Not "millings" but Melling...unless you mean some other company
https://melling.com/aftermarket/oil-pumps/
Oil pickup tube o-ring replacement
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Not "millings" but Melling...unless you mean some other company
https://melling.com/aftermarket/oil-pumps/
Perfect! Sorry I should have included my vehicle info, but you nailed it. And I never would have found that page.
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@Fless is a Magician at that.
It's just research and persistence...
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Two words that are all but lost in today's disposable, instant gratification culture.
I have a 2007 Tahoe (4x4) with the 5.3; it's on tracks, use it on the lakes in the winter.
It started having low oil pressure, when hot, at idle.
Verified it wasn't the sensor via manual gauge.
I left the oil pan on (4x4 so it's a pain to drop it). Instead, I went through the front cover, replaced the oil pump with a high volume melling and replaced the pickup o-ring. Did everything in a morning before lunch. Great oil pressure now.
It started having low oil pressure, when hot, at idle.
Verified it wasn't the sensor via manual gauge.
I left the oil pan on (4x4 so it's a pain to drop it). Instead, I went through the front cover, replaced the oil pump with a high volume melling and replaced the pickup o-ring. Did everything in a morning before lunch. Great oil pressure now.
PatDTN
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Beg to differ on the difference the o-ring makes. My truck suddenly went from barely good to low oil pressure warnings. I dropped the pan and replaced the o-ring plus cleaned a bunch of gunk out of the bottom of the pan and now my oil pressure is the best I've seen it since I bought this 300k mile truck a year ago.
what did the o ring look like?
I'll add you to my list. which is now up to 3 people that have changed just an I ring and noticed any useful difference.
did you happen to try any of the tests, like over full the oil or park down a steep hill? those tests seem to he legit
West 1
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J9 you need to get out more. I personally have done 3 LS repairs where they had no oil pressure on start up and great oil pressure after new Oring installed. It typically does not cause Low Oil pressure. It causes slow oil pressure on start up and then zero oil pressure.
I've not seen that on any message board. it's always hey, my ls went from 40psi hot idle to 15 almost over night. 30 posts to change the o ring, they change o ring, nothing happens. goes back in, adds high volume pump. pressure gets back to 35ish.
in fact I have searched for something that sounds kinda like you're saying. I just had a buddy with a low mileage ls6 c5 that all of a sudden basically lost prime and would take a good 30 secs or more to build oil pressure any time the engine was off more than say 10mins or so. I know forsure the o ring was replaced on it not 5k miles ago, hard miles over a year or so but still, new forsure as he just did the oil pan gasket and rear main. I looked around a lot online and only found a few posts on the ls tech board that sounded like it, but no one followed up after they fixed it. so being it had a stock oil pump he rolled the dice and put a new pump in it.
new pump and it's perfect agian. I personally took the old pump apart and saw nothing that doesn't look normal in it. I'm still baffled.
very weird one.. but yeah, I just simply don't buy into every ls o ring is bad. I only have 2 myself, one in a 08 that's over a 100k and has seen over 300deg oil Temps at track days, I did the o ring while doing the common pan leaks and it was mint. wasn't hard and bearly looked used. my 180k yukon, I did a pan gasket a while back on it. same thing, o ring looked mint. I ended up going to the dealer and buying another oem instead of using the aftermarket ones since it looked so good. no reason to toss in what came in the kit and wonder.
so yeah, I don't work at a shop replacing these all the time. but unless someone does the add extra oil or they can park down hill and see the oil pressure change a lot. I always suggest change the pump and o ring while you're there.
PatDTN
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The ring was flattened and darkened plus it was split on one side and the inside looked much less darkened.
Seems like changing the o-ring is what fixed my problem. Mine was pretty flat and wider on one side, and a little less flat but still clearly not round around the rest of it.
I will repeat what my mechanic said when I called him to see if I should tow it to him or was it something I could fix. He said 90% of the cases with these, it's the oil sender, other 10% it's the o-ring, and he almost never sees an oil pump go out. His cheap test for the o-ring is to look for bubbles on the dipstick. Otherwise customer would have to pay for a pressure test to get a better diagnosis. Starting with oil pressure and then losing steadily until it drops to zero is one symptom. I've seen other people online say pressure starts low in cold weather and then as the engine warms pressure increases. Perhaps this is up until the o-ring is so bad that it just flat out fails like mine did. I dunno.
I suppose changing the oil pump to a higher flow one can mask a failing o-ring too, at least for a time. Who knows. All I know is my pressure is much better all around, and it doesn't drop while driving anymore.
I will repeat what my mechanic said when I called him to see if I should tow it to him or was it something I could fix. He said 90% of the cases with these, it's the oil sender, other 10% it's the o-ring, and he almost never sees an oil pump go out. His cheap test for the o-ring is to look for bubbles on the dipstick. Otherwise customer would have to pay for a pressure test to get a better diagnosis. Starting with oil pressure and then losing steadily until it drops to zero is one symptom. I've seen other people online say pressure starts low in cold weather and then as the engine warms pressure increases. Perhaps this is up until the o-ring is so bad that it just flat out fails like mine did. I dunno.
I suppose changing the oil pump to a higher flow one can mask a failing o-ring too, at least for a time. Who knows. All I know is my pressure is much better all around, and it doesn't drop while driving anymore.
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The bad O rings I have actually touched had become very hard, held the shape after removal showing flat sides and no longer rounded like a new O ring. One was at 270,000 miles, that was the highest mileage failure I have seen. A buddy owned that truck since new and was very good at regular oil changes.
How hard? Technically none of it was really that hard. However, it was a dirty and nasty job, and uncomfortable working on my back under the car. There is lots of opportunity to mess up too. Scraping the mating surfaces of the pan and engine block took a lot of careful work so as not to scratch up the aluminum. If you are prone to rushing into things without spending time watching, not just one, but several videos and asking questions, I wouldn't do it yourself without experience working on cars. I used charm.li and probably 3 or so videos that I referenced. Also, if I had a 4x4, I would not have done it myself, as you would have to remove the front differential to get to the pan. With a rear-wheel drive vehicle, it's a MUCH simpler job.
Are you talking about the o-ring that's inside the pan (for the engine oil pickup tube on the pump), or the dipstick tube where it goes into the engine block?
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I have a separate question if anyone is reading this thread still. I have a friend I was telling the story to and he was "that happened to me too!" but he never solved it. It happened while on vacation, Tahoe loaded down with gear, driving in the mountains. No bubbles on the dipstick, just no pressure. He changed the pressure sender (he's on his third one) none of which changed anything in terms of it reading zero. The problem basically "went away" and has not happened again since being back home. I'm not sure at what point in his trip the alarms stopped blaring at him, and I should probably follow up and ask him that. But has anyone seen anything like this where it could be altitude related?
Why would there be bubbles on a dipstick?
It's a sign that your oil is aerating.
I wouldn't say that changing the pump masks the problem. The new pump comes with a new o-ring for the pickup tube so it gets changed anyway. Plus these oil pumps at high mileage are known to collect little pieces of grit in the oil pressure relief valve in the pump. Almost looks like tiny specks of carbon. Replacing the oil pump takes care of those two items at the same time.
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