756 German Diesel

Clynnt · Apr 1, 2010

756 German Diesel .... With No Load - tractor seems to run fine up to 3/4 throttle ... but cuts out @ PTO rpms (2300) even if just sitting parked
When pulling disk .. RPMs drop when under a load ... I can give is more throttle … but only to the ¾ level as described above … anything past that .. the black smoke rolls & it cuts out …. Keep it down to ¾ rpms .. it’s fine until I lift the disk … then I’m back to the cutting out from too high rpms ..???
This is my first diesel tractor... I know the governor keeps RPMs up under a load on my Gasser ...??
I'm thinking fuel filter would be the first thing to check ... but though these symptoms … would probably be a give-a-way … to some experts …?
Any help will be appreciated

Weldon K · Apr 1, 2010

Sounds like a fuel supply problem . Shut off fuel supply to filters. Remove primary filter . Open fuel shut off valve and check for full fuel flow through line. If it is slow ,there is a clog in the short standpipe and shut off valve assembly in the bottom of the tank. (You can blow it out with compressed air but junk will remain in tank.) I would empty tank by siphoning or draining. Then remove shut off valve from tank and clean. If fuel flow was good, change both filters,and vent system properly. If engine still has problem , injection pump most likely needs service.

pete 23 · Apr 1, 2010

Check for collapsing hose into air cleaner, they do that, a rectangular shaped paint thinner can shoved in the hose over the top of radiator will keep it open. Just one quick thing to check. With a naturally aspirated diesel your volume of air intake is in relation to engine speed and not load. Of course,check air filter itself also.

ih560 · Apr 1, 2010

Sounds like an air supply problem to me as well. I have had the same thing happen to me on my old 90 F250 Diesel. It would only run up to about 1500 rpms and then it would surge rpms and smoke like crazy above that. A new air filter and everything was good to go.

mazemeister · Apr 1, 2010

check easy things first... air filter, etc. probably not fuel filter since you say it runs fine under load, just not at high rpms.

one other thing to consider- i have an 806D with the RD pump, and it would run fine but at high rpms (like 2000+) it would miss, sputter, smoke- turned out to be a chewed up spring in the injection pump. the spring was supposed to return the plungers to take a new charge of fuel, so with it broken, it wouldn't pump enough fuel for high rpms. don't know how your pump works.

Clynnt · Apr 1, 2010

You are a genius…. ! I just went out & looked the air duct over & it looked fine ….. took the air filter out … then fired it up … it went up to 2300 just fine … got of … looked @ air duct … still fine ….. then put the air filter back in … got her ½ way in & it sucked out of my hands & bogged her down bad & the smoke started rolling ! … walked around & the air duct was collapsed ! … crawled up & throttled her down & she smoothed right back out….
Now … ? just clogged air filter ? or does the air duct need attention too ? it looks like there is a wing-nut holding on a second inter air filter …is that the case ? I’d say replace them both if things were that far gone on the outer one ??

ih560 · Apr 1, 2010

You should probably just replace the air filter, it is probably just restricted causing the tractor to collapse the intake hose.

Tom Fleming · Apr 2, 2010

Clynnt, looks like you found your problem. But, remember one thing on a diesel or gasser. Black smoke usually means too much fuel and not enough air. Black smoke is carbon. Carbon in exhaust = too rich. Lot's of reasons for not enough air.......looks like you found yours. I also like to run any engine (gasoline or diesel) a wee rich. run too lean, especially on a gas guzzler, and you can/will burn the valves.

BTW, on a "working" diesel, I like to change the air filters when I change the oil filters.........a good investment for both power and economy. You have now seen how these need to "breath deeply" when up to working RPMs...........

Clynnt · Apr 2, 2010

Follow up …. I bought both inter & outer air filters today … replaced them … & with the better seal on the outer filter … it was worse than ever … ! Thanks to what I learned from all of you last night, this told me there had to be a blockage in the Air Intake Duct … sure enough … it took a while to dig into it but there was a mouse nest plugging the top duct where it entered the canister ! … It took a while to get it removed out of the little spiral fins inside the canister .. but after it was cleaned & put back together … My – Oh – My …. I didn’t realize what I was missing out on , power-wise ….!!!!! Makes me wonder if that was the reason the old guy sold it ???

Thank You to all that helped me track this down !!

756 German Diesel

Clynnt

New User

Weldon K

Member

pete 23

Well-known Member

ih560

Member

mazemeister

Member

Clynnt

New User

ih560

Member

Tom Fleming

Well-known Member

Clynnt

New User

Similar threads