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David brown 990 running on 3 cylinders, stumped

M

Matthewanderegg

New User
Hi, I have a DB 990 running on 3 cylinders. Ran fine last summer, family went to start it over the winter and the oil bath (for air cleaner) was full of water. It ran until I presume they revved it and sucked up water. I have cleaned the fuel system, replaced filters and had infectors rebuilt. Timing is good, pressure to injector on dead cylinder seems good. Aside from a compression test not sure where to go from here. I ran it ok 3 cylinders for about 3hrs in hopes it would clear up with no luck. Can't imagine the compression is so bad it wouldn't fire. Any ideas are appreciated, need it running asap to cut hay.
 


Might not be getting fuel to one injector. Could be air locked. Or it might like happened on my 990 and the line had a hard to spot leak. Crack the lines at the injectors and retighten. If it's air or a loose fitting that should fix it.
 
Need more info, does it smoke white, and clear up when the fuel is taken away from that injector with the line nut loose? Has the valve cover been pulled to see if the push rods are in place, and no damaged rocker arms? Does it pop back through the intake when it runs? That engine has the rotary pump, not common to lose one cylinder on that pump like an inline pump can.
 
compression check. what is it doing? smoking and missing? did you loosen that injection line and see what happens? need info.
 

Check piston height on the missing cylinder, water on a piston can cause a rod to bend. As someone else has posted, a compression check is in order. Had this very issue on a Kubota midsize tractor, bent rod, difference in piston height was very noticeable.
 
I'd be looking for a bent push rod. Seen it many times on a DB. $20 in parts and an hour labor if you adjust the valves while you are in there.
 
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