L2550 - Hard starting at all temps

[North Idaho Wolfman]

Stop with all the testing, I think your meter is lying to you half the time.
It's working properly because it's starting quickly.

If you really wanna see if they are heating you can get a laser temp gun and find out Immediately.

 

[Stinger23]

Stop with all the testing, I think your meter is lying to you half the time.
It's working properly because it's starting quickly.

If you really wanna see if they are heating you can get a laser temp gun and find out Immediately.

It's 68 degrees in the shop and it's being cranked multiple times each day for all of these tests so I'm not sure that it's a valid confirmation of whether it's functioning properly. It also was not starting while cranking for tests until yesterday when it suddenly started doing so. It's possible that all of the little incremental fixes that gained a tenth of a volt here and a tenth of a volt there (100% charged battery, warm conditions, connected to a charger, cleaning, all connections, etc) took it from "too low" to just high enough to function for now. If that's the case, once I take it back outside and the battery loses a little bit of its charge then it may be right back to not starting again. It's all torn apart currently so I can't really drive it outside and see what it does in the cold.

I do have a temp gun so I'll see whether they are heating that way. I'd assume the tops of the glow plugs don't get all that hot but they must get a little bit warmer.

 

[North Idaho Wolfman]

It's 68 degrees in the shop and it's being cranked multiple times each day for all of these tests so I'm not sure that it's a valid confirmation of whether it's functioning properly. It also was not starting while cranking for tests until yesterday when it suddenly started doing so. It's possible that all of the little incremental fixes that gained a tenth of a volt here and a tenth of a volt there (100% charged battery, warm conditions, connected to a charger, cleaning, all connections, etc) took it from "too low" to just high enough to function for now. If that's the case, once I take it back outside and the battery loses a little bit of its charge then it may be right back to not starting again. It's all torn apart currently so I can't really drive it outside and see what it does in the cold.

I do have a temp gun so I'll see whether they are heating that way. I'd assume the tops of the glow plugs don't get all that hot but they must get a little bit warmer.

Put one lead of the meter on the glow plug end put the other end of the meter on the switch side and turn the switch to preheat record measurement, turn the switch to crank record the measurement.

 

[GreensvilleJay]

I'm curious as to age of tractor and hours as that ignition switch only has so many turns before it's 'worn out'. yes, it may 'kinda work' but not be able to pass the 60 amps those glow plugs require to generate enough heat to get engine to start. it will also be intermittant, random, yes-no-nono--almost......

 

[Stinger23]

Put one lead of the meter on the glow plug end put the other end of the meter on the switch side and turn the switch to preheat record measurement, turn the switch to crank record the measurement.

You're looking for voltage measurements here?

When you say to put the lead on the key switch, which switch pin are you referring to? G2 and G1 or something else? Thanks.

 

[Stinger23]

I'm curious as to age of tractor and hours as that ignition switch only has so many turns before it's 'worn out'. yes, it may 'kinda work' but not be able to pass the 60 amps those glow plugs require to generate enough heat to get engine to start. it will also be intermittant, random, yes-no-nono--almost......

It's a 1992 model, unknown hours as the hour meter doesn't work (stuck on 1006) but the paint is worn off all of the "touch" surfaces for shoes and such so it's certainly not been a garage queen prior to my ownership.

Looks like a new switch is only about $25 for the aftermarket version or $95 from Kubota and it's easy to swap so I'm certainly fine replacing it if it seems to be the culprit.

 

[North Idaho Wolfman]

You're looking for voltage measurements here?

When you say to put the lead on the key switch, which switch pin are you referring to? G2 and G1 or something else? Thanks.

Yes you looking for voltage
Yes G1 and G2

 

[Stinger23]

Put one lead of the meter on the glow plug end put the other end of the meter on the switch side and turn the switch to preheat record measurement, turn the switch to crank record the measurement.

1.1v dropping to .95v over 10 seconds on preheat on G2.
2.2v dropping to 2v over 10 seconds on preheat on G1.

GP's all got slightly warmer. 6 deg F front, 4 deg middle, 2 deg rear after 10 sec. I'm not sure how warm the tops of the glow plugs are supposed to get after that amount of time, but that doesn't seem very warm to me. The imbalance makes me want to move the wire to the center glow plug instead of the front to hopefully even out the temp spread. I'm using an IR camera so it's clear as day the rear is barely heating after 10 sec. GP wire got as hot as the front GP.

G1 1v before it started.
G2 1.5v before it started.

Confirmed there is not room for a jumper cable clamp.

30 sec test with preheat, I don't think rear GP is heating. This vid is with wire on center GP:

Also found one spot in the wiring that was 155 deg after 30 sec preheat, at least 20 deg hotter than anything else in that circuit, so I'll be removing the tape to figure out what's going on there.

 

[North Idaho Wolfman]

1.1v dropping to .95v over 10 seconds on preheat on G2.
2.2v dropping to 2v over 10 seconds on preheat on G1.

GP's all got slightly warmer. 6 deg F front, 4 deg middle, 2 deg rear after 10 sec. I'm not sure how warm the tops of the glow plugs are supposed to get after that amount of time, but that doesn't seem very warm to me. The imbalance makes me want to move the wire to the center glow plug instead of the front to hopefully even out the temp spread. I'm using an IR camera so it's clear as day the rear is barely heating after 10 sec. GP wire got as hot as the front GP.

