Hi guys. Got a problem with a 2008 Komatsu WA-500. It has 5400 hours on it with no trouble and regular 250 hour service intervals since new. Oil samples are coming back good and Komtrax has detected no problems with the machine. It is running smooth and has no loss of power at all. But it has started smoking out the crank case vent and exhaust stack. It will smoke out the crank case vent when under a load. There will be no exhaust smoke untill you let off the throttle. It then will smoke out the stack and not the vent. We changed the oil and the smoke was dramatically diminished for about 40 hours of operation. It then started smoking heavily again. Changed the oil again with the same result. Would almost quit smoking. Just a small puff at the stack when letting off the throttle. 40 hours or so and it startes smoking heavily again. Blow by was measured at the vent tube and it exceeds the 9" high limit. registers 15". As i said earlier. It is running good, with normal power and normal fuel consumption. Had a mechanic look at it. and he recommended we work it very hard for several hours to get it heated up and see if it helps. He suspects it may be sticking rings. The problem is this loader is so much larger than what we need for the job. We have been unable to work it hard enough to heat it up. I am thinking about just putting a piece of cardboard between the inter-cooler and radiator and see if i can get it to generate a little heat that way. But i am still not convinced that there is something else going on here. I would think if there was a cylinder problem it would smoke out the stack all the time.. Any ideas or thoughts would really be appreciated guys.

 

Just for some fun, take a close look at the turbo. It sounds suspiciously like you might have a seal gone in there. The excessive crank case pressure is the result of compressed air being driven through the center section, and down the return line.

I have seen many brands of equipment do this, and man, they'll blow oil full stream out the CCV when under load. Sometimes the bad seal is tough to diagnose, other times, the turbo wheels and shaft will rattle around like crazy.

Good luck with it

 

Does it have an air compressor on it? I don't think they do. Bit if it does, a bad air compressor can pump a metric shitton of air into the crank case. You have to eliminate the turbo and air compressor, before you turn on the internals.

 

The mechanic looked at the turbo only for looseness. As quickly as this problem came on, I was suspicious of the turbo. Unsure of exactly how to prove it tho. I have never diagnosed a failing turbo. Would disconnecting the return line and seeing what comes out of it. Oil or air, Be useful?

 

With 5400 hrs it's not a break in issue so loading and heating it up probably won't make it better. I had a similar issue with a Daewoo excavator. The engine ran as it should, power was good. When you changed the oil the blue smoke and blow by reduced but would return in a few days even though everything checked out ok. I purchased the machine used and found it had been on long term rent to the County before I got it. The best I could determine was the rings were worn prematurely from long hours of idling. Can't let the County workers sweat. I found that adding something like STP periodically to the oil between changes and keeping the engine off the low idle helped reduce the smoke but a rebuild was going to be the only fix.

 

It will be a few hours before i can get the machine to check anything. But i did take a quick peek and i can see oil leaking on the downstream connection from the turbo to the muffler system.

 

and the plot...thickens.

Let me know

 

Fingers crossed that its coming from the turbo and the exhaust manifold is dry....... dun dun dun.......

 

Okay here is wwhat i have done. I disconnected hose from intercooler to intake. Clean & dry. no oil. I disconnected oil return line from turbo. Couldnt run engine with it disconnected and was no room to put a catch bucket under it. I did idle the engine for a few seconds to determine whether or not i was getting oil flow thru the return line. and there was oil flow.hooked it back up and started the machine. at idle it was putting out a light haze of blue smoke. I noticed a drain line that came from the bottom of the muffler. the end of it was plugged with dried mud. Cleaned it out. We were looking at the Crank case vent hose and feeling of the amount of air coming from the it. I put my hand over it and blocked it for a couple seconds and noticed that the light blue haze of smoke from the exhaust suddenly got 3 times thicker. then we noticed the drain tube from the muffler was flowing a full stream of hot oil out of it. about a gallon a minute or so. I dont think blocking the vent hose for a couple seconds would have blown anything apart. and i am not sure of exactly when the oil started running from the muffler drain. we saw wet oil on the exhaust manifold the other day where the turbo and manifold join together into the muffler. But now there is oil dripping from there as well instead of just a wet spot. I say turbo is bad.

 

Well, great minds think alike.... and so do ours

Good diagnostic work. Something else to check, while you're at it, is how badly plugged the muffler is at this point. You might end up changing that as well.

 

Thanks for the help. I was initially just grasping at straws to justify my gut instinct that this motor was not gutted. Was sure glad for someone to step in on my side and help me with a plan of attack. I had never expierianced a turbo failure before and learned a lot from this one. And that we saved the company $40,000 by not buying the remanufactured engine the komatsu dealer was peddling to us as our only hope. Thanks again guys.