Onan 7.5 kw genset starter problem

[dickandlois]

375818, Have you applied some grease to the shaft and gear that engages with the multiplier drive gear that connects to the flywheel? the mentioned gear is built into an area next to and to the side of the engine flywheel.

This setup requires less torque from the starter to turn the engine. Different setup on an Onan engine. You did mention you have a Kubota engine. They require more engine oil then the Onan and the cooling fan setup is more like that of cars and trucks.

Not hearing a thump sound when the starter spins up could indicate a winding or brush issue regarding the starter motor.

Starters used are Bendex and Mitsubishi, depending on the engine builder. 

Rich. 

[f375818]

Solenoid is on top of the starter.  No missing or worn teeth on that portion of flywheel that can be seen.  Flywheel was marked when i initially pulled the starter. It has not moved because mark is still in the same place even after reinstalling the starter and attempting to crank the engine on numerous occasions.

 

No multiplier gear in my engine.  Maybe not a Kubota, just my assumption (there's that word again).  Could be a Ford or Chevy or Onan or anything else.  No info on data sheets/stickers or owner's manual. Only name on genset box is Onan.

Winding or brush issue was my first guess.  Starter is a Denso, onan part #:  191-2200. Tried to order a brush set but supplier on inet said "no longer available."

New starter should be here this week, then we'll know.  If not a starter problem, well let's no go there right now.  The thought pains me!!! 

[hermanmullins]

As been said several time before here on the Forum. How is the Ground? I broche this question after something I saw yesterday. I was looking at a 2005 Monaco Signature with a 12.5 KW gen. set. there was a cable attached from the sliding frame of the gen. set to the chassis of the coach. I thought to myself, the owner did not have a good ground on the generator and put the cable there to make sure there was a good ground.

Just my 1 and 1 1/2 cents worth.

Herman

[wildebill308]

Well it will be interesting to see what happens when the OP installs the new starter.

Bill

[f375818]

8 hours ago, hermanmullins said:

As been said several time before here on the Forum. How is the Ground? I broche this question after something I saw yesterday. I was looking at a 2005 Monaco Signature with a 12.5 KW gen. set. there was a cable attached from the sliding frame of the gen. set to the chassis of the coach. I thought to myself, the owner did not have a good ground on the generator and put the cable there to make sure there was a good ground.

 

Good point Herman.  Went back and checked ground connection on genset.  Sure nuff, the connection was loose.  Tightened it down on the gen connection, couldn't see where braided cable from genset to ground was attached.  Just knew that my problem was solved.  Reinstalled starter ( I'm gettin pretty good at this by now) but same result.  Starter spins but will not turn engine.  I then attached a btry jumper cable from genset to vehicle frame with the same results. Spin but no start.

Still waiting for Cummings to ship new starter.  Any other ideas out there???   

[wildebill308]

17 hours ago, F375818 said:

Solenoid is on top of the starter.

If the starter is not engaging the flywheel then this is your problem.  It should be pretty obvious if it is working when bench testing.

Bill

[hermanmullins]

I looked up Onan starters and found that they have a centrifugal bendix and no solenoid on top. So if the started,when installed, runs and the generator won't start either the bendix is not being slung forward enough to engage the flywheel, the engine is turning but not starting or heaven forbid there are no teeth on the flywheel for it to engage.  As can be seen in the picture below there is only a centrifugal bendix.

Herman 

[manholt]

As per OP, 22 hrs ago, there is plenty of teeth on fly wheel and non missing, as he could tell.  Said he had Solenoid on top of starter!  No drop in voltage What are we missing? Fuel in lines, no air?  bad fuel filter...I'm reaching!

[kaypsmith]

I've turned the copper slug over in the old Chevrolet starter solenoids to remedy starter issues that were pretty much as described by this post. Hope the new starter includes a new solenoid. If the new starter does not fix the problem then moving the engine flywheel to another location is the only other thing to do. I don't believe that new brushes is the issue since the starter spins either on bench or in the genny and the voltage remains constant.

