L3650GST Glow Plugs / Will not start

[dkcobbs]

My L3650GST stalled out and now will not start. It has been getting harder and harder to start. We have cracked the fuel lines and have diesel at all four injectors. With a fresh battery, the engine will fire and almost start but just won't quite make it. When we tried to remove the glow plugs to check them we could not get them completly out because of the intake manifold. The local dealer is not being real helpful other than offering to pick it up (for a substantial fee) and look at it in his shop. I will spend the $100 for a shop manual before I go back to my dealer. No one I talk to can believe that the design would prevent the glow plugs from being replaced without taking off the intake manifold but it sure seems that way to us.
Does anyone have experience with replacing the glow plugs on a L3650? Is there some trick to it that we don't see?
Does anyone have the 3650 shop manual that would confirm you do need to take off the intake manifold?
We have been working on this for quite some time now and have tried everything we can think of with no success - any ideas would be greatly appreciated! Thanks

 

[bmiker]

You can test the glow plugs with out removing them. Can use a ohm meter or you can just touch the electrical contact end with a hot jumper from the battery if it pulls a good arc then the plug is working. The next thing to check is the glow plug controller this can be checked with a volt meter connect your meter to the hot wire that goes to one of the plugs then have someone to activate the glow plug switch if you read voltage the controller is working. Hope this will get you started.

 

[Rockyridge]

The only time glow plugs are used are before you start your diesel on a very gold day to pre-warm the cylinder a little. Other then that they are not used at all.
Your problem is almost certainly fuel or possibly not enough air. Check fuel and air filters. Most likely starving for fuel for some reason, but forget the glow plugs at this point.

 

[art]

The 3650 should start without the glow plugs above 50 degrees without to mcuh difficulty.

 

[dkcobbs]

Thanks for the responses - It was the dealer that told me that the glow plugs had to be working for it to start unless it was really warm - 90+ - and questionable even then. We have tested with a volt meter and do have good voltage to the glow plugs. How do you use an ohm meter to test the individual plugs? Just out of curosity, does anyone know if you do have to pull the intake manifold to replace the plugs?

Fuel has been our number one expectation all along but we have tried everything we know and everything keeps checking out. We first drained the tank and put new fuel in from a different source. We bypassed the fuel pump with an elevated reservoir going directly to the injection pump. We have pulled the fuel line at each of the injectors and made certian we have fuel to each of the cylinders. Any other ideas for what we should try this weekend would be appreciated.

 

[Rockyridge]

It was in the 40痴 overnight here in MN and it痴 now in lower 50痴 and I started my L3400 without using the glow plugs. Probably better to use them now but it still should start without them.

It sounds like you have worked pretty well with the fuel side of the problem, what have you checked for air supply?
You don稚 want to run it to any extent without the air filter, but for trouble shooting, you could try staring it with the air filter removed. If it starts and runs then you know it was a plugged air filter.

When it almost starts are you seeing anything (smoke?) coming out of the exhaust? If so, what color is it?

Let us know what you come up with.

 

[Yankee Clipper]

I think you have a problem with the transfer circuit. Did this just start when things got cold or was it getting harder to start? If when cold weather started, maybe the fuel is gelling in the lines or fitler, but it sounds like you have addressed that.

Take the fuel line loose at the injection pump (banjo fitting) and crank the engine over. You should get a jerking stream of fuel as the engine rolls over. If not, there is a small orifice in the fitting that keeps the appropriate flow to the galley. Be sure the orifice is open.

If you don't get flow, put a gauge between the transfer pump and the injection pump - it should read 3-5 PSI. If not, the transfer pump may be worn out or the filters restricted or the supply line out the bottom of the tank is collapsed/twisted/ aged.

The other note about checking th glow plug at the top post is correct - in the cranking mode, you should see battery voltage at the glow plug - if not find out why. Don't test them out of the tractor as they can explode - they need the heat sink of the bore in the head to function correctly.

One last thing - don't ether the engine or you will break the top ring land and it will have to get pistons and rings.

Good luck.

 

[dkcobbs]

Thanks for everyone's ideas - to answer the questions:
We have unhooked the air intake to bypass the air filter. The engine seems to have good air suction when we crank on it. But of course doesn't start.
When it almost starts the exhaust is dark gray, one of the guys helping me calls it black but I believe it is more of a dark gray. There is a substantial amount of smoke - very close to starting.
Yes we already have taken the fuel line off at the injection pump and we do get the pulsing or jerking fuel flow as you stated.
When cranking we do have voltage at each of the glow plugs - I don't have it here at the office but I it was slightly less than the full 12V - I think closer to 10 but I'm not certian of that off the top of my head.
Once again - I thank everyone for taking the time help me out.

 

[mrwitty_1]

One thing I don't see in any of the post is the number of hours on the machine, is there a chance the compression could at the threshold of low and without the aid of the glow plugs not igniting the fuel ? The way I check glow plugs in everything I have ever owned is much simpler to me, I use a volt test light, remove all the leads from the glow plugs, clip the one end of the test light to the positive post of the battery then touch the probe to the glow plug connector, if the light glows the glow plug is OK. After all a glow plug is only a controlled dead short that makes heat. I think from reading your first post that it stalled out then would not start you are looking at a fuel delivery problem. Good luck keep us posted.

