L2550 - Hard starting at all temps

[Stinger23]

I purchased this tractor last summer and it always required at least 10 seconds of glow plugs to start quickly, even if I'd recently shut it off. and giving it about half throttle helps it start quicker as well. Once it's running it runs flawlessly, it's just getting it running that's problematic. Now that it's cold, it's nearly impossible to start. The glow plugs work since they help it start in the summer.

We had a big snow storm coming last week so I attempted to move the tractor into my heated shop before the snow arrived. I plugged in the block heater the day before and it works (block was warm around the heater). It was about 45 deg outside when I attempted to start it and I'd give it 30 sec of glow plug, then it the starter for 15 seconds or so (varying throttle while it's cranking), then I'll give it another 20 seconds of glow plug and then crank it over again. It never once gave as much as a sputter like it wanted to start, it was just cranking with no evidence it was close to running. It also was not smoking at all out of the exhaust when cranking. In this instance, I did this until the battery was clearly getting low. Then I put a charger on it while I regrouped (Google possible ways to get it to start). After the battery was charged I tried to start it again and still had no luck. Then I got out a heat gun and heated up the intake manifold for a few minutes and then I directed the hot air directly into the air intake tube (a few inches away to keep from melting the tube) gave it 30 seconds of glow plug, and it immediately started within a few rotations.

Two day later after the snow was done I tried to start it in my shop (65 degrees) and I had to do this glow plug/crank for 15 seconds/glow plug/crank process 3 times before it started. I expected it to start quicker than this in the shop so now I'm concerned this issue is getting worse. I never shut it off during the 4 hours I used it to clear snow for fear of it not restarting.

So now I'm trying to figure out what's going on. I suspect it's possibly losing fuel prime but I'm no diesel mechanic so I'm sort of guessing here based on the symptoms. When it does finally start it will blow a puff of smoke and then clear up so I don't "think" it's an injector issue but I don't know for sure. Since it runs great otherwise I "think" the fuel pump and injector pump are fine but again, this is sort of a guess.

Any idea what else it could be, or how I can go about diagnosing this issue? Thanks for your time.

 

[North Idaho Wolfman]

Well first off there might be a correlation with your mutiple key attempt start ( other thread ) and your hard starts.
One the glow plugs get heated two ways. one preheat and one while cranking, so your need to confirm they are getting power in both positions.
And just because they are getting power doesn't mean they are working, you need to OHM test each one.

I was very glad to hear that you used a heat gun to get it to start, that is the safe way to get these engine to start when they are having issues.
Ether / Starting fluid is the death of these engines.

 

[Flintknapper]

You might consider doing a compression test on the cylinders as well.

Combination of glow plug issues and low compression would certainly result in hard starting (or no start).

 

[rudder35]

Well first off there might be a correlation with your mutiple key attempt start ( other thread ) and your hard starts.
One the glow plugs get heated two ways. one preheat and one while cranking, so your need to confirm they are getting power in both positions.
And just because they are getting power doesn't mean they are working, you need to OHM test each one.

I was very glad to hear that you used a heat gun to get it to start, that is the safe way to get these engine to start when they are having issues.
Ether / Starting fluid is the death of these engines.

Can you explain why ether is bad for these engines? Some old diesels even had a push button to squirt ether. It fires too early on the compression stroke? Why?

Thanks

 

[North Idaho Wolfman]

Can you explain why ether is bad for these engines? Some old diesels even had a push button to squirt ether. It fires too early on the compression stroke? Why?

Thanks

Kubota diesels are not built the same as OLD diesel engines.
Using ether/ starting fluid will break pistons, break ring lands, brake rings, bend rods, and crack heads.
There are a lot of posts and threads on here that show the damage caused from using those products.

 

[Stinger23]

Well first off there might be a correlation with your mutiple key attempt start ( other thread ) and your hard starts.
One the glow plugs get heated two ways. one preheat and one while cranking, so your need to confirm they are getting power in both positions.
And just because they are getting power doesn't mean they are working, you need to OHM test each one.

I was very glad to hear that you used a heat gun to get it to start, that is the safe way to get these engine to start when they are having issues.
Ether / Starting fluid is the death of these engines.

