6.0L weird oil pressure problem
6.0L weird oil pressure problem Hi everyone, have some weird problems going on with my oil pressure lately heres the background...
2005 chevy blue bird bus (Short Bus) using for a tow rig. 6.0L 4l80e 2wd 227k bought it from a school in southern mn at auction maintenance is unknown ...
When i received the bus i noticed it was at 15lbs oil pressure during the summer and around 30 causing down the highway so i overfilled it by about a quart and noticed oil pressure increased as i added more oil .... now the hot idle is at 25lbs and 40 causing down the highway which from what i read is low but is acceptable.... lately the weather has been getting down into the 40s and 30s here and on cold starts i get like 15 psi and eventually and now 35lbs crusing down the highway. i also heard a lifter ticking for a brief 30 seconds or so then went away. I've changed the oil and used stock 5w30 mobile 1 SYN and a Wix filter. My question is.... does this sound like a dying o ring at the pickup tube or the oil pump going out ? getting somewhat nervous over here...
idle speed is 600rpm and 2300 at 65mph
2005 chevy blue bird bus (Short Bus) using for a tow rig. 6.0L 4l80e 2wd 227k bought it from a school in southern mn at auction maintenance is unknown ...
When i received the bus i noticed it was at 15lbs oil pressure during the summer and around 30 causing down the highway so i overfilled it by about a quart and noticed oil pressure increased as i added more oil .... now the hot idle is at 25lbs and 40 causing down the highway which from what i read is low but is acceptable.... lately the weather has been getting down into the 40s and 30s here and on cold starts i get like 15 psi and eventually and now 35lbs crusing down the highway. i also heard a lifter ticking for a brief 30 seconds or so then went away. I've changed the oil and used stock 5w30 mobile 1 SYN and a Wix filter. My question is.... does this sound like a dying o ring at the pickup tube or the oil pump going out ? getting somewhat nervous over here...
idle speed is 600rpm and 2300 at 65mph
TECH Fanatic
Joined: Jan 2018
Posts: 1,250
Likes: 239
From: Dade City, Fl.
It might be the pick up tube o-ring. If it's a good running vehicle other than the oil pressure issue, I would address the issue. It is possible to change the oring w/engine in vehicle. Put a new standard pressure pump on it while you're in there
TECH Senior Member
Joined: Jun 2016
Posts: 22,299
Likes: 3,619
From: Central Cal.
The way I understand it is, if there is a rolled "groove" on the pickup tube, the "fatter" O-ring is used. If the tube is straight with no groove, the thinner one is used. Is this right?
TECH Fanatic
Joined: Jan 2018
Posts: 1,250
Likes: 239
From: Dade City, Fl.
From the info I have ,yes , as G Atsma stated per the o-ring usage . If there is a "groove" or reduced diameter for which the o-ring would sit in, use the thicker o-ring. GM had a TSB about these O-rings. There has been that many issues with them. TSB #02-06-01-038 . Not sure of the oil pan in the BlueBird ,but I would go out on a limb and guess it is a truck pan and pickup tube.
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How many miles have you had this vehicle? Have you had it a while and it just started having a change in oil pressure? Or, did you acquire it recently and is it possible the oil pressure has been this way a while? With that many miles I wouldn’t be surprised if the bearings are wearing a bit, causing the drop in system pressure. The pressures don’t sound too bad as long as you’re not hammering the engine with high RPMs.
If you do decide to tear into it for the O ring, I would also be prepared to swap the oil pump out (as mentioned). However I think I would opt for the Melling 10295 high pressure pump in this case. If you go through all that trouble and replace the oil pump with an oem replacement, if it turns out the old pump was fine you would end up with the exact same performances you have now.
If you do decide to tear into it for the O ring, I would also be prepared to swap the oil pump out (as mentioned). However I think I would opt for the Melling 10295 high pressure pump in this case. If you go through all that trouble and replace the oil pump with an oem replacement, if it turns out the old pump was fine you would end up with the exact same performances you have now.
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Verdad Gallardo How many miles have you had this vehicle? Have you had it a while and it just started having a change in oil pressure? Or, did you acquire it recently and is it possible the oil pressure has been this way a while? With that many miles I wouldn’t be surprised if the bearings are wearing a bit, causing the drop in system pressure. The pressures don’t sound too bad as long as you’re not hammering the engine with high RPMs.
If you do decide to tear into it for the O ring, I would also be prepared to swap the oil pump out (as mentioned). However I think I would opt for the Melling 10295 high pressure pump in this case. If you go through all that trouble and replace the oil pump with an oem replacement, if it turns out the old pump was fine you would end up with the exact same performances you have now.
