2007 Yukon 6.2 stalls/won’t start when hot

[B-train]

Oh my, how hard is that to do? We’re not mechanics and we don’t have a lift!

Ok, so no oil pump yet, that’s good news!

Let me check the oil pressure, cold and hot again because I may have remembered wrong. I was pretty sure it was low, not horrible but definitely low. Thanks guys!

You don't need a lift for the valley cover o-rings. The intake manifold is the dry type, no coolant in/around it. I only mentioned because I had issues in the past and that was the solution.

My 2007 came from OK where there are hotter summers than here in WI and around 200k I was getting lifter clatter on hot restarts. I did pickup tube o-ring (it was degraded) with some luck and then decided to pull the intake to do the oil pressue sender. That's when I saw the flattened out o-rings under the cover (it doesn't need to be pulled to do the sensor, but I wanted to inspect what I could while in there).

I would say it seems more common on trucks that have had a very hot lifestyle compared to Midwest vehicles and the temperatures they are subject to. My 2008 came from CA, and my 2009 from TX. Both needed the valley cover o-rings to be replaced.

My 2008 currently has 205K and I have about 60 psi cold, 20-30 when warm, about 20 if very hot out. I'd say your oil pressure is normal.

 

[rdezs]

I would also agree not to replace the oil pump yet. You only issue that periodically occurs in that mileage is the oil pumps pressure relief spring and plunger sometimes get gummed up with debris from extended oil changes. In the few that I've ran across, the symptoms were normal oil pressure with occasionally dropping to zero and then bouncing back up.... Symptoms of a sticking pressure relief valve, which you are not describing. Do yourself a favor and make sure you use a full synthetic 5W30, and change it at or before 5000 miles.

What I would do is block the pressure relief valve in the oil pan itself with the 14x1.5 mm plug with a copper washer. You'll find them readily available online, such as Amazon. That valve is a known failure point, gets weaker with age and can bleed up pressure.

If doing that in conjunction with the pickup tube o-ring doesn't bring your idle oil pressure up higher, most likely it's a matter of clearances in the bearings. It will easily go another hundred thousand miles with your oil pressure readings.

If it routinely gets down to lower than 14 PSI at a hot idle, at that point I would think about a 5W-40 full synthetic which will bump up the oil pressure somewhat and compensate for bearings at the upper end of the clearance range. And then go for even more miles.

 

[Campie]

I would also agree not to replace the oil pump yet. You only issue that periodically occurs in that mileage is the oil pumps pressure relief spring and plunger sometimes get gummed up with debris from extended oil changes. In the few that I've ran across, the symptoms were normal oil pressure with occasionally dropping to zero and then bouncing back up.... Symptoms of a sticking pressure relief valve, which you are not describing. Do yourself a favor and make sure you use a full synthetic 5W30, and change it at or before 5000 miles.

What I would do is block the pressure relief valve in the oil pan itself with the 14x1.5 mm plug with a copper washer. You'll find them readily available online, such as Amazon. That valve is a known failure point, gets weaker with age and can bleed up pressure.

If doing that in conjunction with the pickup tube o-ring doesn't bring your idle oil pressure up higher, most likely it's a matter of clearances in the bearings. It will easily go another hundred thousand miles with your oil pressure readings.

If it routinely gets down to lower than 14 PSI at a hot idle, at that point I would think about a 5W-40 full synthetic which will bump up the oil pressure somewhat and compensate for bearings at the upper end of the clearance range. And then go for even more miles.

Nice, thanks guys! We will hold off on the pump then.

 

[Campie]

You don't need a lift for the valley cover o-rings. The intake manifold is the dry type, no coolant in/around it. I only mentioned because I had issues in the past and that was the solution.

My 2007 came from OK where there are hotter summers than here in WI and around 200k I was getting lifter clatter on hot restarts. I did pickup tube o-ring (it was degraded) with some luck and then decided to pull the intake to do the oil pressue sender. That's when I saw the flattened out o-rings under the cover (it doesn't need to be pulled to do the sensor, but I wanted to inspect what I could while in there).

I would say it seems more common on trucks that have had a very hot lifestyle compared to Midwest vehicles and the temperatures they are subject to. My 2008 came from CA, and my 2009 from TX. Both needed the valley cover o-rings to be replaced.

My 2008 currently has 205K and I have about 60 psi cold, 20-30 when warm, about 20 if very hot out. I'd say your oil pressure is normal.