I wasn't sure if the glow plugs got heated while cranking or only while preheating. So that's good info. That's also why I didn't use ether.
Looks like glow plugs are pretty cheap so I'll OHM test them. I assume the pass/fail info for them is in the service manual?

 

[GreensvilleJay]

glow plugs 'generally' are about 1 ohm resistance, draw about 10 amps of current. That spec should be in the WSM or listed in the glow plug data sheet.

when I sold my forkift, the case of ether went with it so NO chance a 'helper' will assist in starting my Kubota and cost HIM a new engine !

 

[Stinger23]

You might consider doing a compression test on the cylinders as well.

Combination of glow plug issues and low compression would certainly result in hard starting (or no start).

I'll look into this. I work on gas engines primarily so my compression gauge is for threading into spark plug holes. so I think I'll need a different tester for the diesel.

 

[Stinger23]

glow plugs 'generally' are about 1 ohm resistance, draw about 10 amps of current. That spec should be in the WSM or listed in the glow plug data sheet.

when I sold my forkift, the case of ether went with it so NO chance a 'helper' will assist in starting my Kubota and cost HIM a new engine !

Thanks for the glow plug info.

 

[Stinger23]

We got more snow today so I needed to use it again and it surprisingly fired right up after only a few seconds (still in the heated shop). It hasn't started that easy since this summer.

 

[Flintknapper]

Can you explain why ether is bad for these engines? Some old diesels even had a push button to squirt ether. It fires too early on the compression stroke? Why?

Thanks

As already stated by NIW (different build of diesel) but please follow that sage advice. Ether is a NO-GO for Kubota Engines.

 

[Flintknapper]

We got more snow today so I needed to use it again and it surprisingly fired right up after only a few seconds (still in the heated shop). It hasn't started that easy since this summer.

Then the mystery is solved. You have a 'Female' Engine.

So by default....it will work when it gets damn good and ready and not before. And you'll never know when that will be.

 

[Russell King]

We got more snow today so I needed to use it again and it surprisingly fired right up after only a few seconds (still in the heated shop). It hasn't started that easy since this summer.

Maybe just try starting each day and see if that gets it to consistently start easy.

I am not sure what that may prove or what information it provides but it would be interesting to know.

 

[Stinger23]

Then the mystery is solved. You have a 'Female' Engine.

So by default....it will work when it gets damn good and ready and not before. And you'll never know when that will be.

Yes, it's ready for action when it doesn't have a headache and isn't tired, hungry, angry, annoyed, and it's a leap year.

 

[Stinger23]

I couldn't find the glow plug diagnostic section in the workshop manual so I'm not positive what the correct values are. All tests are completed with one multimeter lead on the ground side of the battery and the other lead on the center post of the glow plug.

Glow plugs measured 6.7v when heating. I assume this should be 12 volts but I don't know for sure?

After heating they measure 8 ohms until the relay clicks off, then 2 ohms. This is with the factory wiring connected to all of them. So it's possible the ohms reading is combining all three measurements since they're wired together.

 

[North Idaho Wolfman]

I couldn't find the glow plug diagnostic section in the workshop manual so I'm not positive what the correct values are. All tests are completed with one multimeter lead on the ground side of the battery and the other lead on the center post of the glow plug.

Glow plugs measured 6.7v when heating. I assume this should be 12 volts but I don't know for sure?

After heating they measure 8 ohms until the relay clicks off, then 2 ohms. This is with the factory wiring connected to all of them. So it's possible the ohms reading is combining all three measurements since they're wired together.

You can not measure ohms with power connected or the glow plugs connected to any wiring at all.
Remove the buss bar and only measure ohms one at a time.

Also check your meter, as my meter will blow a fuse when you try and measure ohms on a live circuit.

 

[Stinger23]

All three glow plugs measured 0.7 Ohms with all wires and buss bar disconnected.

 

[GreensvilleJay]

0,7 sounds reasonable BUT what did the meter say when you shorted the leads together first ?

 

[Stinger23]

0,7 sounds reasonable BUT what did the meter say when you shorted the leads together first ?

0.1 ohms with leads shorted.

 

[GreensvilleJay]

so you subtract that from 0.7 to get the real glowplug resistance ( 0.7- 0.1= 0.6 ohms. )
check WSM or online to see it that's 'within spec'.