MC-9 / 8V71 Woes

[buswarrior]

When is someone going to invent a BBS posting screen that doesn't lose all your $%&*@ work if you happen to click for Google and leave the page???

I will recreate it all again after retrieving the mouse from the fishtank...

I need a scotch. Blame the equipment, not the operator...

Stupid damned BBS software.

happy coaching!
buswarrior

[lostagain]

Really funny BW... except when it happens to me sometimes, BTDT.

JC

[Depewtee]

BW,

On longer posts I find it useful to type the text into Microsoft Word and then copy/paste to the BBS.

Brian S.

Mouse in the fish tank

[Ed Hackenbruch]

BW, i know your pain.......its happened to me about 4 times today on different sites.

Lin,  i stopped and looked at that Prevost.   Its a 1983, 40' with an 8V71 and 6 speed tranny.  It is basically a shell, has been gutted. Asking almost $16,000  for it. Looks like a church or ministry may have owned it.  Looks a little rough to me. Rode hard and put away wet? 

[buswarrior]

Ok, with these GM transmission ratios,

The 1-2 shift is a 41.6% change, so drops from 2100 to 1226
The 2-3 shift is a 40% change, so drops from 2100 to 1260
The 3-4 shift is a 33.3% change, so drops from 2100 to 1400

So, there is effectively no overlap of gears for a given road speed, except a bunch of mph between 3 and 4. Just like the owners of these coaches tell us!

Or, said another way, road speed dictates which gear you have to use.

And this also shows what might be wrong if you advance time/bigger injector an 8V71 in a GM, moving peak torque up to 1400 rpm from standard timed 1200 RPM, you drop the engine below the power on shifts 1-2 and 2-3, as well as the bottom of all 4 gears is in the toilet a lot longer, road speed wise.

You may have also heard GM owners discussing hill climbing, particularly the 4104 owners, comment they have to give up on 3rd gear, and drop road speed way back to grab 2nd and plow up the hill against the governor with lots of available power, but not enough power to pull with 3rd. They would love to have a gear in the middle, and the numbers show that.

Keeping the technology in perspective, remember that the multi-speed transmissions of the same day required multiple stick shifts to control the auxiliary boxes, and all manner of wild shift patterns and order of using which stick into which position.

The simple 4 speed would have been well regarded, and cut a wide swath across the drivability needs of a line run motorcoach. And these auxiliaries had reliability issues.. the old men I have known who drove those, may remember those days fondly, but do not want to drive those beats anymore!

Once you have equipment, there is a business need to observe the inertia of "run what you know", keep spec'ing the same thing.  There was the bonus of the higher HP of the 8V71 helping hide the wide gear spacing, and the driver's had become familiar with the 4 speed and what to do to stay employed.

Now, fast forward to today's technology, the 18 speed transmission of today (and the top 8 of a 13speed) are spaced  approximately 17% apart, giving a trucker a lovely amount of choice as to which gear to use for a given road speed. Under a 2100 rpm downshift, the 18 speed would only drop 350 rpm or so.

Has anyone looked at whether any of those lovely 6 speed transmissions in the medium duty trucks would fit behind the bevel gears on a GM?

And who has the ratio for the 5 speed, so we can show the incremental improvement over time?

happy coaching!
buswarrior

[belfert]

When is someone going to invent a BBS posting screen that doesn't lose all your $%&*@ work if you happen to click for Google and leave the page???

Why not open another browser or another another tab in your browser if you need to visit another web site?

I suspect it is as much an issue with web browsers as the BBS software, but I really don't know.

[buswarrior]

you have to remember to open another tab before clicking go on the handy Google toolbar thingy...

After you forget, when you click back, your reply post window is nicely blank for you to start again.

happy coaching!
buswarrior

[NewbeeMC9]

you have to remember to open another tab before clicking go on the handy Google toolbar thingy...

After you forget, when you click back, your reply post window is nicely blank for you to start again.

happy coaching!
buswarrior

Some of us need new tabs for our brain ,  some of us have too many tabs and what was I typing about

[BlueScarecrow]

Ok... I think I have figured out what my problem is... My Blower Seals are shot and oil is leaking into the blower. And I have really low Oil pressure, but that might be the 10w 40 oil. Will be doing an oil change this week.

I'd love to include some pictures, but when I click on the Insert Image button [img][img] appears. What's up with that? I also have Avid Media Composer and Sorenson Squeeze for making Flash videos. Anybody know how to include those in a post?

Greatly appreciated.

Thanks!


Regards,
Mike
N9EWS

[buswarrior]

Good news!

Fresh Blower seals are money well spent for the future, and the heavier 40Wt oil will bring up the oil pressure.

Keep us in the loop.

happy coaching!
buswarrior

[luvrbus]

Mike, how did you determind you have bad blower seals also any oil pressure above 5 lbs is good on a hot idle they don't have much on idle and around 50 lbs at above 1700 rpm.
I see you live somewhere around Chaparral Rd according to your zip code I think 85252 is that area ? where do park a bus in that area.
I lived in 85253 zip and moved because the powers that be would not let me build a garage or canopy for my bus.
FWIW my daughter-in-law and her brothers own a chain of Mexican restaurants in the Phoenix area and my son owns 2 restaurants on Frank Loyd and Scottsdale Blvd I am in that area often so maybe at Quartzsite we can exchange numbers  




good luck

[BlueScarecrow]

Hi Clifford... Thanks for writing.

I'm only theorizing, but it makes perfect sense.

Oil is seeping in through the blower seals (or from somewhere) into the blower and when the piston retracts and reveals the intake port the blower blows in fresh air along with some oil and it is combusted along with the fuel. This is the reason for the blue smoke. The reason that it does not run away, is probably that the amount is too small to support combustion.

When I gunned it the other day and it ran away for a few seconds, the amount probably reached the window of combustion and it took off! Since it was only a minute amount, the run-away lasted only a few seconds.

Then too, when the piston retracts and reveals the intake port, the blower blows in fresh air along with some oil in through the intake and right out the exhaust port. The oil lands on the superheated exhaust manifold... turns into white smoke... which travels out through the tailpipe. Remember it takes only a minute amount of oil to give a billowing white cloud.

When I did Special Effects in LA, we built a small cracker out of a 25 gallon drum. We filled the bottom with Johnson & Johnson Baby Oil just to cover the air manifold and we could make smoke all day without refilling the drum.

You are right about the zip. I use my brothers address as a base. He lives on 85th and Chaparral. I've been bouncing it around from location to location until I find a nice spot where it's not a bother to anyone and I have electricity to work on it. I have it parked at my apartment building right now. The owner is cool. Thought the Rolling Stones were in town. 

What do you think of my theory?

Like to hear my theory on gravity?

Thanks again for writing!

If you like... send me an email and I'll send you my contact info.


Best regards,
Mike

N9EWS

[luvrbus]

That is a good theory Mike but the only way to tell for sure it is the blower seals is to remove the air horn where the air cleaner connects to the blower start the engine and take a light and look at each end of the blower on the inside if they are leaking you will see the oil running down on the end plates.
Be careful those rotors are like a sausage grinder stay clear of those babies.




good luck

[BlueScarecrow]

Yikes!!!

I will.

I think I'll take a look just before I change my oil.

I'll save that for one of my dirty day jobs. LOL

Keep your fingers crossed.

Thanks!

[cody]

I think you'll find you've got a great bus, just got to get the rig up to spec a little. The guys here will guide you as needed, lots of very capable guys here that have seen almost any problem and the fix to it.