Onan MDJE 6K Issue: Cranking not Firing

All-

First post, a lot of info but figured more couldn't hurt.

Backstory:
I have a 1980 Grand Banks 42 with two Ford Lehman 120’s and an Onan MDJE 6KW Genset.

I’ve had the boat for 3 years in Ventura CA, and used it for coastal cruising and going out to the channel islands for overnights, 3-4 hours at a time and 3-5 days at time respectively. The rest of the time is parting in the harbor, and it was a live aboard for us for a year initially. The previous owner never really used the boat much and had it in Santa Barbara and his son used it as a Live aboard going to USCB. He fired up the motors and exercised them at the dock. They both have 1250 hours on them and they fire up just fine sound great and don’t put out hardly any back smoke and run great. I change the oil, oil filter and fuel filters on them once a year and I’d say we put about 50-75hrs on them per year.

The Genset has 410 hours on it and I don’t think the PO really ever fired up the genset at all and used it very much. It’s been a bit of a pain for us: when we first got it, I was able to fire it up just fine and we used it for one trip with no issue. ***This is the model that has a raw water pump and a coolant pump set next to each other that all run off a belt from the crankshaft pulley.*** The next trip the Hi Temp cut out shut it down while we were cooking dinner. I started up again the next morning, I noticed it was not spitting water; and found it was the impeller pump. We ran on battery power the rest of the trip. Once back I fixed the impeller pump and it worked fine for the rest of the season 6 X 3-day trips 1-2 hrs two times a day. Next season we went out and on our second trip I noticed that it has stopped pumping water overboard again so I went down to investigate; there was a slow leak on the Raw Water shaft housing that caused the bolts holding the water impeller pump on to corrode; two of them sheared off causing the belt to pull the raw water pump sidewise; I was able to repair with spare bolts and thread/tap onboard. However once running it was leaking water pretty bad from the shaft seal. We ran on battery power the rest of the trip. Once back I looked at what others had done for a sub and tried the March Pump approach, I could not get this to work for some reason on ours no water would come out. We did 3 trips on battery power while I tried to figure out the issue. I sent the raw water pump out to be rebuilt. I got it back installed it with a new clogged style belt (previous was smooth) and the genset fired right up and it put out more water than it ever had before.

Ergo Current Problem:
This month were in the process of getting ready to move our boat up to Santa Barbara, and prior to moving I wanted to change the oil, oil filter, and fuel filters for the genset since they had not been done since I owned the boat and the filters had 1998 & 400hrs written on them so they were pretty darn old. I knew since I got it, they needed changing but again there had only been 10 hours through it and I had deprioritized that since we used it so infrequently. The fuel filters state to change every 1000 for primary and 3000 for secondary in the manual but I figured if I was going to pay someone to get in there mind as well do it all and start fresh. I got super busy for work and didn’t have the time to do it before we moved the boat so I had the local yard come down to the boat to do it for me.

They replaced everything and when they went to fire it up at first, they told me my batteries were dead since it would crank but barley. I knew this wasn’t the case since I had upgraded the battery system when we got the boat 3 years ago (see below), and it had been connected to shore power topped up and floating. They had another tech come down and he fired it up from the helm start position (previous tech was doing it from the genset). The second tech looked at the Genset and thought it had lost prime and recommended changing all the “Crush Washers” as he thought they were leaking fuel. I authorized them to do that. Then the next day I came down to the boat as I was taking it to Santa Barbara. He went to fire it up to make sure there were no leaks and it did the same thing it cranked but barley and would not catch. Having heard it crank normally and this time it sounded a little underpowered but not drastically it sounded like labored cranking. He called the second tech that got it to work before and it did the same thing, we tested both locations, it did the same thing. We used a socket wrench to turn the crankshaft and it moved just fine with no issue. We could hear air coming out and the tech commented “that some air was getting by the rings and with a genset this old it’s not worth fixing and to run it until it dies”. First tech did some battery line tracing and thought he found a bad inline fuse on the battery cables but after replacing it didn’t do anything. I asked if it was a starter issue and they said no; they were under the assumption that it was a battery issue. All three starting batteries are tied together and when we start the Lehman’s which I have to imagine are a lot harder to crank, they crank and catch immediately with no issue. So if it were a battery issue I would think they would not fire or crank labordly as well as they all share the same batteries. The tech punched the starter to the Genset in rapid succession about 15 times then put his hand on the battery leads to the starter and said they were too hot to touch and that shouldn’t be the case. The tech told me to replace the battery lines to the genset and see if that fixed the problem. Then he told me to just throw the thing away and buy a new Kholer (they are a dealer) and put that in. Quoted me ~$15k installed w/ old one removed, and after tax. I don’t want to allocate that kind of money right now to something I think I could get working and then when it is working I don’t use much.

