My Yukon Troubles!

[JimBe937]

Hello everyone! First time poster and viewer!!

I have a 2007 Yukon Denali 6.2L with 255k named Big Bertha! She was gifted to me last year from a friend that was getting a new ride since I had helped with various problems through the years. My wife and I love her!! She's the most luxurious ride we have ever had!

Since getting her I have fixed some things I knew was broken and some I didn't know were broken. She had a terrible oil leak when I got her and the previous owner just kept throwing oil in it. I did some investigating and decided to take it to a local garage to have the rear main seal and oil pan gaskets and cooler gaskets replaced. The oil pressure reading would fluctuate from 0 to 80 and at times seem to work properly which pointed to the sending unit. I asked about replacing the pump too since they would be working in that area anyway. They actually refused and said putting a new pump in could hurt the engine since it was high miles.

That's my first question. How could a new pump hurt the engine? Doesn't the oil system come with a pressure relief valve so it can't actually cause too much pressure? I was miffed, but had them do the rest and she no longer leaks at all! This was fantastic. They also found a oil sender socket on top of the tranny. Score! I think they thought *I* dropped it there! I'm not that careless!

I keep getting random no oil pressure messages and to shut off the engine. Second question: Is this a result of the faulty sending unit? I know what low pressure sounds like and hear no signs of it.

So I bought parts to do the sending unit and dug in yesterday. First thing I notice. The intake ports in my engine are square and not triangular. Give me a 50/50 chance and I'll get it wrong! Annoying!

I unplug the sending unit and find I'm able to unscrew it with my fingers. Not easily, but it's certainly not tightened to spec. So I'm suspecting that the previous previous owner replaced the sending unit without removing the intake manifold and dropped their socket and settled for finger tight. Didn't appear to be leaking any oil. There was no screen under the sending unit as shown below.



I tried putting the screen in and it didn't sit low enough to allow the sending unit to screw in without crushing the screen! I lubed the oil ring on the screen and tried tapping it in. I even tried screwing the sending unit in some and could tell it was hitting the top of the screen. When I took the screen out the little legs on the bottom had started to break off from the pressure. So I eliminated the screen. I read that they added the screen in 2007. Third question: Is it possible mine was a pre-screen model which is why the screen wouldn't fit? Is there more than one screen size? If no to both, maybe the previous previous owner somehow messed up the channel for the screen.


Other misc questions I haven't researched yet!

When I press the button to open the rear most of the time it will go half way and then reverse to close again. Sometime it randomly unlocks the window in the hatch in this whol process. The reverse camera doesn't work. I suspect wires have broken or worn in the wire harness going to the rear. Do they sell a replacement or will I just have to hunt, cut, and patch?

Getting a suspension fault message.



Last! Meet my girl, Bertha!

 

[blondie70]

Nice looking girl !

 

[j91z28d1]

I like thst color.

 

[j91z28d1]

the new oil pump in a high mileage engine is no issue. but also they don't fail very often either. did they do the o ring? they do fail sometimes.


the oil pressure gauge flickering around is probably the sensor. it's pretty common. it's usually suggested to use only oem from a known vendor. not Amazon or ebay. but I have a friend that went thru 2 oem sensors in less than a year. put in a cheap auto part store and it's been OK since. it's a crap shoot. all the sensors are junk in book. normal car oil pressure sensor last the life of the car.


for the screen. if you. don't have afm, which you probably don't on thst year. the screen isn't needed. it was only to filter oil to the afm stuff.

 

[wjburken]

You’re 2007 6.2 does not have AFM so it doesn’t have a screen for the oil sending unit.

I have never heard that replacing an oil pump would cause issues. My guess is they didn’t want to do the work. To remove the oil pump requires a significant amount of disassembly.

Your 2007 likely has auto level and auto ride. Auto level uses air bags on the rear shocks to level the vehicle with an on board air compressor. Auto ride adjusts the dampening rate of the shocks to adjust the ride based on road conditions. Many people try and go cheap when replacing shocks and struts and if not done right, that can cause suspension errors.

 

[JimBe937]

I like thst color.

Thanks! It's an odd color! Sometimes it looks very blue, sometimes darker blue and sometimes greenish. Confuses me how to answer when people ask what color it is!