[dickandlois]

8 hours ago, hermanmullins said:

I looked up Onan starters and found that they have a centrifugal bendix and no solenoid on top. So if the started,when installed, runs and the generator won't start either the bendix is not being slung forward enough to engage the flywheel, the engine is turning but not starting or heaven forbid there are no teeth on the flywheel for it to engage.  As can be seen in the picture below there is only a centrifugal bendix.

Herman 

This is the style that is listed for the 7500 series QD. It is much bigger then the one you pictured. 

 

Rich.

[dickandlois]

On 3/12/2020 at 1:49 PM, F375818 said:

waiting for helper to get back from hairdresser.  

More info:  7.5 KW quiet diesel HDKAJ Spec "J" 2005 model.

Start motor sounds the same in the set as it does on the bench - in other words - "no load".  Genset engine is not turning when starter is engaged.  Sounds as if the start pinion gear is not engaging with the flywheel however the pinion gear was moving when bench tested leading to my suspicion that there is not enough torque to turn the engine.  Ideas???

F 375818, DO NOT OPEN the box the new part came in, until you read and run the test listed below

Just realized I forgot to ask if the starter tries to engage as soon as you press the start switch?  I do somethings so automatically when testing things I just totally forgot to ask. 

THE sound you hear might be the fuel pump starting, not the starter circuit powering up.

You should get 12 volts at the main terminals. Connecting 12 volts directly to the starter solenoid , will spin up the starter; but the engine might not start when cold. 

You can use a battery charger to power the starter, connect the positive to the solenoid - Positive can not touch ground, then connect the ground to a good ground point.

As soon as you make the ground connection, try not to jump it is a rather intimidating sound. A lot like when you are bench testing the unit in a bench vise.

I need to ask, are you waiting for the glow plug, heat up cycle to complete?  That takes  longer in cold weather.   Is the 25 amp fuse good.

There is a delayed start on the Diesel engine when it is cold. Once the glow plugs warm up the control board will enable the starter to be energized.

Rich.

[manholt]

Rich, that's the part I was not thinking of...what we all take for granted, even in high ambient temp, there is a delay and the lower the outside temp, the longer the delay!

On OP's 7.5 it is recommended that you press on the off side of switch you'll hear the fuel pump prime the engine, then press gen on until it starts...make sure there is "no load" on!

[hermanmullins]

Rich, thanks for the correction. The picture I showed was all I could find for the 7.5. As always you have a much better search engine then I have.

Carl, I agree with what you said however I did not know about holding the Gen. stop to prime. I have always just pushed the Gen. start, wait and boom it has always started.

         Now as for the 400 ISL in cold weather, now that's another story. My engine doesn't like cold weather  and if I haven't plugged in the Block Heater, when I start it , it moans       and groans and puff out white smoke and then it will start.  

Live and learn.

Herman

[dickandlois]

9 minutes ago, RayIN said:

If the  starter spins but engine does not, that eliminates glow plugs, as the circuitry delays power to the starter until glow plug cycle is activated for X seconds. My understanding anyway.

Ray, If the glow plugs do not run the programmed heating cycle the control  board will not allow the starter to engage. 

We do not know what the problem is yet. bad 25 amp fuse or control board?

By powering the starter from a good 12 volt supply, bypassing the interlock ,the starter will spin when powered directly. That eliminates the starter from the equation. 

The starter has never spun up yet. there is no definable indication the starter solenoid has energized yet. There should be a load thud even if the starter does not spin up. 

It sure sounds like when the OP bench tested the system it activated the solenoid  and things looked normal. And Generator starters do not fail very often.

Rich.

[f375818]

Rich, that is the correct starter (Denso Part # 191-2200).  My order with the inet supplier is still "processing", with no ship date indicated.

Glow plug prime is not the problem.  Start sequence is only attempted after light on starter switch indicated that glow plug is ready.  Temp in Southeast Georgia has been in the low 80's during the past week or so.  Fuel pump line disconnected during test start attempt.  Believe me, it is pumping as it should be.  Start motor does not require fuel to turn the engine. It is strictly an electrical exercise. Fuel is required only to keep the engine running after the start sequence is successful. 

