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It's getting to be the end of the season and when I decided to build a 2.5 acre lake with my 550 this spring it has been one nightmare after another! I own a diesel shop and my techs and I are scratching are heads! I'll try and be brief;

1. Two days into it number 4 rod and main spun. Pulled engine, turn crank, pistons and cylinders look perfect....sent head out....one new rod for #4 and new bearings back together and running.

2. A month into the project pushing up a hill starts loosing power (this is where it gets interesting). Changed fuel filter, further testing number 1 and 2 are dead only running on 3 and 4.
Moved injectors, still dead. Pulled head, thinking head gasket, sent head out....checks OK. Installed now number 1,2 and 3 are dead. Thinking fuel, no tester, pulled injectors left them hooked to line, low fuel pressure. Installed pump, same thing only hot cylinder number 4. Installed injectors and lift pump, back to 1 and 2 dead.

3. Contacted Martin Equipment, tech worked on it for 6 hours and made 30 phone calls....scratching his head (at least they didn't charge me).

4. Loaded it up and took her to the shop, compression tests 390 to 425 on all cylinders. Pulled front structure timed motor....everything lines up. Pulled exhaust manifold and turbo off fired engine, 1 and 2 both getting fuel. Pulled injectors fired with line on, good atomization and stream.

5. So basically it's in time including pump, it's getting fuel, valves are closed on TDC and has 400 PSI compression still 1 and 2 cylinders are dead.....assuming that it would not build 400 PSI without air we think it's getting air.

Has anyone ever ran into this or can give us a direction? I am 3/4 the way finished with my lake, going bald because of this machine, and spent a whole lot of money! Please help! Thanks in Advance!!!!

Chad
 

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Chad, while I know what you are talking about, I wish that I could help. I am afraid that you will get minimal technical advice on this particular forum. You may wish posting a similar message on newagtalk.com since there a good number of folks who have experience with the 4276. I don't know if much was different on the 4276 engines in dozers vs. ag products. Seems to me that there differences on some other models. I wish you the best with your problem...it puzzles me, too.
 

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I am afraid that you will get minimal technical advice on this particular forum.
Well, it's sad that you feel that way-we have two John Deere Technicians on the site, as well as a lot of other smart cookies 'round here:nunu:
 

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Welcome to DT!

Chad, I will notify the two JD Techs of your thread to make sure they see them, please stand by:good2:
 

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Sorry, Kennyd. My comments weren't meant to offend, but I knew that Chad had an urgent problem. I've seen some threads for larger equipment go for a while before responses are made. I'll try to be more diplomatic in the future.
 

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Sorry, Kennyd. My comments weren't meant to offend, but I knew that Chad had an urgent problem. I've seen some threads for larger equipment go for a while before responses are made. I'll try to be more diplomatic in the future.
No harm done:flag_of_truce:
 

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It seems you have covered a lot of possibilities. Fuel, air and compression in proper timing should make it run. You don't mention checking valve lift to see if cam lobes could be wiped. I doubt this is the problem since you have 400 psi compression, but be sure to at least visually check rocker arms to see if all cylinders are opening approx. the same amount. Are you absolutely sure you are getting plenty of fuel flow from the tank? Low fuel flow can definitely affect power, but shouldn't affect only one or two cylinders. I don't know the fuel line configuration on the 550 but if the fuel line comes out the bottom of the tank, remove the line and be sure you are getting a strong, full flow from the tank. (actually I just checked parts diagram, looks like a screen in bottom of tank.#7 in diagram. Is it clean?) If that all checks ok, I would suspect injection pump. You mentioned installing lift pump and another "pump" so I assume that was a new injection pump? Another thing to check is the retun line from pump and injectors. It can not have any restriction. Let us know if this helps.
 

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