Quick and Dirty Glo-Plug test using a battery charger

GeoHorn

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M4700DT, LA1002FEL, Ferguson5-8B Compactor-Roller, 10KDumpTrailer, RTV-X900
May 18, 2018
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Texas
I have a little Kubota RTV-X900 and it dropped down to almost freezing yester-night.... (Lucky me living down “Souff”).... Anyway, it usually starts on the second compression stroke...as does my M4700 .... never needing Glow-Plug help ordinarily.
However, yesteday the RTV wouldn’t start after a ten-second crank.... so I gave it 5 secs of GP... still no start.... so I gave it ten-secs of GP.... Still no start.

The battery was clearly dying at this point but I then gave it a full 20 secs of GP and as the battery died... it STARTED! :p

Refreshing my memory by reading the OM I see Kubota only suggests 5 secs down to freezing and 15 secs below Zero.... and specifically states to never use GPs for longer than 30 secs. These short “hits’ were so unproductive for my relatively new RTV (2014 with less than 400 hrs and living in Central Tx so cold weather hardly ever an issue... I felt my GPs should be in good shape.). But since it became “cool” this week I was beginning to question “Are the GPs actually WORKING?”...

Anyway, I needed to recharge the battery since I only drove it a short distance after the cold-start... so I connected my battery charger thru the cigar-lighter outlet and turned the charger ON... seeing it registering a 5-Amp charge-rate. 30-mins later it was down nearly to “zero” charge rate...and it came to me to test-out the glow plugs and didn’t look forward to having to raise the bed and access the GPs to test them....

I then simply turned the key to the GP position and observed the charger jump up to 5-AMPs charge-rate during the GP selection.... :unsure:

Sooo..... I’m assured that they are at-least functional after-all.... and the OM simply doesn’t provide sufficient time of application in it’s guidance. Thought I’d pass-along this little “quick and dirty” technique to determine if your Glow Plugs are actually requesting a “draw” of current as a test of the system (if not an actual test of efficiency of each GP.). Hope this helps.

Footnote: BTW, my M4700 never needs any manual application of GP, even down to “freezing” it cranks on the first or second compression-stroke... however, the M4700 automatically energizes GPs during engine-cranking regardless. My JD 4239 compactor engine does Not automatically energize GPs ...and it’s a 1987 model with unknown (likely a lot of hours on it as it’s an old surplus highway-department unit)... and during freezing temps yesterday it cranked right up normally without the use of GP. Makes me feel good therefore that it’s compression is probably pretty good. Just having a good new year! :p
 
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07wingnut

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I have a BX23 with an aftermarket installed ammeter. It registers well over 20 amp draw for 3 glow plugs. Comparing it to yours at 5 amp draw, I would say some of your glow plugs are not working.
 

GeoHorn

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Equipment
M4700DT, LA1002FEL, Ferguson5-8B Compactor-Roller, 10KDumpTrailer, RTV-X900
May 18, 2018
6,080
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113
Texas
I have a BX23 with an aftermarket installed ammeter. It registers well over 20 amp draw for 3 glow plugs. Comparing it to yours at 5 amp draw, I would say some of your glow plugs are not working.
Your ammeter is registering the full demand of the system.

If the ONLY supplier of current were the charger...then Yes, I’d agree. But remember this “quick and dirty” method was in PARALLEL with a fully-charged battery. The charger was only “helping”.... not doing all the work.
 

Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
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Austin, Texas
I live a few miles from GeoHorn and have also hardly ever had trouble starting my old L185F. But I tried starting it a couple of weeks ago in the cold of morning (probably was around 25 to 32 F over night) and it wouldn’t fire off like normal. I generally don’t use it much in the “cold” so imagine it has had bad glow plugs for a while.

It did start but I had to use the starter to keep it spinning until it really caught on.

Replaced the glow plugs yesterday and I actually see the indicator glow now so that indicates that the old ones were not drawing as many amps since I have never seen the indicator glow except in very dim light.

Started right up in similar conditions.

New OEM glow plugs were about $12 each so no big expense either!