If you do decide to tear into it for the O ring, I would also be prepared to swap the oil pump out (as mentioned). However I think I would opt for the Melling 10295 high pressure pump in this case. If you go through all that trouble and replace the oil pump with an oem replacement, if it turns out the old pump was fine you would end up with the exact same performances you have now.
From the info I have ,yes , as G Atsma stated per the o-ring usage . If there is a "groove" or reduced diameter for which the o-ring would sit in, use the thicker o-ring. GM had a TSB about these O-rings. There has been that many issues with them. TSB #02-06-01-038 . Not sure of the oil pan in the BlueBird ,but I would go out on a limb and guess it is a truck pan and pickup tube.
it actually runs excellent its nice and quiet and engine is strong.
Could be that pickup screen is gunked up. Hell, bad oil pressure switch could be off. Swap it out or test with mechanical gauge kit. Oil on pickup tube. Oil cap I've found out when I forgot to put mine back on. I idle at 45-50 and 1day went to 35#, which i had long time ago before changing my pressure switch. Next day I noticed my oil cap missing n idle # back to 45-50.
so i took it for a long drive this weekend being careful and watching the gauge after about 30 minutes of driving the oil pressure was varying from 42-48 lbs going down the highway at about 2500 rpm when i went up hills on the highway i noticed i went down hills on the highway it would drop to 42 then flat land is 48. and 30lbs at idle..... when i shut it down and let it cool down over night i restart and i have 19psi until it starts to warm up ...... in spring i am replacing the following
cam thruster plate on front
oil pickup tube
mellings oil pump (HIGH PRESSURE)
O-ring supplied with kit
all gaskets etc
hoping to get another 50k out of this thing at least .... even with blackish trans fluid : )
cam thruster plate on front
oil pickup tube
mellings oil pump (HIGH PRESSURE)
O-ring supplied with kit
all gaskets etc
hoping to get another 50k out of this thing at least .... even with blackish trans fluid : )
TECH Senior Member
Joined: Jun 2016
Posts: 22,299
Likes: 3,619
From: Central Cal.
I would not replace the pickup tube so much as just clean out the one you have, unless for some weird reason it got damaged somehow. They usually don't go bad. Do all the other stuff you mention though.
And change the tranny fluid if it's black...
And change the tranny fluid if it's black...
yeah hopefully the job doesn't require the motor to be pulled since its a bus its gonna be a pain in the *** to do, the trans fluid was blackish when i got it I've done 4 pan drops and filter changes no chunks on the magnet no glitter really just old fluid. changed it 4 times its still darker in color it has a trans cooler and i assume the entire system holds 16 quarts from my research it has made no difference in shifting or anything like that shifts smooth still crossing fingers
update to this thread,
put a new oil pump in from millings the high press and high volume. turns out that little red o-ring was cracked and has a small chunk missing allowing air to be pulled by. while i was in there put in a custom grind cam from comp and a cam retainer plate etc. i have rock solid oil pressure at 55psi at idle with a hard rev it pegs the gauge at 80. Thanks to everyone whom pointed me in the right direction hopefully this thread will help the next person in line !
put a new oil pump in from millings the high press and high volume. turns out that little red o-ring was cracked and has a small chunk missing allowing air to be pulled by. while i was in there put in a custom grind cam from comp and a cam retainer plate etc. i have rock solid oil pressure at 55psi at idle with a hard rev it pegs the gauge at 80. Thanks to everyone whom pointed me in the right direction hopefully this thread will help the next person in line !
update to this thread,
put a new oil pump in from millings the high press and high volume. turns out that little red o-ring was cracked and has a small chunk missing allowing air to be pulled by. while i was in there put in a custom grind cam from comp and a cam retainer plate etc. i have rock solid oil pressure at 55psi at idle with a hard rev it pegs the gauge at 80. Thanks to everyone whom pointed me in the right direction hopefully this thread will help the next person in line !
put a new oil pump in from millings the high press and high volume. turns out that little red o-ring was cracked and has a small chunk missing allowing air to be pulled by. while i was in there put in a custom grind cam from comp and a cam retainer plate etc. i have rock solid oil pressure at 55psi at idle with a hard rev it pegs the gauge at 80. Thanks to everyone whom pointed me in the right direction hopefully this thread will help the next person in line !
By the way for those looking for answers, the lower oil pressure when cold was kinda the giveaway for the o ring, pressures are always higher when cold since the oil is thicker when cold. Being cold it was harder for the pump to suck up the thicker oil and things contract when cold. The O ring swelled a little in higher temps and helped the pressure.
O rings do go bad over time, they harden and lose their seal, and as you already know, they sometimes crack too. Rubber ages out, pick up an old rubber band and pull on it, same thing happens to rubber in tires gaskets etc.