731with F2L511 Black smoke problems

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lecuyerb

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Hi, I'm fairly new to diesels but have worked on easy stuff for years. I have an older Bobcat skidsteer with a 2 cyl air cooled Deutz. Here is the story. It had used down the diesel in the tank to the lowest point since I owned the machine ~10 years. I filled it up and started it with my normal procedure of about %50 throttle open, then start and ran it normally. At the time it had a trencher attached to it. After running it at %50 for 5 minutes I disconnected the trencher and went to move and it died from load. After that and ever since it takes %100 percent throttle and lots of cranking to start. Then when it starts it smokes like a train pure black and makes all kinds of different noises mostly bad sounding. It is like it is under a serous load? What have I tried: Well I figured I got muck in the fuel system so I replaced the inline and can filter, bled the system and ran it again - same black smoke. I thought maybe a hydraulic valve was stuck and the hydraulic system was causing a load so I re attached the trencher and operated it and all the tilt/arms everything worked. So I am thinking it is an engine issue? Is it possible I clogged an injector or something? How can I tell if both cylinders are working? My thought is one is not and that is the load? I did also check the intake/filter for clogs and it looked real clean. I really like this unit but the engine is tired and uses oil - I would just in frame it but I think this problem would still be there? Any help would be greatly appreciated? Thanks, Brian Elk Grove, CA
 

Tazza

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So when you re-attached the trencher its still the same rite? puffing black smoke.
How did you re-prime the system? did you un-do the screw on the injector pump and operate the lift pump on the right side of the engine to get the fuel moving?
The other thing you may check is the excess fuel button, have a look on the injector pump, there is a small button that is used to feed the engine heaps of fuel for startup. Give it a bit of throttle and see if it clicks down, you will hear it click and it will sit lower than usual. When the machine starts it will pop back up, if there is a problem it *may* be staying in that position.
I have heard a horror story of someone re-priming their machine with a can of engine start, just kept giving it a snort until it had sucked up fuel.
The only other thing you could do is to pull the injectors out and do a compression test and maybe even check the injectors spray pattern to see if the nozzle is spraying correctly. Black smoke is generally excessive fuel, this could be because the injector isn't spraying a mist, but if you have filters no junk should have gotten through.
Let me know how things go, i have a 731 my self, its a great machine. The engine it has is great and was replaced just before i got it, it came with the old engine that i was told was lazy.
 

Tazza

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So when you re-attached the trencher its still the same rite? puffing black smoke.
How did you re-prime the system? did you un-do the screw on the injector pump and operate the lift pump on the right side of the engine to get the fuel moving?
The other thing you may check is the excess fuel button, have a look on the injector pump, there is a small button that is used to feed the engine heaps of fuel for startup. Give it a bit of throttle and see if it clicks down, you will hear it click and it will sit lower than usual. When the machine starts it will pop back up, if there is a problem it *may* be staying in that position.
I have heard a horror story of someone re-priming their machine with a can of engine start, just kept giving it a snort until it had sucked up fuel.
The only other thing you could do is to pull the injectors out and do a compression test and maybe even check the injectors spray pattern to see if the nozzle is spraying correctly. Black smoke is generally excessive fuel, this could be because the injector isn't spraying a mist, but if you have filters no junk should have gotten through.
Let me know how things go, i have a 731 my self, its a great machine. The engine it has is great and was replaced just before i got it, it came with the old engine that i was told was lazy.
Also, what noises does it make that aren't normal that you speak of?
UUM, i just re-read your post, you did dis-engage the aux hydraulics didn't you? the right lever should be in the centre. Even at 1/2 throttle it shouldn't care, mine will only stall when the revs are down low.
 

lecuyerb

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Nov 6, 2006
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Also, what noises does it make that aren't normal that you speak of?
UUM, i just re-read your post, you did dis-engage the aux hydraulics didn't you? the right lever should be in the centre. Even at 1/2 throttle it shouldn't care, mine will only stall when the revs are down low.
Hi, First thanks for the reply. I primed the system with the bleed screw and again at the injector by cracking the lines open/closed per the manual. I have not had the level click ever - I always thought it was a manual primer/pump. I will check that next to make sure it is not stuck down but I am sure I pressed it a few times already. My fingers are crossed though. I am certain the aux is not engaged - that was my first hope - when I re attached the trencher I worked it forward and reverse before removing the trencher again. I have never pulled injectors and am not sure my manual covers that, it must, but just in case is there anything special to know? How do you test them when out? The noises were tough to separate out but I heard belt squeel, knocking (though I have never run it that high of RPM before so not sure if that would be normal). I don't know it the belt noise was from the high rpm and load from the pump that high or other but the knocking was more concerning. I have only run it maybe a total of three minutes since this started. The black smock is massive it clouds the whole area. Thanks again, Brian
 

