miller bobcat problem need help

[eecervantes83]

1st problem I keep popping my breakers both 220 & 120. 220 is more sensitive.
Do I need to replace the breakers from my understanding they become weaker the more they pop.

2nd problem after running longer than 1hr the machine acts up and begins to choke like its out of fuel. I shut it off a few minutes and starts right up. But problem continues after that first hour.

[cruizer]

You know there are various models of the Bobcat, sure would be easy to lookup with say a ......SERIAL #

[eecervantes83]

Serial# kj085052
Bobcat 225 nt
1100 hrs

[Nick Walkley]

Oil level

I have the same machine. I have had the cutting out problem, it was caused by the oil level being low and certain conditions caused the low oil cut out to shut it down. If the oil is up on the dip stick it will be something else. My breakers have not caused any problems.

I hope this helps

Nick

[cruizer]

Well set your engine RPM it around the 62.5hz mark, (Probable set wayyyy too low at present) Then you will stop popping breakers, as volts drop amps increase, thus popping breakers.

As for sluggish, its likely that your not using the correct oil. These small engines and especially the onan needs an oil with Zinc in it. So a couple liters of 10-40 motorcyle oil will smarten the engine up, or quakerstate "DEFY" in a 10-40

Try this easy stuff first before we continue on.

So get yourself a meter that reads HZ, stuff the probles into your 120 Vac terminals, loosen off the 13mm lock nut right side engine just above the valve cover and tighten the 8mm bolt untill the meter reads around the 62.5hz mark high idle no load.

[Tryagn5]

change oil and filter, replace inline filter, change spark plugs....then

If the above does not fix machine, i would bet you have a bad coil which is dropping a cylinder. Easiest way to tell is to run machine when it starts to die, use a temp gun and shoot the exhaust ports see if one is colder by a lot. Replace the igntion coil then.
Kevin

[cruizer]

Unlikely as the onan only has 1 coil, so both sides would be weak, unlike the Kohler which has 2 coils. It is a possibility though that the vacumn operated fuel pump is weak, or is loosing vacumn

[eecervantes83]

I'm going to follow the advice posted and keep you informed of the outcome. Thanks for the help

[Tryagn5]

well..

Unlikely as the onan only has 1 coil, so both sides would be weak, unlike the Kohler which has 2 coils. It is a possibility though that the vacumn operated fuel pump is weak, or is loosing vacumn

i have replaced countless coils on onans. You are correct that it is one coil. However when weak they fire one cylinder with the least resistance. This engine is giving all the symtoms of a bad coil. Fuel pumps are either good or bad. I have never seen a pump work for a hour then quit.
kevin

[cruizer]

Just thinkin that the unit gets hotter ( and it will if there is zero zinc in the oil), that he is loosing compression and thus vacumn pressure to the pump. Engine goes sluggish (cause its freaking hot) but doesn't up and die.

These engines run amazingly cooler with the recommended zinc content. So motorcycle oil is best or Quakerstate Defy are pretty much the only oils with enough Content. As well as Diesel oil. Most guys tend to run straight automotive oil, and wonder why thier engines crash at under 2500hrs. My customers are still running at hrs exceeding 10,000. Hmmm, wonder why.

If I put automotive oil in my $10K EVO engine, it would bake itself pretty darn fast, same goes for ALL air cooled engines.

[cruizer]

Say you've got a Harley, and your low on oil at some hobucking town. No Harley oil around, the recommended oil for it is 15-40 Diesel oil. Why is that. Hmmm, CAUSE of the ZINC content. Gotta keep that engine friction free and COOL!

Just a thought

[MMW]

I don't want to start an argument about what is the best oil but cruizer is right about zinc content. I use Brad Penn oil exclusively in my welder. Has plenty of zinc. Zinc content is not only for air-cooled engines but also for older water cooled cars too.

http://penngrade1.com/

[H80N]

For our power equipment like welders, gensets, pumps, snowblowers, tillers etc... and diesel stuff... ALL get Shell Rotella....

(Commercial Diesel oils are allowed a healthy dose of ZINC and other additives)

[Tryagn5]

no argument on oil ....but

Say you've got a Harley, and your low on oil at some hobucking town. No Harley oil around, the recommended oil for it is 15-40 Diesel oil. Why is that. Hmmm, CAUSE of the ZINC content. Gotta keep that engine friction free and COOL!

Just a thought

The zinc content of the oil is more for the valve guides of the engine. As for vaccum loss normally it is from either worn guides, or ring seal, yes a heavier oil will mask this for a period but will return shortly. Onan in particular run solid lifters, ie, they have no need for light weight oils as the lifters do not need to be "pumped up". Now a kohler 15w40 will kill it, as the lifters are hydraulic and need a thinner oil for the engine to preform in the cold, yes i to agree a syntheic 5w-40, or 5w-50 is an ideal oil as long as the engine has been broken in with the conventional 10w30 base oil.
Back to the onan, no one talks about valve adjustments or decarboning the head, as this should be a must for anyone wishing to keep there onan past a 1000hrs. Lucky the onans are becoming the detriot 2 stroke of the world as they have been replaced in nearly everything by kohler or honda. Personally i hate onans, bolt breaking, noisy, fuel guzzling, high priced parts.....etc
Kevin

[Kpack]

I've got the Subaru engine in my bobcat this is out of the engine manual. Should I not go by it.
ENGINE OIL
Recommendations
Use premium quality motor oil, Class SJ or SL. Look for the SAE
(Society of Automotive Engineers) or API viscosity grade. Referring to
the table below, choose the viscosity grade appropriate for the ambient
temperatures expected during the period of time until the next sched-
uled oil change.
Single-grade SAE 30 oil is preferable when temperatures are 50° and
90°F (10° - 32°C).
If multi-grade oil is used, oil consumption tends to increase if the ambi-
ent temperature is high.