L2550 - Hard starting at all temps

[Stinger23]

Diesel Compression Test Kit

Amazing deals on this Diesel Engine Compression Test Kit at Harbor Freight. Quality tools & low prices.

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Does this compression tester have the appropriate fitting for this engine? I can't find the thread specs for the required tester for this engine so I was hoping maybe somebody has used this tester or has this information?

 

[ruger1980]

Those measurements are better.
It does seem a little slow. Can you measure cranking voltage at the starter? It is showing smoke while cranking so you are getting fuel, it is just not igniting properly.
I would still run a compression test too. Something like this will probably be fine for what you will use it for.

https://www.amazon.com/gp/product/B0D3WVSG82/ref=ox_sc_saved_image_6?smid=A9WGCA5LDF56N&th=1

 

[ruger1980]

Diesel Compression Test Kit

Amazing deals on this Diesel Engine Compression Test Kit at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Does this compression tester have the appropriate fitting for this engine? I can't find the thread specs for the required tester for this engine so I was hoping maybe somebody has used this tester or has this information?

Sorry I was preoccupied. That may have the correct adapter but hard to tell as I don't have the thread dimensions for your glow plug.

 

[GreensvilleJay]

slow spinning, maybe due to LOW battery voltage and current capability.

8.5 volts on glowplugs gets about 50 amps to them ( 8.5 / .16) ,may not be getting hot enough ?

I'd expect 10 volts on the GPs and that'd get 20 amps PER GP.. (so 60 amps just to heat them..)
I wonder what the OM/WSM says as to 'specs' ?

 

[Stinger23]

12.6v or higher is considered fully charged and that's right where mine is so it shouldn't be low battery voltage, though it could be low voltage at the starter due to a bad connection somewhere. That's what I'll test next time I'm near the tractor.

 

[ruger1980]

One more question, does it start better if the throttle is at full fuel? If so there could be an issue with the start spring in the governor assembly.

 

[Stinger23]

One more question, does it start better if the throttle is at full fuel? If so there could be an issue with the start spring in the governor assembly.

It starts better with some throttle for sure. I don't honestly think it would ever start if the throttle was at idle, even in the summer. I give it about a 30% throttle for it to start in the summer. In the winter I've only started it three or four times so I've not figured out what works best yet, but I've certainly given it a lot of throttle to get it to start, not necessarily full throttle.

 

[North Idaho Wolfman]

Address the glow plug circuit before you even bother with the compression.
Which by the sound of it cranking is not an issue.

Contrary to @ruger1980 statement, This Kubota engine requires the glow plugs to work properly for it to fire when cold.
The glow plug circuit works in preheat and while cranking.
I don't have to preheat my glow plugs unless it's in the 20's but if I do, it certainly starts faster.

The chances of a start spring being damaged is really rare, but could happen.
You will have to pull the stop cover and the throttle cover in order to inspect it.
If you go down that path let me know and I'll explain better.

 

[GreensvilleJay]

12.6v or higher is considered fully charged and that's right where mine is so it shouldn't be low battery voltage, though it could be low voltage at the starter due to a bad connection somewhere. That's what I'll test next time I'm near the tractor.

in post #60....
G2 Black/White: 0, 0, 8.4, 7.7

G2 is only 8.4 volts NOT 12.6. BTW 12.6 would usually be at 'room temperature of 70*F'.....

I'm assuming 8.4 is glow plug voltage, but there will be IIR drop between switch and actual glow plugs.

What's rating for the battery ( CCA ) ,age and 'state of charge' ?

Even at 8.4 volts, the 3 glowplugs draw 50 amps out of the battery, so doing that for any length of time , the battery 'terminal' voltage goes down and then stuff that needs 12 volts doesn't get 12 and won't operate properly. It's a vicious downward spiral.

FWIW I needed a second BIG battery on my forklift JUST for the air intake heater( glow plug on steroids ).Without it, starter turned slower after 30 seconds of preheat vs no preheat.

I'd like to see a solid 10 volts at the glow plugs after 30 seconds of preheat'. The experts will know what's 'acceptable'.