G1 1v before it started.
G2 1.5v before it started.

Confirmed there is not room for a jumper cable clamp.

30 sec test with preheat, I don't think rear GP is heating. This vid is with wire on center GP:

Also found one spot in the wiring that was 155 deg after 30 sec preheat, at least 20 deg hotter than anything else in that circuit, so I'll be removing the tape to figure out what's going on there.

Careful with the preheat, on that style of glow plug is closer to full temp at 5 seconds, not 30.

 

[Stinger23]

Careful with the preheat, on that style of glow plug is closer to full temp at 5 seconds, not 30.

Ok, wasn't aware.

Did those voltage drop test results you wanted me to get tell you anything?

I'll buy a new set of glow plugs are the rear one is either dead or nearly dead. Actually I may clean the bus bar first to make sure it's getting a good connection.

 

[GreensvilleJay]

re: found one spot in the wiring that was 155 deg after 30 sec preheat,
You should replace that wire... that spot is 'high resistance' ( high is relative...).no way it should heat up,none. It's only drawing 50-60 amps so similar to electric dryer, EV charging station and they do NOT get hot, not even warm. Voltage doesn't matter, it's current that creates the heat .

Also the switch is 'EOL' End Of Life... NO way it should 'lose' 1-2 volts.

Also tractor is 30 years old, wiring is 30 years old, ANY corrosion from water is bad.

If there's a connector ( splice) between switch and GP busbar, eliminate it. get proper sized wire ( #4 copper should be fine) to connect them.

yes, clean the busbars...'shiny new', new flat washers too.

 

[Stinger23]

Thanks, I'll get a new switch, run a new wire with no connectors other than the G1/G2 splice, and clean the bus bars. If the rear one still doesn't heat I'll replace all of the GP's.

 

[Stinger23]

Ok, I finally got a chance to work on the tractor. Once all the new components arrived. I ran a new 8 gauge wire from the starter power post to the new key switch. Then I ran a new 8 gauge wire from the switch to the glow plugs. I bypassed all connectors so it is a direct run for both of those wires. I also installed a new glow plug in the rear cyl.

Voltage drop from switch to glow plug is now 0.25v.

There are no longer any hot spots in the power wires as any prior hotspots were either bypassed or repaired. I had found one spot in the power wire coming off of the starter going to the switch that was buried inside the loom but getting hot. When I peeled the loom and tape back it was just two wires twisted together with no sort of connector or solder or anything else. It was literally just two wires twisted together and then taped up so they wouldn't fall apart.

I ended up putting the power wire for the glow plugs on the center glow plug hoping it would even out the heat between the glow plugs but the rear one still doesn't seem to heat as well as the front for some reason but they are within a few degrees so it likely doesn't matter.

I didn't try to start the tractor because I preheated the glow plugs multiple times during the voltage tests and I want the cold start test to be with cold glow plugs since it's 65 deg in the shop and you guys (and Kubota) say it should start without preheat.

 

[GreensvilleJay]

NICE, you're making progress !
.25v drop is 'ok', though less is better.
interesting what you found 'under the tape', arrrrrgh,sadly wonder 'what else cold there be ?'
connecting to the center plug is 'technically' better,though the 'straps' are virtually 'zero' ohms
while the glow plug heat should be concentrated, it 'travels to cold' to end plugs could show 'cooler'
make sure battery is fully recharged before starting the engine.
I always give my BX3s 5 seconds of preheat, any day of the year. While not required in summer, it does start slightly easier.

 

[Stinger23]

NICE, you're making progress !
.25v drop is 'ok', though less is better.
interesting what you found 'under the tape', arrrrrgh,sadly wonder 'what else cold there be ?'
connecting to the center plug is 'technically' better,though the 'straps' are virtually 'zero' ohms
while the glow plug heat should be concentrated, it 'travels to cold' to end plugs could show 'cooler'
make sure battery is fully recharged before starting the engine.
I always give my BX3s 5 seconds of preheat, any day of the year. While not required in summer, it does start slightly easier.

There are certainly more wiring issues to find. The headlights aren't working. Not sure when they stopped working as I didn't notice it until I was fixing the flashers and noticed the headlights were dead. They'd worked the last time I needed them. I may just put a light bar on it and move on though as the stock lights aren't great and the loader blocks them anyway.

 

[GreensvilleJay]

BTDT !! Loader's only been off once in 6 years, to fix factory nonwelded weld....... Now have 2 sets of LEDs on my nonROPS roof unit.

 

[Flintknapper]

. I may just put a light bar on it and move on though as the stock lights aren't great and the loader blocks them anyway.

^^^^^

That's what I did. Just added a LED light bar to the ROPS.

I have LED headlight bulbs, but even so....they don't provide much useful light.

The light bar does.

 

[Stinger23]

Yeah, I found a golf cart place with a bunch of extra canopies for cheap that I plan to grab and modify into a tractor roof, then add lights.

 

[Stinger23]

Well, it started right up without preheat. However, it didn't shut off when I turned the key off. So now I've got a new problem to solve. Shop is filled with fumes now so I had to leave.