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Komatsu PC75uu-2 Black smoke under load.

Directional

Member
Joined
Jun 26, 2009
Messages
21
Location
Alberta Canada
Gentlemen

I've got a new to me Komatsu PC75uu-2, and after it's been running a while and is up to operating temperature, it'll smoke black and bog down when under load. On initial startup, it has a little blue smoke for a minute or two, then runs real great for 15 or so, nice and strong, but when the temp gets up, i always get the same black smoke when i'm taking a bucket full. I'm waiting on my local parts place to get a whole round of filters in, fuel, oil, hyd, fuel/water seperator, air, but for now it's just the way it came off the truck.
 

toomanymachines

Well-Known Member
Joined
Feb 2, 2011
Messages
69
Location
mb
I also have tracked down a komatus 75. mine will run for hours without overfueling. at least I have never seen it puff black. Black smoke means too much fuel. Find a guy that can figure out how to turn down the fuel on the injector pump.
It may be another problem though. maybe something is making it run that hard. black smoke means that it is working very hard. could be too much fuel, or the turbo is not providing enough air( too much fuel). I do not think that fuel filters will help, may even make it worse.
YOu may want to check the simple things first like the air filter. replace that first. maybe the air filter is sucking itself closed and plugs further after it runs for a while.
 

WV earth mover

Well-Known Member
Joined
Mar 6, 2011
Messages
110
Location
WV
Mine has always smoked since 2001 and never really gotten any worse other than the bad fumes when working down in a basement ive learned to live with it. Ive tried every filter and oil,fuel additive there is nothing seems to make a diff but it does burn about 1 qt of engine oil every 20-40 hrs depending on work load not really enough to matter just a hassle
 

WV earth mover

Well-Known Member
Joined
Mar 6, 2011
Messages
110
Location
WV
Well not really both of our d4's can use a qt in 12 hrs with heavy use and they dont smoke at all
 

rare ss

Senior Member
Joined
Apr 1, 2011
Messages
460
Location
Western Australia
Gentlemen

I've got a new to me Komatsu PC75uu-2, and after it's been running a while and is up to operating temperature, it'll smoke black and bog down when under load. On initial startup, it has a little blue smoke for a minute or two, then runs real great for 15 or so, nice and strong, but when the temp gets up, i always get the same black smoke when i'm taking a bucket full. I'm waiting on my local parts place to get a whole round of filters in, fuel, oil, hyd, fuel/water seperator, air, but for now it's just the way it came off the truck.

give it a full service, there will be a fuel screen in a banjo fitting usally on the inlet to the transfer pump (if its been put back in the right spot) new fuel filter/s, air filter/s and start troubleshooting after that
I'd check high idle rev's if the service doesnt fix the issue
 

WV earth mover

Well-Known Member
Joined
Mar 6, 2011
Messages
110
Location
WV
The only fuel problems we ever had was when we first got it and had an alge growing in the tank that was a nightmare to kill, it would stall out and you had to take the line off the bottom which was a mess especally with a full tank and clean the suction screen in the tank , took the biggest part of that summer and about 20 fuel filters cause we ended up removing the tank screen and putting an inline filter just prior to the spin-on but we finnally killed it with additives and it never came back
 

rare ss

Senior Member
Joined
Apr 1, 2011
Messages
460
Location
Western Australia
The only fuel problems we ever had was when we first got it and had an alge growing in the tank that was a nightmare to kill, it would stall out and you had to take the line off the bottom which was a mess especally with a full tank and clean the suction screen in the tank , took the biggest part of that summer and about 20 fuel filters cause we ended up removing the tank screen and putting an inline filter just prior to the spin-on but we finnally killed it with additives and it never came back

we used to get a similar black looking fungus, used to block the screens, good additive's can kill it but it takes time to clean out the system
 

WV earth mover

Well-Known Member
Joined
Mar 6, 2011
Messages
110
Location
WV
Yeah we change eng oil at 200 hrs or 1 year ,hydro filter at 400 hrs , fuel filter at 200 hrs and air as needed . we do though have 4 machines that go the full 200 without needing any ever added one of which has 8800 hrs .
 
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