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GMC Forum: Oil Pressure Loss and Noisy Lifters
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  #1  
Old 07-07-2011, 10:03 AM
tdmesa tdmesa is offline
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Default Oil Pressure Loss and Noisy Lifters

I have a 2002 Yukon XL, 5.3L, 2wd.... Sometimes oil pressure drops to zero at idle, like when stopped at a red light. Sometimes nothing happens and sometimes the engine starts clicking. I can raise rpm to 1000 and oil pressure comes back and noise goes away. Oil always changed at 3000 miles. 198,000 miles on Yukon. Motor is strong, no smoke, only 1/2 qt of oil loss between oil changes. I have researched a lot and can't find an answer. I suspect the oil pump pressure relief plunger and spring are not working allowing by pass at lower rpms. That means an oil pump replacement. Oil sensor was replaced with no change. Also, the oil drains down over night and the lifters are all noisy for the first 15 seconds every morning. Anyone seen this before or have any ideas?
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Old 07-07-2011, 09:28 PM
Molson02536 Molson02536 is offline
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Quote:
Originally Posted by tdmesa View Post
I have a 2002 Yukon XL, 5.3L, 2wd.... Sometimes oil pressure drops to zero at idle, like when stopped at a red light. Sometimes nothing happens and sometimes the engine starts clicking. I can raise rpm to 1000 and oil pressure comes back and noise goes away. Oil always changed at 3000 miles. 198,000 miles on Yukon. Motor is strong, no smoke, only 1/2 qt of oil loss between oil changes. I have researched a lot and can't find an answer. I suspect the oil pump pressure relief plunger and spring are not working allowing by pass at lower rpms. That means an oil pump replacement. Oil sensor was replaced with no change. Also, the oil drains down over night and the lifters are all noisy for the first 15 seconds every morning. Anyone seen this before or have any ideas?
GM v8s have always had an oil bypass in the oil filter adapter on the block. The anti drain back valve is in the filter. Although the new AC Delco E core filter, the ADV functions as a by pass valve.

I have seen some references that the bypass valve could have been eliminated in the block some where between 2007 and 2009. I can't confirm this as a fact. The AC Delco PF 48s all have a bypass valve in the filter as the original PF 46 does not, unless its an E-core filter.

http://www.autopartswarehouse.com/de...C25014006.html
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Old 07-14-2011, 06:45 AM
Smokin' Denali Smokin' Denali is offline
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Default

in addition to above, what weight oil are ya using? In warmer months, I would use a minimum 20W/40 of the "high mileage" types made by many major companies . Consider a additive like "STP oil additive" as it leaves a sticky lubricant on the engine parts to help start-up friction problems,

good luck

SD
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Old 08-12-2011, 11:26 AM
tdmesa tdmesa is offline
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Thanks Molson. I will try a PF48 to see how that works. I beg to differ with you on the newer motors. My 2002 has the oil pump moved to the front of the motor, and installs over the crankshaft and mounts to the front of the block. I have looked at many drawings of it. This design has a cheezy piston and spring relief valve. I have read that the piston hangs up due to metal expansion over time (bad engineering at the factory). I am looking for any other possibilities before tearing the front end off of this motor. I did replace the oil sending unit (was a real challenge due to location and no clearance) but I have not put a manual gauge on it. I figure since it is draining back every night, it I will probably be replacing the oil pump with the sticky relief valve.... But again, just checking to see if anyone else has seen a different fix before I tear into her. Much appreciated! I am going to try that PF48.....

Smokin': I run the factory recommended 5/20 weight oil. I don't lose more than 1/4 qt between 3000 mile oil changes with 198,000 miles on her. I don't like to run STP sticky type additives. That stuff scalds on the bearings and clogs oil passageways. I know that a lot of people swear by it, but I am not one of them. I ran it 30 years ago in my 1972 Ford F100 w/390 engine, and it did clog oil passages in the head and gum up the rocker arms until they started hanging up. So my experience was not a good one with STP.... Thanks for your comments.
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Old 08-12-2011, 11:33 AM
tdmesa tdmesa is offline
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@Molson: I was just thinking a bit further. The PF48 might work and it might not work as far as the overnight drainback. I say that, because it will depend on the oil port routing internally. If the stuck relieve valve in the oil pump is first in line before the filter, then she'll stickk drain back. But if the filter is first (from the lifters down) then the oil filter will help with that issue, meaning that the lifters should stay pumped up over night. I have not had any luck finding an oil passageway print to review... I will let you know the results. Thanks again!
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Old 08-12-2011, 12:10 PM
tdmesa tdmesa is offline
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Hey Molson, I just found this oil schematic. Looks like the oil pump, oil filter and oil filter housing all have pressure relief valves........ I will check the filter housing as you suggested before tearing out the oil pump. It appears that the oil filter housing and oil filter are first in line for supply pressure drainback problems, so that might be the issue...... Having knee surgery in a few days so I won't get to this for 6 to 8 weeks. Unless I hire it out. I will post what I find.
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Old 08-12-2011, 12:12 PM
tdmesa tdmesa is offline
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The schematic would not copy however this tag line below did. You might be able to search for him on the web?

This diagram was posted in another thread by member Steve Bryant


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Old 08-12-2011, 05:27 PM
tdmesa tdmesa is offline
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@Molson: My apologies, I confused myself and my response between ADV Anti Drain Valve and PRV Pressure Relief Valve. I went and looked at both filters at Autozone and you can see the difference when you look down the core. Then I called AC Delco. They told me that both PF46 and PF48 have ADV but only PF48 also has the PRV.... That said, I have no clue if the filters that my local lube shop is using has ADV or not. I will guess not to save $$.... I will be using the PF46 to see if it helps. In my case where by my PRV in the oil pump seems to be stuck open or intermittent, it doesn't make sense to me to install another PRV in the system because the pressure will be reduced by the oil pump PRV being stuck open anyway. If I am not thinking clearly, feel free to add your thoughts. I will advise if the AC Delco filter helps with my lifter oil drainback problem..... Thanks again!
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  #9  
Old 10-07-2013, 04:18 PM
2002yukon 2002yukon is offline
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Default I have the Same Issue

I was wondering if you ever found out the fix to your oil pressure issue since I am having the exact same issue. Thanks,
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