Ours came from around there somewhere also but I can’t remember. Only 157,000 miles though so not a lot of wear and tear.

Part number for oil pressure sensor? All I see is this.

 

[Campie]

Ok, I found 12673134 and 12677836. Which one is it?

 

[rdezs]

Ours came from around there somewhere also but I can’t remember. Only 157,000 miles though so not a lot of wear and tear.

Part number for oil pressure sensor? All I see is this.

Those are for the oil level sensor that screws in the side of the oil pan on some models.

I believe you're looking for the oil pressure sending unit, not the oil level sending unit

 

[rdezs]

Look under the category of electrical switch and relay on RockAuto. You want to stick with either genuine GM or ACDelco.

 

[Campie]

Perfect, thanks! I can get the fuel relay also for the fog lights. Thanks!

 

[Campie]

Shoot, the relay in the car does not look like what Rockauto has for the fuel relay. Here’s what Rockauto has but here is what’s in the car. Totally not the same relay.

 

[Campie]

In the car, the fog light relay is the same as the fuel relay.

 

[rdezs]

That's interesting. Take yours into the dealer parts counter if you can't find a part number on it. That's one of those things I would want to stay with OEM

 

[Campie]

OK, been a while since I have posted about our issue and some bad news. Sent an oil sample into Blackstone and got very high metal content in the oil and it only had ~3500 miles on it. Plus, there are now two transmission codes.

Guessing the metal in the oil is causing the crank sensor to malfunction under load and the car just shuts off.

The bolts on the power steering motor are seized so the crank sensor can’t be easily changed.

Anyone need a nice parts car? I think we are done and looking to move into something newer and hopefully more dependable.

If all we wanted to do was drive around town in a big, comfy, powerful car, I’d keep it forever, but I can’t risk being in the middle of nowhere with the camper and having yet another issue.

 

[91RS]

Every Blackstone report I ever did said something was bad, even on my 12k mile Corvette. I stopped doing them, there is absolutely no way every engine I’ve ever owned was on the verge of failure. Waste of money.

 

[Campie]

Every Blackstone report I ever did said something was bad, even on my 12k mile Corvette. I stopped doing them, there is absolutely no way every engine I’ve ever owned was on the verge of failure. Waste of money.

Lol, we’ve had the exact opposite experience… odd…

 

[j91z28d1]

OK, been a while since I have posted about our issue and some bad news. Sent an oil sample into Blackstone and got very high metal content in the oil and it only had ~3500 miles on it. Plus, there are now two transmission codes.

Guessing the metal in the oil is causing the crank sensor to malfunction under load and the car just shuts off.

The bolts on the power steering motor are seized so the crank sensor can’t be easily changed.

Anyone need a nice parts car? I think we are done and looking to move into something newer and hopefully more dependable.

If all we wanted to do was drive around town in a big, comfy, powerful car, I’d keep it forever, but I can’t risk being in the middle of nowhere with the camper and having yet another issue.

just for info. the crank sensor is under the starter. the cam is in the front cover the ps pump might be blocking

 

[donjetman]

@Campie
Please post your analysis #s.
I've done > 100+ used fluid analysis reports in the last 15 yrs and obviously find the info they provide useful, interesting and entertaining. It helps to know what your looking at. Doing multiple UOA over time so as to get a trend is important. I've spent 15 yrs on BobIsTheOilGuy forum educating myself.
UOA has saved 1 of my engines.
I have used 5 different labs over the yrs: Oil Analyzer Inc (Polaris), Blackstone, JGLubricant Services (Polaris), Wix, and DetroitDiesel.

 

[Campie]

just for info. the crank sensor is under the starter. the cam is in the front cover the ps pump might be blocking

Oh right, sorry! Either way, the bolts are seized…

 

[Campie]

@Campie
Please post your analysis #s.
I've done > 100+ used fluid analysis reports in the last 15 yrs and obviously find the info they provide useful, interesting and entertaining. It helps to know what your looking at. Doing multiple UOA over time so as to get a trend is important. I've spent 15 yrs on BobIsTheOilGuy forum educating myself.
UOA has saved 1 of my engines.
I have used 5 different labs over the yrs: Oil Analyzer Inc (Polaris), Blackstone, JGLubricant Services (Polaris), Wix, and DetroitDiesel.

Happy to share!

 

[donjetman]

Here's a video about UOA: