MC-9 / 8V71 Woes

[BlueScarecrow]

Hi Gang!!!

Thanks for all of your wonderful advice.

Yep... you hit the nail on the head. There is 10W 40 in it. Saw it on the shelf at T&A and the guy said that is what everybody is using. I goofed!

Ok... so I'll change the oil about a week before Quartzsite and I'll beat the hell out of it on the way up. That should be a good test.

Somewhere along the line it's loading up with oil, and after warming up the white billowy smoke (not steam) goes away and there is a light blue smoke when I'm driving down the road.

I just don't know enough about diesels yet to figure out just where the oil is collecting.

What's a good day to get to quartzsite when Don is there?

Thanks!


Mike
N9EWS

[Van]

I'm with Clifford on this. Check the air filter and fuel filters replace if not done already,FWIW good luck see ya in QAZ

[JohnEd]

Have the 10W40 analyzed.  You need to know if there is traces of metal and what type of metal.  That  can also tell you if you have air leaks into the engine.....that AZ sand takes care of everything in short order.  Also shows coolant leaks that are starting and not clearly evident looking at the oil.

I am not a doomsayer.  I am opt and encouraging.....truly.   You do want to know what the situation is and Don and Clifford can tell you your next steps from the info you provide.

I "think" that you are supposed to see blue(oil burning) smoke if it is loaded with 10w40.  It should also blow that stuff all over everything including your toad.  Yuck!

It was mentioned but I will repeat:  If you are a gallon low after a few hundred miles don't fill it up at that point.  Drive it a couple hundred more miles and recheck.  If it is holding that level then just keep it at that level as though that were full.  I must have heard that here 50 times.

And YES I do envy you   I'll repeat

John

[Dreamscape]

Change the oil/filter and drive the darn thing! Check oil level after a couple of hundred miles, only add if over one gallon low. Make sure you let it sit for at least 30 minutes before checking to make sure it's drained down. Don't try to keep it topped off, let it find it's own level. Ours runs well at just under a gallon low, other useage is due to a few leaks!

Paul

[Van]

51? LOL!

[JohnEd]

Mike,

5th  GEAR???  Is it a stick?  I guess you would count that way with the converter locking being a "shift".

I have met Knuts with automatics that they select gears manually with.  They drive with the tach and don't trust Alyson in the least.  Can't be true for all buses but I took it to heart.  I have it on unimpeachable source that "most" of the Pre's with autos are in need of overhaul at 150K miles.  Seems the Alyson is not able to protect the engine fully and the bus needs to be "driven" and not just "steered".

I wish you all manner of good fortune on your travels and journey,

John

[belfert]

A lot of busnuts would recommend shifting a 740 by hand.  I recall BW recommending that anyone being paid to drive a bus with a 740 shift it by ahnd.  It seems silly as the reason I buy a vehicle with an automatic is so I don't have to shift it.

I have an Allison B500 in my bus and I let it do ths shifting.  To me at least it seems to shift at the right times.  The only time I manually shift it is if I need more bite with the Jake Brake.

[Ed Hackenbruch]

 And i am just about opposite of Brian.  The only time i don't manually shift my 644 is by accident......usually distracted by something and not paying attention to my rpms. 

[JohnEd]

I pondered this for a while and a light bulb went off one day when reading a post about 740's.  Not that I know personally, be sure, but this was the gist.  The discussion was about the shift points of the Allison and that those were "adjustable" and could be reset for up and down.  Also that the forced down shift function could be disabled by a number of things going out of whack over the years.  Wear and tear and deferred maint and ignorance also set the stage.  My conclusion was that some of these beasts actually NEEDED to be manually shifted to stay in the ball park of acceptable revs and load while others didn't need it as much.  As well, the Allison was not the genius some think and looking down the road the driver was very often more clever that the trans. at staying in the power band and not loosing speed going into or staying on a grade.  I think many, rather than get the big buck overhaul, installed a tach and took charge.  It seems that "all" professional drivers shift the auto either manually or pulse the throttle to "force" shifts that the "brain" can't be programed to make at whatever point.

I personally see the Allison as the way to a torque converter to allow starts on hills by rookies, faster up shifts, and even possible down shifts and getting some of the abuse of the engine/drive train relieved so things last longer.  Access to a "retarder" option might be a factor in San Francisco new purchases.

I agree with BW, the driver needs to be involved in the operation of the Allison.  Course, if you never leave Nebraska, all bets are off.  Its dealing with the grades that are the problem.

And FINALLY....the clincher:  Really heavy duty D mech and shop owner told me that "most" Pre's had bad engines at 150K miles due to lugging.  Those wonderful behemoths are bought and driven by big buck Dudes that get an ego sensitive check ride and then "steer and stab" the bus till they sell it which is usually when some clever Bunny tells them they need a $20K overhaul.  They, the engines, take that stuff for about 150K....I am told and they never even spill a glass of water on the dash.  "The dealer said it's time we bought a brand new bus Martha."  And that "low mileage" deal goes on down the road.  So I am told by the guy that gets the $20K to correct the damage and shared that data to HELP me not HURT myself.  Generous Dude!  If Mr. High Finance was driving YOUR bus you would probably leave your finger prints swelling up on the back of his head cause a savvy driver gets 450K miles out of an 8V92.