 

[ruger1980]

Address the glow plug circuit before you even bother with the compression.
Which by the sound of it cranking is not an issue.

Contrary to @ruger1980 statement, This Kubota engine requires the glow plugs to work properly for it to fire when cold.
The glow plug circuit works in preheat and while cranking.
I don't have to preheat my glow plugs unless it's in the 20's but if I do, it certainly starts faster.

The chances of a start spring being damaged is really rare, but could happen.
You will have to pull the stop cover and the throttle cover in order to inspect it.
If you go down that path let me know and I'll explain better.

I am not making claims I am just reiterating what Kubota says about their own engines. The snip I added is right from the WSM and the OP manual says to key on and directly start with no mention of preheat. And I do understand that the glow plugs heat during crank but that is limited unless you have a long crank.

 

[GreensvilleJay]

Use of 'preheat' is generally based on how friggin cold the engine is.
I KNOW my BX23S starts 'better' (faster, easier, smoother) when it's given 5 seconds of 'preheat' any day of the year Winter,Spring,Summer or Fall. It 'costs' me nothing,so I do it every time...it starts easily, every time.

Yes, I know not all diesels were created equal but since this one has manual preheat, I'd preheat based on temperature (cold =10 seconds, colder 20 seconds,real cold =30 seconds) or whatever the manual suggests.
I'll still harp about the low volts on the GPs though. With low power to them, they won't generate the heat they should according to the book....heck say they should have 10 volts, only getting 8, that's a 20 % LOSS in heat they SHOULD be getting. On a warm sunny day maybe not a big deal, but where I am ,cold Canada it IS a big deal.

Another post says 2 different style GPs.... wonder if they're internally different ? Maybe the installed ones produce less heat (BTUs) than the required ones ? Hmm, anyone ever see 'charts' for GPs like they have for spark plugs ??

 

[Stinger23]

Battery is 810 CCA, 930 CA, 9/22 date. It holds a charge for a long time just sitting so it seems to be in good shape and I've had it on a trickle charger the whole time it's been in the shop since I keep cranking and preheating it during these tests and such. So it should be at least north of 80% charge.

11.63v at the starter when cranking with battery at 12.89v. Fired up immediately twice in a row, can't explain that as I've cranked it probably about 60 seconds during these tests and this is the first time it's started. It did sound like it was getting close to starting when I cranked it for the video I posted this morning though.

 

[Flintknapper]

Fired up immediately twice in a row, can't explain that

Explanation for that was given back in post #12.

 

[Stinger23]

Disconnect that wire and the wire off the added glow plug indicator and use a meter to see if they are the same wire.

Disconnected the wire from the indicator and GP, 1.2 ohms.

Connected G2 to the wire going to the GP, bypassing the indicator and I get battery voltage on the wire on preheat when not connected to the GP. It immediately started when trying to check cranking voltage.

I then connected the wire back to the glow plugs and on preheat it's 7.02 volts. It's possible there is a dirty connection somewhere on this wire, but I've not located it yet as most of the connectors are all buried under the fuel tank.

G1 I can't find in the harness so I've not been able to connect that one to the glow plug yet.

 

[North Idaho Wolfman]

Disconnected the wire from the indicator and GP, 1.2 ohms.

Connected G2 to the wire going to the GP, bypassing the indicator and I get battery voltage on the wire on preheat when not connected to the GP. It immediately started when trying to check cranking voltage.

I then connected the wire back to the glow plugs and on preheat it's 7.02 volts. It's possible there is a dirty connection somewhere on this wire, but I've not located it yet as most of the connectors are all buried under the fuel tank.

G1 I can't find in the harness so I've not been able to connect that one to the glow plug yet.

G1 and G2 should be spliced together.
Do yourself a favor and pull the fuel tank if that's what's stopping you from getting to the wiring.

 

[Stinger23]

G1 and G2 should be spliced together.
Do yourself a favor and pull the fuel tank if that's what's stopping you from getting to the wiring.

