RE: 6V92TA DETROT DIESEL QUESTION

[Mex-Busnut]

Dear Friends:

The bus we are about to get is equipped with a 6V92TA Detroit Diesel (non DDEC version). it was just overhauled.

Today a friend who owns buses commented that the 6V92T is famous for diesel leaking into the oil, and causing the engine to blow. Has anybody heard of this?

Thanks in advance!

Dr. Steve,
central old Mexico

[Geoff]

While it is possible to get diesel in the oil the 6V92 it is not famous for this not-to-uncommon problem. 

[lostagain]

Your friend doesn't know what he is talking about.

JC

[Busted Knuckle]

Dr. Steve,
I have to disagree with your friend!
While it possible and can happen, the 6V92 is no more famous for it than any other.

What happens is many of them that are bought and taken south of the border are so wore out before going south that without proper care and attention they will have a small problem that gets ignored and becomes a serious one such as "blown" engine from washing out the bearings or such!

Two common causes that are easy to find and fix that leak fuel into the oil are cracked cross over tubes (between the injectors) and bad injectors themselves!

The biggest issue here is "hired" drivers who don't have an investment in the equipment they drive don't check things out like they should. And many times even if they find a problem they don't have it checked right a away and that is when you get "blown" engines!

If the oil is checked daily it is not hard to catch fuel in the oil and fix it before a BIG problem develops!
  BK 

[JohnEd]

I wish people would elaborate on this stuff more.  I ain't no expert.....Geoff IS (I'm told by many).  I only hear of one way for D to get in the crank case.  That is when the fuel line that feeds the injectors starts to leak inside the valve covers.  That hose apparently should be a periodic maint item or subjected to some sort of test but I have never heard of either being done.  That in itself means nothing.  The newer Ds have a low oil lite and a "overfull" light and maybe that is a alarm for D in the oil....don't know if that is the purpose.  If there is a lot o D in the oil you should be able to smell it on the dipstick.  Any present is a major concern.

Here is the bottom line:  do an analysis of the oil and the coolant and be certain all is well.... and a whole lot cheaper...or can be.   ANY coolant in there is a death sentance for the engine unless it gets overhauled.  The wet sleeve 92's are known to ruin the o ring seal in the bottom of the sleeve and leak colant into the oil.  Overheating the engine can cause that and overheating causes other horribly expensive problems like cracked heads at a couple grand a pop.  D in the oil is easier to fix.  First get the oil analyzed, then get a expert 2 cycle mech at a DD shop to inspect the engine and then get a bus garage mech to look over the bus frame and suspension and if it is converted you should have a Knut test every friggen system for proper operation.  "friggen systems can be electrc or gas or D fired/powered....don;t forget.

Good luck with your adventure.  Many here can refer you to the various experts you will need to make an informed purchase.  If the seller cannot put the overhaul documentation in your  hand RUN AWAY.  Never deal with a liar.

John the unqualified

BK posted while I was hunting and pecking.  Thanks BK

[TomC]

I've been in the trucking industry for 34 years now.  I've seen all makes of engines have the same problems. Oil in the fuel, fuel in the water, water in the oil, cracked cylinder heads, dropped valves, broken valve springs and rocker arms, spun bearings, connecting rods out the side of the blocks, etc. I can only think of one series of engines that were really clunks- and that's the British made V-8's by Cummins.  Most all other truck/bus engines have been very reliable.
The 6V-92TA has been the staple of bus locomotion for many years, until the Series 50/60 took over.  Now that Detroit does not make the Series 50 or 60 for on highway use, and Caterpillar is out of the scene, basically now Cummins is the big player with the ISL in both Diesel and Natural Gas form being the main transit bus engine.  The ISM (and now the ISX 11.9) and 15 liter ISX are the big players.  Detroits DD13 will be in Setras, and others who want to buy the engine.  Volvo has their own bus and engine now.  Other players like DAF, MAN, will be eventually getting into buses also.  But except for the Setra bus, Detroit is basically out of the bus market.  Good Luck, TomC

[Mex-Busnut]

I have been away from an Internet onnection for many days. I want to thank all of you for your comments. I am learning a lot from all of you great teachers.

