Fairly new bus owner, located in Holliston, Ma.
Pretty sure I learned an expensive lesson regarding the shutdown damper.
I have developed a pretty serious oil leak ( leaks). Oil in front valley and left side valley, coming down the front of the engine and the inspection ports below the exhaust manifold have a lot of oil in them.
The trigger mechanism ( which was not complete , it had no spring and not connected to solenoid) was not locked under the shutoff arm. I left my house to go for a spin and got less than a quarter mile. The Damper arm flipped and closed the damper. Got towed home ( 450.00) ouch. Driver messed up the underside of my bumper , got a mechanic to come manually reset the damper arm ( which my ignorance prevented me from recognizing and doing ) 240.00 cost. ouch.
In subsequent idlings ( did not take it back out because my front air had a problem) I noticed a lot of oil leakage that I did not notice before.
Upon much research , I know about 500x more about this engine than I knew a month ago. I do not however know how to rebuild a blower.
Have a few questions , would really appreciate some info. Thank you in advance.
- What can I expect to pay for the repair?
- Should I have mine rebuilt or buy a new rebuild and have someone put it in?
Wondering, if the Damper is down would the engine still start?
Could it destroy the Blower Gasket by trying to start it with the damper closed?
Is the consensus now to completely do away with all that damper kit and install a CO2 delivery system of some sort for a runaway engine situation?
Do away with the shut down pull the valve covers and if the fuel control rod for the injectors have 1 screw with a lock nut for each injector,that type is a spring loaded rod and you do not need the shut down,blower rebuilding is fairly easy, removing one and re installing runs into labor which is money average price is going to be 2 to $3000.00 ,it is best to rebuild your blower you need to pull it to get the number to get the correct blower anyways bearing and seal kits are less than $200.00 the Chinese made junk kits are less than a $100.00
Usually having the emergency damper flap engage at idle speed does not hurt the engine. At full fuel and max rpm I do not know. I have not read the answers. Perhaps others here know.
If engaged the engine will spin but not start. The cranking noise will sound different than normal cranking. Usually speaking here the emergency flapper damper operation on N series DD's ...
... Is kinda required special secret knowledge. Do not fret. Years ago three very nice homes lost their entire roofs due to a series of unfortunate events regarding fire engine pumpers.
The apparatus operator did not know about the emergency shut down flap. Pulled the wrong manual shutdown. Anyhow, it is easy to learn up on this stuff regarding N series and some T DD's.
There's no need to pull the emergency flappers from the engines. These are relatively simple systems and if not working properly get the parts and fix it. Once fixed it will just sit there quietly until you either engage it to stop a problem or to do your routine testing of its function.
If you're missing parts, contact Luke at US Coach. He'll likely have the parts you need to put things back together.
On my maiden voyage home from NJ to WI with my current bus I inadvertently hit the emergency shutdown toggle while reaching for the reverse solenoid. Had no idea what had happened, and I sat there in a truck stop blocking the main passageway in front of the CAT Scales. Luckily someone from the shop gave me a hand getting it going again. You're not alone in having a flapper deploy at the wrong time. I was lucky and no damage was done since I was at idle.
Before assuming the worst about your blower, get the engine cleaned off and find out where the leak is.
Quote from: richard5933 on April 11, 2021, 12:17:52 PM
There's no need to pull the emergency flappers from the engines. These are relatively simple systems and if not working properly get the parts and fix it. Once fixed it will just sit there quietly until you either engage it to stop a problem or to do your routine testing of its function.
If you're missing parts, contact Luke at US Coach. He'll likely have the parts you need to put things back together.
On my maiden voyage home from NJ to WI with my current bus I inadvertently hit the emergency shutdown toggle while reaching for the reverse solenoid. Had no idea what had happened, and I sat there in a truck stop blocking the main passageway in front of the CAT Scales. Luckily someone from the shop gave me a hand getting it going again. You're not alone in having a flapper deploy at the wrong time. I was lucky and no damage was done since I was at idle.
Before assuming the worst about your blower, get the engine cleaned off and find out where the leak is.