Tazza

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Hi, First thanks for the reply. I primed the system with the bleed screw and again at the injector by cracking the lines open/closed per the manual. I have not had the level click ever - I always thought it was a manual primer/pump. I will check that next to make sure it is not stuck down but I am sure I pressed it a few times already. My fingers are crossed though. I am certain the aux is not engaged - that was my first hope - when I re attached the trencher I worked it forward and reverse before removing the trencher again. I have never pulled injectors and am not sure my manual covers that, it must, but just in case is there anything special to know? How do you test them when out? The noises were tough to separate out but I heard belt squeel, knocking (though I have never run it that high of RPM before so not sure if that would be normal). I don't know it the belt noise was from the high rpm and load from the pump that high or other but the knocking was more concerning. I have only run it maybe a total of three minutes since this started. The black smock is massive it clouds the whole area. Thanks again, Brian
I have never pulled my injectors either, but to remove them you remove that arm that sits on the shoulder of the injector its self, remove the tube line and i think you use a slide hammer that you screw on to pop them out. I'm sure you won't have one that you can simply screw on.
Like i said, i have a spare engine for mine, if i get a chance i will have a go at pulling an injector and see exactly what is involved. As for testing, i would remove the injectors and tube lines at the injectors and pump, re-attach 1 line or 2 if possible with the injectors hanging out the back of the engine bay. I will attempt to show you this too. Crank the engine and check the spray pattern, but don't touch anything! the diesel can penetrate your skin and cause nasty problems! The spray should be narrow and even, without any droplets forming at the nozzle.
I thought that button was to shut the engine off, then was told it was excessive fuel. On a cold day give it a touch of throttle, press the button and flick the key, it will start almost instantly, but with lots of smoke.
See how you go.
 

Tazza

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I have never pulled my injectors either, but to remove them you remove that arm that sits on the shoulder of the injector its self, remove the tube line and i think you use a slide hammer that you screw on to pop them out. I'm sure you won't have one that you can simply screw on.
Like i said, i have a spare engine for mine, if i get a chance i will have a go at pulling an injector and see exactly what is involved. As for testing, i would remove the injectors and tube lines at the injectors and pump, re-attach 1 line or 2 if possible with the injectors hanging out the back of the engine bay. I will attempt to show you this too. Crank the engine and check the spray pattern, but don't touch anything! the diesel can penetrate your skin and cause nasty problems! The spray should be narrow and even, without any droplets forming at the nozzle.
I thought that button was to shut the engine off, then was told it was excessive fuel. On a cold day give it a touch of throttle, press the button and flick the key, it will start almost instantly, but with lots of smoke.
See how you go.
Removal of the injectors is a snap.
Remove the tube lines and tap off lines from the 2 injectors. Un-do the nut on the plate that holds the injector down. Wiggle the injector pulling it up wards and presto! If its a little hard to pull up, use a pair of vice grips on the flat surfaces and pull up wards.
I had a go today, was very easy. I removed the tube lines at the pump too and turned it 180 degrees and re-attached them, so it was hanging out the back. Attach your injectors here and crank it over and see the spray pattern. From the looks of the nozzles it looks like a wide cone shaped spray, not a narrow one like i thought. With running your diesel low, it may have caused damage to your injector pump, this could explain the smoke too.
Remember, diesel under high pressure can pierce the skin, don't touch anything when its under pressure. Better to be safe than sorry!
Check the excess fuel button first, start easy, then work up to the hard, and expensive.
 

lecuyerb

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Nov 6, 2006
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Removal of the injectors is a snap.
Remove the tube lines and tap off lines from the 2 injectors. Un-do the nut on the plate that holds the injector down. Wiggle the injector pulling it up wards and presto! If its a little hard to pull up, use a pair of vice grips on the flat surfaces and pull up wards.
I had a go today, was very easy. I removed the tube lines at the pump too and turned it 180 degrees and re-attached them, so it was hanging out the back. Attach your injectors here and crank it over and see the spray pattern. From the looks of the nozzles it looks like a wide cone shaped spray, not a narrow one like i thought. With running your diesel low, it may have caused damage to your injector pump, this could explain the smoke too.
Remember, diesel under high pressure can pierce the skin, don't touch anything when its under pressure. Better to be safe than sorry!
Check the excess fuel button first, start easy, then work up to the hard, and expensive.
Wow thanks checking out how to do that. I played with the lever last night and it did not seem to do much. Seemed to move about the same way as always - at least as best I can remember. I will pull the injectors and try that next maybe a day to get back out there. Thanks again, Brian
 