Here is my line of thinking/troubleshooting.  Battery checked and is good.  All battery connections from battery post up to starter motor checked and good.  Fuses checked visually and with multimeter- both checks confirm good fuses.  Starter motor is getting good power and spins but does not engage with flywheel.  If start motor were good and functioning properly it would engage flywheel and attempt to turn flywheel.  If engine were locked up and the starter was functioning properly it would engage the flywheel and draw so much current that it would very quickly overheat and blow some fuses.  This is not happening.  Anyone see any "holes" in this line of thinking??  Still waiting on new starter.

  

[dickandlois]

29 minutes ago, F375818 said:

Rich, that is the correct starter (Denso Part # 191-2200).  My order with the inet supplier is still "processing", with no ship date indicated.

Glow plug prime is not the problem.  Start sequence is only attempted after light on starter switch indicated that glow plug is ready.  Temp in Southeast Georgia has been in the low 80's during the past week or so.  Fuel pump line disconnected during test start attempt.  Believe me, it is pumping as it should be.  Start motor does not require fuel to turn the engine. It is strictly an electrical exercise. Fuel is required only to keep the engine running after the start sequence is successful. 

Here is my line of thinking/troubleshooting.  Battery checked and is good.  All battery connections from battery post up to starter motor checked and good.  Fuses checked visually and with multimeter- both checks confirm good fuses.  Starter motor is getting good power and spins but does not engage with flywheel.  If start motor were good and functioning properly it would engage flywheel and attempt to turn flywheel.  If engine were locked up and the starter was functioning properly it would engage the flywheel and draw so much current that it would very quickly overheat and blow some fuses.  This is not happening.  Anyone see any "holes" in this line of thinking??  Still waiting on new starter.

  

Think you have covered all the bases. Just the fact, of checking things and then needing a control board would not be good.

From you reply, it sounds like you may have tested the starter by applying 12 volts directly to the starter solenoid / bendex and the starter does not get the required current to spin up the motor or in gauge  the the solenoid. 

Real lucky in my area to have a fantastic starter and alternator rebuild shop. When one is on the road they can be hard to locate. Replacement under those condition most likely the best option.

Keep us in the loop

Rich.

[hermanmullins]

Rich,

I know you know this but here goes. With a starter with the solenoid on top two thing happen when current is supplied. First the solenoid plunged is pulled in which causes the bendix to move to engagement. at the same time as to plunged moves it then engages the Battery power to starter. (via the brass bolt from the battery, through the brass disc. to the brass bolt out to the starter motor)

Where I am having difficulty is if the starter it running when energized by the solenoid why isn't the flywheel turning? You can can take the solenoid apart clean and polish the two brass bolts and the brass disc. But that doesn't seem to be the issue.

Am I missing something or, sorry, are we getting the whole truth and nothing but the truth?

Herman

[dickandlois]

Herman, The problem could be in the Solenoid. The OP is on the road and working with the tools at hand. That makes things more difficult along with finding the part required. I do not know if they are in a no travel situation and that does not help. Right now there are a number of new challenges for all of us.

I have an appointment in Decatur IN. for some work  the end of July. Will need to know from them and other states if we can actually drive at he time. Interesting for sure and adding a new member to the family, arriving in August. 

Planing is going to be interesting.

Rich.  

[hermanmullins]

Rich, since the OP has stated that the starter in "running " but not turning the engine over, the only way that could happen is if the plunger has broken off from the lever that engages the bendix. However the OP stated that the bendix was moving while it was being bench tested.

Can you see where I'm confused. 

Herman 

[dickandlois]

Herman,

Rich, since the OP has stated that the starter in "running " That fact was posted about a bench test! 

another post, Tightened it down on the gen connection,( Referring to a ground cable) couldn't see where braided cable from genset to ground was attached.  Just knew that my problem was solved.  Reinstalled starter ( I'm gettin pretty good at this by now) but same result.  Starter spins but will not turn engine.  I then attached a btry jumper cable from genset to vehicle frame with the same results. Spin but no start.

This fact tells me there is not enough current to pull the solenoid pin backwards / inwards,  this action pulls the bottom of the lever forward. This action in gauges the starter gear into the flywheel. spinning the engine.