Detroit sent out service bulletins in the early 80's telling you to remove those and gave deep discounts for parts to replace it with FWIW .I have tub full of the old 2 screw injector fuel rods ,the new spring loaded rods will not over speed like the older rods did if 1 injector sticks the other 7 work to keep driving.You never see a flapper on the 92 series
Quote from: luvrbus on April 11, 2021, 12:46:28 PM
Detroit sent out service bulletins in the early 80's telling you to remove those and gave deep discounts for parts to replace it with FWIW .I have tub full of the old 2 screw injector fuel rods ,the new spring loaded rods will not over speed like the older rods did if 1 injector sticks the other 7 work to keep driving.You never see a flapper on the 92 series
This is a 71 series - does the same apply?
RE: Tools needed to rebuild Blower on the 8V71 natural long block.
The tools are specialized correct? Around 2k new and 1K used. Does that sound right?
The service bulletin was for the 71 series
If someone is still running the old style injectors/rods, won't it still need to be there? As in you can't just pull it without changing other parts to keep the engine safe, correct?
Quote from: richard5933 on April 11, 2021, 01:21:16 PM
If someone is still running the old style injectors/rods, won't it still need to be there? As in you can't just pull it without changing other parts to keep the engine safe, correct?
The primary purpose for the emergency shut down was to stop (kill) the engine when 1 injector stuck,they really were not running away it just sounded like one was,with a true run away on a 2 stroke the flapper will not prevent it or stop it
Quote from: luvrbus on April 11, 2021, 01:43:03 PM
The primary purpose for the emergency shut down was to stop (kill) the engine when 1 injector stuck,they really were not running away it just sounded like one was,with a true run away on a 2 stroke the flapper will not prevent it or stop it
How can the engine run away w/o enough air for combustion with the air inlet choked off?
Covering the intake works with stuck injectors or a governor out of wack,in a true runawy they suck enough air from the oil pan and with the oil from the pan suck through with the air,you set back and watch the show till it is over, phone books boards and CO does you no good
Not sure about all the spring loaded injector rods and all the new fangled gear.
I do know that on my bus until the air pressure builds the only way to stop the engine if something goes wrong is either with the flapper or to run around to the engine and do it manually. If for no other reason, this is reason enough for me to keep the flapper functional. Lots could go wrong during those first few minutes, enough to need to shut things down in a hurry.
That is why you should start from the rear. Then you close enough to pull the shutdown rod and it will stop without blowing your blower seals. :^
Quote from: Dave5Cs on April 11, 2021, 09:36:58 PM
That is why you should start from the rear. Then you close enough to pull the shutdown rod and it will stop without blowing your blower seals. :^
In an ideal world that's a great idea. Not always possible/practical to pop the engine bay every time we do a start, and even when it is the only gauge back there is for oil pressure and I like to watch to see that everything is okay during startup and warmup. Can't be in both places at once, so no matter where you start it there are potential problems. Bottom line to me is having the ability to stop the engine from the front position without relying on air is a good thing. It's never happened, but there are many other failures which could disable the 'regular' engine shut down, and using the flapper from idle is not likely to destroy the blower seals (not that I'd suggest making a habit of using it.)
Owners never maintain the shut off ,the shaft and the seals get wore so bad enough they pass enough dirt and dust to ruin a engine,it is a old tech that was around and worked for around 40 years before Detroit changed but they still use the crappy seals in their blowers
"Owners never maintain the shut off ,the shaft and the seals get wore so bad enough they pass enough dirt and dust to ruin a engine,it is a old tech that was around and worked for around 40 years before Detroit changed but they still use the crappy seals in their blowers "
What steps would you take with this engine if you were me or it was yours as it were?
This is a link to pictures of the bus.
https://www.icloud.com/sharedalbum/#B0H5yeZFhDLl4R
The bus is pretty solid. 8V71 Natural, Allison 500 Trans I believe .
New King Bolts, New parts on the steering mechanism, all new Air susp bags, No bad rust, Has a Cat 8.5 KW gen with a couple thousand hours on it. All fluids have been changed and bus regularly serviced in that regard for the last 12 years or so by the previous owner.
Has an on demand propane water heater that works well. 3 AC/Heat pumps on the top. Hydraulic Jack system, New Cat Coach batteries, Nice inverter setup with 2 big deep cycle batteries as well,
Needs new Radiators sometime in the future, no leaks etc but they are losing some fins .
Needs new Black and grey water tanks right now.
Needs wipers converted to electric. They work but have some small air leaks.
May need a tire or two sometime in the next year or so.
Coach A/C compressor is not connected to the engine, may be siezed as well. Guessing a rebuild on that. Which I might think about if we were doing a ton of driving but we are not at this point.
Any and all input much appreciated.