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engine replacement time?

Started by woodbeard, June 19, 2007, 07:12:28 PM

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woodbeard

WOOOOHOOOO!!

Still a few bugs to work out, but so far, this is a HUGE improvement!
Cut 1400 board feet today, twice what I was doing last week
AND.. I didn't even get to the big poplars yet, this was all logs about the same size as last week, and almost all of it in 1x6
AND.. I used about 2/3 the fuel doing it! And by that, I mean I cut 1400bf with 2/3 the fuel I used to cut 700bf.

The main bug is the surging up and down it does at idle speed ( 1800rpm ) while running the hydraulics, and sometimes the carriage up/down and feed motors. Mostly the hydraulics, though. It keeps speed when I run use them at full throttle (blade engaged) though I can still hear it pulling down a bit.
Is this an issue with the governor mechanism?
Or is this an electrical issue?
The alternator light comes on, and flickers while sawing at higher feed rates. Doesn't happen in wider cuts at full load, just when I'm zipping thru the 6" cants.
My thinking is that maybe the alternator is wore out again, and the motors are pulling juice from the Honda magneto, thus robbing it from the plugs?
Or maybe I just hooked something up wrong?


jesse

how many hours did the onan have on it

woodbeard

Not really sure about that. The mill shows 2400. I got it it with about 1800 hours on it. The mill is a '92 model, but the motor was replaced somewhere along the line. Not sure if it was new or used at the time, either.

Slabs

The engine "surgeing" at idle when using the hydraulics may actually be alternator loading.

The hydraulic pump may well be demanding in excess of 100 amps and at idle speed the alternator may not be able to keep up with the demand.  100 amps is about 1400 watts and approx. 2hp not taking into consideration mechaincal-electric conversion losses.

If you really want to make sure, disconnect the alternator and operate the hydraulic pump with the engine running at idle.  If the surgeing doesn't happen, it's just normal loading.  An undercharged battery could also be a culprit with the battery not providing it's fair share of power at engine idle.
Slabs  : Offloader, slab and sawdust Mexican, mill mechanic and electrician, general flunky.  Woodshop, metal woorking shop and electronics shop.

woodbeard

Actually, the hyd. pump draws 200 amps.  :o
The alternator is the one WM specifies for it.
The battery was a tad low this morning, a little over 10 volts across the terminals with engine off, and 12 volts while running.
I adjusted the throttle linkage and got it to hold idle while running the pump and motors (at the same time, even! )  Toward the end of the day it started surging a bit again, but it would usually catch up and idle again after a few surges.
I'll check voltage again tomorrow.

Anyhow, I went over my numbers again, and seems I was off by 300bf, so it was only 1100 bf. Still pretty good, though, considering I spent about an hour moving logs, and another hour getting a new blade wheel belt.
Today, I got into the big poplars, sawing 2x6x16' and sawed around 1700bf
They dragged a bunch of red oak down the hill for me to saw, so I will be on this job a couple more days
8)

woodbeard

Well, it is doing the surging up and down thing again.
I did like Slabs suggested, and disconnected the alternator, and indeed, it stopped doing it, and idled normally.
I should be able to get through tomorrow fine, then I will pull the alternator off, and have it tested.
So, what exactly is alternator loading? I have a vague idea, but not entirely sure of the details.

Slabs

The alternator is probably doing just what it should do-producing all the energy it can at the rpm during idle.  The engine may not have the capacity to support the alternator demand at idle speed.

I'd rather see the alternator voltage up around 14 at operating rpm but it's probably doing an adequate job as it is.  If you're still not happy with it a bench check will tell all.   Make sure the battery is up to snuff while you're at it.  A good overnight trickle charge should help.  Again, the battery not giving it's fair share to the hydraulic pump could signal diminished capacity.
Slabs  : Offloader, slab and sawdust Mexican, mill mechanic and electrician, general flunky.  Woodshop, metal woorking shop and electronics shop.

woodbeard

Ok, I think I get it.
Keep in mind that "idle speed" is 1800rpm in this case. WM hydraulic mills ( maybe others, too- I don't know ) are set up this way to keep the battery charged.

woodbeard

Took the alternator and battery in this morning.
Alternator tested good, battery bad.
Glad I spent the extra money on the WM alternator, and the premium battery with the 3 year replacement. I'm on my second replacement now, with a little over a year left. Think I can get one more out of the deal? :D
Haven't put it all back together yet, gotta weld that stupid little alternator bracket part that keeps breaking.

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