My question is given what I have described does anyone have any idea what the issue could be; anything to look at?

I have a portable jump starter on board JIC a battery gets drained, so I can hook that up directly to the genset and see if that works to eliminate the battery issue.

Due to the labored sounding nature of the starter I would think it would be that rather than an oil pressure sensor or something like that.

It seems very odd to me that I could have it running multiple times and literally had it going a week before (probably started it 5 times throughout the day installing water pump) with no issues and then all of a sudden it stops working, after an oil and fuel filter change. I wouldn’t think a battery cable would just go out: The are 0 AWG in a straight run from the battery to the genset ~8ft.

Upgraded Battery System Details:
2 X 215AH House Batteries & 3 X 105AH Start Batteries (One for each motor and genset).

We use the Genset for 1-2 Hours in the AM and PM just to cook (electric stove), top off batteries, and shower with hot water, with our current set up our 120v demands are very low, This is by design since I hate listening to the genset at anchorage. I monitor the electrical system and get by pretty easily.

Hot Water Heater: Our Port motor has a loop off the coolant through the hot water heater so we could use only this while at sea to heat the hot water but at anchorage it takes a while.
Refrigerator: We generally don’t run this and keep all the perishables a yeti cooler with another for ice and still have ice to spare after 5 days at the islands: Most trips are 3 days.
Oven/Stove: I purchased a Coleman camping range powered by the small propane bottles and that serves as our back up range w/o power.

We have had to do multiple 3-day trips at the island’s w/o a Genset over the last 3 years and have had no issues with running on batteries and the backup stove. I watch everything pretty closely and have the backup jump starter JIC.

If I cannot get the Genset going I just got a Honda Wisper Watt 2KW for another project that I can bring onboard and use instead as I have seen many people do this. It will be much more quiet and have way less vibration than the Onan.

I also thought about converting our 1980’s Sub Zero fridge to a modern efficient 12V one for $1000. I could also upgrade the stove to a propane one for $1000. That could save a lot on our energy budget. I know brining propane onboard presents its hazards but seems like those can be mitigated easily.

I’m not planning on selling anytime soon but how much would it hurt resale to not have a working generator onboard? My though would be if I can’t get it going to remove it as it would just be one less thing to ask for a repair allowance for, maybe that is a bad idea.

If that thing is not cranking over fast, it will not start. Those starters draw LOTS of amps and batt and cables need to be top notch. And starters have bushings that get dry/sticky and that slows cranking speed. Also make sure that when you crank it that the fuel stop solenoid pulls in. If it does not, it will not fire. Check that glow plugs are energized when in preheat.

Sounds like a wiring or starter problem. First, check and clean all wire and connections to the starter. If that doesn't fix the problem, pull the starter and take it somewhere to have it checked. I'm not too sure about the people who have been working on it. That comment about "air" and the "rings" sounds bogus. I would expect to hear air being compressed by the pistons and then going out the exhaust as a normal sound.

Tator

I doubt it's anything battery since the other engines start ok. It could be in the connections to the generator starter or in the starter solenoid. If the solenoid contacts get badly pitted, they sometimes make contact but can't supply full amps. It can appear as an intermittent problem. The contacts are the ends of the terminals coming from the battery and to the starter plus a copper disk they make contact with. The disk rotates slightly each start, extending the life. Eventually the terminals and the disk become badly pitted, sometimes not making enough contact to power the starter, power it weakly or occasionally a normal contact. If you're handy, you can disassemble the solenoid and file the disk and contacts. Or I replaced my MDL-3 starter with one on ebay for $80, a lot less than your mechanics bill.

Starter Bushing

When I bought my boat the MDJE was not in operational condition. It sounded like it was laboring to crank. Turned out it had chewed up the bronze oil light busing at the end of the bendix. Bought a replacement at McMaster car for a few dollars, installed it and I was up and running.

That was my problem. Yours may be different.

Simple things first.
Check the battery voltage with a meter.
Take all the cables off, battery and generator, and clean the terminals with a wire brush. Hot wires mean resistance somewhere.
Take the starter off the generator and crank it. See if the starter is spinning fast with no load.

