Had the boat out on a nice day, but unfortunately had to motor as there was no wind.
Engine ran fine, sounded fine, but it wouldn't rev past 1600 RPM, and the throttle was on the stop. Everything seemed tight and correct in the throttle, and changing RPMs was smooth.
1600 seems too low to me, but the boat was doing 6.1 - 6.5Kts...
Something seems off to me, but I'm not sure what!
What does the tachometer show in the slip in neutral?
Craig
Quote from: Craig Illman on July 18, 2023, 05:26:20 AM
What does the tachometer show in the slip in neutral?
Craig
At idle about 800. Haven't tried to rev it at the slip.
I would do as Craig suggests and get a no load RPM and see what that is. Do the values of no load and load match? The engine has a governor to keep it at a max RPM so you won't hurt it by pegging the throttle with no load.
You might also want to get a digital laser RPM meter to check the RPM at the crank pulley. The Tach on our diesels uses the alternator AC pulse to determine the revolutions. Problems with set up and the alternator itself can cause the tach reading to be inaccurate or fluxuate.
pby : Another thing to check when the RPM is questionably low is your boat speed.
A thought
Quote from: waughoo on July 18, 2023, 08:12:52 AM
I would do as Craig suggests and get a no load RPM and see what that is. Do the values of no load and load match? The engine has a governor to keep it at a max RPM so you won't hurt it by pegging the throttle with no load.
You might also want to get a digital laser RPM meter to check the RPM at the crank pulley. The Tach on our diesels uses the alternator AC pulse to determine the revolutions. Problems with set up and the alternator itself can cause the tach reading to be inaccurate or fluxuate.
That's a good idea. The RPM's sound correct for the engine noise though. It doesn't sound like its rev'ing like crazy. Good to know though.
Quote from: pbyrne on July 18, 2023, 05:22:44 AM
Had the boat out on a nice day, but unfortunately had to motor as there was no wind.
Engine ran fine, sounded fine, but it wouldn't rev past 1600 RPM, and the throttle was on the stop. ...1600 seems too low to me, but the boat was doing 6.1 - 6.5Kts...
Something seems off to me, but I'm not sure what!
If you are going over 6 knots your boat is going over 1600 RPM. Get a laser tach on Amazon and check your true RPMs.
Quote from: Noah on July 18, 2023, 03:57:37 PM
Quote from: pbyrne on July 18, 2023, 05:22:44 AM
Had the boat out on a nice day, but unfortunately had to motor as there was no wind.
Engine ran fine, sounded fine, but it wouldn't rev past 1600 RPM, and the throttle was on the stop. ...1600 seems too low to me, but the boat was doing 6.1 - 6.5Kts...
Something seems off to me, but I'm not sure what!
If you are going over 6 knots your boat is going over 1600 RPM. Get a laser tach on Amazon and check your true RPMs.
Looking at amazon offerings, do you really need to tape something to the belt for it to work!?
No.You stick some white reflective tape (included) to the main crankshaft pulley and aim the laser at it through the belt.
Quote from: Noah on July 18, 2023, 04:52:09 PM
No.You stick some white reflective tape (included) to the main crankshaft pulley and aim the laser at it through the belt.
Ah! That makes more sense. Do you put the tape inside the pulley groove or on the outside edge, front face next to the belt groove?
Wherever it will stick as close to center, and where the laser will "see it" Clean off engine with some degreaser and/or acetone first.
Ok. Laser Tach on order.
Reading this thread, I will say that nothing has been done to the engine https://c34.org/bbs/index.php/topic,11302.msg90447.html#msg90447.
Oil changed last year, fresh fuel, starts immediately, and hasn't missed a beat the couple of times we had her out. In fact you can hear it here: https://c34.org/bbs/index.php/topic,11687.0.html
For completeness what/how should I be verifying the linkage, cables etc, to make sure I've inspected everything. The engine sounds fine to me other than it's not rev'ing as high as I think it should; by sound anyways.
At the moment I'm going to:
1) check RPM at idle in slip
2) check RPM with Laser Tach
3) Alternator (which I'm not sure how to do)
3)???
4)???
I'm 2 hours away from the boat, so I have to check everything when I'm there.
It is easier to have a helper when checking tach with laser. One person on laser and one in cockpit at throttle. Run though idle to full throttle (in neutral)—communicating with each other, and charting the results every 100 RPMs or so— comparing actual (laser) to tach readings. Error rate/difference may vary and not be constant throughout the range. You may want to just make a deviation chart and use/memorize /refer to it instead of trying a adjust out the tach error.
Quote from: Noah on July 19, 2023, 09:14:49 AM
It is easier to have a helper when checking tach with laser. One person on laser and one in cockpit at throttle. Run though idle to full throttle (in neutral)—communicating with each other, and charting the results every 100 RPMs or so— comparing actual (laser) to tach readings. Error rate/difference may vary and not be constant throughout the range. You may want to just make a deviation chart and use/memorize /refer to it instead of trying a adjust out the tach error.
Got it.
Anything else I can focus on? If I find the RPM's are too low on the engine then what?
No clue, I am not a mechanic. Others may respond with more helpful info. However, if your boat goes 6+ knots (confirmed by GPS in slack water) with tach reading 1600, I suspect your tach is reading incorrectly.
