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Author Topic: detroit 8v71 question!  (Read 1302 times)
4106-123
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« on: August 30, 2007, 07:43:59 PM »

 i just got my 4106 back together enough to crank the engine after doing interior remodel replacing dash ect for the last 3 months  i  have been running the engine for short periods to check the new air gage and to check for leaks i usally run it for about 3 mins mostly idling then shut it down.well today i was moving it around the yard and i decided to kick the fuel   to it one time in neutral. when i did it stayed a a high rpm for quite sometime long enough i thought about using the emergency shutdown. also there was a huge cloud of blue smoke.  the bus has a air throtle and i just put a reliabilt blower on it just before i started the interior remodel. the engine had only been running for about 4 mins so i know it was not warmed up. i started it back up after that scare and it seemed ok after i reved it agian a few times, not quite a much smoke. my assumption is it was running up on engine oil. it does not smoke on crank up idling and after it warms up i dont notice a lot of smoke at rpm. i notice the breather tube huffing but dont know whats considered normal. when i put the blower on the rack on both sides move freely  so i dont think the gov or injector rack is a problem.this is my first detroit  so im on a fast learning curve. i would apreciate some imput thanks george
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luvrbus
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« Reply #1 on: August 30, 2007, 07:47:39 PM »

thats just unburned fuel by not getting hot enough to burn drive it for a few miles and clean it out
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Dallas
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« Reply #2 on: August 30, 2007, 08:01:39 PM »

What luvrbus said!

IF you look back through the archives you'll find the recurring topic of smoke. Most of the time it's from idling.

Old Detroits hate to idle. They never get warmed up enough to completely burn the incoming fuel and the velocity of the air isn't enough to scavenge the cylinders completely.

As soon as you can take the old girl out for a good hard run and get her circulation pumping and make her breathe hard.

Next, take the bus out and do the same thing.

You will be surprised how much smoke your going to get out of the exhaust for the first 25 or 50 miles or so, but it's most likely nothing to worry about, it'll clear up.

Good luck, have fun!

Dallas
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Buffalo SpaceShip
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« Reply #3 on: August 30, 2007, 08:44:34 PM »

As soon as you can take the old girl out for a good hard run and get her circulation pumping and make her breathe hard.

Next, take the bus out and do the same thing.

Sounds like words to live by!  Cheesy I love it.
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Brian Brown
4108-216 w/ V730
Longmont, CO
TomC
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« Reply #4 on: August 30, 2007, 09:02:07 PM »

I notice you said blue smoke which is not fuel-fuel is black smoke.  With starting the engine for only short periods, it was enough to get the oil pressure up but not to warm up where the clearances on the piston, rings and cylinder were expanded to their running size.  Hence you were running with loose clearances and built up an excess of oil just outside the cylinder in the air box.  When you revved it up it blew the oil back into the cylinder where the engine burned the oil along with the fuel raising the engine rpm up without control.  This is one good example why it is better to let the engine sit for several months until you are able to take it for a drive of at least an hour compared to just running it for a few minutes.  Rest assured, that unless the engine severely over revved, it should be alright.  I know when I first set out, I put out a bit of blue smoke until it is warmed up-and this from an engine with less than 30,000 miles on it.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #5 on: August 31, 2007, 03:36:40 PM »

I'm a simple guy...throttle linkage stuck when you goosed it, and then came free. And/or the exhaust for the airline stuck.

Won't stick again until you leave it for awhile.

When was last time you lubed all the moving bits?

happy coaching!
buswarrior
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Frozen North, Greater Toronto Area
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