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Alternator to Tach signal issue?

Keefer Douglas

Keefer Douglas

Member
Odd issue on our 382 (hull #195, Perkins 4-108 that is not original but likely roughly same age as the boat).

Occasionally the tach will show an obviously incorrect rpm, sometimes way too high, sometimes zero. Zero is pretty clearly a lack of signal from the alternator, but the opposite I'm not sure about. Seems most common when first starting engine but then it will recur randomly.

Alternator is a 100 amp, dual pole Balmar, poles wired separately to the two battery banks, with a Max Charge external regulator. I have checked with a strobe rpm gauge and it is calibrated perfectly, when it is working properly. Also already replaced the regulator, which was fried (I think) by running too long on a dead battery (long story).

My suspicion is that the dual poles wired to different sized battery banks (all AGMs though) are somehow messing with the regulator/tach and causing the bad signal, but must admit I don't really know how this would happen.

Anyone ever seen anything similar?

Plan is to do away with this setup and route all charging sources to the house bank only, with a battery connector to take care of the engine start battery. According to Balmar if you just bridge the poles the alternator functions the same as a single pole model. We shall see, but would appreciate any wisdom that may be out there. Would rather not buy a new Balmar, those things ain't cheap!
 
My tach is wired to the max charge. I would assume that is how yours is unless some previous owner didn’t do it that way. I was having tac problems not unlike yours and it was a tired tach. The cheap things I buy at West Marine don’t seem to last very long. One warning, if the thing is wired to the max charge, the tach will just stop registering for a while when the Max Charge moves to float. Balmar told me 15 years ago that was a glitch theY had not fixed and, with a brand new max charge a year ago I learned they still haven’t fixed it.
 
FWIW,
TinyTach makes a unit that uses a sending unit that clamps around an injector line and measures the pulses. Installed one three years ago. Could not be happier.
David Smead from Ample Power in Seattle back in the '90's challenged the necessity for a separate starting battery since a properly charged and monitored house bank could do it all.
I have not had a starting battery since 1993. Haven't had to row home yet.
When I go for a day sail since the batteries are fully charged, I turn off the alternator field and let it spin free.
 
john english said:
FWIW,
TinyTach makes a unit that uses a sending unit that clamps around an injector line and measures the pulses. Installed one three years ago. Could not be happier.
David Smead from Ample Power in Seattle back in the '90's challenged the necessity for a separate starting battery since a properly charged and monitored house bank could do it all.
I have not had a starting battery since 1993. Haven't had to row home yet.
When I go for a day sail since the batteries are fully charged, I turn off the alternator field and let it spin free.
Click to expand...

John Do you have the Yanmar or Perkins engine. If Perkins where did you install the Tiny Tac
 
I have the Yanmar. The TinyTach display is small. Some imagination is needed for an ideal location due to its size. I had relocated the entire instrument display just to the right of the helm and carved up a bit of blank plastic to accept the display where the 3" tach hole.
 
terry_thatcher said:
My tach is wired to the max charge. I would assume that is how yours is unless some previous owner didn’t do it that way. I was having tac problems not unlike yours and it was a tired tach. The cheap things I buy at West Marine don’t seem to last very long. One warning, if the thing is wired to the max charge, the tach will just stop registering for a while when the Max Charge moves to float. Balmar told me 15 years ago that was a glitch theY had not fixed and, with a brand new max charge a year ago I learned they still haven’t fixed it.
Click to expand...

Terry, very interesting about the Max Charge - that certainly seems to explain why the tach drops to zero sometimes. As for the opposite problem, I did the rewire today so we'll see if that fixes it when we go out sailing this weekend. If not, next up is probably changing out the tach itself. It is probably pushing 40 years old at this point so no surprise if it is just worn out.

The regulator is model MC-614. I don't think it is one of the ones that supports dual voltages, but with my new setup it won't be necessary.

I agree that a starter battery isn't strictly necessary in a well designed system, but I do like the peace of mind that comes with a separate bank in case of emergency. And the Xantrex Echo-Charge I put in there to take care of the start battery is a really great product - easy to install, set it and forget it!
 
"And now for something entirely different".. Monty Python somewhere between 1969 and 1974
May Ron Popeil bless our souls beamed from outer space on the Home Shopping Channel re-runs. The (my) "Showtime Rotisserie Grill" is imho he ultimate rib machine. The personification of "Set it and forget it" No experience necessary and joke, It's terrific! 1.8KW restive load @ 120 volts...........however,
We're gonna need a bigger boat (battery)! "Jaws" 1975
Yum Oh!....Rachael Ray when she was thinner..........
:D
 
Keefer
On Dana we have a weird event that we call "crazy tach". When there isn't any more room in the batteries to put another amp hour of power, the tach display goes nuts. The engine RPMs never change but the tach goes from 1000 rpm over to 1000 rpm under and doesn't sit in one place for a moment. The first time it happened I freaked out. Spoke to numerous "experts" who had no clue. Finally found an old timer who said to just put another load on the system to draw a bit more amps out. Now when we get the "crazy tach" we switch on the bilge blower fan and the tach settles right down. I don't know if your problem could be related to this but it might be worth looking into.

