2011 Yukon XL - Hot while towing, fluctuating oil pressure, general weirdness.

[Dadnali68]

Hello all,

I've got a 2011 Yukon XL Denali. Had it for about a year, has about 170K on it. Truck has been a blast! Comfortable, smooth, affordable, and fairly easy to work on. It's a GM truck after all!

I've had to do a lot to it. Upper and lower control arms, front brakes, calipers and lines, tires, pcm relay, starter relay, AC relay (pattern here?). Also oil cooler lines amd the heating and cooling unit in the driver seat.

Some things I've noticed while driving it that I want to know if you all see it as well. Oil pressure. Goes from above 40 to under 20 when hot. I've seen it go slightly lower when coolant goes over 210 but never enough to be scary. Truck likes to heat up to over 210 when either the AC is off or when towing heavy. It has never gone above the line between 210 and 240, but in the summer or when pulling our 30ft camper which weighs over 6,000 lbs it goes over 210. This truck tows incredibly well for a half ton, but it definitely works hard and I want to know if this is an average experience.

All in all, great truck. Has been great for my family and has opened my eyes to how fun SUVs are. Would love any input people have on my trucks quirks and if there is anything any of you have done to, shall we say, increase the durability and longevity of your ride? Thanks for reading!

 

[intheburbs]

Pay more attention to your transmission temperature than your engine temperature. On both of my trucks, I leave the digital display on the trans temp.

Change your fluids regularly. Especially the rear axle and the transmission fluid. Do the full fluid replacement on the trans - 16 quarts. Every 50k or less if towing long distances.

The rear axle is the weak point on the half-ton trucks. Do you weigh your rig when loaded and towing? Make sure the rear axle isn't overloaded. CAT scales has a handy app that makes weighing a breeze.

 

[Marky Dissod]

Oil pressure. Goes from above 40PSI to under 20PSI when hot. I've seen it go slightly lower when coolant goes over 210F but never enough to be scary.

Fully synthetic / Group 4 5W30? Is Engine Half@$$ still enabled?

Truck likes to heat up to over 210F when either the AC is off or when towing heavy.
It has never gone above the line between 210F & 240F, but in the summer or when pulling our 30ft camper which weighs over 6,000lb it goes over 210F.

3 things will help:
Better ATF cooling by upgrading ATF cooler and/or adding fan to it
ecm & tcm tune - improves cooling AND gear and TCC operations for better trans durability / longevity
3.42 or 3.73 axle gears (understandably more expensive, but very highly effective; it does more than just improve the peak tow rating ...)

Pay more attention to your transmission temperature than your engine temperature. On both of my trucks, I leave the digital display on the trans temp.

Pessimistic, maybe, but I replace coolant AND ATF as soon as reasonably possible whenever either one hits 239F.

 

[Dadnali68]

Pay more attention to your transmission temperature than your engine temperature. On both of my trucks, I leave the digital display on the trans temp.

Change your fluids regularly. Especially the rear axle and the transmission fluid. Do the full fluid replacement on the trans - 16 quarts. Every 50k or less if towing long distances.

The rear axle is the weak point on the half-ton trucks. Do you weigh your rig when loaded and towing? Make sure the rear axle isn't overloaded. CAT scales has a handy app that makes weighing a breeze.

I do the same, watch trans temp like a hawk when towing. Never went over 235. 50k seems reasonable. Truck only gets like 8k a year so that'll be a while (I work from home). Should also add that the camper is my parents and I use it 2-3 times a year, never driven more than 200 miles from home at this point. I have not weighed the rig because with how infrequently I use it it never even crossed my mind to weigh it!

 

[Dadnali68]

Fully synthetic / Group 4 5W30? Is Engine Half@$$ still enabled?

