Broken Down off of I-10 Louisiana

[Scott & Heather]

This seemed to happen pretty quickly. Oil pressure while driving typically sat around 40 psi give or take while under load driving...would sometimes creep to 50 psi under full throttle. Now it's barely 25 psi under full throttle. Someone explain to a guy trying to learn how worn lower bearings causes low oil pressure.

[chessie4905]

Normal bearing clearances in any engine allow the oil to cool and lubricate the clearance between the connecting rods and crankshaft journals, or cylinder block main bearing journals and crankshaft bearing surfaces. Also any other bearing areas in engine, of which there several. The oil sheds from these areas during rotation in a designed amount. As bearings wear, more oil is shed, to the point that the oil pump, which is designed to have some extra capacity, can't  keep up with the excess oil shedding and max oil pressure starts dropping some. A quick bearing loss or pressure regulator malfunction can cause this. The regulator is designed to maintain proper range oil pressure, regardless of engine speed or temperature. It opens to lower oil pressure or closes some to raise it. This goes on constantly during it's  life. Sticking closed some, can cause abnormally high pressures. Sticking open, can cause lower or no pressure. Btw, a broken pressure spring can cause this.

[muldoonman]

Scott I'd call Stewart Stevenson down south and see if they know of anybody they would trust up there. I know when I had mine into San Antonio a couple years back , the Shop Foreman ,Tom, just had a couple Ole Fellas that worked on 2 strokes and said the one in Harvey had several mechanics as the Fishing Boats still had a ton of them running. They also had service trucks to go to the docks. You have a towing service contract like CoachNet?


LA - New Orleans
1400 Destrehan Ave.
Harvey, LA 70058
Tel: (504) 347-4326

[bobofthenorth]

This seemed to happen pretty quickly. Oil pressure while driving typically sat around 40 psi give or take while under load driving...would sometimes creep to 50 psi under full throttle. Now it's barely 25 psi under full throttle. Someone explain to a guy trying to learn how worn lower bearings causes low oil pressure.

Pumps don't of themselves generate pressure.  Pumps move volume - restrictions create pressure.  More restriction = more pressure so loose bearings let more volume through which in turn lets the pressure drop off.  When the pressure gets above what the engineers wanted the relief valve opens.  Based on your description of the onset of symptoms my money is on a stuck relief valve. 

[Utahclaimjumper]

 Most oil pumps have a pressure relieve valve that is simply a ball or piston held on a seat with a calibrated spring behind it.  Many times a piece of crud will be trapped between the seat and ball or piston ,, allowing some of the normal pressure to escape through the valve,,, you see the result on the pressure gauge,,the engine see's it with lower operating pressure,, and a sensor see's it as a fault and shuts the engine down..>>>Dan

[Dave5Cs]

And the relief Valve would be found where on the pump? Or

[luvrbus]

if either regulator fails on either side of the engine it will dump oil back into the pan that sounds like your issue ], a cracked  pickup tube the pressure will not hold steady

[luvrbus]

if either regulator fails on either side of the engine it will dump oil back into the pan that sounds like your issue ], a cracked  pickup tube the pressure will not hold steady it cavatates you over come that by adding a gal or 2 of oil to get going .

[Scott & Heather]

Ok this is good info. Thanks for schooling me. I can't seem to find a shop anywhere near Lafayette that I trust. I've literally spent two days calling them all. I ask them if they can work on a two stroke Detroit and I get the "wah? Duh?" response. I found a single shop (literally just one) in Baton Rouge 70 miles away that immediately said "yep, we don't get them too often but we have a couple of guys here that know their way around two stroke Detroit's" and I think that's mainly because of all the marine repairs they have to do for boats there. So I have to try to convince State Farm that it's necessary to tow me there. That's gonna be a very very expensive tow bill for them so I expect a fight. Man I wish I had a friend nearby who could walk me through doing this myself. But I just can't take the chance.

[windtrader]

Call the traveling monkey

[chessie4905]

Maybe you could try the Prevost group via Facebook. Maybe Cliff has a contact person. Yeah, I know you have a MCI.

[richard5933]

Call the traveling monkey

He's working in Texas on a Wonderlodge right now, so he's close...

[Scott & Heather]

Hey guys, I've called Scott Crosby more than once. He never wants to work on my coach. This time he said to me he doesn't work on DDEC anything. So I can't ever make use of his services as much as I could really use his help and would happily pay his rates. It doesn't make sense to me because DDEC or not rolling in new bearings and dropping the pan has nothing to do with DDEC. But oh well. I have to get it up and running with concerts scheduled in Florida for the next month. So to a shop it is. I've narrowed down to two shops in Baton Rouge:

All Truck Parts and Equip
Baton Rouge Diesel Services Inc

I'll call them both tomorrow morning and try to see which one I like better.

[luvrbus]

there is no difference in  a ddec than the mechinal except the oil pan has reusable gasket Scott look for United Engine they own S and S and have closed some old locations   

[Scott & Heather]

Thanks Cliff. No United Engine nearby... yeah I didn't think this was a big deal but he's busy and headed the other direction so I just have learned to just figure this stuff out on my own. It's par for the course.