Jim
 
After another weekend out sailing (and a lot of motoring through the Chesapeake summer doldrums), I think we are starting to see the pattern. It does indeed sound a lot like what you describe Jim. At any rate it all seems to resolve after the voltage has been stable for a while (either absorption or float) but any big change seems to drive it "crazy". I'll try the blower next time. Not something I ever would have expected, but if it stays the way it is I guess I can learn to live with it! Just one of those boat quirks...
 
Keefer
If your's is the same issue, at least it's telling you that the battery bank is as full as it can be. That's not a bad thing.

Enjoy the boat. Send a photo!
Jim
 
This (and the new profile pic) are from this past weekend, taken by some friends rafted nearby. Still don't have any while sailing, but I must say she looks pretty good from far away, lit up by a beautiful sunset. Don't we all though ;)
 

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You know, the wife and I were just talking about this the other day. We have never used the blower on our previous boat, this one, or any of the various charters we've done. Never had a problem, but that certainly doesn't mean we are in the right! Would be interested to hear what others do.
 
John & Keefer
I don't think it's required for a diesel engine as opposed to a gas engine. At a fuel dock the blower should be run after fueling in case something ended up in the bilge. But it does supply cooler and cleaner air to the engine compartment which isn't a bad thing. Our blower is a noisy affair which we don't much hear when the engine is running but we certainly know we left it on when the engine is stopped.

Jim
 
jimcleary said:
John & Keefer
I don't think it's required for a diesel engine as opposed to a gas engine. At a fuel dock the blower should be run after fueling in case something ended up in the bilge. But it does supply cooler and cleaner air to the engine compartment which isn't a bad thing. Our blower is a noisy affair which we don't much hear when the engine is running but we certainly know we left it on when the engine is stopped.

Jim
Click to expand...
Yes...can’t hear it when the Perkins is running...so the fumes from diesel are not potentially explosive? That’s good to know. I hate turning it on before starting and running it after shutting down to clear out heat. Good to know
 
Diesel fuel is, or can be, just as explosive as gas, but it only happens at a much higher temp. I think running the blower for fresh clean air to the combustion mixture is the biggest benefit, other then solving "crazy tach". If you clean or change your air filter on the engine at the end of the season, you'll probably find an oily residue on the filter. That's from the engine breathing the oil and fuel fog that is found in the unvented engine compartment. If we ran the blower more when the engine is working, there would be less to clog the filter and the engine would be a much happier camper.

Jim
 
jimcleary said:
Diesel fuel is, or can be, just as explosive as gas, but it only happens at a much higher temp. I think running the blower for fresh clean air to the combustion mixture is the biggest benefit, other then solving "crazy tach". If you clean or change your air filter on the engine at the end of the season, you'll probably find an oily residue on the filter. That's from the engine breathing the oil and fuel fog that is found in the unvented engine compartment. If we ran the blower more when the engine is working, there would be less to clog the filter and the engine would be a much happier camper.

Jim
Click to expand...
Jim
Also propane I guess. Guess I will keep turning it on first before starting. Always did it that way. Let it run after shutting down for a minute.
My Dumb question...Where’s the air filter?
Did you get any pictures of your trip to Mystic?
 
Its under a bowl shaped on the starboard side of the engine. It is a cylindrical wire mesh. I used to take the wire mesh out and spray it with carborator cleaner, after I learned that lack of air was making the exhust black.
 
John & Bert
I have the Yanmar, which has an air intake/filter on the port side of the engine. The filter inside the housing is a foam shaped over a SS mesh. I clean the foam with a bath of simple green, then replace it about every 5 years. I'm not familiar with the Perkins air intake system.

Jim
 
John, you are absolutely right about propane. It is a gas at ambient temperature/pressure, and also heavier than air. Good news is that there is a relatively narrow range of propane/air concentration at which it is explosive. Bad news is once it is in the bilge, it will seek out the lowest point and stay there. Blower helps of course, but far better to be vigilant about keeping it out in the first place! Not quite as bad as gasoline, but good old diesel sure is great in the hot, enclosed, dirty (Jim Cleary excepted - I have never seen an engine room quite so spotless as his!) spaces we sailors like to put it in.

Full disclosure: I am an NGL industry analyst by profession - ethane, propane and butane are my bread and butter...

On my previous boat I replaced the old air intake with an automotive style filter, and also routed the blow-by from the PCV through an oil separator and then back to the new air intake. Previously the oil and presumably some unburned diesel that get by the piston rings were routed straight down to the bilge. That seemed to clean things up noticeably without any change to engine operation. Haven't gotten that far yet on the Perkins.
 
