I have a 2007, 5.3 Yukon xl 1500 SLT. I rebuilt the top of the motor last year , getting rid of the DOD. The vehicle has 226000 miles on it. Runs very well. I am a little frustrated with the oil pressure. When the car is cold, the oil pressure will get up to 60 during driving and idles around 40. After the car warms up, it idles about 20 and 38 during driving. There is no ticking and she runs very strong. If. When I change the oil , it helps for a while. Is is possible the oil pickup tube o ring is the culprit? I had the oil pump replaced about 20k ago but I don’t know if they replaced the o ring. Would it be helpful on a high mileage engine to run a thicker viscosity ? Thanks in advance for any guidance.
Oil pressure issue
- Thread starter UPSdriver
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When the AFM was deleted, did you remove the oil pressure relief valve mounted in the oil pan, and plug it? If not, those relief valves get weak over time and could be releasing pressure. If you do go in and drop the oil pan to take care of that, I would definitely go ahead and replace the o-ring while you are in there.
If that was addressed during the AFM delete, and the towers are plugged under the valley cover, the only other source for pressure loss other than the oil pump itself which has a built-in pressure relief valve..... Would be excess bearing clearance. Usually the cam bearings.
What oil filter are you using and what weight oil? Some brands of oil filters seem to have more of an effect on oil pressure than others. You might try a Wix XP. If the oil ports have been properly plugged, and a change in oil filter doesn't bring results, at your mileage I would try a 10w40 full synthetic.
Keep in mind GM recommends 5W30 in North America..... Most people assume it has to do with the fuel mileage requirements for the fleet. Because in the rest of the world GM recommends 10w40 in most locations for the same motor.
If that was addressed during the AFM delete, and the towers are plugged under the valley cover, the only other source for pressure loss other than the oil pump itself which has a built-in pressure relief valve..... Would be excess bearing clearance. Usually the cam bearings.
What oil filter are you using and what weight oil? Some brands of oil filters seem to have more of an effect on oil pressure than others. You might try a Wix XP. If the oil ports have been properly plugged, and a change in oil filter doesn't bring results, at your mileage I would try a 10w40 full synthetic.
Keep in mind GM recommends 5W30 in North America..... Most people assume it has to do with the fuel mileage requirements for the fleet. Because in the rest of the world GM recommends 10w40 in most locations for the same motor.
donjetman
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1st, you don't have a problem. You may want to have a problem, but you don't.
A thicker oil (higher viscosity) like Mobil1 5w50, Redline 5w60, etc, etc, should increase the oil pressure (resistance to flow). Also use a oil filter that isn't a "high efficency" filter like a Wix, NAPA, etc, etc.
Another oil system leak source is the barbell/dogbone in the oil galley above the oil filter. Tranny has to come out to replace it.
A thicker oil (higher viscosity) like Mobil1 5w50, Redline 5w60, etc, etc, should increase the oil pressure (resistance to flow). Also use a oil filter that isn't a "high efficency" filter like a Wix, NAPA, etc, etc.
Another oil system leak source is the barbell/dogbone in the oil galley above the oil filter. Tranny has to come out to replace it.
I completely forgot about the dog bone in the rear. Never seen one leak though, the OEM plastic ones seem to do their job forever.
While GM considers something under 10 psi at hot idle as acceptable, I think we all know that a healthy LS vitals in excess of 25 psi hot. If it's recently dropped down to 20 psi I would call that a concern, but not enough to be extremely worried about..... But keep in mind if it's dropped to 20, it may continue to drop. That's where the concern is. At over 200,000 miles with unknown frequency of oil changes over its life, it's quite possible that 20 psi is due to normal wear in the bearings. If that's the case it will probably run for years, eventually slipping down to 15 or 20 psi and still continue to run fine. The heavier weight oil is a good way to address that.
While GM considers something under 10 psi at hot idle as acceptable, I think we all know that a healthy LS vitals in excess of 25 psi hot. If it's recently dropped down to 20 psi I would call that a concern, but not enough to be extremely worried about..... But keep in mind if it's dropped to 20, it may continue to drop. That's where the concern is. At over 200,000 miles with unknown frequency of oil changes over its life, it's quite possible that 20 psi is due to normal wear in the bearings. If that's the case it will probably run for years, eventually slipping down to 15 or 20 psi and still continue to run fine. The heavier weight oil is a good way to address that.
