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Old 06-08-2015, 08:07 AM   #1
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1997 Freightliner 3126 white smoke and power loss

I just purchased a 1997 school bus with a 3126. Under load when the turbo starts to spool it starts blowing white smoke and losses power. I thought clogged fuel filter but symptoms are the same after the change. I checked the turbo and the compressor is spotless inside and shaft play is less then 1/16" and spins freely. Any suggestions? I'm new to the diesel seen.
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Old 06-08-2015, 08:42 AM   #2
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Blown head gasket. White is steam from the coolant getting into the combustion chamber. Just based upon what I'm reading.
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Old 06-08-2015, 09:14 AM   #3
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I would agree white equals coolant getting into the combustion chamber.

I would take it into a shop to have it professionally diagnosed before much longer.

If you do have a bad head gasket it could fail totally and hydro-lock your engine at speed. At that point you can break connecting rods, crankshafts, and other very expensive parts.

Good luck.
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Old 06-08-2015, 09:51 AM   #4
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I checked the oil and it didn't look like water was making into the oil but I suppose water could be going only into the combustion chamber. How would I verify the head gasket and is it reasonable to replace it myself?
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Old 06-08-2015, 10:29 AM   #5
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If the only time you are getting white smoke is under acceleration it probably won't show up in the oil--it is getting consumed in the combustion process.

Which is also why you need to address the problem ASAP. If the only time it leaks is during acceleration that means if it fails big time you are going to dump a lot of water into the combustion chamber all at once. Water does not compress. When it doesn't something else has to give which is usually a connecting rod, crank, or piston.

As to replacing a head gasket by yourself, it all depends upon how handy and skilled you are.

It isn't rocket science but it is a big job. Unless you have more than two arms it will take more than one person when it comes time to lift the head off and to put the head back down. Not only is head work in a bus a PITA but it is heavy and awkward to boot.
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Old 06-08-2015, 05:39 PM   #6
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Is your coolant going down? is oil level on the dip stick increasing? these are signs of bad head gasket. is the smoke white,or a blueish white?, if you take the oil cap off when its running, is there lots of blow by, meaning lots of smoke blowing out.
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Old 06-08-2015, 07:14 PM   #7
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Gb. This is the kind of questions I'm looking for. I can't be at my bus today but it doesn't feel like blow by past the rings I.e the more I push on the peddle the more smoke pours out. This is push on the throttle and feel the turbo spool and then smoke and the turbo cuts out. Like the engine management opens waste gate and cuts fuel.
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Old 06-08-2015, 07:40 PM   #8
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Is it pure white or blueish? Could be an injector.
Does it smell like coolant.
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Old 06-08-2015, 08:24 PM   #9
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Does it have a misfire when it starts blowing smoke? Or does it just run out of power? A head gasket is pretty easy to diagnose on diesel because of all the compression all the time. An injector going bad could give you the low power, white smoke, and it will also give a misfire. The bus being new to you, and having these problems will be hard to diagnose because you can't give us any long history to it.
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Old 06-09-2015, 11:24 AM   #10
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The smoke is white and smells bad from what my wife said following the bus home. There is no smoke at all when parked or under light load so it is to be sure. I don't feel what I would feel during a gasoline misfire but you can feel the engine struggle as the manifold pressure increases and starts to smoke.
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Old 06-09-2015, 11:30 AM   #11
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I probably won't get to work on the bus until Sunday but I'll try and Check the coolent and oil level tonight. Has anyone used a remote OBD-2 adaptor on a 3126? Any idea one how much info it provides and wither or not it may be able to help diagnose this problem and others in the future?
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Old 06-09-2015, 11:51 AM   #12
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OBD-2 is a passenger car standard. Medium duty trucks like our buses use the J1939/1708 protocols. If it has the data port.
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Old 06-09-2015, 12:02 PM   #13
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Thank you scooter. I'm leaning a lot here.
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Old 06-09-2015, 12:09 PM   #14
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Thank you scooter. I'm leaning a lot here.
This is definitely a learning resource, and we can all share our common experiences. But listen to folks like Cowlitz- people in the industry- when they offer advice. Even if/when I start having problems that I can't figure out, I'll probably be taking my bus to the local truck shop to get looked at
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Old 06-09-2015, 07:35 PM   #15
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Is it pure white or blueish? Could be an injector.
Does it smell like coolant.
your right a injector will give the same signs as a blown head gasket, one other thing, if the gasket is gone there should be signs of over heating.
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Old 06-10-2015, 10:35 AM   #16
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The oil and coolent levels look the same as before the 45min drive home. I would think the coolent level would be significantly lower if it was leaking through the combustion chamber. Also the engine temp stayed steady at 2/3 of temp gage range. I did notice the oil pressure fall maybe 10lbs or more when the smoke starts. That may just be the simalar affect of removing your foot from the throttle. I leaning back towards a fuel delivery problem.
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Old 06-10-2015, 06:00 PM   #17
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The oil and coolent levels look the same as before the 45min drive home. I would think the coolent level would be significantly lower if it was leaking through the combustion chamber. Also the engine temp stayed steady at 2/3 of temp gage range. I did notice the oil pressure fall maybe 10lbs or more when the smoke starts. That may just be the simalar affect of removing your foot from the throttle. I leaning back towards a fuel delivery problem.
It does sound like a injector problem, those engines are know for blowing the tips off the injectors, but they are know to break piston rings, and blow head gaskets.
if it was me, I would start by removing the injectors, you can have them tested, the oil seals go bad and cause blow by. when there out you can do a compression test as well. I had lots of smoke and it was light blue/white, I replaced all 8 injectors, all is good.
but you really should take it to a shop if your not sure, its costly to replace them and its not the problem.
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Old 06-13-2015, 08:50 AM   #18
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I think at this point I will pull all the injectors and have them cleaned and tested for $35 each and replace any with rebuilt if the are found to be bad. If all are good then I will continue on with pulling the head. I haven't read into the head gasket procedure yet but I would assume that pulling the injectors is part of the procedure. In the end I must know this bus intimately before our journey begins. Once I cross over to Mexico the roads are steep, ruff and often remote on our way through every Central American country on our way back to Nicaruaga.
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Old 06-13-2015, 09:02 AM   #19
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Although, finding a bus mechanic in Central America is easy considering that almost everyone uses public transportation and the only public transport down there are our retired school buses. Driving a personal Skoolie down there is like driving a newer custom Coach up here. If you have a problem there will be plenty of help to get you back on the road but at a price. If you know what your talking about you are far less likely to pay for something that didn't need repair. I.e. Pay for a new injector if all they did was rinse out the fuel filter or water separator. (Not even replace it)
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Old 06-13-2015, 10:13 PM   #20
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I think at this point I will pull all the injectors and have them cleaned and tested for $35 each and replace any with rebuilt if the are found to be bad. If all are good then I will continue on with pulling the head. I haven't read into the head gasket procedure yet but I would assume that pulling the injectors is part of the procedure. In the end I must know this bus intimately before our journey begins. Once I cross over to Mexico the roads are steep, ruff and often remote on our way through every Central American country on our way back to Nicaruaga.
$35.00 to clean and test. that's they way to start, and a good price, I'm sure they would replace the o-rings too, hopefully this is all it takes care of your problem.
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