blowing carbon/soot out of a Onan/Cummins

[bigb]

My Onan/Cummins QD3200 is still puffing some smoke under load so I thought I's see if I can blow some soot out of the muffler and spark arrestor. The manual shows only one plug on the bottom of the muffler but as you can see I have two, anyone know if they are both intended for soot cleanout? (I already removed one plug and as you can see there is some soot accumulation)

[mla2ofus]

If the engine is in good shape it sounds like you have an over rich fuel problem or an intake restriction.

[Welder Dave]

If the plug comes out easy, why not take it out? Might be worth putting some Seafoam in the fuel to help loosen carbon and soot deposits.

[milomilo]

Start it up a and run some spray Sea Foam through it. It will clean the valves, piston and muffler Stay up wind as it can get very smoky. Keep the engine well revved up. Instructions are on the spray can.

[bigb]

If the plug comes out easy, why not take it out? Might be worth putting some Seafoam in the fuel to help loosen carbon and soot deposits.

It draws fuel from the motorhome tank and I'm not sure I want to put Seafoam in a DPF equipped Sprinter.

[bigb]

Start it up a and run some spray Sea Foam through it. It will clean the valves, piston and muffler Stay up wind as it can get very smoky. Keep the engine well revved up. Instructions are on the spray can.

Won't it runaway?

[M J D]

It draws fuel from the motorhome tank and I'm not sure I want to put Seafoam in a DPF equipped Sprinter.

Exactly. That snake oil will cause more problems than it will ever solve. I would remove the muffler and go at it that way

[bigb]

If the engine is in good shape it sounds like you have an over rich fuel problem or an intake restriction.

Well it only has 190 hours and being 10 years old I don't suppose it was worked very hard. Intake is open, new air filter and new fuel filter. New 15/40 oil. Been working it hard but still puffing a bit when loaded over 50%, maybe the injector is dirty affecting the spray pattern? Has not burned any oil whatsoever in the 10 hours run time I've owned it. Going to pull muffler/spark arrestor plugs (3 in all) and load it up heavy this weekend for a few hours.

[CAVEMANN]

I don't think the seafoam is a terrible idea, the key is a very controlled quantity at a time, I would use the non aerosol and introduce it through the air intake, another option is to mist water into the intake with it running, used to be pretty common on gas engines. Being a diesel you'll have to control the amount of fuel(seafoam) to prevent runaway.

[bigb]

I don't think the seafoam is a terrible idea, the key is a very controlled quantity at a time, I would use the non aerosol and introduce it through the air intake, another option is to mist water into the intake with it running, used to be pretty common on gas engines. Being a diesel you'll have to control the amount of fuel(seafoam) to prevent runaway.

I remember doing that with my V-8 muscle cars when we still used cubic inches to identify our engines. On my big block Olds I ran methanol mixed with water in a tank under the hood, I guess I was one of the first "meth heads". At 11.25:1 compression I needed it when the octane/lead started going down to prevent detonation.

[forhire]

Diesel generators do not really like running unloaded for extended time, although I can't imagine having any issue after only 10 hours. I typically like to see 80% load or better otherwise it can coke up and/or wet stack. I'd add some plug in electric heaters to get your load up to near 100% and see how it does. Run it hard for about an hour. When Kohler came out and load banked my standby genset I expected some fancy load testing machine. Nope, just a big box fan with a lot of switchable resistance elements. They toggled the elements to reach the 130% peak power maximum. It was kinda nice, middle of the winter, dumping 27kW worth of heat. Everyone was warm and toasty.

I'm not sure about the plugs. I'd pull them and see. Most standy machines have a weep hole that drains any rain that may get in. One year my stack dumped some pretty tar looking soot during high winds/rain. I now make a point to make sure I don't go all year without running the machine hard at least once if the power doesn't go out. Clearly exercising was sooting up everything pretty bad.

[bigb]

Diesel generators do not really like running unloaded for extended time, although I can't imagine having any issue after only 10 hours. I typically like to see 80% load or better otherwise it can coke up and/or wet stack. I'd add some plug in electric heaters to get your load up to near 100% and see how it does. Run it hard for about an hour. When Kohler came out and load banked my standby genset I expected some fancy load testing machine. Nope, just a big box fan with a lot of switchable resistance elements. They toggled the elements to reach the 130% peak power maximum. It was kinda nice, middle of the winter, dumping 27kW worth of heat. Everyone was warm and toasty.

I'm not sure about the plugs. I'd pull them and see. Most standy machines have a weep hole that drains any rain that may get in. One year my stack dumped some pretty tar looking soot during high winds/rain. I now make a point to make sure I don't go all year without running the machine hard at least once if the power doesn't go out. Clearly exercising was sooting up everything pretty bad.

Thanks, I've only had it for 10 hours and those 10 hours have been run hard. The PO had it for 10 years and 180 hours so I suspect it was not run hard during his ownership.

[forhire]

Thanks, I've only had it for 10 hours and those 10 hours have been run hard. The PO had it for 10 years and 180 hours so I suspect it was not run hard during his ownership.

Does it puff black smoke when you power something on that adds a heavy draw, like when your AC cycles on? Or is it puffing on a stable draw? I'd expect it to puff a little when you add a load, kinda like a truck might at the bottom of a hill. It'd put a clamp meter on it and watch the load and smoke.

+1 mla2ofus, I'd check the air filter. My VW diesels drop milage when the filter needs changed. A quick test would be to pull the air filter and see if it improves, unless your in a dusty environment, of course.