Dustin Jackson
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I don't see a problem, my oil pressure sits at like 19 after it's really hot and at 39 cruising on the highway. Been like that for years.
Charlie207
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My rebuilt engine sits at 38-40psi hot, when cruising at 1400rpm. That's normal.
Dropping to 20psi at a hot-idle is probably worn oil pickup o-ring, or maybe even worn cam bearings. Did you replace those bearings when you did the DoD-delete?
Dropping to 20psi at a hot-idle is probably worn oil pickup o-ring, or maybe even worn cam bearings. Did you replace those bearings when you did the DoD-delete?
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With that mileage, you absolutely don't have an oil pressure issue, IMO. I just had a new oil pump and o-ring installed, and my oil pressure is just about the same as yours. And, prior to my replacing the oil pump and the o-ring, I had exactly the same oil pressure, as after replacement.
donjetman
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No, WE all don't know.
But, YOU are entitled to your opinion.
Well, let me put it this way. When you rebuild an LS engine and verify all the bearing clearances, and with the OEM oil pump and oil pressure spring, it will idle hot all day long at 35 PSI. As they age I've seen that number very gradually come down. Sometimes it's due to o-ring issues and other things..... But when those are addressed as mentioned above, and the oil pressure remains at 20 psi.... Will you have left is bearing clearances. According to GM that's just fine and not an issue. They find 10 psi acceptable. (!!!) And granted, it can go for another hundred thousand miles at 20 psi hot idle. Usually. I think the biggest factor and gradually increasing bearing clearances is definitely something we all know..... More frequent oil and filter changes slow down that process tremendously. I understand the GM oil life monitor is actually highly rated, and was done with several years of study with oil analysis. I'm just not sure, and I have my doubts, if their studies were actual real world conditions. I feel the safe bet is to change it every 3,500 to 5,000 miles. (The oil life monitor can vary all the way up to and beyond 8,000 miles.) I will say I have a co-worker with a 2014 Silverado pickup with the 5.3, he changes his oil once a year around 10,000 mi and he has 165,000 miles.... And holding about 32 psi hot idle. He drives it easy, and he commutes 15 miles each way to work on a 55 mph highway with no stops. Everybody's real world experience is different.
swathdiver
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Where did you learn of this oil weight recommendation for overseas vehicles?
That about where mine has dropped to lately. Three months ago it was 4-5 psi higher, highway is the still the same.
Marky Dissod
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Your doubts are neither entirely right, nor entirely wrong.
In principle, GM's Oil Life Monitor tracks and accounts for lots of things that odo mileage just can't:
*How often the engine is shut down and restarted, engine temp at restart
(likely ignored by vehicles with 'snooze feature', quite possibly to that engine's detriment)
*How much more time the engine spends at operating temp vs 'warming up'
*How conservatively or aggressively it's driven, vs how much time it spends with the TCC locked
(obviously worst to drive aggressively while warming up only to shut down before fully warmed up)
*How much time the engine spends idling (odometer alone cannot account for this at all)
The Oil Life Monitor is basically a 'bank' of engine RpMs.
The more slowly RpMs are accrued, the better, obviously.
The above list and several other factors 'penalize' those 'RpMs' more quickly than one might expect.
If the engine suffers an overheat, even briefly, the OLM drops to 0.
However, GM defines an overheat as 257F (if not hotter), whereas I define it as 239F.
(By the way, EVERY UNDERHOOD FLUID should be changed ASAP after an overheat, including brake fluid, is how paranoid I am.)
If it spends most of its service life getting 20MpG (or better), it needs oil changes
less often than an otherwise identical vehicle that gets 10MpG.
The OLM tries to account for whatever nuances are left after MpGs.
However, it is entirely possible to account for every mechanical factor,
and STILL be influenced by the environmental lobby.
More to come ...
Marky Dissod
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GM recommends oil changes when it hits 15%, but never over 1 year regardless of miles.
Your skepticism is shared by NYC cabdrivers, by the way.
FYI, most NYC cabdrivers / livery drivers / chauffeurs apply the following 'skew' to the Oil Life Monitor:
Mostly all highway miles (NOT NYC), change oil & filter @ 17%, NEVER over 5000 miles.
More highway than local miles, change oil & filter @ 20%, NEVER over 4000 miles.
