Saginaw Michigan - Service a 2008 Hybrid Yukon?

[Zylin]

My daughter just went to Saginaw, Michigan due to a death on her Bo's side of the family. Our 2008 GMC Yukon Hybrid was losing oil, so I just had her leave the truck ( she has already flown home with her very young son ).

I started calling around and I cannot find anyone that will touch the Hybrid. Personally, if it's losing oil, I wouldn't think it would have anything to do with the hybrid; however, I also know the high voltage is an issue if you are unfamiliar with what's in bounds vs. out of bounds. And out of bounds comes with a very nasty bite.

My ask of the forum, does anyone know a trusted shop anywhere near Saginaw that could take a look at the truck?

 

[j91z28d1]

sorry I don't know anything about the area but I can tell you there's nothing special about the hybrid tahoe oil system as are where it can leak from. short of maybe a rear main seal that they need to pull the tranny for. then it's one plug on the hybrid battery, wait a few mins, check for volume across the wires, there never is. the safety plug removes the battery completely from the circuit. then unbolt the orange cables on the tranny. rest is normal.

but unless it's just a slow leak, it's very rare for a rear main to just start pouring out oil, short of a boosted race motor that builds to much crank case pressure and blows it out, I've literally never heard of anything but slow leak that slowly get worse from a rear main.

if I had to guess, without being there. for all of a sudden losing a lot of oil there's a oil cooler bypass block off plate above the oil filter that can leak pretty good sometimes, or the top back of the motor behind the intake manifold, there's the oil pressure sensor. sometimes they get old, or are replaced with non oem gm sensors and they can pop the plastic top and start leaking.

did she give you any details of the location and amount of oil? if it's just a few drops, might be OK to just top off the oil and drive it home to deal with yourself?

 

[Zylin]

No details and I didn't ask for more details. She's the type of person when asked what kind of car she would like her answer would be "white".

I'm getting ready to fly up to retrieve the truck. Was just hoping to get lucky and know the extent and timeframe for fix before heading up.

Many thanks for the details...

 

[j91z28d1]

good luck with it.. I totally get just get her home and I'll deal with it.

let us know how it goes. Hopefully you find a good shop.

 

[Tonyv__]

Have you tried any actual GM dealers? Dealership is usually my last stop but I imagine they’d have to service something they once sold.

 

[petethepug]

Is there a puddle of oil under the truck or is the dip stick measuring the loss? Is it a low oil press warning light?

Fortunately the 6.0L motor is common GM territory until you get into the hybrid system. Just need a little more info

 

[Zylin]

Update. Found a shop and have the truck there - Redmond's in Saginaw. They say the engine is making a noise and is not holding oil pressure. It's not a bad indicator. Waiting for an estimate to tear the truck apart. I'll get more details soon.

Trying to decide if I should just sell it for parts or invest in getting back on the road. More to follow.

 

[Zylin]

Holy cow, they want $1,000 just to Remove Cylinder Head To Check Valves and Springs (One Side).

What would be the cost if it's a bad valve or spring?

 

[j91z28d1]

well pulling heads off the truck is a lot of work, but why are they pulling heads.


valve springs only require them to pull the valve cover to inspect for a broken one. it's not a common thing seen posted here. but it has happened. that doesn't involve oil pressure at all thou and a tick on these ls engines can be anything front a broken exhaust manifold bolt, not big deal to drive home. to a lifter failing and will be very bad to drive on.

did they talk about replacing the oil pressure sensor and the small screen under it? that's usually the first thing to test.

did you see any oil leaking?

 

[j91z28d1]

oh, just incase they bring it up, these ls engines have 2 style heads, one called rectangle port and one called Cathedral port.

the rectangle has a bit of a history of dropping a valve seat, that would require pulling the head to see, but your hybrid 6.0 does not have that kinda of head. you have cathedral port heads, as far as I know I've never seen anyone report dropping valve seats out of a cathedral port head.

I don't see any reason they need to pull a head to inspect anything, they can diagnose a failed lifter or a broken valve spring from removing the valve cover on the top of the head.

 

[Zylin]

oh, just incase they bring it up, these ls engines have 2 style heads, one called rectangle port and one called Cathedral port.

the rectangle has a bit of a history of dropping a valve seat, that would require pulling the head to see, but your hybrid 6.0 does not have that kinda of head. you have cathedral port heads, as far as I know I've never seen anyone report dropping valve seats out of a cathedral port head.

I don't see any reason they need to pull a head to inspect anything, they can diagnose a failed lifter or a broken valve spring from removing the valve cover on the top of the head.

Daughter reports never noticing any oil on the ground

 

[j91z28d1]

Daughter reports never noticing any oil on the ground

that's atleast good. I guess gauge only what she saw?

the normal shop will just put a new sensor in, what that costs depends on the shop. sensor is between 50-100$. labor depends on if the mechanic knows they can change it without pulling the intake manifold off. it's a bit difficult but you can replace it without.

the correct way is to remove the sensor and screw in a mechanical test gauge. start it and confirm if it has actually oil pressure or not. then go from there, if it doesn't have any, then you can test at a port on the from drivers side of the engine, that port is hard to get to, but will tell you the pressures stright off the pump. if you have it there, that narrows down where the pressure is bleeding off, if it doesn't have it here, it's pretty much a oil pump pick up o ring failure, but that being bad will usually have some pressure, just low. or the pump itself, which is rare but anything can happen. these hybrids do have a different more high volume/pressure pump called a variable displacement. (said to be more efficient) I've not read of any failures of them thou.

 

[Zylin]

At this time, since I have given her a different vehicle, I'm going to sell. It needs the home of a great mechanic and I'm a software geek, aka not hardware.

I've posted on Craig's list if anyone is interested.

