Shibaura Engine running generator

[zzjea]

This may be way off topic for a tractor forum but I've looked at a lot of places to try to solve my problem and maybe here is where the smarts are.

I have a 2001 40' diesel motorhome (MH) with a 7.5 kw Generac diesel generator being run by a Shibaura 3 cylinder diesel engine, the kind some folks have in their tractors. I know this is a long shot but maybe someone has an idea of why I very seldom can start the engine. I have tried just about everything in the book relating to electrical. First of all, nothing is easy to get to unlike most tractors where you can often see everything, so that is an issue too. It is in an enclosed metal housing in the front of the motorhome with the front having access via a fiberglass door on the MH that folds down. I can see the front of the Shibaura by removing the front metal cover. Yesterday I took out the glow plugs and tested them and ohms looked ok (about 1 ohm each) and also started glowing after about 12 seconds when on 12v test. I can turn the flywheel by hand so it is not seized or stuck and I did get it to start which it will do about once a year.

The starter is trying veeery hard to turn the engine over and acts like it is low on amps. I have put 2 new starters in it thinking that was the problem. I have also put in a new starter solenoid and they are connected to 4 6v batteries in series near the rear of the MH. The MH with an ISB Cummins (300hp) has 2 12v batteries to start that engine. The crossover switch to connect all 6 batteries does not help with starting the Shibaura. I have not tested the amp draw at the battery yet as it is a little difficult to do. The batteries (4 6v) are charged up and produce 12.5-14v if plugged in to shore power (120vac) via the converter. However, obviously I want to be able to run the generator when not on shore power.

Could the dc cable running from the rear of the MH where the batteries are to the generator in the front (about 30+ feet) be degraded over time (2001)? I have cleaned all positive and negative contact points that I know of and can see, so the grounding seems to be ok. The engine will run if it will crank. The starter does not run continuously trying to start the engine. Rather, it gives a quick whirl of less than one revolution and then tries again with less ump each time. I do not know what miracle happened yesterday when it started. Even then it took multiple tries before it kicked over. There is not enough space to a bigger starter if one were available.

Is there anything else with the engine that might cause the hard start? Would new glow plugs make a difference?

Like I said earlier, it did start after fiddling with the glow plugs and I ran it for 30-45 minutes with 2 air conditioners on, but it would not start after I killed it. It has not run in over a year due to this issue so I let it run for a while to make sure it would run. The actual generator works perfectly if the engine will crank. The generator has only about 350 hours on it. The MH has less than 31,000 miles. We go on short trips and stay for several days when we can.

Well that's my story. I hope someone has some ideas of how to solve this issue that has been going on for several years (I've owned it for 4). Thanks for any feedback.

John
Kingwood, Tx

 

[Industrial Toys]

I'm guessing it's a power issue. Long runs or bad connections. A volt meter at the generator would tell the tale when trying to crank.

I don't generally believe that cables deteriorate. Others on here disagree and apparently have witnessed it. 12 volts is a really crappy voltage to overcome distance, becoming a bigger issue as current requirments increase.

I have a couple of mobile intended 3 cylinder diesel gensets. Both 7.5s, Inverter and regular. They really require quite little starting current. In fact, one, the regular alternator Onan had starting issues for years. I replaced the starter motor, redid cables and connections. There was always a delay in the starter motor starting which I thought was in the control board and meant to be. Recently, after years, I found some ground connections in the main control box, that required a little polishing up and the thing works like new.

 

[3Lfarms]

You are using the “house batteries” to start the generator, correct?
How old are the four 6v batts? Those deep cycle golf cart batteries are not good starting batteries as they can’t supply large cranking loads, but are intended to run small loads for long periods.
Most people only get 6 to 8 years out of those golf cart batts unless they are exceptionally well maintained.
I would disconnect the starter leads from the house batts and connect a known good 12v battery. You can use one of the batts that normally starts the Cummins.

 

[WranglerX]

Check voltage at starter when its cranking, if it drops more than 6-8 volts (24 volt system?) then you either have a bad battery in string or bad cable.... Awfully long run for stating battery cables and wire gauge can also have effect, cable to small can cause poor current flow .....

Dale

 

[jaydee325]

Did this generator start as expected any time during your ownership? When did it start acting up?

I'd assume at some point in the MH's life the generator started satisfactorily? So what has changed? Did this condition degrade over time?

