Oil pressure question
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Junior User
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From: south fla.
Oil pressure question
Hi
My problem started about a month ago. My 350 dually 7.3 starts ok but if I dont rev it up and get the oil pressure up within about 10-15 seconds it will shut off. If I try to let it idle it will not stay running. It will restart but quits after 4-5 seconds on the second try. This only happens after the truck has not been run for 6 or 7 hours. Any sooner and the oil pressure comes up right away. Oil only has about 3500 mi on it. HPOP is full as well as full on the dipstick. Odometer reads 176500. But I only got this truck 4 mo ago. Pressure switch ???
Thanks in advance
My problem started about a month ago. My 350 dually 7.3 starts ok but if I dont rev it up and get the oil pressure up within about 10-15 seconds it will shut off. If I try to let it idle it will not stay running. It will restart but quits after 4-5 seconds on the second try. This only happens after the truck has not been run for 6 or 7 hours. Any sooner and the oil pressure comes up right away. Oil only has about 3500 mi on it. HPOP is full as well as full on the dipstick. Odometer reads 176500. But I only got this truck 4 mo ago. Pressure switch ???
Thanks in advance
Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Not the pressure switch. The PCM is completely blind to oil pressure. The pressure sending unit is wired directly to the gauge cluster, and that's it.
It sounds like the HPOP res is emptying after sitting for a while. You're checking it to be sure it's full before you ever crank it? And checking it by pulling the plug in the top of the res, correct?
It sounds like the HPOP res is emptying after sitting for a while. You're checking it to be sure it's full before you ever crank it? And checking it by pulling the plug in the top of the res, correct?
Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Well, if the HPOP res is full, the actual HPO pump may be on its dying leg. Since the injectors are driven by high pressure oil, a dying pump means a poor or non running truck.
Alternatively, I have heard of a bad LPOP causing similar symptoms. I think you'll want to get a manual gauge to test the oil pressure in the HPOP res (it's actually low pressure oil in the res), and something like the AE software to take some readings of the high pressure oil. A little further diagnosis should be done, I think.
If you have good LPO, and a low HPO number, then it's probably your actual HPO pump. If the LPO reading is low, I'd start off by replacing it.
Alternatively, I have heard of a bad LPOP causing similar symptoms. I think you'll want to get a manual gauge to test the oil pressure in the HPOP res (it's actually low pressure oil in the res), and something like the AE software to take some readings of the high pressure oil. A little further diagnosis should be done, I think.
If you have good LPO, and a low HPO number, then it's probably your actual HPO pump. If the LPO reading is low, I'd start off by replacing it.
Post Fiend
Joined: Feb 2006
Posts: 11,892
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From: Middle Tennessee
This still sounds exactly like the HPOP anti-drainback check valve. If you are sure it is full when cold before sarting, then go ahead and start it without giving it the gas, then when it dies, check the HPOP oil level to see if it went down. If so, you may have a stuck or obstructed drainback valve or low oil pressure from the LPOP. Just a stab.
Post Fiend
Joined: Feb 2006
Posts: 11,892
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From: Middle Tennessee
Originally Posted by jtharvey
If you have good LPO, and a low HPO number, then it's probably your actual HPO pump. If the LPO reading is low, I'd start off by replacing it.
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Junior User
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From: south fla.
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Lead Driver
Joined: Oct 2004
Posts: 7,413
Likes: 1
From: Columbia, MO
Yeah, a failing HPOP would probably exhibit the signs of failing, all of the time.
To put a manual gauge on, use the spare port on top of the HPOP res.
To put a manual gauge on, use the spare port on top of the HPOP res.
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Junior User
Joined: Nov 2006
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From: south fla.
Ok I filled HPOP resivoir to the top yesterday and did not run it more than 5 minutes. Checked it this afternoon and was a pint low. Do I need a new spring in the anti drain back or what
Thanks again and again.
Thanks again and again.
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