8V92 vibration

[JohnEd]

I went and looked at a 87 Pre with a 8V92.  It was cold iron and the ambient was 60 degrees.  It fired on maybe the third rev, loped twice and settled into a heart warming fast idle.  God they sound good  In the instant it first fired it coughed a white smoke, basketball sized, puff.  After that it seemed to lope again and a second small puff.  Then it seemed the gov kicked in and brought it smoothly up to idle.  In between the white puffs there was a black puff.  Doesn't this describe a tight engine?  Blipping the throttle gave no smoke at all.  It is a DDEC. 

With it running about 15 min I went up and sat in the drivers seat.  I wondered how fast the air throttle would respond to inputs.  I pressed the acc pedal down slowly and watched the tack climb.  At 12 or 13 hundred I felt my seat and feet vibrate.  50,000 pounds and I hit its "harmonic"?  What happened?  Do they do that?  I may make an offer if all is well but I don't think it is is my hunch.

Thanks,

John

[PCC]

How long since it has been started and ran?

Is it a rear engined bus?

8V92 with DDEC1?

The best is to take it out for a run before deciding, but that is a good engine, if it is run regularly, and not idled every once in a while.

Keith
PCC

[Just Dallas]

Removed

[robertglines1]

I have a 89 prevost with a 8v92..it is a ddecII system and has no air throttle..the throttle is a electrical sensor on pedal that sends a signal to the computer to give it fuel...no vibration at any speed...If it hasn't been run in awhile..I'd run it some and see if it don't straighten its self out...how many miles? I had a cam follower return spring break and set up a vibration..caught it early and no damage..Bob

[TomC]

Diesel engines are not balanced like race car engines.  Having a vibration at a certain rpm when sitting still happens on many big vehicles.  I assure you, you won't feel it when driving.  Good Luck, TomC

[JohnEd]

I did not drive it yet.  The vib was while sitting and the trans in neutral.  Given the size of the thing and it 50,000 lbs I was taken aback that I could feel anything the engine did way back there.

It is a rear engined Prevost conversion by Liberty.  It has 150K miles.  It had been run within the week and most probably within a day.

DDEC doesn't have a governor or an air throttle

So what do you thing about the smoke and vib?

Thanks Guys,

John

[wal1809]

I like smoke and vibs .  Sorry brother could not resist.  How bad was it?  The reason I ask is when I first got my bus, everything made me think the classic "Oh %^&*, I got a problem".  I was being over sensative and still am to some degree but the more I ride the better it gets.  So describe the vibe!!!

[Timkar]

From my limited experience, the engine sounds ok. Had an 88 Eagle that did the same thing and it had a fairly fresh rebuild. You need to take it for a run. Is that the one in Eugene that the owner is in his 80's and doesn't want to drive to Yuma anymore? I have seen it for sale for quite a while. Sure looks like a nice coach.

[Dreamscape]

John, Take that puppy out and drive it, whatever you felt may no be tipical. Check all  points for drips when you get back, take an IR gun with you and then shoot some temps when you return on everything you can point it at.

Paul

[JohnEd]

Timker,

It is in fact that very same man.  Seems like a nice guy and seems open and a little knowledgeable.  What was he asking before and how long ago did you notice he was trying to sell it?

Wal,

I think I have listed all the conditions.....didn't drive although the seller was hot to get me behind the wheel.  I suspect that it runs and drives well.

The plus.... and.... minus here is the maintenance.  A professional shop next door to his enterprise does their own maint on their equip his routine maint.  He has full confidence in them and they do have a yard full of big  D equip and trucks.  First problem I found was when I asked about the oil used he said it was "40 dash something, not sure,  but those guys really know what they are doing over there".  I asked about maint records and he wasn't sure they had documented all the oil changes or antifreeze charging but he said could have them "put a folder together or dig up some".

I asked about the tires and said I noticed two new Michelin's on the tags.  He started cursing Michelin. He said they were great till they got to be 4 years old then the sidewalls "blew out on all of them...one right after another....terrible tires".  Had two fronts fail but was traveling slow and had no trouble getting pulled over and they didn't do any damage.  Lets hear it for Prevost and the 80 year olds every where.  Mich wanted to give him 50% credit for used miles but he didn't want their tires anymore and went with TOYO.  Now Mich can spot a tire failure attributable to low pressure from down the street and in the back of a pickup.  That they wanted to credit him would seem to bear up his claim that they were not run with low pressure.  The fly in that ointment is that he said "I have the guys next door check it out before I leave  and they are real good about all that stuff".  When my life and 25 grand are on the line I "check all that stuff myself" and the tires and oil don't get looked at only once before a multi thousand mile trip with a 4 month layover.

Only two roof airs and the OTR AC is only available for the driver.  Small compressor.  Genny was a 11KW unit.

Had propane furnaces and carried 54 gal that lasted a year.  A plus for me. But had an electric HW heater that also got heat from the engine.

All in all a nice coach.

Thanks for your help and advice.  I think I will look at quite a few before I pull the trigger and this sort of discussion is an education itself for me at least.

John



 

[Timkar]

Hi John,
Price hasn't changed from when I first saw it. I think it was around Nov/Dec 2009 that I first spotted it.
Here is latest ad I found about it.


http://eugene.craigslist.org/rvs/1704764919.html

Tim

[Len Silva]

Hi John,

All I can say about is that I like the interior a whole lot more than the other one you posted about.  The mirrored ceilings and swirly carpet just don't work for me.

Len

[JohnEd]

The mirrored ceilings and swirly carpet just don't work for me.

Me neither, Len, me neither.

Thank you all for your very useful comments.  Thank you

John