More Generator

[GDeen]

While at Aggieland with Loc and Tony C last weekend watching the ags whip my Sooners, I noticed an issue with the generator on Sat evening.

Went in the house and noticed some light flicker. Went to the Inverter panel and saw the number 2 jumping back and forth between "good A/C in" and "inverting." When the panel showed bad A/C, it was showing no current from the generator on #2 - #1 just fine. Voltage and frequency looked fine (~129v and 60 hz). It would just jump from current to no current, and charge to inverting. Also noticed a slight vibration when this occurred.

Went outside and the generator was doing a little bit of what caused me a problem about a year ago - oscillating, but on a much smaller scale. The oscillating coincided with the bad power on the 2nd leg. I shut the genset off as fortunately it was cool and all we needed was battery power for the night.

When I got home, I tried it again. It ran fine for a while with good numbers, but then started the flickering, and switching from bad to good A/C in on the 2nd inverter. Also did the vibration or oscillation deal.

Any ideas? I called and spoke with the guy at So-Tex generator who repaired the speed control and dampening setting (which keeps it from chasing itself by speeding up and slowing down the rpms- my interpretation). He was not sure what to think. He did say if the infamous generator shaft bearing starts going bad, you can get bad power.

I also had a complete shut down a few weeks ago dry camping in Norman in very high heat. Turned out to be a bad slow burn 8 amp ceramic inline fuse behind the panel. When I mentioned that to the So-Tex guy, he thought that was probably tied to the voltage regulator the way I described it. As Jon says, fuses blow for a reason and I had hoped this one was just old age and heat. They are recommending a 10 amp replacement so that made me feel all the better about the problem being solved.

Anyway, I am open to any suggestions as to trouble shooting other than taking it down to So-Tex which is likely what will happen. Any reason to believe this could be coming from the invertor/charger side?

[Jon Wehrenberg]

I would defer to Ben C and his opinion on this electrical stuff, but any time I have seen intermittent or varying electrical current it has always been a poor connection or ground.

If you will recall about a year ago I went crazy trying to identify an inverter going from normal charge voltage to off the scale high charge voltage. While nothing leaped out at me as the cause, when I got done cleaning and retightening every connection from the inverters to the batteries, including all connections at the circuit breakers and disconnect switches as well as battery connections and grounds my problem went away.

I am not familiar with generators, but I suspect there is a connection that is not quite right and somehow a voltage regulator is a part of the issue, unless this is truly a mechanical issue as was suggested and bad bearings are the root cause. I would see if there is a way to rule out the bearings as an issue, and once satisfied they are or are not the problem I would start looking at every wire and every connection.

[Will Garner]

Gordon,

I don't like the sound of replacing an 8 amp fuse or "breaker" with a ten amp fuse or "breaker." That could be a formula that results in the wiring becoming the "fuse" when it melts because the ten amp did not "break" when the 8 amp would have. There is a reason for what you are experiencing and I don't believe it to be the size of your fuse.

[GDeen]

Will,

I hear you and appreciate your input. I was told that the new standard was a 10 amp fuse in that spot. That caused me to believe they may have been experiencing unnecessary failures. It is a definite point to consider though.

[gmcbuffalo]

Gordon have you called the Generator Company on this? I would ask about the fuse sizing also.
GregM

[GDeen]

Just to be clear - the genset ran fine for a couple of days after the fuse replacement. I am not convinced the two problems are related. I was hoping the prior failure was due to an 11 year old fuse just failing in light of time, high heat and vibration. Furthermore, given that the recommended replacement was 10 amp, i figured that must be on ongoing problem. I am certainly not a fan of installing large breakers or fuses or safety systems to short cut the proper cure another problem.

What I will do next time I am out at the barn though is put an 8 amp back in and see if it fries. If so, that may be the start of where to looking for the problem. I spent some time with it yesterday and of course couldn't get it to mimic the problem again. This causes me to believe that it is not bearing related as it seems that once that starts to go, it should continue to cause trouble.

I am guessing voltage regulator or something similar to what Jon has suggested. Yesterday there was a little oscillation or vibration yesterday, but once it got itself lined out it quickly smoothed right out under load. Could still be temperature related as the higher temps or longer run time caused something in the system to change - bad ground as Jon suggests, erratic voltage regulator, who knows? This even though water temps last weekend during this problems were not very high relative to what we normally run (160 vs 195-205).

One other thing that makes no sense - my oil pressure was lower than what I am accustomed to seeing - running abut 30 psi whereas in the past it has been 50+. Can't imagine that has anything to do with it but open to suggestion. Trying to figure out everything that is different or has changed since we had several hundred hrs of basically trouble free running.

[Jon Wehrenberg]

Lower oil pressure is a huge issue. If your coach ordinarily ran at 50 PSI and it all of a sudden dropped to 30 PSI there is no doubt you would be on the doorstep of Detroit Diesel when they opened for business.

Low oil pressure that has reached that point over time is usually an indicator of bearing wear. An instant drop in oil pressure could be debris in the pickup screen, a pump going south, or a hole or loosening of the pickup tube so the pump is picking up air. There might be other reasons but I haven't had my 2nd cup of coffee yet.

Usually low oil pressure is associated with high temps, but you ruled that out.

[Steve Bennett]

Gordon, check the oil level. If you have an injector problem, it may be causing the rough running, and could be diluting the crankcase oil with fuel. It also could be an indication of some other electrical issue effecting the oil pressure sender, although I would doubt that is the problem.

[GDeen]

Gordon, check the oil level. If you have an injector problem, it may be causing the rough running, and could be diluting the crankcase oil with fuel. It also could be an indication of some other electrical issue effecting the oil pressure sender, although I would doubt that is the problem.

Will do Steve - it was right on when I pre-trip checked but will check again once I get back out there. Also received a PM to the same effect suggesting I might have diesel in the oil. Will also pull a sample.
Thanks

[Jon Wehrenberg]

Is that likely with fuel supply lines to the injectors external? I know it was a not so rare problem on an 8V92, but fuel ran in lines to the injectors through the head.

[Steve Bennett]

The supply is external, but the injectors can leak into the combustion chamber and run past the rings into the crankcase.

[Jon Wehrenberg]

But isn't it likely fuel leaking past the injectors into the cylinder is going to burn, wheras fuel leaking from the heads, ends up in the crankcase via oil return galleys?