2012 Chevy Tahoe low oil pressure/ shop says I need new engine!

[Fless]

The first thing to find out is if they cleaned or replaced the screen that's under the oil pressure sender.

 

[ivin74]

As far as the metal in the oil/shiny oil, is that something to be concerned about?

If you drove the suv long with low oil pressure you may have damaged it. That would cause the oil to have metal flakes.

Do as the others members suggested,
Do a mechanical pressure test
Test the pick up tube o ring.
Has the vehicle had synthetic oil changes? Conventional oil gumps up and plugs the oil passages.
If those tests pass it's time to rebuild the engine. The bearings are to worn out that the oil is not pumping up to the top of the engine.

 

[Aburns70]

don't take my word as official, just my experiences mixed with what I've read that makes sense to me. other guys here have way more experience with low oil pressure diagnostics over the web. in person with some tools is much easier haha.

so the o ring is on the suction side of the oil pump, if that o ring cracks it can suck air along with the oil, and you get foaming of the oil on the output side after the pump showing up at low pressure. it's a pretty common post around here at about the mileage you have, but others have changed it over low pressure and it not get much better. so it's a legitimate thing but not 100% you fix. that's why the test is to either add extra oil so it's above the o ring, or since the o ring is at the front of the engine, if you get on a steep hill nose down, oil will go forward and cover the ring to. I've not needed to do either test, but it's said you'll see the pressure come right up. you really should drain any extra oil you put in it back out thou after the test. high oil level can cause it's own set of problems.


I don't know how long these engines will run without oil pressure before they start to knock and tapping, but it should be tapping if it really has no oil pressure. heck, most ls engines tap a little with good oil pressure haha. so before you do anything drastic, I do think it's worth putting a real gauge on it. so the thing is, there's a little fine screen under the oil pressure sensor. because the sensor happens to be inline with the oil going to the active fuel management stuff and it needs to be extra clean for that. but if this screen gets clogged up, it's not blocking oil pressure to the main engine bearings, but it will block it from the pressure sensor and the AFM. what we don't know is if the shop replaced that screen or honestly if the sensor itself is even good.


it is what it is about the cost.. we all don't know what we know, and I've been taken before myself. drives me nuts but it happens. the gimmick is he probably billed you as if he had to remove the entire intake manifold to get to the sensor, which does make it eaiser and shop manual might even call for it. but it's not needed, I've replaced it both ways. it's not fun at all, but it can be done by laying across the engine with the right tools. but it's also very hard to replace that screen like that too since you can't really see what you're doing back there and you need a pick or a hook of some sort to pull it out.


any info on the maintenance history? the big question is usually was oil changes done every 4-5k miles, or by the much long change oil dash light. the long changes leads to gunk and sludge build up, which leads more clogging of that screen and the afm nightmare issues you'll read about if you search for afm.

so yeah, if you can test it either at the oil test port at the front of the engine with a mechanical gauge, or it hooked into the sensor port with the screen removed, you'll have a better idea what's really going on. how you get that done, I really don't know without knowing what you're comfortable with doing yourself.


I forgot to ask, once the oil pressure hits zero, how long do you have to have it off for the oil. pressure to come back up on restart. like 5 to 10mins or hours for the engine to cool completely?

So a couple things, a big chunk on the shops bill was removing the manifold, and the labor/time needed to do that.

2nd- I got the low oil pressure warning at around 5psi while driving to work, but never hit 0, then the warning turned off and then turned on again a minute or two later right as I was parking the vehicle. I drove about 4-5miles to get to work once the first warning came on.

I purchased the vehicle back in may from my brother in law. He always said the oil had been changed regularly and before him it was his dads car before he passed away. But going back to before there was never any inclination of knocking noises or the such coming from the engine, and has always sounded like everything was running like a charm.

 

[Geotrash]

The first thing to find out is if they cleaned or replaced the screen that's under the oil pressure sender.

^^^ This. Find out with absolute certainty if the shop replaced the filter screen. I can virtually guarantee that this is your culprit. Lots of techs know to replace the sensor but not all of them know there is a screen under it that MUST be thoroughly cleaned or replaced at the same time. You may need to water board the tech to get the truth though.

 

[j91z28d1]

^^^ This. Find out with absolute certainty if the shop replaced the filter screen. I can virtually guarantee that this is your culprit. Lots of techs know to replace the sensor but not all of them know there is a screen under it that MUST be thoroughly cleaned or replaced at the same time. You may need to water board the tech to get the truth though.

I think you're right.


man I feel bad for people dealing with stuff like this.

 

[B-train]

I think you're right.


man I feel bad for people dealing with stuff like this.

