Re: Onan


seafeverofcuan <seafeverofcuan@...>
 

Hi Gary,
Thank you again. The symptoms that you describe do sound identical so I will follow your advice.
We are back home in Ireland and as yet don't know when we will return but I will keep you posted.
Kind regards,
Trevor

Sea Fever of Cuan
Sm 425

Ireland

--- In amelyachtowners@yahoogroups.com, amelliahona <no_reply@...> wrote:

Hi Trevor,

I have read your post several times and I believe I know what your problem is. I had a similar problem in that my Kubota engine would intermittently not crank, either from the galley switch or the engine control panel switch. Sometimes it would crank fine, next time it would crank, but at a sluggish rate etc, and then the next time it wouldn't crank at all. I believe that you have a faulty ground side contractor that either has high internal resistance or a sticky solenoid. To verify this, totally by pass the ground side contactor. Wire directly from the ground lug on the starter motor to the engine frame ground or the engine tray ground using a wire the size of the battery wire that supplies the starter motor. If your cranking problem is solved then replace the ground side contractor at your leisure as it isn't necessary except as a means of preventing stray current corrosion. In my case it was the ground side contractor that was the problem. Of course it could be an intermittent or high resistance positive side contractor. The reason a high resistance contactor might allow for partial cranking is that as current flows through the high resistance it heat up and can break the contact etc. so you get all kinds of intermittent or slow/sluggish cranking. Internally these contactors are two copper discs that are pulled together by the solenoid providing a large surface area contact for the heavy current flow (hence the name contractor). Each time the open and close there is some electrical arching that eventually can cause high resistance or warping of the contactor plates.

I believe removing the glow plug relay really was totally unrelated to your getting the engine to crank during the next cycle attempt after its removal. The glow plugs aren't necessary to start the engine, especially in warm climates, and I think the intermittent contractor problem just serendipitously allowed the engine to crank after you did this.

As for the engine intermittently stopping without any indication of a real fault, this sounds like a loose spade connector, corrosion at a spade connector that is sensitive to heat or vibration, perhaps a cold solder joint on a circuit board etc. You might try removing each spade connector in the the control box and elsewhere and treating with a touch of Corrosion X, inspecting and re-insterting. Trouble shooting this type of intermittency can be frustrating and tedious. Your can rule out a faulty sensor by bypassing each one during a typical run and substituting your eyes & pre-start/run-time inspections to make sure everything is well, (e.g. verify the sea water impeller is ok and that water is being pumped which I think you did, verify the oil level is full and that the engine isn't overheating with your IR thermometer, verify that the exhaust temp is ok with the IR thermometer etc as you bypass each sensor).

As for the burned out stator, "stuff happens", darn it all. But as an aid to help prolong the life of the generator, we try to run the genset under NO electrical load for five minutes prior to shutting down to allow the windings to cool. Same with the desalinator motors etc. Not a sure fire preventative measure but heat is the enemy of all things electrical and this can't hurt.

Good luck and share with us what you find.

Gary Silver
s/v Liahona



--- In amelyachtowners@yahoogroups.com, "seafeverofcuan" <seafeverofcuan@> wrote:

Dear Gary,
Thank you so much for such an informed response. A copy of that has already been saved to the ship's computer, it's a pity Onan couldn't explain there own product range in such a straight forward and succinct manner.
The generator burnt out the stator and had to be rebuilt in August last year, since then the Kubota engine never ran smoothly and often shut down indicating an over heating problem. Our laser thermometer always proved it wrong and we simply restarted it and it would run for between twenty minutes and four hours the shut itself down as overheating
and I couldn't source the problem, it was never overheated.
This time the engine stopped dead during normal running while using the washing machine.
Strangely there was no code light, so I was stuck to diagnose the problem, therefore I started from scratch.
First up only 10.65 volts at the starter which proved to be the earth strap from the starter relay to the tray, it looked fine yet when I tugged it, it parted in my hand.
New strap and 12.3 volts up the line from the battery to the starter, yet still no warning code and the engine would not crank .
I employed the local highly recommended service company who are not Onan agents they sent two technicians neither of whom could get it to crank and walked away.
So I went right back to basics again, air, fuel, power, during these checks I pushed the start switch really quickly three times in frustration, and up popped four flashes for over charging.
So even further confused, I followed to the letter, the instructions and got half a crank which made me think there might be an airlock.
So I opened the bleed nut, put a diaper over it cranked some more but still no go. then I switched around the two
K3 AND K4 relays, no difference.
For no good reason I removed the K3 relay which powers the glow plugs, it cranked and started.
I let it run a while shut it down and restarted. Tried it the next morning and it wouldn't crank or start, repeated the process without bleeding and it started although it would not start from the galley switch.
When I left the boat in Mexico it was starting from both switches and running fine and I think that I probably have a problem with either a short in the glow plugs or the starter switch on the generator either or both occasionally drawing voltage away from the starter, certainly Bill's posting re. battery and cables would indicate that as a possibility.
The help line at Onan was worse that useless, never taking time to read my emails and suggesting all sorts of really stupid solutions.
I am now back in Ireland and still waiting for them to tell me who their marine agent is in Mexico.
When I return I intend to be well armed with replacement parts.
Hopefully there is some learning in here somewhere for the group and thank you very much for your help.
Kind regards,

Trevor

Sea Fever of Cuan
Sm425
Ireland



--- In amelyachtowners@yahoogroups.com, "Judy and Bill aboard SV BeBe" <yahoogroups@> wrote:

I found the minimum CCA Cold Cranking Amps required by the Onan MDKAV. It is 360 amps at 12.0 volts.