Mr. Busted Knuckle:

Very informative comment (as is usual for you) about the need to check the oil on a regular basis. You are hereby granted the title of ODB: Ornery Doctor of Busnutology, with honors, from the University of Hard Knocks.

However, not to quibble, dear sir: just to inform:

What happens is many of them that are bought and taken south of the border are so wore out before going south that without proper care and attention they will have a small problem that gets ignored and becomes a serious one such as "blown" engine from washing out the bearings or such!
  BK 

Very, very few buses are brought into Mexico from the U.S. There are MANY manufacturerers making buses (and trucks and autos) in Mexico. And Mexico has a trade agreement with Brazil, so we get Brazilian-made Man, Mercedes, Busscar and Irizar and we export Dina (acronym for Diesel Nacional) and a few others to Brazil and the U.S.

Mexico closed its borders to imported vehicles in 1960, and set up many plants here. Only since NAFTA has the border begun oppening up.

But Mexican bus companies do NOT like buses with automatic transmissions. We have far too many hge mountains to climb. FLEXIBLES made here here were 8V71 Detroits or 350 Cummins, with 10-13-speed manual trannies.

The bus I am about to get is made by MASA (Mexicana de Autobuses, Sociedad Anónima). As far as i know. it has never been North of the Rio Grande.

See a pix and description of my Mexican bus here:

http://www.busconversions.com/bbs/index.php?topic=2547.360

Thanks again to all! Keep them comments coming!

Dr. Steve
San Juan del Río, Querétaro, Mexico (6,800 feet above sea level)

[Busted Knuckle]

Dr. Steve,

Thank you for the compliments and the title! (It's actually a very funny coincidence. I always tell people I have been a lifetime student @ the school of hard knocks! )

OK, now I do understand what your saying about there being many Mexican bus manufactures and all that. But I also know of 2 different used bus dealers in my small little area of the United States who tell me the majority of the buses they sell go directly south of the boarder! (where too? I don't know, but one did indicate that a lot of his were actually purchased by a couple of brothers from Guatemala. The other told me he had NO IDEA where they went, as the buyers always pay him in cash and leave. Then about a week later he and his guys take 3-6 buses at a time to Brownsville, TX and just leave them in the back parking lot of a hotel and return home with out seeing or talking to anyone! He also said "Hey I got my $ up front, I don't care where they take them, or what they do with them!")

That is why I stated the part about them being taken south f the boarder, as I have no knowledge of the ones already built there.

But I do stand by my opinion that pure lack of maintenance and overheating are the 2 main reasons for a 6V92 any worse than any other engine.
Now your 8V71's (or any 71 series) are a lot more forgiving about being overheated than any 92 series due to the 71 being a "dry liner" and the 92 being a "wet liner" cylinders of course this would have nothing to do with fuel getting in the oil, but everything to do with "coolant" getting in there.)
FWIW   BK 

[Mex-Busnut]

O.K., honorable Dr. Busted Knuckle, sir. You gave me (and yourself) the answer. I have been in Central America many times, As I know you know, these are tiny countries, both geographically, and also in population. The largest is Guatemala, with under 16 million people. The others are 1-5 million. The buses to Brownsville are going to Central America, and driven down Mexico's Gulf coast.

Mexico has over 110 million people. Over 35% live under poverty level, and own no car.  On a typical day of travel here, I can probably count over 1,000 highway buses, far more than I would see in the You Naughty States in a days' travel.

[buswarrior]

South of the border?

Scary parallel to Buffalo and upper New York State...

happy coaching!
buswarrior

[Barn Owl]

6v92 is a dependable engine. Overheat it and it dies like the rest of them. There is some other reason for Mexico to run manual vs. auto-tranny. Autos are a dream on steep hills and tight spots.

[TomC]

The main reason that most Mexican vehicles are manual transmission is backyard mechanics can fix manual transmissions.  It takes a specialist to do an Allison overhaul with gauges for testing and a transmission dyno.  Good Luck, TomC