| Author | Message | ||
| Nick Rating: N/A |
We made a run from Elkhart, Indiana to the Terre Haute area the other day and ran into a nasty rainstorm. Like being in a monsoon. When we pulled into the campground and were registering, I noticed our 1976 MCI 8 with 8V71 was putting out a very noticible cloud of blue smoke while idling. Never has done this before. I checked the oil, it is full, the smoke was coming out of the exhaust. Bus ran fine all the way here. No overheating, no loss of power. Driving down the road I did not notice any smoke, but again, it was pouring rain and may have been hard to see. We have the old oil bath air cleaner. Someone uggested that maybe we got water into the oil in the air cleaner, raising the level and forcing the oil up and out to burn off. Since we are in a campground with neighbors parked on top of us, I don't want to run the engine a lot until we leave Monday and smoke out the folks next door. Any ideas? | ||
| John MC9 Rating: N/A |
The questions should be: Is it really blue, or is it white (looks bluish in the rain)? Is the crankcase over full? Are the crankcase breathers restricted? What type/grade oil are you using? Is it idling smoothly? How long idling before it begins smoking? Does it smoke when you accelerate after a long de-acceleration? | ||
| ChuckMC9 (Chucks)
Rating: N/A |
Hey Nick - Since you haven't heard anything from the Pros yet, here are a couple of reposts... ------- From Abajaba: There are three colors of smoke from a diesel, normally. White on startup is unburned fuel that is making it through the engine without being ignited. This is an indication of low compression and will quite often clear up after the engine runs a few minutes and gets warmed up to the point where the rings are making a better seal. You will most often see this when the engine is low in temperature like 30 degrees or colder. Sometimes slightly higher temperatures when the engine is getting tired. Blue smoke is an indication of oil consumption as it is in a gas engine. It is time to get some work done on the engine as it is using oil. Black smoke is an indication of insufficient oxygen for the amount of fuel. The fuel IS burning but it doesn't burn completely. Another reason that this might happen is if the engine is turbocharged and the turbo has shelled itself out. -------- From TomC: Number one reason for smoking - a dirty air filter or obstruction in the air intake system. White smoke = misfiring cylinders($) or a bypass blower valve is stuck open. Blue smoke = lubricating oil being burned (worn rings, turbo bearings etc.) Black or gray = incomplete fuel combustion (restricted air filter or muffler, lugging the engine, defective throttle delay, high altitude, restricted liner ports, improper injector timing, jack rabbit starts etc.) PS: You must have a sticks n bricks in Elkhart - you're always there!  \ | ||
| Tim Hoskinson (Tdh37514151)
Rating: N/A |
One sorce of sudden oil consumtion can be oil seals in the blower leaking. This will allow oil to flow into the air intake ports. You can remove the air way from the intake side of the blower and look for oil on the rotors to conferm this problem. Best of luck to you. | ||
| Nick Rating: N/A |
Thanks for the input, guys. The bus is not using any more oil than normal, and the crankcase was not overfull. The breathers seem to not be restricted. Using Rotella 40 weight oil. The bus was idling and running fine, I noticed the smoke as soon as I stopped and stepped outside. We'll bve leaving here Tuesday for the Escapee rally in Du Quoin, Illinois, about 180 miles. Will report on what happens on that trip. I am past due to clean the oil bath air filter, I suspect that may be part of the problem. Chuck, we don't have a sticks and brick home anywhere, we're fulltimers. We just stop in Elkhart quite frequently to get parts, visit friends in the area, etc. | ||
| airless in Jacksonville Rating: N/A |
The oil you are using is probably causing the smoke. I found when I used the incorrect oil ie rotella 40 that my bus would smoke. I use the cf2 detroit recommended oil no smoke no problem. | ||
| Brian Brown (Blue_velvet)
Rating: N/A |
Airless, 40wt. Rotella T is indeed a CF2 rated oil. Are you perhaps confusing it with Delo 400?? http://www.shell-lubricants.com/products/pdf/RotellaTSG.pdf Are 'ya still smokin', Nick? Curious what it could be. Sorry I can't be much help, bb | ||
| John MC9 Rating: N/A |
So we narrowed it to two: 1. Is it really blue, or is it white (looks bluish in the rain)? 7. Does it smoke when you accelerate after a long de-acceleration? 1. would be water. 7. would be valve stem seals. A commercial bus driver would not take notice of the smoke, and the problem would not be noticed until it was major. How many miles are you expecting to drive, vs the commercial outfit? I guess, what I'm trying to say, is.... stop looking at the exhaust. Relax and enjoy the trip! If the problem persists, seek help.. | ||
| Nick Rating: N/A |
We will be leaving tomorrow for the Escapee rally in Du Quoin, Illinois. I'll let you know if it is still smoking. John, I really could not swear it wasn't white smoke in the rain, but it sure looked blue to us. On acceleration after a long de-acceleration, I have not noticed anything amiss. A puff or two of black sometimes climbing a hill, but that has always been present. | ||
| Brian Brown (Blue_velvet)
Rating: N/A |