Now I need to compute the loss of amperage based on the approximately 5 meter run of wire from the battery. If anyone can help with this it will be appreciated. I am not on the boat until next week and I am not sure of the wire size.

Bill
BeBe, SM2k, #387
On the hard in Gocek, Turkey with Emek Marine


--- In amelyachtowners@yahoogroups.com, "Judy and Bill aboard SV BeBe" <yahoogroups@> wrote:

Gary & all,

Does anyone know how many amps are pulled in the starting cycle?
Starter = ?amps
Glow Plugs = ?amps
Computer, etc = ?amps

I think that in some cases hard starting may be the result of low amperage delivered to the genset. As you know the wire run from the starting battery to the genset is something like 5-6 meters. I have suspected that a higher cranking amp starter battery and/or larger gauge wire, or both is in order. I have found that cleaning positive and negative wire termination points improve Onan starting. This leads me to believe that amps delivered to the starter motor is critical.

I am aware that some owners have increased the positive and negative wire size, some have located a battery closer and some have increased the size of the starting battery. What I would like to know is the amps required vs the amps delivered.

Hope this helps or adds to the discussion.

Bill
BeBe, SM2k, #387
On the hard in Gocek, Turkey with Emek Marine


--- In amelyachtowners@yahoogroups.com, amelliahona <no_reply@> wrote:

Hi Trevor:

Perhaps you have already solved your problem but let me seek some clarification on your problem. Do you have the shop manual for your genet?

1. I am confused from your post whether this is a problem with the engine cranking or whether this is a problem with the engine running.

a) If the engine suddenly stops, in my experience, this is usually due to one the several sensors on the engine (sea water temp over heat, low oil pressure, etc) telling the engine to shut down. You need to methodically work through each sensor (I don't have my shop manual here but I think there are at least 6 different sensors). They may actually be sensing a fault condition or there may be a faulty sensor, you will have to determine what is the case and repair accordingly. The sensors are mostly either normally open or normally closed switches and can be tested using a multi-meter.

b) If the engine won't crank (turn over as in trying to start it) then you have one of four problems;NOTE: THESE ENGINES HAVE TWO STARTER MOTOR SOLENOIDS (aka CONTACTORS). There is one on the + side and one on the - or ground side. Both solenoids have to work for the starter motor to work crank the engine.

1- a faulty positive side (12 VDC) contactor, check to see if you have 12 volts on the supply side of this contractor, then see if you have 12 volts on the output side of the contractor while someone tries to crank the motor with the start switch, if you have 12 volts in and 12 volts out when activated then this contactor is ok next ,
2- a faulty negative or earth side contractor (starter to ground on the tray). This contactor is mounted below the starter motor and is somewhat out of sight unless you bend way over. If you bypass this contactor you will NOT harm your engine. If bypassing this contactor allows the engine to crank when the start switch is activated then you either have a bad ground or a faulty ground side contactor.
3- a faulty starter motor, If you can measure 12 volts on the supply to the starter motor with your multimeter when the start switch is activated and you have a known good ground side contactor and known good positive side contactor, yet the motor won't crank, then your starter motor is faulty. Just to verify this you can remove the starter motor and take it to a shop to have it tested and/or repaired.
4- a faulty starter switch. If you don't see 12 volts on the control line to the contractors (both + and - side contractors) when the start switch is activated, then you probably have a faulty starter switch.

Once again, cranking (the engine being turned over by the starter motor) is a whole different problem from running. If you have already solved this, please let us know what you found. If not, give us some more details and perhaps we can add some more suggestions.

Best of luck,

Gary Silver
s/v Liahona
Amel SM2000 Hull #335
on the hard at Jolly Harbor, Antigua



--- In amelyachtowners@yahoogroups.com, "seafeverofcuan" <seafeverofcuan@> wrote:

Dear All,
my generator stopped dead while running a few days ago. No flashing lights. It cranked a couple of times then silence
I have checked the raw water, fresh water,systems, changed the fuel pump, a suspect earth strap from the solenoid to the tray . I have 12.7 volts at the solenoid if I short the terminals the engine will crank, but I don't want to let in run incase of further damage.
I have swopped over the relays for the starter under the white casing lid, but nothing all I get is the flashing green light at the start switch for a few seconds, I can feel the new fuel pimp working but no engine cranking.
The genset had a new rotor,stator and control panel last October at 1000 hours after burning out.
If anyone can shed some light I would be most grateful. I am in Mazatlan Mexico where the local service companies are willing but have no knowledge or access to Onan.
Many thanks.
Trevor

Seafever of Cuan
No 425

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