Best way to check injection timing Kubota.

[tdi1fun]

Thanks in advance for the help.
I have a Kubota L275 and after I had the injectors cleaned I am getting a very noticeable ignition knock at lower RPM. I have the service manual and it says to just crack the injection line fitting and look for fluid to set the injection timing to the flywheel marks. The question I have; is this the best way to do this, it does not sound very accurate. Does anyone know of a better way? Also could a bad injection pump cause the extra knocking noise? The injectors were pretty bad before I had them serviced. 1700 hrs on engine The cylinder compression is right on spec.

 

[Bigbear]

Well let me first say WELCOME TO TBN, and there are others out there that could better answer your question,,,,,,,, but I will give it a shot. First, did you have a mechanic do the service work? If so, then he should be the first one to answer your question. I would assume you did because you say the cylinder compression is right on spec.,,,,, and that is usually something a mechanic would check.
I really don't think the injection pump would cause this problem, but then again, I'm not a mechanic, (only backyard). It might be air in the lines, or could be the injectors are to out of spec, to function proper. Have you checked the muffler, it might need cleaned or replaced also, could cause to much restriction (back pressure). Also, are you getting any white, black, or blue smoke from the exaust, this will also tell a story as to what might be wrong.
I know this does not help much, but maybe one of the other TBN'ers will offer some better advise. /forums/images/graemlins/grin.gif

 

[tdi1fun]

Thanks for the feedback Bigbear
Like you I am a backyard mechanic and do almost all of my own work (the price is right). I had the injectors professionally rebuilt but i diddent get the test specs after they were finished so that could be a possibility. The local Kubota dealer has them do all their injector work and highly recomended them. My muffler is clear and all the air is out of the lines. I noticed that I don't have as much power after the injectors were rebuilt. I don't get any smoke at normal operation And I get hardly any smoke at full load only a little blackish white. (almost like it needs more fuel). Maybe the nock is normal for this engine?

 

[Ranch_Hand_Supp]

tdi1fun, if your lower RPM knock was not there before the injector clean.....I would guess air is in the lines.

Setting the injection timing the way you described is how I would do it.....but, I would remove #1 injector line [do not bend it], may also remove glow plugs if it has them, so I could turn the engine over by hand smoothly. With a steady hand or a steady helpers hand turning the engine over in the correction direction, watch for the fuel to start rising out of the pump...when you see that stop!! and look at timing marks.
Do that at least a couple of times before you adjust. Then check and recheck. Good hands and eyes are the secret.

Hope this helps
Ronald

 

[tdi1fun]

Thanks for the info Ronald I will try that this weekend.
I have run the engine 3-4 hours after the injector cleaning wouldnt the air in the lines have worked its way out by now? /forums/images/graemlins/confused.gif

 

[Bigbear]

Just curious, why did you have the injectors worked on in the first place. It sounds like the injectors are not working right, even though they are rebuilt. I agree, the air should be out of the lines by now, have you noticed any rise in the oil level? If that's all you changed, then I would think that is still the problem. I had an injector replaced awhile back and it still smokes some, but now has lots of power.
Not sure of the price on injectors, but might be worth springing for some new ones.

 

[Ranch_Hand_Supp]

tdi1fun, Air in the fuel lines can be hard to bleed out sometime...why? beats me. I have had some to bleed out easy and some that has worn me out. Sometimes I will tap the fuel lines with my wrench and in my mind..... I am trying to get that air bubble to move.. if there is one? I am talking Diesel engines in general.

I am assumeing that they took the injectors apart when they cleaned them and checked pop off pressures and spray pattern when they reassembiled?

Ronald

 

[tdi1fun]

I originally had them cleaned to help with hard starting in the winter. The injectors are practically new they replaced the tips and nozzles then they said that they rechecked the pop off pressure and spray pattern.
Another thing i saw when i was checking the timing, was the fluid in the fitting on the pump after it came up for the injection cycle would go back down as i kept rotating the engine to see the next cycle. Is it possible for fluid to go back into the pump or is there suppose to be an internal one way valve on it?

 

[Ranch_Hand_Supp]

</font><font color="blue" class="small">( Another thing i saw when i was checking the timing, was the fluid in the fitting on the pump after it came up for the injection cycle would go back down as i kept rotating the engine to see the next cycle. Is it possible for fluid to go back into the pump or is there suppose to be an internal one way valve on it?

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tdi1fun, Good eye!!....the lowering you see is the inj. pump trying to take another mouth full of fuel to get ready to feed the injector. If the injector line was still on and had no air in the line , it would not drop.

As you keep rotating...and when the moment you see the fuel just starting the rise STOP and look at timing marks. If you see bubbles [air] coming out while you rotate? Air is getting in or has got in the system.

Ronald

 

[dedejr]

i had the same problem with my ford pickup 7.3 and the problem was glowplug one dont work i change and no more probleme