These facts, 

Where is the generator frame grounded to the coach chassis frame?  Measure the resistance between the generator frame and the  Chassis frame.

                Thought ! could one connect a jumper cable between the generator frame and a good on the chassis frame.

Remove the positive 12 volt cable from the stud at the end of the solenoid. 

Connect a battery charger positive  cable terminal to the stud the original positive cable was connected. ( keep the connection clear of any ground points) Then connect the ground cable from the charger to a good ground point. The starter should instantly react. pushing the starter gear forward (in gauging the starter gear with the flywheel gear ring)

        This action removes the delay for the glow plugs.  If the ambient temperature is high, this helps / lowers the need for the preheat step.

Rich.

 

[hermanmullins]

On 3/12/2020 at 11:11 AM, F375818 said:

Starter motor turns but will not crank genset.  House batteries new and fully charged. Removed starter for bench test again, starter motor turns, meter shows 12.4 vdc while starter is under test.  Reinstalled starter in genset with the same results-start motor solenoid engages with starter spinning but still will not crank genset.

 

 

Here is where I got the information. 

I have never seen it but this starter (as pictured) may be one that all the solenoid does is make power contact which spins the motor and by centrifugal it will throw the Bendix into the flywheel. If this is the case then yes the motor may be turning at a very slow rate but without enough RPM and torque to throw the bendix into the flywheel. 

Installed bad - bench test good - reinstalled bad. Has to be a bad ground.  Someone suggested to run a jumper cable from the gen. set to the chassis, has that been done? 

 

Speaking of Generator Ground. Take a look at this gen. set. See the tan wire, it is a ground strap added from the gen. slide to the coach chassis.

 

 

Herman

[dickandlois]

Herman, Your Onan is a totally different animal.

Your unit uses a Kubota engine. The engine  has a set of gears between the starter and the flywheel teeth. The gear setup act as a torque multiplier.  

The OP,s unit is a 7500 KW unit, yours is a 12.5 KW . your unit puts out 5 KW more the the 7500 unit.

The air intake , cooling system, oil filter setup are all different.

To my thinking, the exhaust system is not setup right> The exhaust pipe should end out side the footprint of the  coach  about 2 to 3 inches minimum. The exhaust fums can buildup quicker under the coach. ANY Opening under the driver or passenger areas could easily allow the exhaust fums into the living space.

NOT GOOD Herman !!!!!

Sure  hope the exhaust pipe is much longer then what shows up in the picture.

Rich.

The OEM Part number for the Generator pictured is 191-2229

[f375818]

Herman, I am not trying to be disingenuous.  All the tasks/results are as i describe them. Possibly i am confusing everyone with the pinion gear slinging forward but with not enough force to actually engage with and turn the flywheel.  In one my original post i alluded to the possibility of the starter spinning but not developing enough torque to actually turn the flywheel. As has been posted, there may be a possibility of something broken with or on the pinion gear.  The starter is still mounted in the genset.  Got a Dr appt in Savannah this PM.  Won't be able to get back to it until tomorrow.

Not on the road.  I'm at the sticks & bricks in coastal Ga.  Haven't seen an electrical motor repair shop in this area for at least 10 years.  Maybe a lost art. I'll check around the port shipping area while in Sav today. I have to be in Brunswick this weekend, should have time to check port area there also.

Solenoid operation has me questioning my test's findings.  I may be wrong but as i understand the operation of a solenoid it is essentially a mechanical relay that is used in high current situations.  In other words, it simply relays voltage /current from on device to another. It either works or doesn't work. Since the starter motor spins i figured that the solenoid was working properly. Is this not correct??

Genset in my coach resembles the one in Hermans picture in that it is enclosed by panels for sound reduction.  Mine is not mounted on a slide.  Can be removed only by raising the front of the coach off the ground maybe by 1-2 ft and then getting something like a transmission jack under it to slowly lower it after disconnecting wiring and unbolting from the frame.  Actually it looks as if they designed it to be lowered and removed by a forklift.

