743 bogging down

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srs

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Dec 9, 2005
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i have a 743 that runs good, but for awhile now it has been bogging down alot on us. Its always been hard to start when it is cold outside, i hear a clicking sound when i hit the glow plugs, but i don't know if they work or not. Once it starts, fires right up ever time all day, just sounds like its straining. Trying to work and it will bog down, drive to quickly, say, up a small incline, it will bog down, and esp. when i load the truck and try to lower the arms and curl back the bucket at the same time it almost will stall. we have changed the fuel filter, removed and cleaned the fuel tank and line filter, keep the air filter clean, but it still bogs down. someone told us the injector pump may be wearing out, but im not a mechanic. Could a hydro filter cause it to bog down? I'm stumped.
 

Tazza

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Your hydro filter wouldn't cause this problem.
Does the engine smoke after it has started? all i can think of is the engine may be worn and has too much blow-by giving you a lack of power, buit this usually means its hard to start.
If it blows smoke ot could be worn rings and bore or even an injection problem.
How many hours has it clocked up on that engine? if you know.
On the engine, on the right hand side there is a breather tube, is there alot of air and or smoke coming out of here? plug it with your finger for a second or 2 and feel how much air comes out.
 

srs

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Dec 9, 2005
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Your hydro filter wouldn't cause this problem.
Does the engine smoke after it has started? all i can think of is the engine may be worn and has too much blow-by giving you a lack of power, buit this usually means its hard to start.
If it blows smoke ot could be worn rings and bore or even an injection problem.
How many hours has it clocked up on that engine? if you know.
On the engine, on the right hand side there is a breather tube, is there alot of air and or smoke coming out of here? plug it with your finger for a second or 2 and feel how much air comes out.
it just blows white smoke when its trying to cold start, then after its running the only smoke it blows is just a small amount when you hit it wide open or close the throttle from wide open, which i think is normal, can't even really tell what color it is. also, i stuck a little plastic soda bottle on the blow by tube and no oil gathered there. ill check it with my finger though. as for hours, i am not sure, the dealer "fixed" it by making it so the hour meter never shut off, so i pulled the wire, and i dont think the hours were correct anyways compared to the age of the machine. we just service it the same time we do the truck and the truck gets more hours on it.
 

Tazza

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it just blows white smoke when its trying to cold start, then after its running the only smoke it blows is just a small amount when you hit it wide open or close the throttle from wide open, which i think is normal, can't even really tell what color it is. also, i stuck a little plastic soda bottle on the blow by tube and no oil gathered there. ill check it with my finger though. as for hours, i am not sure, the dealer "fixed" it by making it so the hour meter never shut off, so i pulled the wire, and i dont think the hours were correct anyways compared to the age of the machine. we just service it the same time we do the truck and the truck gets more hours on it.
Well if there is no oil thats a good sign that its probably not a problem with your bottom end (pistons and rings)
If it was your injection system i thought it would blow smoke, unless the injector pump isn't delivering enough fuel.
Its normal for it to blow black smoke when throttling up or down suddenly. White smoke at startup is also totally normal.
It has to be an engine problem somewhere... Where is goodtech when you need some good advise!!
 

skidsteer.ca

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Jan 20, 2006
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Well if there is no oil thats a good sign that its probably not a problem with your bottom end (pistons and rings)
If it was your injection system i thought it would blow smoke, unless the injector pump isn't delivering enough fuel.
Its normal for it to blow black smoke when throttling up or down suddenly. White smoke at startup is also totally normal.
It has to be an engine problem somewhere... Where is goodtech when you need some good advise!!
There should not be much air coming out of the blowby tube either, and what does come out should come at a even, steady rate, a puff, puff from the tube indicates one really bad cylinder. If you have changed you fuel filter, (and checked that you have good clean fuel), and you air flter is clean(a plugged af make for black smoke, with power noticabl down ,the smoke would be noticable to) Genrally bad injectors make for hard cold starting and greyish smoke, smoke does not go away quickly (ie 20 30 seconds) during warmup. To test glow plugs Hook a voltmeter to you batt and see if the volts drop when you hit the glow plugs (a 1 v drop is about right) if no drop you may need a relay somewhere. indicates no power going to you glow plugs. Use a test lite to verify by probing the glow plugs. Finally unhook the bar between each glow plug, take a test lite for trailer wiring, hook the ground clamp to the + on you batt a probe each glow plug(where you removed the power strap), the lite should come on as it gets it ground through the glow plug element, no lite = burnt out glow plug. If you blowby is normal, low power is likely fuel related, the glow plugs are only a starting issue, Ken
 

richard

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Dec 21, 2005
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27
There should not be much air coming out of the blowby tube either, and what does come out should come at a even, steady rate, a puff, puff from the tube indicates one really bad cylinder. If you have changed you fuel filter, (and checked that you have good clean fuel), and you air flter is clean(a plugged af make for black smoke, with power noticabl down ,the smoke would be noticable to) Genrally bad injectors make for hard cold starting and greyish smoke, smoke does not go away quickly (ie 20 30 seconds) during warmup. To test glow plugs Hook a voltmeter to you batt and see if the volts drop when you hit the glow plugs (a 1 v drop is about right) if no drop you may need a relay somewhere. indicates no power going to you glow plugs. Use a test lite to verify by probing the glow plugs. Finally unhook the bar between each glow plug, take a test lite for trailer wiring, hook the ground clamp to the + on you batt a probe each glow plug(where you removed the power strap), the lite should come on as it gets it ground through the glow plug element, no lite = burnt out glow plug. If you blowby is normal, low power is likely fuel related, the glow plugs are only a starting issue, Ken
I had a 450 Case dozer that did that one time. For me the problem gradually got worse and eventually would not run. Turned out to be the injection pump......had to have it rebuilt.
 
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