I have a 1986 Kenworth w-900 with a cummins 444. I pulled a load the other day and the truck ran fine, never ran hot or lost oil pressure. After running the load I noticed what seem to be a knock. The engine runs fine, no missing, no smoke. Still has plenty of power. I am trying to find out what maybe causing the "knock". It seems like there might be a faint fuel smell in the oil. Can a injector cause a knocking sound? Thanks.
1986 w-900 big cam 444, need help dignosing
Discussion in 'Trucks [ Eighteen Wheelers ]' started by TaggHL, Sep 2, 2014.
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Have you run the overhead? A loose/missing push tube will cause an audible knock.
Fuel in the oil might be due to a bad injector seat, but an oil analysis should be done to see if there is actually fuel in the oil. New cups are cheap, but it'll be a few hours labor to pop them in. -
I have not tried anything yet. I was trying to find a good starting point. You say run the overhead, would that be the first thing to check before going to the injector?
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get an oil sample see if you have alot of fuel in the oil
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An oil analysis comes first. If it says there is fuel in the oil, you might as well just order new injectors and cups before you do anything else. You'll have to run the overhead after you install them anyway.
Another sign of bad injector seat is black fuel. Pop your fuel filter off and see what color the fuel is in it. This is often a sign that combustion gasses are getting past the injector cups and into the return fuel. (Park facing downhill before you do so you can bump start it rather than cranking the starter to death or using ether) -
Not likely a bad injector with no smoke, need to listen to the engine and locate exact cylinder a long screwdriver with the handle to your ear will do for that.
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