New starter has shipped and is scheduled for delivery by fri PM.  After post from Herman i intend to go back to the bench test to reconfirm action of started and pinion gear.  don't know anything about disassembly/cleaning brass things inside solenoid but will give it a go. As suggested by Rich, i will not open starter package until diagnosis is confirmed.  If not needed and non-returnable i will have a spare to haul around.   

   

.    

[dickandlois]

The information you offered clears up how you genset is installed.

Yes from your info. the generator removal requires a fork lift or a pallet jack . in that case there is a section of the front cowl that needs to be removed so the unit will clear, plus a few other items.  I do feel for you working under the coach is a very tight space. Glad you are home. Offers more options. I might be able to find a part number for the starter solenoid , but if it does not work properly on the bench and you are planing on replacing the starter. Open the new one and run the same test you ran on the OEM unit. Should they both react the same, then you need to run the jump test used on the bench when the new starter is installed, to see if the new one engages. Should the starter not in gauge, Then the group need to think of other options. If it does spin the engine. Reconnect the OEM power wire to the solenoid. Plug the supply side fuel line and see if the starter spins up. It should, but if not then one needs to consider a wiring issue between the control board and the starter or the control board comes into play !

       I would strongly suggest placing 12,000 pound jack stands under each frame rail while working under the coach !!! Air bags with no air in them. Any damage to the air supply lines or bags can cause a quick loose of air. Should one decide to remove the generator, you might need to move them to under the axle, so the forklift or pallet jack has some extra room, Width wise, the  trade off is height. The QD 7500 series generators weigh in at close to 750 lbs. 

       The jack stands need to be on wood blocks or concrete to keep them from sinking into the ground.

     As you may have found out, you need to remove the fuel filter to get access to the starter and you will get fuel from the pump running out of the fuel system. Can get messy ! While on the fuel filter issue, how long has it been sense it was replaced?

Good Luck at your appointment. Seeing them more often these day also !

Rich.

STARTER SOLENOID REPLACEMENT WARNING

This test involves high electrical currents, strong arcing and moving parts that can cause severe personal injury. Do not conduct
         this test near fuel tanks or when flammable vapors are present. Wear safety glasses. Keep fingers away from the pinion gear.

         The starter solenoid is separately replaceable. To determine whether the problem is in the solenoid or in the motor:
     1. Secure the motor assembly in a vice after it has been removed from the genset.
      2. Using a heavy jumper cable, because of the large currents involved, connect the motor terminal on the solenoid (the one closest to the
               motor) to the positive (+) terminal on a 12 volt battery.
      3. Using a heavy cable from the negative (–) terminal on the battery, briefly touch the mounting flange on the motor.
           • If the motor does not spin up quickly and smoothly, replace the motor/solenoid assembly.
           • If the motor does spin up quickly and smoothly, the motor is probably okay: replace the solenoid.
       The solenoid is removable by disconnecting the motor lead from the solenoid terminal and removing the two solenoid  mounting nuts. When installing a new solenoid, make sure the solenoid plunger engages the shift fork.

[f375818]

Finally received new starter motor.  Pulled the old motor (again) and bench tested both motors side by side using the same power supply (12v btry). Both motors reacted the same.  Good spin up with the pinion gear slung forward.  The only difference was the new motor slung the pinion gear forward with at least 10 times the force as compared to the old motor.

Installed new motor in the genset and after priming the new fuel filter it cranked right up with very little effort.  Going back to my original post,  "Is it possible that the start motor reacts as indicated during bench test (no load) but does not have enough torque to turn the genset (max load)?", it appears that is exactly what was happening. Now, why did that happen?  Apparently a solenoid that was working but certainly not very efficiently.  As some have posted, it may simply be that the contacts need to be cleaned up.  I'll take it apart next week and see what i can do.

More info...Found a sticker near top on onan case that said engine type is in fact a Kubota model D722ES with output 14.9KW.  Not sure why they would include that output on a 7.5KW genset.  Who cares, it works for me.  Starter motor has no multiplier or other gearing.  Pinion gear engages directly with the flywheel to turn the engine.

Thanks to all who replied to this topic without judgement and yes, thanks to Herman also even if he is a little quick to judge others.