Brian

Brian H · Post by **Brian H** » Jun 26th, '09, 18:43

The previous message should have been 11 x 12 RH two bladed propeller, not 11 x 13.

Brian

Joe Myerson · Post by **Joe Myerson** » Jun 27th, '09, 05:20

Hi Brian,

I can't believe that the lanolin has anything to do with your problem. In fact, I'm surprised that it stays on the prop long enough to repel those little b*stards!

How thickly do you put it on at launch? I tried it (as mentioned in earlier threads) for two seasons, and while it was better than last year--when I forgot to apply any protection to the propeller--it seemed to be almost useless.

When you solve your present difficulty, please let us know how well the lanolin works. I, for one, still have a tub of the stuff. If there's a way to get it to work, I'd like to know.

Thanks, and best of luck with your real problem.

--Joe

j2sailor · Post by **j2sailor** » Jun 27th, '09, 09:41

Here are a few common things that diesel gurus Nigel Calder and Peter Compton say to look for when you have acceleration/ loss of power problems:

Calder:
Clogged fuel filters
Clogged air filter
Improperly matched prop
Fouled bottom
Rope wrapped on prop
Dirty,clogged, or defective injector(s)

Calder emphasizes that dirty filters cause many problems like this.

Compton adds these:
Acceleration limiter on governor mechanism not set correctly (could this be slipping or set too low?)
Control cable travel restricted
Water in fuel
Air in fuel line (bleed the engine)

Best - J
www.skippertips.com

John Vigor · Post by **John Vigor** » Jun 27th, '09, 15:33

Well, Brian, let's recap.

There doesn't seem to be a problem with the engine. It apparently behaves quite normally.

You say the propeller shaft turns, but we don't know at what speed it's turning when you lose forward drive. If the shaft slows down, but engine speed stays steady, then the problem lies either in the gearbox, or the flange that joins the gearbox to the propeller shaft. It is just possible that there is slippage between the flange and the shaft. If you watch the shaft speed closely, you might be able to spot the shaft and the flange turning at different speeds.

But if the flange and the shaft appear to move as one unit, as they should, then the problem is more likely in the gearbox.

The purpose of the gearbox is twofold. It engages the engine with the propeller shaft when it is "in gear," either forward or astern, and it separates the engine from the shaft when it is in "neutral."

There is a rudimentary clutch that requires you to slow the engine down to idle before changing gear. The change should be made smartly and swiftly. Do not try to ease the lever into gear slowly and tentatively or wear will occur, and this might result in your gears engaging, going into neutral on their own from time to time, and then re-engaging. This may be your problem.

Check the level of lubricating fluid in your gearbox. There should be a small dipstick attached to the gearbox. Make sure it's full.

Incidentally, we don't know what kind of boat you have, or if the propeller is fixed, folding, or adjustable pitch. I would guess that an 11-inch diameter, two-bladed, fixed prop is not the optimum size for your engine. On my 25D with a 1GM engine I experimented with props and finally settled on a 12-inch diameter three-bladed fixed prop with a 9-inch pitch. Your prop seems to me to be overpitched . . . but that seems to be besides the point at the moment, because you say it has worked satisfactorily in the past.

I don't think the lanolin is affecting anything, especially if you didn't slather it on an inch thick, otherwise your prop wouldn't drive you at all at any time.

I'm beginning to think your next step is to consult a gearbox expert, who will remove the box and take it for bench testing. I once had a gearbox that just suddenly wouldn't go into reverse. I was approaching a dock at high speed at the time, hoping to slew in broadside before an admiring audience of friends, so the episode rather sticks in my mind.

After the Hurth experts failed miserably to correct the problem, and tried to sell me a new gearbox, it was fixed by a canny old Scot who worked on fishing boats. All it took was two extra shims in the right place and I was in business again.

Cheers,

John V.

The Cape Dory Board