So I'm going to drive 300 miles to pick up the bus I bought, sight unseen. 1985 MCI 96A3 with 6V92T. Gotta fix a minor problem on it before I can drive it home. Too good a deal to pass up, so I took a chance.
PO says it's not building oil pressure. When it suddenly lost pressure, they shut it down and haven't driven it since.
PO said bottom end was rebuilt 3 years ago, and mechanic said very little wear on main bearing surfaces. He also said oil pump gears looked great. Bus has been very well maintained.
PO feels it is perhaps the oil pressure regulator or relief valve, or possibly something in the pick-up.
Could be a faulty gauge, but PO also said they checked line going to compressor and saw no oil coming there.
I will be bringing spares of the valves, along with filters, oil, etc.
Just wondering where else we might look for problems?
Thanks
Pull the oil pan I almost bet the pickup tube has broken or the last guy that did the bottom forgot to install the support and torque the bolts on the pump,I would not start the engine till I pulled the oil pan JMO
Thanks. Definitely planning I'm pulling the pan.
Hey, Twisted Sister fan, I ran into a similar problem with a customer's 8V92TA and it turned out that the
crankshaft woodruff key on the oil pump gear had sheared off so the oil pump wasn't working.
You should make sure the front crankshaft pulley bolt is super tight because if it is loose the key breaks. In fact, just tightening the bolt will get the pump working again (if that is the case). The woodruff key is just a guide and is quite thin.
Geoff,
That's an awesome tip. I had considered maybe broken teeth on the pump gears, but not a sheared key.
Gonna make sure to bring balancer puller and check it out if regulator and relief valves are good.
Thanks!
So I removed the oil pan and replaced both the Oil Pressure Refief valve and the Oil Pressure Regulator, along with the pick-up tube for good measure, but still no oil pressure. Im going to go down next weekend and pull the oil pump and check it out.
Oil was flowing out of a hose connection, one where apparently it wasn't flowing from before, on the left(passenger) side of engine, close to bellhousing, when I disconnected it. Still no pressure on the guages, back or front.
If not the pump, any idea what direction to go from there?
Thanks
nothing left but the oil pump or the drive,as Geoff said the drive slides on the crankshaft into the pump and has a key
Passenger side is the right side.
OK.
I removed and disassembled the oil pump and inspected the gears. Everything lookd good. I took it to a diesel mechanic for a second opinion, and he concurred.
He suggested I replace the oil filter. I did so and put everything back together and, viola, we have strong oil pressure. Go figure.
Anyway, i plan on relocating the oil filter to a more accessible spot. It was not easy slithering underneath the engine and tranny to get to it.
Lots to do.
I'm concerned that a plugged oil filter wouldn't allow oil pressure. I would cut it apart and inspect the debris. A lot of metal, and start inspecting bearings. Was there any debris in bottom of pan when you removed it, or had previous owner removed it and cleaned it?
There was debris, but it appeared to be silicone sealant from the pan(no gasket). Did not see metal. When I get it home next weekend I will cut the filter apart and see what I can find.
There was, however, a small amount (drops) of coolant in the bottom of the pan. That concerns me, for sure.
I had the same problem with my transit bus-the oil filter was underneath in the middle of the bus-which is fine for changing the oil over a pit, but horrible to get to any other time. Since the oil filter was already remotely mounted, I had longer oil lines made and a spin-on filter (Cummins type) mounted just inside of my right engine access door. Now easy to get to and also inspect. Good Luck, TomC
A plugged filter wasn't his problem those engines by pass the oil cooler and filter if either one becomes plugged
Quote from: luvrbus on April 21, 2019, 11:07:56 AM
A plugged filter wasn't his problem those engines by pass the oil cooler and filter if either one becomes plugged
Do you have a suggestion as to the cause?
I am at a loss to say what the problem was. It apparently wasnt any of the aformentioned suggestions. I did blow compressed air through the line going to the oil pressure manifold(for lack of a better word).
All I know is when I put the oil pump back together, re-installed it and changed the oil filter. I had oil pressure.
Thanks
The oil is pressurized at the pump it goes through the adapter plate since you have a remote filter I am presuming the engine has the double oil cooler which has a by pass valve to by pass incase the filter or cooler is plugged. I have no answer to why you have oil pressure now but it was not because of a plugged filter because the valve on the adapter plate will open and return the oil back to the galley lol what ever you did it worked that is all that important in the end
It's crazy!
Does that engine have Thermatic oil filter housing or the standard by pass, the Thematic has a large nut {valve) in the center they stopped using those in 1988 but some are still around
Quote from: luvrbus on April 21, 2019, 11:46:58 AM
Does that engine have Thermatic oil filter housing or the standard by pass, the Thematic has a large nut {valve) in the center they stopped using those in 1988 but some are still around
Honestly, I have no idea. I was focused on removing the old filter and installing the new, while making myself flatter than I thought possible. I'll take a look at it when I get it back to the house next week.
"Whatever you did, it worked in the end" Hopefully this doesn't repeat in the future.
From your lips.....
I got the bus home!
Picked it up in Valdosta GA this morning. Got about 65 miles north on I75 and I noticed that the oil pressure had gone to just below 50 psi(was at about 55 for most of the 65 miles) and then we lost oil pressure and she shut down.