You need to first pull all of the batteries related to the generator and have them load tested after fully charging them. There is no way to effectively trouble shoot this condition until you know you have known good, fully charged batteries. Once you know this, then systematic trouble shooting will tell you where the problem is. I'm guessing you have one or more bad batteries or a bad cable/connection. Once these options are ruled out, then start looking at starters/solenoids/etc.

Good luck.

 

[Industrial Toys]

Maybe just the genny grounding. I found a bad ground on my recent aquisition, the Onan 7.5 Quiet Diesel, by providing my own ground cable, from battery to starter motor and discovered a bad main ground on the generator frame.

A cheap HF load tester is really good at finding bad connections in a starting circuit. Beats trying to start the thing, and taking readings.

 

[zzjea]

Thanks for the feedback. I went over today to the MH (storage lot) and did some testing. While on shore power (120ac into coach), the positive connector at the genset case read 13v and when starting, it went down to 10-12v. I then pulled the shore power (batteries only) and it went from about 12.4v down to 7-8v when cranking. I disconnected the power to the genset from the coach and ran a pair of heavy gauge jumper cables from my car's battery directly to the positive connector on the genset with the car engine running. It produced 14v to the genset but only about 10-11 to the glow plugs. The engine did what it always does and tries to crank but no go. My helper (wife) was not there for a cranking test via the car battery, so I do not have info on that.

I am attaching a video of the few seconds I tried to start it. It gives you the sight and sound which may be a clue to someone. I had to keep pressing the start switch to get the multiple tries, it did not do it on its own. As I nstated earlier, I have cleaned every connection I can find except in the genset control box (very hard to get to without pulling the genset out of the MH).

 

[Industrial Toys]

I have to say, I have never in my life heard a three cylinder Diesel try and start like that. In fact, I went back to the OP to make sure you did say Diesel. I'm kind of stumped. It actually sounds very much like my single cylinder YANMAR trying to start with not enough battery, without the decompression open.

How many volts for the video test? 10 volts might do it if it isn't too cold. I mean, it might groan, but slowly turn over. 7 volts, forget it.

If possible, I would have put jumpers from a good battery, positive to the positive lead on the starter and negative to the starter housing, usually where the flange bolts to the engine. Eliminate the generator wiring to the starter. Then, if it works, take one off, or the other to see which is the problem.

 

[zzjea]

I have to say, I have never in my life heard a three cylinder Diesel try and start like that. In fact, I went back to the OP to make sure you did say Diesel. I'm kind of stumped. It actually sounds very much like my single cylinder YANMAR trying to start with not enough battery, without the decompression open.

How many volts for the video test? 10 volts might do it if it isn't too cold. I mean, it might groan, but slowly turn over. 7 volts, forget it.

If possible, I would have put jumpers from a good battery, positive to the positive lead on the starter and negative to the starter housing, usually where the flange bolts to the engine. Eliminate the generator wiring to the starter. Then, if it works, take one off, or the other to see which is the problem.

If I do that, then there is no solenoid so some big sparks.. Also, there will be no glow plug or fuel pump action as they need power from the starting circuit. I guess I could leave the battery circuit active and just disconnect it from the starter and let the sparks fly when connecting the starter to the other 12v battery. Also, the flywheel is easy to turn by hand even with the starter engaged. The starter is new (last year) but has only been used to try to start this darn thing every once in a while. I don't know if it has been degraded with these futile attempts to start the engine but even new, it did not seem any different than now.

I do have an extra ground strap I installed that attaches to one of the bolts on the starter and to a welded bolt on the chassis frame rail.

This is a case where I have lived without really needing the generator (we don't boondock), but I want it to work if and when I do need it.

 

[Industrial Toys]

At this point, I would not be concerned if it starts. I would want to see it turning over at a nice speed.

You are not jumping it to start at the starter. Just feeding it there. Normally the B+ goes from the battery to the starter. So you go straight to the starter. Same idea with the ground.

I don't understand how t he flywheel can be easy to turn even with the starter engaged. Please explain.

You sure you didn't get a 24 volt starter or something like that?

Any diesel I know of has a good amount of resistance to crank it, even before hitting compression. The fact, that that flywheel jumps 90 or so degrees so effortlessly leaves me puzzled.

Doing some reading. It's a nice engine, sought after in that generator.