Nick, not that this will help your present smoking issues, BUT... the puff puffs of black going up hill are your engine telling you to downshift, because you're lugging the engine into a rev range where you're getting inefficient combustion. Sometimes it can't be avoided at higher altitudes with a non-turbo DD, but usually a combination of downshifting and backing off the throttle to maybe 3/4 the telltale puffs will soon let you know if you're climbing in the proper gear. Avoiding running into the lug-range and staying off the governor is the key to keeping temps down while climbing. If you have a tach (I don't), this is probably about 1700rpms or so. It seems a bus has a certain gear and speed it will want to pull any hill, and it's always grade and altitude dependent (and how much weight you're carrying around, obviously). And I watch my exhaust all the time from my left rear view. I can almost invariably keep black smoke (unburnt fuel) from coming out of the engine by modulating my throttle and driving in the proper gear. Black smoke = wasted fuel = higher temps. Hot engines and wasting $3/gal. fuel should be avoided, if you can help it. Most of the transit drivers around here leave fellow motorists in a huge cloud of smoke at every stop and it's obvious that they're just mashing the throttle and oblivious to how their busses work (or don't care). That said, almost every time I do a DTS (dead throttle start), there is a puff of black when the governor takes up the slack after I let out the clutch. Dunno if autos do the same thing. It's much more noticable where I live (at 5000 ft.) than when we're at sea level, and I'm told that this is normal. Maybe more than you wanted to know, but... HTH, bb | ||
| John MC9 Rating: N/A |
Nick- I typed that last one late, so gotta' skuse my thought process.... It's always good to pay attention to the exhaust, like Brian said. You can see if anything's going wrong, before you're sitting still in the middle of the highway.. So yeah, good that you take notice! What I meant, was not to over-worry about what you're seeing while it's idling in the rain. If it doesn't pump blue smoke when you accelerate after a long deceleration, or pump blue smoke when you first start it, it's not likely stem seals. And if it isn't doing it all the time, I'm not too sure I'd be overly concerned. It's a two stroke, don't let it give you one. I'm no diesel mechanic, but I've worked on "a few" automobile diesel engines, and they're all the same regarding the reasons for smoke. Some diesels will puff smoke of almost any color, out of the clear blue, just for the hell of it. Could be something in the fuel, or the air.... If it goes away, fuggetaboudit.. I wouldn't let it ruin an otherwise perfectly decent day. | ||
| airless in Jacksonville Rating: N/A |
Brian you are correct.. I assumed since rotella cf2 is so hard to find that possibly he was using the rotella normally found at the truck stops which is cf4 in most cases. As I understood it at least Rotella claims their single weight can be used in anything regardless of what it actually required. When I used it I smoked when I got the bus it did not smoke. When I changed the oil back to a cf2 oil from Rotella the bus has not smoked since. | ||
| John MC9 Rating: N/A |
Airless- Good grief. I assumed that c4 was better than cf2. I wonder how many others thought the same. Mine started to smoke also, after I started dumping it in! &*%$... | ||
| Nick Rating: N/A |
Ok, so we drove 180 miles today, mostly on the interstate. When I started it up this morning it blew the usual cloud of white smoke for a few seconds. Usually this quickly goes away. But today while it was idling while we hooked up our tow vehicle, it was still was pumping out a decided amount of blue (definitely blue, not white)smoke, It has never done this before. Once on the road, whenever I was on the throttle, I was seeing a very noticeable amount of black smoke, which would go away as soon as I let off the throttle. This was in Indiana and Illinois, no steep hills to climb. We stopped at a Flying J for fuel, and pulling out at slow speeds there was again a lot of blue smoke that quickly eased up and changed to black as I accelerated onto the highway again. Cruising along at 60 no smoke unless I stepped down on the throttle, then a good puff of black smoke. Arrived at the campground here, and more blue smoke while I was idling and backing into the site. I've had this bus over four years and live and travel in it fulltime, so I know it pretty well. This is a brand new thing, not something that has been ongoing for a while. I know that black smoke is unburned fuel, and again, I am past due to clean the oil bath air filter. (One problem with living on the road fulltime is finding a place where you can work on your bus. Most campgrounds frown on it.) I suspect that once I clean the air filter it may get us back to normal. Or at least whatever is normal for me. I sure hope so. | ||
| Brian Brown (Blue_velvet)
Rating: N/A |
Nick, I think your suspicions are very likely. You know this already, but the oil bath filters need regular and routine maintenance, along with other items on the coach… oil changes, lube, wheel bearings, brake adjustments, etc. If you need a place to work on your rig, find a wrecking yard along the way, or a truck garage that’ll allow you to pay for some space to work on your bus. Some might let you park there for free for the few hours it might take to do some maintenance/ troubleshooting. Or just pay for the service at a mechanic. I’d avoid your typical “big truck mechanic” unless they have specific experience with 2 stroke DD’s and hopefully busses. Whatever you do, get the problem diagnosed right away in case it’s doing damage to your engine OR it’s something else entirely. Ignorance ain’t bliss… it’s expen$ive. bb p.s. if you’re getting some white smoke on startup, preheat the motor for 30 minutes or more (depending on ambient temps) with a block heater, or a Webasto, if you have one. I do this with my block heater whenever the mercury drops below 50 and it cranks off on the first downstroke with no smoke. And yes, healthy DD’s can and do start in cold temps, but a warm engine is a happy engine. It’s easier on the starting/ charging system and better moving parts. The more tired the motor, the more white smoke, and the more it needs a block heater. |