3 things will help:
Better ATF cooling by upgrading ATF cooler and/or adding fan to it
ecm & tcm tune - improves cooling AND gear and TCC operations for better trans durability / longevity
3.42 or 3.73 axle gears (understandably more expensive, but very highly effective; it does more than just improve the peak tow rating ...)Pessimistic, maybe, but I replace coolant AND ATF as soon as reasonably possible whenever either one hits 239F.

Full synthetic valvoline 5W-30 every 4-5k. Motor still has AFM/DOD. I actually have an external trans cooler and the special fitting that goes into GM radiators. Bought it years ago for my 07 silverado but sold the truck before I installed the upgrades. Would be interested to learn about the tunes but would probably stay away from gearing changes right now just because truck is mostly a commuter/dad bus back and forth to daycare. A tall gear would be more fun at red light though lol!

 

[Scrappycrow]

A tall gear would be more fun at red light though lol!

You mean "short" gear. The easy way to remember the difference is that "short" gearing is for "low" speeds and "tall" gearing is for "higher" speeds.

 

[Dadnali68]

You mean "short" gear. The easy way to remember the difference is that "short" gearing is for "low" speeds and "tall" gearing is for "higher" speeds.

Oops yeah got that backwards.

 

[Joseph Garcia]

Your 40+/20 psi hot hot oil situation is normal for this truck. If the hot idle psi drops below 20, then you may want to watch it closer.

 

[Geotrash]

Full synthetic valvoline 5W-30 every 4-5k. Motor still has AFM/DOD. I actually have an external trans cooler and the special fitting that goes into GM radiators. Bought it years ago for my 07 silverado but sold the truck before I installed the upgrades. Would be interested to learn about the tunes but would probably stay away from gearing changes right now just because truck is mostly a commuter/dad bus back and forth to daycare. A tall gear would be more fun at red light though lol!

Which external cooler do you have and where did you mount it?

I have a whole thread on lessons learned on keeping cool when towing in the summer heat. I often tow with a 2012 Yukon XL Denali, and after much experimentation I found that any trans cooler much larger than the OEM unit mounted in front of the radiator (e.g. a Trucool 40K) will have a detrimental effect on engine cooling because it restricts more of the airflow through the radiator. So much so, that towing 7500 lbs up steep grades over the blue ridge or out west, can trigger the high engine temp warning with everything else being stock.

I ended up going with a Derale 13960 mounted below the front bumper and behind the secondary grille, which I opened up to increase airflow. Game changer. Transmission stays nice and cool, and no more engine cooling problems. I also installed a new OEM radiator and a fan assembly designed for the K5L (enhanced cooling) package, which mine did not come with from the factory.

 

[Dadnali68]

Which external cooler do you have and where did you mount it?

I have a whole thread on lessons learned on keeping cool when towing in the summer heat. I often tow with a 2012 Yukon XL Denali, and after much experimentation I found that any trans cooler much larger than the OEM unit mounted in front of the radiator (e.g. a Trucool 40K) will have a detrimental effect on engine cooling because it restricts more of the airflow through the radiator. So much so, that towing 7500 lbs up steep grades over the blue ridge or out west, can trigger the high engine temp warning with everything else being stock.

I ended up going with a Derale 13960 mounted below the front bumper and behind the secondary grille, which I opened up to increase airflow. Game changer. Transmission stays nice and cool, and no more engine cooling problems. I also installed a new OEM radiator and a fan assembly designed for the K5L (enhanced cooling) package, which mine did not come with from the factory.

I purchased a Hayden cooler and their respective fitting adapter. Last I knew it was in a box in my parents garage. No plans to do anything about it anytime soon, towing season is over. However if I ever had to replace the radiator I would probably add this in as a "might as well since I'm here anyway."

I like the mounting and fan assembly suggestions, I'll definitely be coming back to read this should I find myself making these changes!

 

[petethepug]

If you don’t have any history on the radiator, replace it. They’re notorious for allowing sand, and then dust to embed so they heat soak when trying to do their job when towing.

It’s the equivalent of having an undersized core not made to share the oil cooler in its core.