sticky injector?

[Bradtot]

Hi All
Last weekend My Henan Quinlai (similar to foton jinma etc etc) 304 tractor with a Laidong LD30 engine started running on 2 cylinders.
It has 105 hrs on the clock and has been running well up until the weekend.
I had no warning it just started running on 2 of the 3 cylinders.
Now I am no mechanic but have a basic knowledge of how it works.
To find out which cylinder was not firing I started by removing the rocker cover to see if anything was broken..and I found nothing wrong.
I then started the engine and observed the rockers all working correctly.
I then cracked open one at a time the fuel lines going into the injectors and the middle one made no difference when cracked even though there was fuel spurting out from the injector pump. The other 2 cylinders when I cracked open made the engine run rougher, so there was something wrong with number 2.
I removed the injector and tried blowing air through it and from the nozzles I could see fuel coming out, but not as even as I thought it should be. I then placed the injector in an ultrasonic cleaner with Isopropal alcohol and cleaned it for about 5 mins.
I removed the injector and placed compressed air through it again and it was much better, so I thought.
I refitted the injector and started the engine and it was exactly the same, only running on 2 cylinders.
I then thought I will swap number 2 injector with number 3 and see what happens, well when I did this and did the same test while the engine was running by cracking open the fuel line it was number 3 that did not make any difference. This concluded that there was still something wrong with that injector.
I removed the good injector and tried blowing compressed air through it and I could not, it seemed blocked where as the faulty one would let the air go through and out of the nozzles.
I tried to dismantle the faulty injector but could not.
I tapped it gently with a hammer and then tried the air input again and now nothing came out, just like the good one.
I refitted the injectors back in thier original positions and started the engine and all was back working again. I have done another 4 hrs and it hasent missed a beat!
My conclusions are that the injector spring inside had jammed in the open position and when I tapped it with the hammer it freed up.
Has anyone ever heard of this?
The injector had KD stamped on it.
I have found the same injector pictures on alibaba so I know they are availible. I will be buying a spare for the future.
Kind regards
Brad the now deisel mechanic...LOL:laughing:

 

[SPIKER]

Sounds plausible that you knocked loose what was causing it to stick, it SHOULD have made a slight difference when cracking it as fuel would have had 2 directions to go. It could run thru injector that was leaking (still igniting) and or around it onto the head when line was opened.

Usually you need a high pressure machine to clean the injectors popping them off one at a time w cleaner going thru taking off gum/varnish. For these injectors it is high pressure I think in the 2000PSI range from memory that pops them off.

Mark

 

[Bob Rooks]

Mark is correct. It takes about 2,200 psig to lift the pintle off the seat inside the injector. This high pressure is from the individual barrel and plunger assemblies in the fuel injection pump. You most likely had some contaminated fuel that prevented the pintle from seating. You should be aware that when this condition exists, and it is not uncommon, that the cylinder walls get washed down with every fuel injection and the lube oil gets diluted. You might want to get your oil checked, or change it.
Injectors cannot be cleaned in the manner you posed. They are disassembled, cleaned. broken/worn parts replaced, reassembled and calibrated. Calibration is performed on a very expensive test bench that costs about ten-plus times the price of your tractor. Best to just take them to a diesel shop or replace them with new.

 

[Bradtot]

Hi
Thanks for the replys
Not knowing at first how they should have worked was my original problem. I am used to electronic petrol injectors( I have a V8 Range Rover and landrover TD5 deisel). I have cleaned the Range rovers injectors with using the ultrasonic cleaner before with good results.
Since this has happened I have done 8 more hrs and still no more problems.
When it started missing on the injector it may have run for about 3 mins before I stopped it and started looking for the problem.
Its due an oil change anyway so I will do this on the next weekend coming. I have 119hrs on this tractor so far and my only complaint is that I have to be very careful when I have a full load of sand in the front bucket as it tends to want to tip over. I have many a soiled underware.. I am now really careful and do things slowly ready for this to happen mainly when I reverse I have had the back wheels in the air and it then crabs when trying to steer. I am looking at reversing the rear wheels to give a better stance.
Once again thanks for the replies.
Brad

 

[zonta223]

You are using a large weight to act as a counter balance yes?

Hi
Thanks for the replys
Not knowing at first how they should have worked was my original problem. I am used to electronic petrol injectors( I have a V8 Range Rover and landrover TD5 deisel). I have cleaned the Range rovers injectors with using the ultrasonic cleaner before with good results.
Since this has happened I have done 8 more hrs and still no more problems.
When it started missing on the injector it may have run for about 3 mins before I stopped it and started looking for the problem.
Its due an oil change anyway so I will do this on the next weekend coming. I have 119hrs on this tractor so far and my only complaint is that I have to be very careful when I have a full load of sand in the front bucket as it tends to want to tip over. I have many a soiled underware.. I am now really careful and do things slowly ready for this to happen mainly when I reverse I have had the back wheels in the air and it then crabs when trying to steer. I am looking at reversing the rear wheels to give a better stance.
Once again thanks for the replies.
Brad

 

[Bradtot]

Hi Zonta
The rear wheels have big weights on them.
I sometimes have a grader blade attached and or the 5 foot slasher, but this limits me for turning circle and reversing as I sometimes forget they are on the back.
Also if I just want to move some sand quickly then I dont have anything on the back.
I mainly think the the FEL is actually too big for the size of tractor I have, it has a FLD 30D FEL attached with 4 way bucket.
It came with the backhoe (LW 6) and when I have this on the back I can really feel it as in stability and heavyness.
I am now very used to what is going to happen and therfore do things slowly.
Brad