If you can't combine the batteries, use a set of jumper cables (car) to get twice the juice. See what that does...

First of all, your mechanics are idiots. Secondly, your mechanics are idiots.

Check the connections, its one of the things that Lepke said - go for the simplest easy thing first, which would be all the battery connections, particularly the grounds.

Solar panels. Keep the fridge and get some solar. Propane stove is an excellent idea, don't have to start the engines to make coffee in the morning.

Do not listen to the guys who said just trash it. If they didn't do a compression test they are talking out their butts. It sounds like a bad cable connection somewhere.
Cranking the engine for 5 seconds with a bad connection will get it hot enough to feel by touch. Perfect time to use an infrared camera. Start at the positive battery post, feeling along the cable to the starter, then follow the negative wire from the block back to the negative terminal.

Also check the glow plugs.

Hi.
We have a similar Cummins powered Onan generator.
Parts manuals and fairly comprehensive service manuals are available free to download on the net. It may be something simple such as needing to do this:

PRESTOLITE STARTER ASSEMBLY
Before assembling, soak the bronze bearings in oil.
They are absorbent bearings, designed to hold up to
25 percent of their own weight in oil. Be sure the felt
oil pad is in the outer end of the commutator end
bearing.

or any of the others that have been suggested so far.

Yes this model is noisy, vibrates violently and is a job to service in tight confines, but parts are still available from Cummins and Onan, and non-genuine filters etc are available. Any competent auto electrician will be able to rebuild the starter motor if that is needed.

Our boat had been used as a floating apartment for many years (decades?)before we bought it 14 months ago, and had few hours on the mains and generator and no maintenance records. I have bugger-all mechanical or electrical skill, so having a trustworthy mechanic and electrician and not being afraid to spend the $$ when needed
is the key for long term reliability.

We have just completed a 6 month cruise to the Whitsundays and back and were at anchor for over 140 days using the generator twice a day for at least 3 hours. There were a couple of generator issues but it sure beats paying $15K plus for something that does the same thing and will have similar problems as it ages.

Oh yes and carry a spare diesel fuel lift pump.


Don

Thanks All Very Helpful Stuff.

High Wire said:

Do not listen to the guys who said just trash it. If they didn't do a compression test they are talking out their butts.

Also check the glow plugs.

Click to expand...

^ Glow Plug is working Gets Hot; yeah and I thought a CT was needed to properly diagnose that as well.

Xsbank said:

First of all, your mechanics are idiots. Secondly, your mechanics are idiots.

Solar panels. Keep the fridge and get some solar. Propane stove is an excellent idea, don't have to start the engines to make coffee in the morning.

Click to expand...

^ That gave me a good chuckle; I thought the same thing but I'm not the most savvy when it comes to working on motors; I know my way around and I can read and instruction manual, and follow directions so I guess that probably puts me in the 95%. I'm just lacking a lot of experience and with that comes confidence so with a professional I was hoping for some more from them, and not me the amateur shaking my head. Good call on Solar it's defiantly on the list. I also am contemplating upgrading the alternators, they are starting to give me some issues i.e. voltage output but not reading amperage output underway, need to do more testing though.

Lepke said:

I doubt it's anything battery since the other engines start ok.

Click to expand...

^ That was my initial thought too. Solid run of battery wire from genset to an isolater/disconnect switch, then from there to battery; all starts are tied together.


After reading all this I am heading down to the boat this weekend; I have my portable Tractor Jump Starter and I am going to disconnect the battery leads to the starter and try and start with that. That would isolate the Power issue since I would be providing a known working power source with a very short lead and direct contact.

My thought would be if it works then I need to trace the battery lines and find the issue. If that doesn't work and it does the same thing then it is a starter issue.

If it's a starter issue I am going to take it to a local shop and see if they can rebuild it.

I'll make sure to check prime on the motor too.

I'll also take a video of what it is doing w/ sound since a picture is worth a thousand words I'm sure a video is worth a million.

Hopefully it's as simple as rebuilding the starter, and I can put the genset woe's behind me.

I think the hardest part is going to be getting the damn sound shield off so I can access the starter

sound sheild

First thing I did when I bought my boat was to remove the sound shield off my MDJE and toss it overboard! I was still on the blocks in the yard.

Certainly louder but there is nothing worse than a 15 minute job taking 3 hours because of a sound shield.