Quote from: Noah on July 19, 2023, 12:24:33 PM
No clue, I am not a mechanic. Others may respond with more helpful info. However, if your boat goes 6+ knots (confirmed by GPS in slack water) with tach reading 1600, I suspect your tach is reading incorrectly.
LOL. Fair enough.
Something else that came to mind is that the boat was just moved to a marina where we used the marina's fuel. Prior to that it was jerry can fed from Shell Gas Pumps. I'm thinking maybe I should consider the possibility the filters need changed.
Previously, they were changed infrequently from what I can tell. It was on my list for fall maintenance with the oil change for winterization.... but maybe it needs to be done now? Seems wierd that a top up ONCE would cause an issue with filters though...
pby : If you are going 6 kts or more thru the water @1600rpm - right off the top of my head I'd say you have a bad tach!!!
Check it with your laser tach instrument!!
A few thoughts
If the Tach is off before you trash it exercise the DIP switches or rotary switch setting. Contacts can become oxidized and produce false readings. There's troubleshooting for that in a manual for the gauges. If you don't find it on C34 Wiki I can probably find it elsewhere.
pby : I believe that the tach range for your engine should be 0 to about 2800 rpm (maybe slightly more when not in gear!!) Idle should be about 1000 rpm so it idles smooth and doesn't rattle you teeth!!
Try Ken's suggestion about cleaning the Tach wire connections at the alternator. Hard to tell you which colored wires on your alternator?? (mine are the white and the brown wires)
A few thoughts
Westerbeke's spec for maximum RPM of the M35B is 3000. You should achieve it underway in forward, or you may be over -propped.
My M35B can only get to 2800 rpm (tach reading) before the lever physically hits the binnacle guard. At 2300-2400, I'm going 7 knots in calm waters.
Andy
I presume that there are no harness plugs -- so that the Tach signal is wired directly to the alternator?
Quote from: Ron Hill on July 20, 2023, 02:48:55 PM
pby : I believe that the tach range for your engine should be 0 to about 2800 rpm (maybe slightly more when not in gear!!) Idle should be about 1000 rpm so it idles smooth and doesn't rattle you teeth!!
Try Ken's suggestion about cleaning the Tach wire connections at the alternator. Hard to tell you which colored wires on your alternator?? (mine are the white and the brown wires)
A few thoughts
I'll do that! I found some photos that might help, but I don't see any wires in them, so maybe not very useful.
Quote from: KWKloeber on July 20, 2023, 02:01:07 PM
If the Tach is off before you trash it exercise the DIP switches or rotary switch setting. Contacts can become oxidized and produce false readings. There's troubleshooting for that in a manual for the gauges. If you don't find it on C34 Wiki I can probably find it elsewhere.
This it?
Quote from: AndyBC on July 20, 2023, 07:52:36 PM
My M35B can only get to 2800 rpm (tach reading) before the lever physically hits the binnacle guard. At 2300-2400, I'm going 7 knots in calm waters.
That's what I remember the boat doing last year. It's not quite doing either of those numbers, and that's why it feels like something is off. Other than the tach literally isn't reading more than 1800 full throttle...
This sheet from Vee 3 speaks to contact oxidation.
I have other gauge troubleshooting guides from Vee 3 that I will upload when I have some time.
pby : The picture needed is the REAR of the alternator where the tach wires attach.
Noting the alternator paint job - I find it nearly impossible to believe that the adjusting nut on the top bracket has paint that has never been broken!!!! Factory Paint???
A few thoughts
Unless the PO had done any rewiring of the alternator, the factory schematic says that the tach signal is Brown #14. And unlike the earlier Universals, Westerbeke ran it thru the RV plug (no reply about whether the harness plugs were previously eliminated.)
To drive the Tach the Alt needs to send an alternating current signal -- something like 4-5 volts minimum.
Easy peasy to check at the "S" terminal on the Tach.
An unrelated observation from your pictures. Your hoses are 23 years old. You should consider adding their replacement to your project list.
My 2 cents.....
Ok. Used the laser tach and the following was observed at the slip in neutral.
Idle:
Tach: 800
Actual: 1000
Full throttle to the stop:
Tach 2500
Actual: 3000
All linkage and stops looked correct and working as expected when moving through motion by my lovely wife and I watched it.
Checked racor and found no water and diesel looked clean to the eye. Have heard that marina is sensitive to fuel quality and there are no reported issues with fuel at marina.
The problem I have is that we didn't see 2500 on the tach but 1600, and the engine didn't sound like it has running full out.
Some local folks have said they have had issues with weeds at the head of the channel that require clearing when boat feels sluggish ...not sure if that was the issue?
All I can say is that at the slip in neutral the engine sounded good.
Quote from: Ron Hill on July 21, 2023, 03:19:48 PM
pby : The picture needed is the REAR of the alternator where the tach wires attach.
Noting the alternator paint job - I find it nearly impossible to believe that the adjusting nut on the top bracket has paint that has never been broken!!!! Factory Paint???
A few thoughts
Ok! I'll look there.
That photo was from April 2021. That's the original westerbeke belt as far as I know. Since been changed, and paint cracked. I actually needed the part number today as I'm shopping for another belt!
pby : Just take your old belt to an auto parts store where they sell a good Gates brand belt. They can measure it and get you a new one.
Now if your alternator/pully is Original OEM you probably need a 395 size belt.
FYI, I also carry a spare belt - as a just in case!!
a few thoughts
Pby
B engines use a
Dayco 15395
Westerbeke 30475
The resources are all on here!