And, please Dear Lord, I am not putting down any that actually own one of these beasties and can do it their way by rights.

John

[Depewtee]

I have an Allison 740 in my '84 MC-9 with 6V92T and I let it shift 1st and 2nd, but I am in charge of 3rd, 4th, and 5th.  If not, it has a tendency to buck a lot at those shift points depending on the grade, speed, and throttle position.

Brian S.

[cody]

Drive them hard, easy for me, I'm married, I have road rage, parking lot rage, walmart rage, etc, mine likes the rpms up a bit.

[RJ]

BrianS -

If you have a HT-740, it is a four-speed gearbox, not a five.  What you're experiencing as a "shift" is, in reality, the torque converter locking up.

IIRC, the sequence is 1C - 2C - 2L - 3L - 4L, where C = converter unlocked and L = Locked converter.  (I may have the lock-up sequence wrong, if so, me bad!)

Running around town, if you just leave the shifter in 3rd, you'll avoid a lot of the hunting back 'n forth between gears.  Obviously, once you hit the highway, you upshift it to D.


Belfert -

IIRC, you've got a S-60 mated to your B500, right?  The torque curve on the 60s is vastly different than the two-strokes, so it can be lugged down a lot lower rpm-wise before downshifts are necessary.

That being said, however, it is still advantageous to downshift manually when pulling grades to keep the engine near the top peak of the torque curve.  By doing so, you also keep it in a range that helps cooling, too.


Mike (Scarecrow) -

Change the oil to Straight 40wt, CF-2, 1% or less sulfated ash.  Chevron Delo 100, Shell Rotella T, Exxon XD-3 and Texaco Ursa are three common and popular brands.  Available thru a local petroleum distributor, comes six gallon jugs to a case, in five gallon pails, or 55 gallon drums.  Takes approximately seven gallons for a complete oil/filter change on your MCI.

Don't fire up the engine simply to "warm it up" without driving it.  Great way to build up sludge & gunk.  Far better to simply start it, and as soon as the air pressure is up to 120, drive it off.  And then drive it enough to bring everything up to operating temps.

Not sure where you're located (hint - put your city/state in your signature line), but yes, a several hour run to Quartzsite the end of next month at 65 - 70 mph will blow a lot of the gunk out, especially with the correct oil in the 8V.  By the time you get to Q, it may be running nice and clean, so you may not need as much hand-holding!



JohnEd -

Entertaining and informative post, and, regarding the Big Buck Dudes and their Prevosts, probably "right on".

Greyhound was the first non-transit bus company to really put the Allisons to the test in revenue service, back in the early '70's.  Once they found out that the slight fuel mileage penalty was less than the cost of rebuilding clutches, the handwriting was on the wall.

Sadly, there's a whole generation of drivers out there that have no clue how to drive a stick-shift coach, they just stab 'n steer.  And even then, they have no clue about manually shifting the automatic for certain conditions.  Sad. . .

Time marches on, I guess.

FWIW & HTH. . .

 

[Lin]

John and RJ,

I would like some clarification on this lugging thing.  My 8v71/Spicer combo when running 2000 rpm in 1st, meshes perfectly to about 1100 rpm in 2nd.  Hence, it would seem that one must run at lower rpm when building speed.  I don't remember exactly now, but the rpm differential becomes narrower as you climb the gears.  2000 rpm in 3rd is just over 1400 rpm in 4th.  So I guess the point is that one should not try to cruise or climb below 1600rpm in a 2 stroke.  Am I missing something here.

Further, I have been looking into buying another bus, the one we are trying to make a deal on is a Prevost.  So I may be becoming sensitive to slights against Prevost drivers.  Anyway, the PO was the 2nd owner, and he had it for 14 years.  It had an inframe at about 160,000 so one might say that there is something to your observation that the engines do not last as long as they could due to poor driving habits.  However, that engine was about 18 years old when it was rebuilt.  My non-expert opinion has been that time counts as much as mileage.  When seller says that the engine was rebuilt only 10,000 miles ago in 1989, I consider it an old engine.

[luvrbus]

You hit the nail on the head Lin Detroit has a process you do when storing a engine for over 30 days and no bus nut pays any attention to it.
You can fog a rebuilt and never run it and it is good for years 
Are you buying the Prevost in Texas or another. 

good luck

[Lin]

Clifford,

That's the one we want to buy.  The only issue is that I don't want to pay for it until I get there.  The seller refuses to take a deposit since he wants to be free to sell it.  His experience tells him he can not count a deposit as a sale.  He is now going through it and fixing some things that would be added onto the price.  He says it will be ready to go by the end of next week.  I plan to fly out then.  There are some places on the back and front that have peeling clearcoat.  I was hoping to get those faces sanded and re-coated.  He has offered to sand and re-coat the entire bus from the bottom of the windows up for an extra $1500. after I buy it.  It will certainly enhance the appearance and sounds like a good price.  The big problem is that it just seems too nice to let me inside.  I don't remember, did I send you the pictures?