More local than highway miles, change oil & filter @ 25%, NEVER over 3500 miles.
Mostly all local miles (stop'n'go, LOTS of idling, also lots of restarts), change oil & filter @ 33% -
NEVER over 3000 miles.
If they intend to keep that car after the lease is up,
some oil changes may occur as often as every 2500 miles / every 5-6 weeks,
depending on the nature and number of miles accrued.
The ones that intend to keep it after the lease is up also disable Engine StopStart and Cylinder Deactivation.
By and large, they are NOT keeping the ones that do not allow disablement of DFM.
Again, a simpler way to account for all of the above:
the better the lifetime average MpGs, the less often the oil changes.
the worse the lifetime average MpGs, the more often the oil changes.
Your skepticism is shared by NYC cabdrivers, by the way.
FYI, most NYC cabdrivers / livery drivers / chauffeurs apply the following 'skew' to the Oil Life Monitor:
Mostly all highway miles (NOT NYC), change oil & filter @ 17%, NEVER over 5000 miles.
More highway than local miles, change oil & filter @ 20%, NEVER over 4000 miles.
More local than highway miles, change oil & filter @ 25%, NEVER over 3500 miles.
Mostly all local miles (stop'n'go, LOTS of idling, also lots of restarts), change oil & filter @ 33% -
NEVER over 3000 miles.
If they intend to keep that car after the lease is up,
some oil changes may occur as often as every 2500 miles / every 5-6 weeks,
depending on the nature and number of miles accrued.
The ones that intend to keep it after the lease is up also disable Engine StopStart and Cylinder Deactivation.
By and large, they are NOT keeping the ones that do not allow disablement of DFM.
Again, a simpler way to account for all of the above:
the better the lifetime average MpGs, the less often the oil changes.
the worse the lifetime average MpGs, the more often the oil changes.
Dustin Jackson
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@swathdiver After the AFM delete, oil pump, and o-ring it didn't change the oil pressure but I did end up using a standard oil pump instead of the high flow or high volume options so it's possible that a different pump would have given better results but I am satisfied with the numbers I have
Look up the various GM models under the brand name Holden in Australia.
Just wrapped up the neighbors AFM delete. Plugged the towers, and plug the pressure relief valve in the oil pan. We installed a Melling 10296 with the +10 PSI spring that comes pre-installed. LS7 lifters, measured for push rods and the 7.4's came out at .085 preload.
L92 OEM camshaft. All new stuff under the front cover. 34 PSI@hot idle. 1500 RPM is 56 PSI. Did the crank relearn, which requires running it up to 4,000 RPM. Peaked out at 72 psi. We did a lot of stuff while we were in there, new water pump of course and new radiator. Cut out the section of OEM hose in the transmission cooler lines. Use compression fittings to go to AN6, and converted the transmission cooler at the radiator to AN6 fitting. Purrs like a kitten. We also replaced all the O2 sensors with genuine GM, as well as the oil pressure sending unit, Cam and crank sensors.
Just wrapped up the neighbors AFM delete. Plugged the towers, and plug the pressure relief valve in the oil pan. We installed a Melling 10296 with the +10 PSI spring that comes pre-installed. LS7 lifters, measured for push rods and the 7.4's came out at .085 preload.
L92 OEM camshaft. All new stuff under the front cover. 34 PSI@hot idle. 1500 RPM is 56 PSI. Did the crank relearn, which requires running it up to 4,000 RPM. Peaked out at 72 psi. We did a lot of stuff while we were in there, new water pump of course and new radiator. Cut out the section of OEM hose in the transmission cooler lines. Use compression fittings to go to AN6, and converted the transmission cooler at the radiator to AN6 fitting. Purrs like a kitten. We also replaced all the O2 sensors with genuine GM, as well as the oil pressure sending unit, Cam and crank sensors.
That looks better than zero mile crate engines but I've seen pics of
There's a theory out there that says they align hone after installing the bearings at the factory due to cheap casting shift. others say it's just the lowest possible quality cam bearing anyone has ever seen to save a buck
I've heard from multiple sources that the factory align homes the bearings after install..... But not 100% sure that I buy that. If the bores were that far off, and replace the cam bearings, you'd never get the cam in. And it seems like if it did, you wouldn't be able to turn it. Anybody object to that theory? LOL
