stopped smoking but,why??

Y

yeehaw48

New member
Newb, here, but not to diesel. I recently got a 2006 900 rtv that when first started it would smoke a lot, and you could also notice a slight "vapor" trail under a load.
Just on a guess I noticed some pressure build-up when the oil filler cap was removed (i.e.-blowby) with the engine running. I removed what I would call "the bladder" from the pcv valve(lack of proper terminolgy) located on top of the valve cover. To my shock the smoking stopped. Could this be pointing to a more serious issue?? The machine has 1475 hrs and basically new to me, so I can't tell a history. I got this from a will of a past family member. Any help or guidance would be greatly appreciated..thanks in advance.:pat:
 
Sounds like it can't get rid of the blow by and the crankcase pressure is allowed to build. Once the crankcase pressure builds it will push out where ever it can, probably past the rings or seals somewhere.

Rings could be a little stuck from sitting.
I'm not familiar with how Kubota vents the crankcase. I'd check a manual and make sure the bladder you speak of (it may a type of reed valve which allows flow in one direction only) is OK and installed correctly.

I'd give it an oil change after that and see what happens.

I'm sure you'll get others here to chime in with more experience with this crankcase vent.

Good luck!
 
Good point Realtree. :tiphat: There is an engine vent tube under the engine pointing towards the ground.. Black rubber ...It could be blocked... dirt dabbers cause real trouble here and about ruined my plasma cutter...blocking the air in the tiny end of torchs' air intake and going way up in it .. could be the same way there...
 
I don't think there should ever be pressure stored in the crank case to the point it 'exhales' when you remove the oil filler. That has never happened on mine and I always run it until it's hot before I change the oil.

It sounds to me like the breather tube could be plugged. The breather is part of the cylinder head cover. It looks like there are no moving parts in it. The hose might be plugged as Collie suggested. It would be relatively simple to remove the hose and run a wire or something flexible through it, or soak it in mineral spirits and run some sort of brush through it.

Look up the cylinder head cover in the Kubota on-line parts list. It's under engine.

Fitch
 
Thanks guys for the info provided. Looked up the item I removed and it is listed under the head cover section on the the rtv-x900w section. It is listed as item 050, with a Kubota part #1G911-05203 part name is called a comp valve breather. It basically vents the valve cover back into the intake I think. Will check for and breather tubes tomorrow, but I didn't see any that I can recall. Thank You all for the help...:thankyou2:
 
As stated it might be the breather tube.
Also check the intake air filter, if that is old and getting clogged it will cause smoke and if you remove the pcv/bladder on top of the valve cover this will allow more air in changing the pressure which will help the smoke issue.
Just something to check and eliminate.
 
That narrows it down to excessive engine oil, Piston ring and cylinder worn or stuck or incorrect injection timing.

If you suspect excessive crankcase pressure then that will explain the white/blue smoke.

Excessive crankcase pressure will act like the piston ring and cylinder worn or stuck.

Hopefully it is just a plugged pcv or vent valve line.

Dose the 2006 have the closed breather system?
 
yes I believe it is what you call a closed breather, the vent from the valve cover goes directly into the air intake manifold, I do believe..thanks
 
Also if the machine sat around for a long time the fuel might be bad and will cause white or blue smoke. Injection nozzle trouble will do the same thing.
 
I remember when paper air cleaner elements were a new thing to the farmers and when they would replace the outer element they never changed the inner because you couldn't see any dirt on it. there was a rash of bad turbochargers replaced because the seal on the cold side was leaking and the tractor would smoke. it turns out the only problem was the inner element were plugged and the intake just pulled the oil around the seals in the turbo and the head. I would change the elements and reconnect the pcv. I think when you removed the diaphragm in the pvc all it did was allow the intake vacuum to lesson.
 
The breather on mine, 2004, vents to the atmosphere through a hose that takes it down near the bottom of the engine. On yours it goes to the intake manifold. It also has some sort of valve or compensation device in the valve cover. You might take that out and make check that it's clean and functioning properly.

Fitch
 
aurthuritis said:
I remember when paper air cleaner elements were a new thing to the farmers and when they would replace the outer element they never changed the inner because you couldn't see any dirt on it. there was a rash of bad turbochargers replaced because the seal on the cold side was leaking and the tractor would smoke. it turns out the only problem was the inner element were plugged and the intake just pulled the oil around the seals in the turbo and the head. I would change the elements and reconnect the pcv. I think when you removed the diaphragm in the pvc all it did was allow the intake vacuum to lesson.
Click to expand...

Bingo, I think you and pop58 nailed it replaced the inner filter and cleaned the diaphragm,the filter was very dirty and light didn't show thru it very well. Also fitch was also correct in that I also found it very dirty and stuck I do believe. I started the machine back up with everything re-connected and I had very lite smoking for about 10 sec. and just a puff after it warmed somewhat, and the engine was sped up.

Thanks for everyone's help, you guy's are :a1:
 
Just for reference, that breather on the top with the rubber flap is the same as a PCV valve on the valve cover of a car engine. PCV = Positive Crankcase Ventilation.

It's is designed to allow air out of the engine's valve area and crankcase, while not letting air back in, thus creating a low pressure are to help prevent blow by past the rings and valve seals which causes the engine to smoke with a tinge of blue.

Later they vented the rubber pipe that did just exit to ground , into the intake track to help clean our air we breath.

Without this vent the engine is sucking and puffing air through the pipe and that is not good for the engine as it's not filtered and was only meant to vent air out not in.

Too much crankcase pressure will push oil out of crank seals as well as cause smoking.
 
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