Rebuilding a starter is easy, unless its totally baked (which yours obviously isn't). New brushes and a commutator file and clean, clean the bearings/bushings and make sure its nice and clean, (did I say clean? It might not come off the boat again in your lifetime) especially the shaft and Bendix gear before you hook it back up. If you bench test it, make sure you put a sandbag or something on it, the torque can yank it out of your hands. I'll bet there are a million Youtube videos of rebuilding a motor?

This assumes you've checked your cables, which I would almost put money on. Grand Banks has (had?) a peculiar solenoid that paralleled the house and start batteries when you push the start button. I'm assuming you have one, perhaps even 2 if you have twins and I'm assuming it works properly? It should be on the forward engine comp. bulkhead, I'll bet that hasn't been touched since 1980. I threw mine away as I didn't want another point of failure and the engine alternator is supposed to keep the start batteries healthy so they were separated.

Your willingness to toss the sound shield is proportional to the noise you like to listen to. The damn thing will usually run until it doesn't so its not like changing your underwear regularly...

All-

So I went down this weekend to have another look.

I forgot to take a video but if I were to describe the way it is working it almost sounds like it is dragging? Like as if it were not getting enough power.

13.4V at the starter from the battery (thats what we float at)

I traced the battery cable; 1/0 stranded wire solid run from genset to battery no loose connections on the terminal or at the starter.

I disconnected the generator from the batteries and attempted to jump it from my portable jump starter (yes it was fully charged), it did the same thing that it was doing before sounded exactly the same; I noticed it did smell like burnt electrical; jumper cable connections on the post were solid so it wasn't coming from that.

Since it did the same thing on the jump pack as the battery it's leading me to believe its the starter. I didn't have enough time to pull it off but I'm going to have the local guy do it and then take it to a shop to get it rebuilt.

RE; Sound shield, the reason I don't run the genset as much as I should anyways is its too loud and annoying for me at anchorage so taking it off would make it much worse. I am looking into getting some sound down material to line the roof deck of the engine compartment I'm hoping that will help with the noise.

Thanks,

I have the same Onan genset, I definitely have a love/hate relationship with mine... it sounds like a cement mixer full of bricks when running.. but We love the hot water, all the power it makes and how happy life is aboard all because of the noisy beast. They are a pretty simple unit, parts are reasonable, lots of mechanics work on them (but from your comments I wouldn't let your mechanics work on anything on the boat!)

Get the starter to a starter/alternator repair shop and it will more than likely be the last time you ever touch the starter.
With all that sunshine in SO CAL solar could help you limit genset time, add batteries and keep the sub z refer.. it uses power but it will keep plenty of ice for the obligatory sundowners out at the islands!

As a prior SB slip holder you are in the best place to keep a boat in California!
HOLLYWOOD


Also , I'm in the keep the sound shield camp... it will give you something to stick the additional insulation too!

Note this thing has multiple glow plugs: One visible in air intake, and one inside each cylinder. You said GP was working, but the in-cylinder ones are most important.

Also need to be sure the fuel solenoid moves when you hit start. Mechanism is plainly visible.

Jump packs can't get enough connection with the clamps to rival what a good batt and good cables can do, ampere wise.

Measure volts at starter lugs when cranking. If below 10v, system is not very healthy: Batt weak, cables weak, starter dragging.

Good first step would be to tear down starter and clean and lube.

I have the 7.5 KW version of the MDJE and it works well after replacing the coolant circulating pump and the leaking heat exchanger. Mine has no sound insulation and vibrates like a paint mixer like everyone has described but it's a reliable lump. I concur with the others that say take the starter to have it checked or if you feel like learning, take the starter apart yourself. You may just need to clean the brushes, commutator and solenoid contacts, put a little oil on the bushings and button it back up. These gens are about as simple as it gets. Oh yeah, get the manual. It will describe how to adjust speed, valve lash etc. It's a great engine to learn diesel mechanics on.

Kevin

RyanZ said:

I noticed it did smell like burnt electrical; jumper cable connections on the post were solid so it wasn't coming from that.

Thanks,

Click to expand...

Follow your nose. Starter, circuit board or relays

I'll fourth or fifth those who said to not let those "mechanics" back on your boat. Throwing the jenny away, because they can't figure out how to start/repair it is ludicrous.

I also have the 7.5k MDJE and they're comparatively simple to work on. Sounds like the problem is in the starting circuit. Battery, solenoid, or starter. Even a Walmart automotive group 27 battery in good shape and charged will easily start the Onan MDJE. If you've eliminated the batteries and cables, then take the starter off and go through it or take it to a shop, if that's not your skill set. The problem is most likely a simple fix.

