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Finally Running, But Leaking


Mack B Mike

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Hello All,

I have a couple issues with my 56 B61 that im looking for some help with, I finally got my B Model running after it was sitting for ~15 years resolved the issues with the S/P switch, stuck rack and few other issues. When i run the engine for any time greater than 5 to 10 mins the is some black fluid that starts comming out of the exhaust also the liquid is comming out of a leaky ex manifold gasket at the #6 cylinder, im an not sure what is causing this but the liquid is flamable that is leaking, i am assuming that this is un burnt diesel but i am not sure what to do about this, the engine runs extremely well at idle and goverened speed, also starts very easily when warm, but needs a shot of ether when cold every time. to me it does not seem that a cylinder is not firing properly, along with the fuel leaking there is alot of blue smoke which does subside somewhat after engine has been running for ~20 minutes but still is present. ill take any ideas of a possible cause

thanks

Mike.

:bulldog1:

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Is the thermostat working and allowing the engine to warm up to operating temp (180)?

10 or 15 minutes isn't long enough run time to warm it up, especially in the winter, and it may just be "slobbering" from insufficient combustion temperature.

As you said the black stuff is coming out a leaky exh. manifold gasket, that just happens to be the easiest place for it to escape, it could be coming from any or all of the cylinders.

Take the truck for a run, long enough to get it thoroughly warmed up, then see how it is.

If it doesn't reach 180 degrees water temp, put a new thermostat in it, low operating temperature causes sludging, slobbering, and dilution of the engine oil from unburned fuel going past the rings.

Try this before doing anything more drastic.

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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Is the thermostat working and allowing the engine to warm up to operating temp (180)?

10 or 15 minutes isn't long enough run time to warm it up, especially in the winter, and it may just be "slobbering" from insufficient combustion temperature.

As you said the black stuff is coming out a leaky exh. manifold gasket, that just happens to be the easiest place for it to escape, it could be coming from any or all of the cylinders.

Take the truck for a run, long enough to get it thoroughly warmed up, then see how it is.

If it doesn't reach 180 degrees water temp, put a new thermostat in it, low operating temperature causes sludging, slobbering, and dilution of the engine oil from unburned fuel going past the rings.

Try this before doing anything more drastic.

And to add to what Herb said; Pull a load with it if possible.

Rob

Dog.jpg.487f03da076af0150d2376dbd16843ed.jpgPlodding along with no job nor practical application for my existence, but still trying to fix what's broke.

 

 

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Guest Bollweevil

Mike, there are three elements involved in starting a fire. The first two are fuel and oxygen. In a diesel engine the third is combustion pressure. The lower the ambient temperature is, the more difficult it is,for a fuel with a lower flash point to burn.

In very cold weather it is not uncommon for older engines to bypass some of the fuel out of the exhaust. When an engine bypass's enough fuel through the combustion process, to leak through the exhaust and run down the side, we say that it is slobbering. The bad part of this situation, is that It can also bypass the piston rings and wash down the cylinders. Now, to get to your question as to why it is hard to start, well you have fuel , and you have oxygen, you know that , because you can see it smoke, what you don't have is enough combustion pressure, or compression to start the "fire", and keep it burning. You have said that your diesel baby has been setting for 15 years. It would help you to know some history regarding this engine. Why was it parked? Was the engine week, had it been built? It may be hard or impossible to find out. If the pump was gummed up , the injectors might be also, it might have some stuck rings. Since it is leaking out off number six, it could have a bad injector. Check each cylinder with an infrared gun to see if some are colder. Starting fluid WILL break rings. Heaven forbid but you may have to go back and revisit the recent pump work. Marvel Mystery Oil is a good upper cylinder lube, you could add some to the fuel and the crankcase. The cold weather we are having has a bearing on what you are doing, so don't get in a hurry, unless you have a hot load to Miami. James

t

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Hi Mike, You've gotten some good advice that is probably the problem. I use an engine heater in cold weather to help eliminate the blue smoke and blown by unburnt fuel from Baby Skiddle's END673 which doesn't have a thermostat - only shutters. Without the engine heater no about of pre-trip warmup idling will eliminate the smoke or leakage. Only driving down the road with a load for at least a half hour will work and I'll lay down a smoke screen that any World War II destroyer crew would be proud of until she's warm. :thumb: Bob

Ain't a Mack? Take it back!

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along with the fuel leaking there is alot of blue smoke which does subside somewhat after engine has been running for ~20 minutes but still is present.

blue smoke could be burning oil which is not a good thing keep checking your oil... i had an 85 superdog and it was blowing out blue smoke and everyweek i would hav to ass a quart or 2 of oil so that could be your blue smoke problem..and i hav that same exhaust manifold problem on my superdog now and i decided to replace all of the manifold gaskets and that solved my problem so u could try that.

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