Go Bottom7305 Cub Smoking
 | Shawn Donnelly
Join Date: Posts: 1 
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2002-10-06 43460
I own a 7305 Cub Cadet with about 250 hours on it. It seems like it is runng rich in fuel. (Always smoke blue, as in fuel) Is this commen with Mitsubishi's? My neighbor has the same problem with his 7305
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| DK35vince
Join Date: Feb 2002 Posts: 689 Western,Pa. 
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2002-10-06 43461
Rich in fuel=usually black smoke
Oil=usually blue smoke ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2002-10-07 43486
These are gas engines I guess. Exhaust smoke in diesels and gas engines has different interpretations, but blue is oil. Black is rich in gas, but may be hot or restricted air intake in diesels (too much fuel or too little air is about the same).
I'd make sure the oil has the correct level and viscosity. then, I'd check for blow-by from the crankcase breather--at 250 hours there shouldn’t be any. I might check for excess oil under the rocker arm cover, although it might be difficult to judge how much is excessive. And I might run a compression test.
In diesels, diagnosis often is made based on whether there is exhaust smoke, when and whether it's black, gray or white. Most diesels don't see blue exhaust unless there's a part failure, because worn diesels have low compression and become hard to start. They tend to be rebuilt before they turn into oil burners.
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| Ted@Abbeywoods, LLC
Join Date: Posts: 1
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2002-10-07 43511
Dear Shawn,
Your engine is a Mitsubishi K3M-D15R 30hp 3 cylinder liquid cooled diesel, it is the successor to the earlier 27hp K3M-D14R. I don't know what you are seeing or when so it is hard to say what is going on, is it at startup, is it while under load? Tell us some more, please.
I have never seen a K series blow blue while at normal operating temp even under full load. I've seen plenty of black due to poor fuel, bad injectors, the wrong injection timing, etc. But blue? I've only seen that when they start up when really, really, really cold, or started when cold without using the glow plugs, or started when cold after only a token preheat. But this clears up after normal operating temp has been reached.
The condition you describe is not normal by any means if it occurs when operating at proper temp. It could be as simple as poor fuel, especially if your neighbor has the same problem. I suspect you have a trip to the dealer coming up. Good luck. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-10-08 43543
Thanks Ted! I know you know Cubs. I know that some models have either gas or diesel engines but I don't recall which models. The description does sound unusual for a fairly new diesel. Perhaps that's why I though it might be a gas engine.
I know that on my 1710 I consider some puffing of gray exhaust when adding throttle or before the engine is up to operating temp to be normal. But it’s definitely gray rather than blue. The puffing also was reduced after I set the valves. Earlier I reduced the puffing a lot by discovering that the thermostat was stuck partially open (actually a gasket was installed on the wrong side of the thermostat). There’s a couple of ideas here and I hope an illustration of fairly normal operation. I hope we'll hear more about the problem.
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