 

[JimBe937]

the new oil pump in a high mileage engine is no issue. but also they don't fail very often either. did they do the o ring? they do fail sometimes.


the oil pressure gauge flickering around is probably the sensor. it's pretty common. it's usually suggested to use only oem from a known vendor. not Amazon or ebay. but I have a friend that went thru 2 oem sensors in less than a year. put in a cheap auto part store and it's been OK since. it's a crap shoot. all the sensors are junk in book. normal car oil pressure sensor last the life of the car.


for the screen. if you. don't have afm, which you probably don't on thst year. the screen isn't needed. it was only to filter oil to the afm stuff.

I got a Dorman sensor from Amazon. Guess if it fails, I'll try OEM.

No AFM. I didn't even know that was still a thing after the failed 8-6-4!!! I need to read up on this!

Thanks!

 

[JimBe937]

You’re 2007 6.2 does not have AFM so it doesn’t have a screen for the oil sending unit.

I have never heard that replacing an oil pump would cause issues. My guess is they didn’t want to do the work. To remove the oil pump requires a significant amount of disassembly.

Your 2007 likely has auto level and auto ride. Auto level uses air bags on the rear shocks to level the vehicle with an on board air compressor. Auto ride adjusts the dampening rate of the shocks to adjust the ride based on road conditions. Many people try and go cheap when replacing shocks and struts and if not done right, that can cause suspension errors.

I'm paying this shop $108/hr. I don't he cared the amount of time it would have took. He was already dropping the tranny and pan. From the video I saw, replacing the pump at that point shouldn't have been but a couple hours more! He honestly seemed to think putting in a new pump would blow the engine up and he didn't want that responsibility. Was that a thing back in OLD 40, 50, 60, 70 cars??

Ahhh ok that's where I'll start. I don't know if they have been replaced, but something in that may have failed due to age for sure.

Thanks!

 

[wjburken]

I'm paying this shop $108/hr. I don't he cared the amount of time it would have took. He was already dropping the tranny and pan. From the video I saw, replacing the pump at that point shouldn't have been but a couple hours more! He honestly seemed to think putting in a new pump would blow the engine up and he didn't want that responsibility. Was that a thing back in OLD 40, 50, 60, 70 cars??

Ahhh ok that's where I'll start. I don't know if they have been replaced, but something in that may have failed due to age for sure.

Thanks!

Every mechanic has their thoughts based on their experiences.

Replacing the oil pump is not a “while I’m in there” type job when doing the rear main seal, in my opinion.

To get to the oil pump, you need to remove the water pump, pull the crank pulley on the front, and pull the front timing cover just to get to the oil pump. To remove it requires removing the oil pick up tube which requires the oil pan to be dropped, which requires the front differential to be dropped and the steering rack loosened.

I get that you’re paying the shop a decent hourly shop rate, but he’s probably working on flat rate so if he can’t do better than flat rate time, he may not want to do it.

 

[j91z28d1]

I'm paying this shop $108/hr. I don't he cared the amount of time it would have took. He was already dropping the tranny and pan. From the video I saw, replacing the pump at that point shouldn't have been but a couple hours more! He honestly seemed to think putting in a new pump would blow the engine up and he didn't want that responsibility. Was that a thing back in OLD 40, 50, 60, 70 cars??

Ahhh ok that's where I'll start. I don't know if they have been replaced, but something in that may have failed due to age for sure.

Thanks!

been around cars basically my entire life and never once hard someone say don't replace the oil pump on a high mileage engine or it could blow up. that's a new one on me.


there's a old wives tail about don't change tranny fluid if it's never been done on a high mileage tranny. but that's all but debunked at this point, and today's trannys don't last long enough without fluid changes for it to matter. back in the th350/th400 days you might see a truck with 300k on it that never had a fluid change and guys would say don't touch it. in the land of 6,8 and 10 speeds they seem to last about 100-150k at most if they never get serviced and then lunch themselves for one reason or another.



ahh the old. 8-4-1. yep gm will never learn haha. these Gen 4 afm engines will do 8 and 4. the newer gen 5s dfm can do more like the old 8 4 2 I believe it is. but they just break even more often.

sounds like you got a good one before all the nonsense you need to turn off or delete.

oh yeah. search about the updated valve cover. it has better baffling so it doesn't suck in as much oil thru the intake. Definitely worth doing, and do a search here for adding a catch can to the pvc. it's pretty cheap and generally considered worth the 30$ or so.