Was able to get in off the highway onto an off ramp.
We installed a new oil filter and we were on our way again!:) Oil pressure stable at just under 60 psi for the next 3 hours, then it sorta spiked to about 72 for an hour. We got to within about five miles of my house when the pressure dropped to just below 50 psi again.
Wasn't sure we'd make it, but we did.
I had it at high idle for the past 30 minutes or so, and pressure was about 40ish, seems to be holding.
Thoughts?
Thanks:)
Do you have any thoughts on the coolant in the pan?
What causes sudden lack of OP and coolant in the pan? (I'm thinking "out loud" here)
Quote from: daddysgirl on April 28, 2019, 03:44:47 PM
Do you have any thoughts on the coolant in the pan?
What causes sudden lack of OP and coolant in the pan? (I'm thinking "out loud" here)
I don't know that one has to do with the other, but it certainly could.
For some reason the oil filters are getting clogged very quickly and causing the loss of oil pressure.
The likely cause of the coolant is probably the liner seals. I'll have to drop the pan and pressurize the system and see if I can spot the leak into the pan.
If it's picking up coolant and emulsifying it with the oil and then clogging the filter with the result, you'd better not run it any more until you get the coolant problem sorted out. Antifreeze can be death to main and rod bearings.
Jim
Quote from: brettpearson67 on April 28, 2019, 04:05:11 PM
I don't know that one has to do with the other, but it certainly could.
For some reason the oil filters are getting clogged very quickly and causing the loss of oil pressure.
The likely cause of the coolant is probably the liner seals. I'll have to drop the pan and pressurize the system and see if I can spot the leak into the pan.
Has the by pass valve failed?...What about the gauge or pressure switch if the pressure is fluctuating...
I'm not trying to hit you with too many things at once, just typing out loud so you'll have a record of everything easy to check.
Quote from: Jim Blackwood on April 28, 2019, 04:36:00 PM
If it's picking up coolant and emulsifying it with the oil and then clogging the filter with the result, you'd better not run it any more until you get the coolant problem sorted out. Antifreeze can be death to main and rod bearings.
Jim
Yes, I am going to drop the pan pressurize the coolant system, and see if I can determine the source of the coolant. It was just a few drops in the bottom of the pan, but obviously that is something that needs to be addressed immediately. Now that I have it home, I can get to it.:)
Quote from: daddysgirl on April 28, 2019, 04:47:01 PM
Has the by pass valve failed?...What about the gauge or pressure switch if the pressure is fluctuating...
I'm not trying to hit you with too many things at once, just typing out loud so you'll have a record of everything easy to check.
If you are referring to the oil bypass valve in the pan, I just replaced that, along with the oil pressure regulator valve, and the pickup tube.
I am wondering now, though, could it be possible that the lines to the filter are plumbed backwards? The reason I ask is that the bypass valves in the filters are not working, it seems. If the filters get clogged, should that valve not open up?
Just a goofy thought and I don't even know if it apply's or not but oil filters have a anti drain back valve that keeps the oil from backing down from the engine.Jap filters used to be bad to stick open and when you let your Jap Trap set over night and then fired it up the next morning ,the engine would dry start and for a few seconds it would knock like a thrashing machine.Is it possible that this valve could malfunction the other way and refuse to let oil through???
Quote from: brettpearson67 on April 28, 2019, 04:05:11 PM
I don't know that one has to do with the other, but it certainly could.
For some reason the oil filters are getting clogged very quickly and causing the loss of oil pressure.
The likely cause of the coolant is probably the liner seals. I'll have to drop the pan and pressurize the system and see if I can spot the leak into the pan.
Just pull the inspection covers there is no need to drop the pan to see if it is a liner leaking the water jacket is above the inspection covers
Quote from: luvrbus on April 28, 2019, 07:02:16 PM
Just pull the inspection covers there is no need to drop the pan to see if it is a liner leaking the water jacket is above the inspection covers
I didn't know that. Thanks!
That sure will save a lot of time and effort.
Quote from: brettpearson67 on April 21, 2019, 05:20:14 AM
There was debris, but it appeared to be silicone sealant from the pan(no gasket). Did not see metal. When I get it home next weekend I will cut the filter apart and see what I can find.
There was, however, a small amount (drops) of coolant in the bottom of the pan. That concerns me, for sure.
This is one of my weaker subjects, so let me know if I am wrong please...
Is there any chance a piece of silicone got up into one of the lines, causing the jumping pressure?
As for the bypass valve...I was thinking of the valve that is in the inlet passage of the oil cooler adapter? I believe that is the valve that kicks in if the cooler is plugged?
I believe he has a electrical problem in the shutdown system it resets while he is changing the filter ,the filter getting plugged is another subject it may have the wrong filter you can run 1 without a filter with plugging the lines if he has a remote mount filter
Quote from: luvrbus on April 29, 2019, 07:44:00 AM
I believe he has a electrical problem in the shutdown system it resets while he is changing the filter ,the filter getting plugged is another subject it may have the wrong filter you can run 1 without a filter with plugging the lines if he has a remote mount filter
If it's electrical, can he isolate and disconnect the low oil pressure circuit just long enough to see if that is the issue? Or would that be too dangerous to the engine if both gauges are reading properly?