 

[dkcobbs]

The hours on the tractor are slightly under 700 - we will be trying some of your suggestions tomorrow and see where we get.
Thanks

 

[Rebel]

I hate to say this but it sounds like an injection pump problem.

One thing to check is the fuel shut off solenoid (assuming it's not built into the pump). Make sure that with the key in the run position and linkage is fully extended or retracted (which ever the case) buy manually push or pulling on it.

Another trick is gasoline on a rag. With the air cleaner removed while cranking the engine wave a gas soaked rag around the air inlet (DISABLE YOUR GLOW PLUGS FIRST!) If you have good compression the engine will temporarily run on the fumes from the gas.

 

[Rockyridge]

(When cranking we do have voltage at each of the glow plugs - I don't have it here at the office but I it was slightly less than the full 12V - I think closer to 10 but I'm not certian of that off the top of my head.)


Im confused, maybe some real diesel people can provide some education here. I thought the only time there was any power (voltage) to the glow plugs was when the key was turned to the left (or what ever needs to be done with your equipment) to pre-warm the cylinder before starting on cold mornings. Other then that the glow plugs have no function and if there is 12V there that indicates some other problem. Do some diesel engines provide power to the glow plugs every time they are started or possibly under certain conditions under control of some sensor?

Thanks for any information you can provide.

 

[dkcobbs]

Saturday we went ahead and pulled the intake manifold, removed and tested each of the glow plugs and all 4 tested good. We also rechecked the fuel supply and had fuel at each of the fuel lines going into the injectors. We pulled one injector but couldn't reconfigure the fuel line to allow us to test it. Removed the air hose to the intake manifold to rule out air obstruction. When all is said and done, we are back to where we started except for rulling out the glow plugs. Very good suction on the air intake when cranking, fires consistently but not quite enough to start. My basic understanding of diesel is you all need is fuel, air and compression and we seem to have all three. Just about ready to give up and pay the piper for the dealer to work on it.

 

[Rebel]

My basic understanding of diesel is you all need is fuel, air and compression and we seem to have all three.

That is correct, but you also have to have proper timing. I am a diesel tech by trade and work on stationary engine generators. Unfortunately I'm not familiar with the injection system that Kubota uses. (Not a Kubota owner yet...got a deal cooking though).

Based on all of your input I think we can narrow it down to 2 possible problems;

1. Air being admitted to and or trapped in the injection pump, it takes very little air induced into the fuel supplied to the injection pump to cause problems. Are you sure that all of the air has been eliminated from your system? Sometimes an airlock can give a guy real headaches. The gas on a rag trick can be used to help work the trapped air out of the system.

2. Your injection pump is toast. The injection pump shops that I deal with on occasion have told me that since the introduction of ultra low sulfur fuel they have seen a rash of failures on pumps with a lot of hours. Everybody would be well advised to run a lubricity additive in their fuel to prevent premature failure due to the relative dryness of the ultra low sulfur fuel.

 

[DiezNutz]

1. Air being admitted to and or trapped in the injection pump, it takes very little air induced into the fuel supplied to the injection pump to cause problems. Are you sure that all of the air has been eliminated from your system? Sometimes an airlock can give a guy real headaches.

Amen. Dkcobb, when you pulled the feed line off the pump to do the "elevated reservoir" trick, the pump could've lost prime - it doesn't take much. Could you tell that the pump was actually drawing down the fuel? Sure I realize this didn't cause the original trouble but it has a way of masking the real problem and making it impossible to diagnose. Also, it does nothing in the way of proving or disproving that your fuel filter is clogged.

Btw- On all but the coldest days, if you cranked the engine long enough, it would start w/out glow plugs because compression alone eventually heats a cylinder enough to sustain combustion.

The injection pump shops that I deal with on occasion have told me that since the introduction of ultra low sulfur fuel they have seen a rash of failures on pumps with a lot of hours. Everybody would be well advised to run a lubricity additive in their fuel to prevent premature failure due to the relative dryness of the ultra low sulfur fuel.

Just playing devil's advocate...while the sulfur content has been reduced, the refiners are supposed to be putting in additives (mainly corrosion inhibitors) to restore the lubricity of the fuel. Common misperception is that sulfur is the lubricant; it is not but the processes that remove it also reduce the fuel's natural lubricity (so I guess net effect is it might as well be). It also makes the fuel more corrosive, hence the extra corrosion inhibitors which also have the added benefit of restoring lubricity.

Perhaps more realizable problems from switching to ULSD are older seals failing (I wonder if leaks don't account for some of those pump rebuilds), and plugged filters (and pump) 'cause ULSD has a way of loosening old deposits.

Now with all of that said, yeah I'm still gonna run additivies like I always have



not many people realize that other additives have been introduced to maintain the same degree of lubricity. Or so they say.

 

[dkcobbs]

On at least three occassions, including last week after testing the glow plugs, we have cracked the fuel lines at the injectors and made certian that we had fuel at all four injectors when we cranked the engine. It is my assumption (always subject to being corrected) that if we had an air lock problem then we would not have fuel at each of the injectors.