Duramax Diesels Forum Truck of the Week
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Old 09-03-2019, 02:13 PM
Johnboylb7 Johnboylb7 is offline
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Default Lb7 low oil pressure at running temp

Hello there
Im having some issues and not finding much on this issue to solve my problem. Was towing a car trailer a week ago and as i came to a stop light the low oil pressure indicator light came on and it had a slight knock and noticed my electrical oil gauge was bouncing up and down.Took it home and parked it well since then i have installed a mechanical gauge into the oil filter housing did an oil change also i run Lucas oil stabilizer and 15 40 oil. On initial startup i have good oil pressure,mechanical one says 90 my stock one says 60. Go and drive it around for a little bit till it gets to running temp and then come to a stop light and sit there for a minute and my oil pressure drops to about 6 psi for a split second then jumps back up to 10 or so. I just did head gaskets at the beginning of this year has had no issues for 8 months. Is there anyone that knows how to trouble shoot to see of its the oil pump? or should i just pull the motor and replace everything i can involving oil?
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Old 09-04-2019, 07:30 AM
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Just double check that your not making oil.
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Old 09-04-2019, 08:07 AM
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Quote:
Originally Posted by Brent@LDS View Post
Just double check that your not making oil.
This exactly
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Old 09-04-2019, 04:16 PM
Dkatubi06 Dkatubi06 is offline
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Low oil pressure light comes on at 7 psi I believe. Definitely check to make sure your not making oil
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Old 09-07-2019, 03:19 PM
Johnboylb7 Johnboylb7 is offline
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I double checked im not making or loosing oil. Gonna pull the motor out and then pull the pans off and see what is going on in a couple weeks. Is it possible that the lucas oil stabilizer is clogging everything up?
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Old 09-07-2019, 05:10 PM
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Quote:
Originally Posted by Johnboylb7 View Post
I double checked im not making or loosing oil. Gonna pull the motor out and then pull the pans off and see what is going on in a couple weeks. Is it possible that the lucas oil stabilizer is clogging everything up?
Worst stuff to put in an engine EVER. Effed up a 5.3 pretty good till it ran hot and finally burnt all that sh!t out. The oil change after dad put the bottle in the truck, when he pulled the drain plug nothing came out. Had to poke a stick in it only to get a giant silicone-ish turd looking thing out. Then came the oil. After that it ran horrible and had terrible oil pressure. Like I said till the water pump went out and dad was pissed and just kept driving home. Got quite warm. Changed the pump and oil, which was a bit odd smelling if I remember right. After that, oil pressure was as good as new. Idled better.

May sound like a complete BS story, but thatís what happened. I canít say for sure thatís whatís wrong with your truck, considering 15w-40 is already thick, adding something like the Lucas goop isnít gonna help pressures.
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Old 09-07-2019, 07:18 PM
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Lol I run a quart of that shit in my tracker every 3k oil change. I rev/drive the absolute piss out of it like it owes me nothing though. Makes my crappy hydraulic lifters actually pump up. It saw 5500rpm and wot for an hour straight down in Mexico while we were on the beach. Still kickin .

But that shit is just a bandaid and I donít believe it was designed with diesels in mind. Donít think Iíd run it in my diesel at any point. Better off fixing the actual issue
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Old 09-07-2019, 07:26 PM
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Ah, good old "Motor Honey".
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Old 09-09-2019, 10:52 AM
Johnboylb7 Johnboylb7 is offline
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Well did another oil change with no lucas in it this time and a new filter and the problem still consist. Think imma pull the pan tonight to inspect everything i can see from that point look at the pickup tube and hoping its just clogged.
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Old 09-09-2019, 11:02 AM
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This thread popped up and magically my truck started to drop oil pressure. It still makes ~15-20psi hot but is averaging ~30psi hot towing at ~1850-2000rpm. When I pulled the truck out for injectors it would hold a solid 40-45psi hot towing and verified this over a 2200mi tow in 90f weather. I am wondering if she is finally getting tired at 270k?

It's not making oil according to the dipstick, going to pull an oil sample to see if a bearing decided to die (doesn't look like a bunch of metal flake). 2500mi ago the oil analysis looked great. I don't want to dump 10qts of amsoil just to see if an oil change fixes it unless the oil comes back bad/full of fuel/full of coolant.
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Old 09-09-2019, 11:24 AM
Johnboylb7 Johnboylb7 is offline
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Yeah spec says running temp at an idle it should be no lower than 14. Mine at running temp drops to 6 and the low oil pressure light comes on.
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Old 09-09-2019, 11:31 AM
Johnboylb7 Johnboylb7 is offline
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How do i post a picture in the comments ive tried everything just not figuring it out
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Old 09-09-2019, 11:37 AM
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Biggest issue with posting photos is ones too large. Reduce it down to 195.3kb or less

Or you can upload it to a hosting site and link the file to here
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Old 09-09-2019, 12:24 PM
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This probably going to cause a $hit storm......


I purchased Emma with about 180K miles. She had low oil pressure when warm at idle.


I changed the oil to what I have used for ever... Rotella T6 15w-40 full synthetic.


From that oil change on, I have never had a low oil pressure problem, and she is at about 330k miles.


I'm not selling oil or picking a brand, I'm just saying what worked for me.


Good luck
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Old 09-09-2019, 01:25 PM
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Quote:
Originally Posted by zakkb787 View Post
Worst stuff to put in an engine EVER. Effed up a 5.3 pretty good till it ran hot and finally burnt all that sh!t out. The oil change after dad put the bottle in the truck, when he pulled the drain plug nothing came out. Had to poke a stick in it only to get a giant silicone-ish turd looking thing out. Then came the oil. After that it ran horrible and had terrible oil pressure. Like I said till the water pump went out and dad was pissed and just kept driving home. Got quite warm. Changed the pump and oil, which was a bit odd smelling if I remember right. After that, oil pressure was as good as new. Idled better.

May sound like a complete BS story, but thatís what happened. I canít say for sure thatís whatís wrong with your truck, considering 15w-40 is already thick, adding something like the Lucas goop isnít gonna help pressures.
Iíve had it fix a 5.3 with a lifter tick. Poured a bottle in it and the tick went away and the truck still runs to this day. Has about another 80k on it from then. Hell I even poured a bottle in my truck and pressure went way up. Even sounded quieter but that could just have been a placebo. Did a lot of reading about oil pressure and decided it didnít need to be that high and never ran it again.
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