Agreed......I can't fathom just taking someone because they are unsuspecting (no offense OP). IF that's what happened, it will eventually catch up to that person....

There has been a great number of suggestions here, so I have nothing to add in the diagnosis department. I would definitely do an quick look at the oil on the dipstick though. Run it for several minutes, then shut it off and wait a few minutes. Then pull the dipstick and wipe it on a new, clean white rag, or a dark color like navy blue or black. After that, check onn good light for anything shiny in the oil area. I've used dark colored shirts in the past for this and the contrast can sometimes make it easier to see.

If you don't see anything shiny, then go forth with above mentioned checks/tests.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[georgerenner]

So a couple things, a big chunk on the shops bill was removing the manifold, and the labor/time needed to do that.

2nd- I got the low oil pressure warning at around 5psi while driving to work, but never hit 0, then the warning turned off and then turned on again a minute or two later right as I was parking the vehicle. I drove about 4-5miles to get to work once the first warning came on.

I purchased the vehicle back in may from my brother in law. He always said the oil had been changed regularly and before him it was his dads car before he passed away. But going back to before there was never any inclination of knocking noises or the such coming from the engine, and has always sounded like everything was running like a charm.

Merry Christmas! I too have had the same problem and please allow me to explain what I found. My engine is the L92. So find out what engine you have and start from there. My oil pick up o ring was cracked and in cold weather I would get the same warning. I changed the sensor, but in my l92 I did not have a oil pressure sensor screen so I wasn't able to eliminate that issue.

So a couple things, a big chunk on the shops bill was removing the manifold, and the labor/time needed to do that.

2nd- I got the low oil pressure warning at around 5psi while driving to work, but never hit 0, then the warning turned off and then turned on again a minute or two later right as I was parking the vehicle. I drove about 4-5miles to get to work once the first warning came on.

I purchased the vehicle back in may from my brother in law. He always said the oil had been changed regularly and before him it was his dads car before he passed away. But going back to before there was never any inclination of knocking noises or the such coming from the engine, and has always sounded like everything was running like a charm.

The first thing to find out is if they cleaned or replaced the screen that's under the oil pressure sender

Merry Christmas! Fless is right! You should check the screen! SOP 101! My L92, in my 2007 Yukon, Denali, had the same problem, but doesn't have the screen, here is the reason why. Your Tahoe, LC9 engine has AFM, and this needs a large quantity of oil to operate, my L92 does not. This is the second part of the problem. Bearing wear is the third. Your engines bearings are probably good. Your AFM is not a good feature. I recommend disabling it. I use a Range Technology disabler on both my 2011 Suburban with the 5.3l LC9, and my 2011 Yukon, Denali with the 6.2l L94. It is a ten hour shop job to replace the oil pickup tube seal, a simple o-ring in a very hard to get to location. I did it a year ago on the L92 engine. I even replaced the oil pump while there. My oil pressure improved on cold start up but would drop to around 10psi at idle after it warmed up. I did inspect the camshaft bearings and found them correct, not damaged and no metal in the oil pan. But my oil pressure is still low. I attribute that to normal bearing wear as I have 230,00 miles on the engine and I drive it hard. I surmise your bearing wear should be normal, your o-ring is cracked, your oil pressure sending unit screen is plugged up, and your AFM is activating causing a pressure drop. Fix the pressure screen 1st, disable the AFM 2nd, and replace the o-ring 3rd. Then you can go racing again! Also I always ran full synthetic and Duralube. God bless!

 

[Aburns70]

Hey just getting back on here now after the holidays and about to head into the shop and talk to the guys about the truck. I appreciate the feedback and atleast have a little bit of information on what we can do to problem solve the issue vs just saying I need a new engine. I will update later today once I have talk to them, but I am also going to be calling around to a few other shops this afternoon to get a second opinion.

 

[Doubeleive]

Hey just getting back on here now after the holidays and about to head into the shop and talk to the guys about the truck. I appreciate the feedback and atleast have a little bit of information on what we can do to problem solve the issue vs just saying I need a new engine. I will update later today once I have talk to them, but I am also going to be calling around to a few other shops this afternoon to get a second opinion.

there are a lot of what if's
but I would find a shop that's not going to ream you for starters
unless you can see glitter in the oil then I would order a oil test kit from blackstone labs, the test is like $30-35 and that is best way to judge the engine condition without tearing it down.
aside from that I would ask around about cost to drop the pan and check and/or replace the oil pump o-ring/pick up tube.
if it is not the pick up tube or oil pressure sensor sensor screen then it's probably time to shop engines