Pulled some more panels and was able to get to the splice where somebody added this indicator to the stock harness. In the pic you can see that it's connected to a black wire with a white stripe which is the same color as G1 so I disconnected it from both ends and an ohms test of 0.2 ohms indicates that it is G1. Picture attached of the splice where the indicator connected to the black and white wire G1.

So the way they had the indicator switch wired in is that G2 went to the indicator and then the other side of the indicator went to G1 in the harness.

Now I've got it wired so G2 and G1 both connect to the same spot in the harness So they now both go to the glow plugs. I'm not sure how to test whether they are actually heating or not, as I've read that removing one and trying watch it glow is not a good idea. What's the best way to figure out if these glow plugs are actually getting hot? I'm still only getting 7v at the glow plug on preheat so I'm not confident they are heating, or not heating in a reasonable time.

Measuring on both sides of each connector, I appear to lose 0.1 to 0.2 volts at each connector. There are six connectors total. So the connectors appear to account for about half of the total voltage loss from the switch to the glow plugs. If the GP's don't seem to be heating well, I may have to just bypass all of the stock wiring and run one solid wire from the switch to the glow plug. That should get me 9.0-9.5v or so to the glow plugs.

[Edit] I checked the voltage on the glow plug wire before the splice into the stock harness and I get 9.6 volts during preheat. But when I check it at the glow plug it's 7.4 volts after I cleaned every connection between the switch and GP. So, I'm losing significant voltage somewhere between the glow plug and the splice. I did pick up 0.5 volts by cleaning all of the connectors and adding oxide inhibiting compound to them.

 

[GreensvilleJay]

simple ,easy test..
no key required.

connect DMM on the GP bus bar,set to volts....
use a 'battery jumper cable'...connect to GP busbar and then +12 of battery, yes you WILL get sparks...
what does the DMM read after 5 steamboats ??

BTW 'busbar' is the 'straps' that connect all the GPs together

If you had a DC ammeter good for 75 amps, I'd suggest using that , but most guys don't have them.

 

[Stinger23]

simple ,easy test..
no key required.

connect DMM on the GP bus bar,set to volts....
use a 'battery jumper cable'...connect to GP busbar and then +12 of battery, yes you WILL get sparks...
what does the DMM read after 5 steamboats ??

BTW 'busbar' is the 'straps' that connect all the GPs together

If you had a DC ammeter good for 75 amps, I'd suggest using that , but most guys don't have them.

I don't think there is room for a large jumper cable clamp to reach the bus bars. Minimal clearance between the intake manifold and injectors. I'll see what I can do though, I've got a few different cables and one may be small enough.

To clarify, where are both DMM leads connecting? One to the bus bar and the other where?

What are we trying to test here, as in, what's the end goal? The engine started immediately the last two times I cranked it so if seeing if it starts is the goal then we can't do that currently.

 

[GreensvilleJay]

+ve of meter to GP busbar, -ve to ground.

It'd be nice to KNOW what the voltage is.

Say it's 10 volts, then when you turn key to start, you should get the same 10 volt reading. If you don't it's either bad wiring, bad connections or bad switch. In order to pass 50-60 amps ,you need PERFECT wiring and connections. Compare the wiring to say your electric dryer ( 40 amps) . I can't recall IF you've replaced the ignition switch, so the 'battery cable bypass test' is important.

 

[Stinger23]

+ve of meter to GP busbar, -ve to ground.

It'd be nice to KNOW what the voltage is.

Say it's 10 volts, then when you turn key to start, you should get the same 10 volt reading. If you don't it's either bad wiring, bad connections or bad switch. In order to pass 50-60 amps ,you need PERFECT wiring and connections. Compare the wiring to say your electric dryer ( 40 amps) . I can't recall IF you've replaced the ignition switch, so the 'battery cable bypass test' is important.

I got it, you're just wanting to bypass "everything" and checking voltage drop to see what's to be expected under ideal wiring conditions.

I've not replaced the key switch or anything else yet as I prefer to diagnose rather than throw parts at it and hope for the best.