This is my first post here. We have a bobcat s220 that we bought new in 2009. It has over 22,000 hours on it now. When the engine is warm and we shut it off for a couple minutes and fire it back up again around 1,200 rpm (estimate) it starts running rough and blowing whitish blue smoke that smells like unburnt fuel. Sometimes it only lasts a couple seconds other times it lasts longer. Doesn’t use any oil or coolant. We’ve had bobcat out to look at it and they haven’t found anything. We’ve replaced fuel lines from the tank, checked the pick up tube in tank, new fuel filter, rebuilt turbo, rebuilt injection pump and new injectors. And it still does it. It maybe seemed a little bit better for a week after having the injection pump rebuilt but it wasn’t perfect. The squeeze bulb is firm and I’ve even squeezed it when it was running rough and that didn’t help it. Any help is appreciated.
Does the blue smoke clear up after re start, at that many hours, rings, maybe valve seals, is my first guess. I'm sure others will chime in.
Yeah it clears up. Whenever it has sat for say longer than an hour it starts up and runs fine but if the engine is warm and we shut it off for say 5 minutes and start it back up it idles fine but once you rev it up it’ll run rough and blow the white/blue smoke for a couple seconds then clear up. The longest I’ve seen it run rough was probably about 30 seconds.
Does that have a turbo?
Yes it does. I forgot to add that we had that rebuilt too.
Never mind I re read your post. Although it could still be a bad turbo seal. Leaky injector?
How many hours since last engine rebuild?
You have 1 or more injectors that are leaking fuel into the cylinder/s when the engine is shut off. Replace ALL of them.
It’s never been rebuilt
That’s what I’ve wondered if the new injectors we bought were bad.
You didn't get them off some weird website did you? Are they genuine OEM? The fail rate of aftermarket injectors is quite high. Do you have a fuel shop nearby that can check them?
Our local injection shop ordered them right from denso.
Its still consistent with leaking injectors. Was anything done to the injector pump? A failing pump could contaminate new injectors. *just saw it was new
There is a possibility of leaking valve seals but usually the smoke doesn't completely clear up
I'm sure that engine is plumb worn out out with 22,000 hours!
Lol. My uncle runs it 90% of the time and doesn’t like how the new bobcats don’t have a “flat floor”. So he doesn’t really want to upgrade. Other than the issue I’m asking about it really runs well. And doesn’t use any oil. Maybe I’ll have to pull the injectors again and have them tested.
Smoking from unburned fuel? Timing, low compression, injectors not spraying well. At 22k hrs, it's LONG due a rebuild.
An update to this post. Our mechanic and fuel shop both came to the conclusion that it was the mechanical advance gear that is on the injection pump. The mechanic welded it together and had to move it three teeth off of the original mark. It runs like a new machine now!!!! I haven’t seen it run this good for years. And we learned you can’t take a regular non advance gear from the older tier Kubota engines and put it on the v3800 tier 3. It doesn’t work. The teeth are machined at a different angle.