zetor 551 not firing on one cylinder

[greendragon3]

hi guys , we are currently restoring our 5511 and when we road tested it before stripping it down for paint it was only running on three cylinders , we took out the injector and cleaned it but no good we then swapped the fuel pump with a spare we had but still no good , now we are wondering would it be something in the head itself , when the tractor is running and you loosen each injector the tractor dies out slightly and runs one one less cylinder until you re-tighten the injector , however when i loosen this troublesome cylinder the engine note does not change at all even thought there is plenty of diesel being sent to the injector !!!!!!

i was wondering if it could be a head gasket or damaged valve ??

please help as we are at our wits end at the minute and it is holding up our progress .

 

[Renze]

lube the fuel pump. a unit is sticking un upmost position and the spring cant push it back. take the side hatch off and soak it with penetrating oil, then put it back and overfill the pump housing with diesel fuel, then run it for a while untill it gets loose, then change the diesel for engine oil, then run it for an hour then change the oil and fill to level.

 

[bjarne_iversen]

Hi
Since you have tested two pumps i find it not likly to be the pump.
Try swaping the injector wiht anoter cyl, if this make no difrens you most likli have a stuck valve due to soot.
Bjarne

 

[Renze]

oh right, you already swapped fuel pumps...

Try taking the injectors out, then re mount them to the fuel lines so they spray aside of the engine, then toll the engine around with the starter and check the spray pattern. It should give a blast of fuel mist, a straight shot, or just a drip is bad.

Also check valve clearance, if its too tight the valve could stay open during compression ...

 

[sb]

take the rocker cover of and have a look in . check the pushrods

 

[bignikki]

I have been thinking of taking my injectors out to get them serviced because of the black smoke that chucks out when I'm going uphill. Would making the injectors fire outside the cylinder, like you suggest here, tell me what state they are in before I get them done?

 

[Renze]

Yes, if they dont spray a cone of diesel mist, but a splash or even a drop, you know they are bad.

 

[bignikki]

Would I need to have the diesel return pipe fitted too?