metalic kohler gen set noise

[robertglines1]

Try ing to diagnose a metalic knock in a kohler 4 cyl diesel of the early 80's vintage. Oil pressure 60psi no fuel in oil. has injectors in exterior position outside valve cover.  when you break line at injector it kills cly same on all 4.  metalic click seems to originate from front cyl about 1/2 way down behind a access plate on side. ? is this where you adjust valve lash? could it be a bent push rod? really don't think it is a rod/just not the same knock sound plus the oil pressure has not fallen.   Ideas   Bob  l

[luvrbus]

Perkins Diesel ? sounds like carbon build up time for a spray bottle of water lol 

[robertglines1]

lite miss in intake? to break up carbon at a idle.

[Gary '79 5C]

OK, I'll bite.

Never heard of clearing/cleaning out carbon buildup with a water mister, but since I am from W Va, there is alot of living I have not encountered.....

Is this sprayed into the air intake to "blast" the buildup ??

[Chopper Scott]

We used to pour cold water down gas burners if they got carboned up. Get the engine up to operating temp and more if possible or safe and trickle water in the air throat while it is running. The colder charge breaks up the carbon depsits. It's like fogging a motor only with cold water.

[Hi yo silver]

 Luvrbus, Yep, it's a Perkins.  Bob, you must'a woke up before breakfast this morning! Thanks for your help. Maybe you were right, it's not a major problem. I love LITTLE problems. Guys, where does the carbon accumulate and how does it cause a knock? It didn't sound too loud when I started it to show Bob yesterday, so I ran it for about 15 min. under load and it gradually quietened somewhat and smoked less, almost no smoke, then began to get a little louder and the smoke (looks white) seemed to be a little more.
Bob, I say we will try the solution and keep 'em posted, waddayu think?
Dennis   

[Hi yo silver]

Here's another question.  How do you set the speed at idle?
Dennis

[JackConrad]

Dennis,
  A carbon knock is when carbon builds up on top of the piston and hits the head when the piston is at TDC. The carbon usually builds up from not putting enough load o the engine. Back in the early 70's, I worked as a mechanic for a Chevrolet dealer. During the winter, we had a lot of small block chevy's come in with carbon knock from people letting there engines idle in the mornings to warm up the interior before they drove slowly to work in the city traffic. Those engines were a wedge head combustion chamber design and had very little piston/head clearance. We would slowly pour about 1/2-2/3 of a quart of ATF down the carburetor, then rapidly pour in the rest of the quart killing thew engine. Let it set about 15 minutes, restart and blow a bunch of carbon out the tailpipe.

[luvrbus]

Water is best for a diesel no chance of a runaway the temps are so high in the combustion chamber on a diesel it turns to steams and breaks the carbon lose,I do that on a engine that is ready for work cleans it up good saves on the wire brushing


good luck

[JohnEd]

Dennis,
  A carbon knock is when carbon builds up on top of the piston and hits the head when the piston is at TDC. The carbon usually builds up from not putting enough load o the engine. Back in the early 70's, I worked as a mechanic for a Chevrolet dealer. During the winter, we had a lot of small block chevy's come in with carbon knock from people letting there engines idle in the mornings to warm up the interior before they drove slowly to work in the city traffic. Those engines were a wedge head combustion chamber design and had very little piston/head clearance. We would slowly pour about 1/2-2/3 of a quart of ATF down the carburetor, then rapidly pour in the rest of the quart killing thew engine. Let it set about 15 minutes, restart and blow a bunch of carbon out the tailpipe.

I have done that many times in gas engines.  Great idea....for gas only.  A DD will certainly run away as ATF is fuel to a DD.   I think starting the engine after I put atf in the cylinders would be a run-away.  Don't know how you would do that without the engine running but people are resourceful.

I have heard that naptha is the absolute best for cleaning fuel systems and injectors and that you connect the spill line to the container that you are feeding from to use it all in the engine.  Anybody?

Thanks,


John

[TedsBUSted]

. . .It didn't sound too loud when I started it to show Bob yesterday, so I ran it for about 15 min. under load and it gradually quietened somewhat and smoked less, almost no smoke, then began to get a little louder and the smoke (looks white) seemed to be a little more. . . .

With the smoke and knock possibly linked, I would suggest moving the injector to another cylinder to see if the knock follows the injector. Of course it could also be a pump issue, which wouldn't move with the injector, but the injector swap would be an easy first test.

---

[JohnEd]

If the piston is smacking into the head hard enuf for you to hear a knock just imagine how much force is being applied to the wrist pin and bearing.

I suggest you find the cause and correction for this "quick like a bunny".  Maybe try a repair shop for a professional analysis?

John

[Hi yo silver]

Well, I can only conclude that the problem was carbon build-up. I have only run this genny for maybe fifteen or 20 hours since I have had the bus, and then, not under much load. Bob and I built a fire in it this morning and after some minor pecking for a couple of minutes, it quieted down and the exhaust cleared up nicely.  I decided to try the water mist trick gradually anyhow.  The only real effect we could see was some black accumulation on the ground from the exhaust after a while. There was only one thing to do when Marilyn asked how the generator was doing. I dusted my hands, smirked, and told her, "Oh yeah. Nuthin' to it. We took care of it!" Right, Bob?
Thanks, guys for your input. I'm hoping it just needs to run more often, and under a good load. Also, I thought maybe I would run some oil additive through it for a while, then do an oil change.
Dennis     

[luvrbus]

Black soot is all you will get most of the time fwiw

good luck

[Chopper Scott]

I once had a tranny in a pickup rebuilt because it was knocking. Still ran ok but I was being anal and it bothered me. Better rebuilt at home than down the road. New tranny sounded the same!!!!!!  Eventually put a floor jack against one of the mufflers and it quit....... Caved it in some more and never had any more problems. Such is life.....