Just bought a case 680g that I knew was lacking power and I was hopeing I can figure it out. Started by replacing fuel filters and cleaned the glass bowl. Did not fix issue still starts hard when cold and has very little power. Shakes really bad too but does not smoke very bad out exhaust (has typical color). Used heat gun on manifold found rear 2 cyl (closest to cab) were running very cold. Loosen those 2 injectors and found no change in shake. They both had fuel coming out of the fittings and I was thinking those 2 injectors could be bad? Was also wondering how I can check engine compression on this motor? Any help out there I would appreciate let me know any other things I should check or do to figure this issue out thanks.
Pull those two injectors and either get the adapter for a compression tester, or stick an air hose in the injector hole and see where the air blows out, the other cylinder, intake, exhaust, crankcase...
If it has the little, skinny pencil injectors, I think they are pretty cheap. Maybe $50 a piece? Might as well put all 4 in. After you get the shop to pop-test them that is. How's the blow by? If the compression is bad enough in those two cylinders, and it's not valve related, you should have lots of blow-by, not to mention lots of smoke from unburned fuel.
Maybe blew out the head gasket between cylinders?
It does have the skinny pencil looking ones and saw they were cheap on eBay as well so was thinking about putting 4 new ones in. Also it dose not have a lot of blow out the crankcase vent at all. I also pulled the air filter out to see if I could anything coming back through the intake but didn't hear much at all. I will look into the injector adapter to check compression as well as be able to put air in them to listen for it though a valve or into the crank case. Thank you very much for everyone's input.
I'm with Lan on this one. Have both injectors out when appling air and see if it travels to the other poor running cylinder.
Just did a comp test on all 4 cyl and found they all were at 350 psi. I was thinking its a fuel delivery problem at this point? I was gonna try putting 4 new injectors in and see if that takes care of the problem.
If the valves have not been adjusted in awhile they may be loose. That would rob power and cause hard starting since the valve set effects engine timing.
Your engine is a case 336 BD and it has two heads. If you had the same or close to the same pressure across the four, i would replace the four injectors and try it. I would also like said, do a quick valve adjustment.
Intake valve clearance is .015 hot or cold. Exhaust clearance is .025 cold /.020 Hot. Those specs are from an OEM service manual. If you need the procedure for the adjustments let me know.
they're known to snap cranks
I don't see how that would be an issue with my concern dayexco. I have good compression