First thing i would do is find someone else to work on it. They don't appear to be the brightest bulbs.



Second. Get a good meter that has min/max capability and does ac a and DC current. I have 6 different meters on my service truck. All have different features needed to do the job.



Once you have a good meter. You want to verify the proper voltage at the starter Post. Put the meter on dc use alligator clamps and put it on the b+ post and the b- post or case if it's case grounded. Hit the min/max and try starting it. The meter will record the voltage drop. You just hit the min/max button to scroll to the minimum reading. Write it down so you can review it later. Next if the voltage drop is less than about 2vdc. Check the current draw. Set the meter to current then hit the min/max button. Try to start it. Then look at the meter and write down the max amps. Also try a second time but don't set the min max. Just look at the live cranking amps. Write that down. Then see if you can find the spec for the starter. They should have current/voltage specs. To compare with your readings.



If you find the voltage drop is high. I would get a short set of new or known good cables and battery. Then try it again. If it cranks normally then you know you have a problem with the batteries and or cables. You can also run a voltage drop test at the battery with the meter reading min max. You shouldn't see voltage drop below 10vdc. If it does replace the battery and retest.

That seems like a thorough trouble-shooting process but won't the min/max capture the inrush current and wildly overstate the current? I would ignore the inrush and just check the cranking volts and current.

How long are the cables? Is the battery next to the unit? Did you attempt to jump-start by attaching the cables to the battery or the starter? Solenoid or starter? That wasn't clear to me.

Xsbank said:

That seems like a thorough trouble-shooting process but won't the min/max capture the inrush current and wildly overstate the current? I would ignore the inrush and just check the cranking volts and current.

How long are the cables? Is the battery next to the unit? Did you attempt to jump-start by attaching the cables to the battery or the starter? Solenoid or starter? That wasn't clear to me.

Click to expand...

Yes min/max with capture the current inrush. you will want to know what that is as well as continuous cranking draw. you have to take into account breakaway trq and cranking trq.









here is some additional t/s info
https://www.google.com/url?sa=t&rct...-manual.aspx&usg=AOvVaw3RTONBkQtPQxmh_PxzEVWv

So is a starter issue or it won't start issue?

Greetings,
Mr. ASD. I suspect it isn't cranking fast enough to start so it's both.



MY $.02...Pull off the starter and either service it yourself OR have it professionally looked at if you don't feel confident to DIY. I'd be very surprised if a shop charged more than a couple of hundred for a complete rebuild.


Completely disconnect ALL batteries/power before putting a wrench on anything. Don't ask me how I know


Sound shield? Yup. Major PIA but you should only have to do this once. Our Onan has a sound shield as well and I've had to remove the starter motor by FEEL. Couldn't see a thing.

RT Firefly said:

Greetings,
Mr. ASD. I suspect it isn't cranking fast enough to start so it's both.



MY $.02...Pull off the starter and either service it yourself OR have it professionally looked at if you don't feel confident to DIY. I'd be very surprised if a shop charged more than a couple of hundred for a complete rebuild.


Completely disconnect ALL batteries/power before putting a wrench on anything. Don't ask me how I know


Sound shield? Yup. Major PIA but you should only have to do this once. Our Onan has a sound shield as well and I've had to remove the starter motor by FEEL. Couldn't see a thing.

Click to expand...

Agree on the battery cables!!!

At this point just order a new starter (rebuild the old one as a spare). I use the below to get my Onan parts. The only draw back is you have to wait about 15 days for the part. Lot cheaper than Cummins.

https://www.jackssmallengines.com/

It may have a cranking limiter circuit breaker. My Onan 7.5 does. If it does and it is tripped or bad it will crank but not start. The key is to look at the fuel solenoid and see if it is actuated during cranking as others others have mentioned.
If not, it may be the cranking limiter circuit breaker. I think it is labeled emergency something on the front of the gen set. I also think there is a low oil pressure switch in that same circuit. So either one could be bad.
Good luck.

My Onan 8kw would start and run for a minute then quit. I determined it wasn’t getting fuel and removed the lift pump. The entire inside of the pump, brushes and commutator and points were submerged in fuel as the seals in the pump had failed. Shows to go you how forgiving diesel fuel is as there was some sparking inside the case. I replaced it with a generic pump, at least a third of the price of the Cummins pump and it’s been fine for three years. Just tossing this out here as your fuel pump might be toast too, certainly mine can’t be the only one that fails?