Keefer Douglas said:
John, you are absolutely right about propane. It is a gas at ambient temperature/pressure, and also heavier than air. Good news is that there is a relatively narrow range of propane/air concentration at which it is explosive. Bad news is once it is in the bilge, it will seek out the lowest point and stay there. Blower helps of course, but far better to be vigilant about keeping it out in the first place! Not quite as bad as gasoline, but good old diesel sure is great in the hot, enclosed, dirty (Jim Cleary excepted - I have never seen an engine room quite so spotless as his!) spaces we sailors like to put it in.

Full disclosure: I am an NGL industry analyst by profession - ethane, propane and butane are my bread and butter...

On my previous boat I replaced the old air intake with an automotive style filter, and also routed the blow-by from the PCV through an oil separator and then back to the new air intake. Previously the oil and presumably some unburned diesel that get by the piston rings were routed straight down to the bilge. That seemed to clean things up noticeably without any change to engine operation. Haven't gotten that far yet on the Perkins.
Click to expand...
Thank guys!
 
Just for safety sake I keep the blowers on always as long as the engine runs . I just changed out the blowers to the high speed ( just moves more air) ! Since those air cowls are with in wheel reach i often reach back and put my hand in the out flow and smell the my hand ! do i smell just heat ? or oil ? Im getting to feel for the engine temp with out getting out the laser temp gun . Besides it keeps the engine a little cooler. Fresh air cant be bad.
 
Keefer
Thanks for the kind words. A few years ago I rigged up a system with 2" pipes and two 1/2ton chain falls to move the engine out into the main cabin for the winter. While it was there it was cleaned and painted. The engine compartment was also refurbished.

I'm interested in your system to trap the residue from the breather. Could you maybe do a diagram and list the components?

Jim
 
Keefer
I don't think my old Yanmar has a breather on the valve cover. Back in the late 70s they weren't into much of the pollution controls. I'll take another look this weekend.

Jim
 
Jim,
The primary purpose of the breather is to regulate pressure in the engine case. If there wasn't a way to vent the air/fuel/oil getting past the cylinders, then pressure would build until... I guess you'd blow the head gasket? Or at least start leaking a lot of oil. The stuff coming out is just a byproduct of this process that engine builders in the 70s were indeed happy to route out of sight / out of mind. As usual Wikipedia provides a pretty good summary: https://en.wikipedia.org/wiki/Crankcase_ventilation_system

Not sure how it was done on the old Yanmars, but on both the Universal and Perkins it is simply a hose coming off of the crankcase, often simply ending somewhere below the engine.

Incidentally the only reason I know anything about this is because this system failed on my wife's old Mazda, which then failed an emissions inspection. Of course the part was located in a place that required removing 8 other things to get to it. $1000 later on a car worth maybe $2000, I had learned a little about crankcase ventilation, and was moved to investigate how it was done on my boat engine...
 
Keefer
OK, reading all that it sounds as if the systems were in place on auto gas engines of the mid to late 60s. I wonder, if by 1978, the diesel engine manufacturers got on board with that. I know there is nothing coming off the value cover on the Yanmar. This weekend I'll look all around the engine to see if I can find anything. It makes sense to not have that crud vented into the enclosed engine compartment.

Where are you guys going to cruise to this summer?

Jim
 
Good luck! As usual we probably won't have enough time to get out of the Chesapeake, but we'll be out on the Bay most weekends anchored somewhere nice and quiet!

How about you?
 
Keefer
Right after the 4th we are heading up to Block Island and Newport for about 3 weeks. I was thinking of jumping down to the Bay for Sept and October, but we have our 4th Grandbaby due in early October so that rules out a journey. Maybe next year. Thinking about sailing the Bay in the fall, then storing somewhere down there, then cruising there again in April & May before heading North again by June. I'm working on selling that to Bonnie.

Jim
 
Jim,
Congrats on the new grandbaby - nothing better! We would of course love to see you down here in the Bay any time. And May, September and October are probably the best months of the year so I think your plan is a good one. Happy to put in a plug for our home port if and when you do come.

And of course the same goes for anyone else out there in Morgan-ville who may be visiting or passing through the Bay. Always happy to meet anyone with such evident good taste in boats! :)
 
Keefer
I just looked at the Yanmar to see if I could find a breather pipe. After searching the engine manual and looking on the engine itself, I finally located the breather pipe. It runs from a plate above the injector pump on the stbd side to the underside of the intake manifold on the port side. Now that I see where it goes, I think it would be easy to intercept it and add a filter to it. I'll put that on my list of "not-so-priority" stuff to do. I think my first job will be to just make sure the piping is clear and not clogged.

Jim
 
My Morgan/Perkins ('82) routed crankcase vent back to the air intake. Like most cars of the vintage. No PCV valve, open hose. The engine eats the blow by.
A diesel can feed off of engine oil, and runaway as if the throttle is wide open. This might happen if the mechanical lift fuel pump diaphragm started leaking fuel into the crankcase. Scary event. You need a way stop the air going in. Metal can over the intake inlet. Another reason to check engine oil before starting...high is as dangerous as low in a diesel.
 
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