lecuyerb

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Wow thanks checking out how to do that. I played with the lever last night and it did not seem to do much. Seemed to move about the same way as always - at least as best I can remember. I will pull the injectors and try that next maybe a day to get back out there. Thanks again, Brian
Well I finally determined what was causing my problems on this yesterday. I had tried removing the injectors and running them outside and all looked fine so I started into more testing. The engine would not start at all and I was sure it was a diesel delivery problem - too much diesel causing the soot. Well after checking injector pressures I moved to compression tests - all with very special gauges I borrowed and one cyl was way down on pressure. I knew this engine had that problem as it used oil and had blue smoke at the rate of a quart every 3-4 hours of use. I thought it is time to do an inframe and fix the cyl leak. Well it only takes about 1.5 hours to tear the top end off the 511 and I had zero problems with doing it and parts would only be 2-300. After I got both cylinders off I spotted a problem the rear piston was cracked from the oil ring through the skirt. The cyl look fine no gouges or wear patterns I could see. Well I removed the piston from the rod and decided to remove the front piston from its rod. In doing this part I noticed the rear rod was dropping under the lip of the block when I rotated the crank to get the fron piston heigher so I held it up. After removing the front piston I rotated it so both were even. That is when I notice another problem the rear rod had 1/4 to 1/2 of play on the crank journal. I cant see yet but there can't be any bearing in there at this point. Long story short I left the block in the bobcat and started cleaning the other parts. I manged to disassemble the heads and wash and bead blast most everything from the top end. Today I will pull the block and tear it down and see if the crank is ruined and if the rod is gone too - I expect they both are gone for good. So anybody out there got a recommendation on where is the best place to buy parts? It seems the cheapest is ebat.de but getting the parts is a problem. I would love to find a used crank and rod. There is a crank on ebay for $300 but I think it is india not German? Anybody got a used f2l511 for sale? Before I buy parts I would put a good runner in there if I can find one. Brian
 

Tazza

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Well I finally determined what was causing my problems on this yesterday. I had tried removing the injectors and running them outside and all looked fine so I started into more testing. The engine would not start at all and I was sure it was a diesel delivery problem - too much diesel causing the soot. Well after checking injector pressures I moved to compression tests - all with very special gauges I borrowed and one cyl was way down on pressure. I knew this engine had that problem as it used oil and had blue smoke at the rate of a quart every 3-4 hours of use. I thought it is time to do an inframe and fix the cyl leak. Well it only takes about 1.5 hours to tear the top end off the 511 and I had zero problems with doing it and parts would only be 2-300. After I got both cylinders off I spotted a problem the rear piston was cracked from the oil ring through the skirt. The cyl look fine no gouges or wear patterns I could see. Well I removed the piston from the rod and decided to remove the front piston from its rod. In doing this part I noticed the rear rod was dropping under the lip of the block when I rotated the crank to get the fron piston heigher so I held it up. After removing the front piston I rotated it so both were even. That is when I notice another problem the rear rod had 1/4 to 1/2 of play on the crank journal. I cant see yet but there can't be any bearing in there at this point. Long story short I left the block in the bobcat and started cleaning the other parts. I manged to disassemble the heads and wash and bead blast most everything from the top end. Today I will pull the block and tear it down and see if the crank is ruined and if the rod is gone too - I expect they both are gone for good. So anybody out there got a recommendation on where is the best place to buy parts? It seems the cheapest is ebat.de but getting the parts is a problem. I would love to find a used crank and rod. There is a crank on ebay for $300 but I think it is india not German? Anybody got a used f2l511 for sale? Before I buy parts I would put a good runner in there if I can find one. Brian
I wish you found out that problem last year..... I had a spare engine that i sold with my 731, i could have pillaged it for you :(
Keep hunting around e-bay i guess.
You may be able to get the crank ground and a new bushing put in the con rod by an engine shop.
 

Tazza

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I wish you found out that problem last year..... I had a spare engine that i sold with my 731, i could have pillaged it for you :(
Keep hunting around e-bay i guess.
You may be able to get the crank ground and a new bushing put in the con rod by an engine shop.
My 731 had a replacemnt engine installed before i bought it. It came from a Dynapac roller.
It would be an idea to go hunting for a running engine from machinery, it gives you more options than JUST bobcat gear. I believe generators used these too, it will just give you more options of where to call and see what you can dig up for a reasonable price.
You may still be lucky enough to get the crank ground and the con rod bushed and a new set of pistons and rings.
I hope you get it all sorted out, the Deutz engine they run really is quite a good engine.
 

mikie

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Feb 4, 2007
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My 731 had a replacemnt engine installed before i bought it. It came from a Dynapac roller.
It would be an idea to go hunting for a running engine from machinery, it gives you more options than JUST bobcat gear. I believe generators used these too, it will just give you more options of where to call and see what you can dig up for a reasonable price.
You may still be lucky enough to get the crank ground and the con rod bushed and a new set of pistons and rings.
I hope you get it all sorted out, the Deutz engine they run really is quite a good engine.
y.ou can probably get the crank built up and ground down to specs. thats what i did on my 743b. then you know what you have and not buying a problem to throw more money at.
 

oiu789

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When testing get the injection lines loose and the snug them down wrap a rag around line to catch diesel run engine and crack loose a line see how the engine responses snug it down and go to the next cylinder and so on.
 

oiu789

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Dec 23, 2017
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When testing get the injection lines loose and the snug them down wrap a rag around line to catch diesel run engine and crack loose a line see how the engine responses snug it down and go to the next cylinder and so on.
This like pulling plug wires on a gas engine
 
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