2008 GMC Yukon 1/2 ton SL hybrid for sale by owner - Saginaw, MI - craigslist

First, let me talk you out of this vehicle. 230,000 total miles. Engine does not hold oil pressure - most likely needs new engine. Hail damage from Texas hail storm. Typical cracked dashboard of GMC...

saginaw.craigslist.org

OR if anyone has a solid charity, willing to donate.

 

[j91z28d1]

shame to see, but I get it. wish it was local to me.

edit, you put a crate motor in it 70k miles ago? wow I'm shocked it would have a motor issue that quickly.

good luck.

 

[91RS]

You’d be better of taking it to a dealership. You’ll have a much better chance of someone being trained to work on it there. Even if the issue isn’t with the hybrid system, GM still says to disable it before doing engine work.

If it has an actual issue with oil pressure, it’s probably cam bearings.

 

[j91z28d1]

You’d be better of taking it to a dealership. You’ll have a much better chance of someone being trained to work on it there. Even if the issue isn’t with the hybrid system, GM still says to disable it before doing engine work.

If it has an actual issue with oil pressure, it’s probably cam bearings.

standard practice if anyone ever needs to disable a hybrid anything to work on it. you just pull one safety plug out. you'll probably have to Google the location as they seem to be random. the Tahoe is under a plastic cover under the rear seat. a chevy volt into under a pop up panel in the console. once you do that the system is dead. it's like pulling a battery terminal off. unless your going inside the battery pack itself, there's nothing else needed. and even then there's not much in the pack that can hurt you without trying. the orange safety plugs actually split the packs in a way that the voltage left connected wouldn't hurt you unless you fill a bath tub with salt water and tossed it in with you haha.


if I read it right and it had a crate motor in is 70k ago, unless it was a bad rebuild, I don't know how it would eat any bearings so quickly. these also have a different volume and pressure oil pump in them. you could probably spin a rod bearing and still have 20psi at idle, let alone a rod bearing. I'd bet money it's just a oil pressure sensor and the tick is probably a broken header bolt.

I'd love to put eyes on this thing.

 

[91RS]

You have to verify the high voltage system is dead. Assuming it is dead is how you wind up dead. High voltage is no joke. That’s why most places won’t mess with them. I’ve done high voltage training and still avoid them like the plague.

The AFM oil pump is barely different, it’s like 20% more volume, that’s not going to make up for a failed cam bearing. The new GM pumps are all the AFM pump anyway.

 

[j91z28d1]

You have to verify the high voltage system is dead. Assuming it is dead is how you wind up dead. High voltage is no joke. That’s why most places won’t mess with them. I’ve done high voltage training and still avoid them like the plague.

The AFM oil pump is barely different, it’s like 20% more volume, that’s not going to make up for a failed cam bearing. The new GM pumps are all the AFM pump anyway.

if you want to verify, it's 2 seconds with a DC volt meter, check pos to neg and then both to case ground. eh. there's no caps in the system. nothing to store energy. short of an accident that crushes the battery so bad it shorts internally, there's nothing there. and even then wait 2 mins and the cells well be drained from the short.

I've been thru tons of training too, half my fleet these days is electric. meh, this isn't some 10,000v ac high power line. those guys are crazy. the arc flash alone will melt your skin off.

these is 40 small battery cells at 7.2v each, the orange plug breaks the connection and that's all your got is 40 individual 7.2v to touch and less overall capacity than your 12v car battery.

blah.. electric car bad is over blown these days, if you understand the basics to the point you can wire a relay you can work on them.


its not a simple afm pump, it's a variable displacement oil pump, it's the only application to ever use one stock on a ls engine. gm didn't start using them till the newer LT direct injection engine out now for everything else..

so at full displacement it flows a ton and has much higher pressure. if you look at gm service limits for a standard ls pump, hot psi at idle can be as low as 7 without being considered bad. on these pumps anything under like 27psi at hot idle is considered bad. my truck runs 60 pretty much all the time, and I've only see it down around 45 once. long trip towing on old oil.

 

[91RS]

Umm, if you've had EV training, I don't think you would be talking about EV batteries like that. It can be second nature and not be a big deal to you, but these batteries are not "nothing." They have enough voltage and amperage to kill you instantly. There's a reason they sell insulated tools and such for working internally on EV batteries. The battery cells are only nothing when they're completely disconnected from the rest of them and not in the pack. Don't tell people they can mess with high voltage without training, there are already too many people online that overestimate their abilities of working on cars, but most of the time that won't get them killed.

We're not talking about LT oil pumps, we're talking about LS oil pumps. This is the 07-14 section.

 

[j91z28d1]

Umm, if you've had EV training, I don't think you would be talking about EV batteries like that. It can be second nature and not be a big deal to you, but these batteries are not "nothing." They have enough voltage and amperage to kill you instantly. There's a reason they sell insulated tools and such for working internally on EV batteries. The battery cells are only nothing when they're completely disconnected from the rest of them and not in the pack. Don't tell people they can mess with high voltage without training, there are already too many people online that overestimate their abilities of working on cars, but most of the time that won't get them killed.

We're not talking about LT oil pumps, we're talking about LS oil pumps. This is the 07-14 section.

old thread, sorry for the late reply, missed it and only saw while looking for a towing post. but I can't leave it as you trying to scare people away from battery's.

Yes I have ev training, more than most and I will be getting some of the first rounds of sodium batteries to test.
half my fleet is now ev. no one uses insulated tools. even the warranty techs come out with some black tape wrapped around wrenches. it's fine.

basic knowledge is all that's needed, and a little bit of research to find how your specific pack is wired and where the disconnect is. it's not rocket science. I feel the internet is going the wrong way with electric car info. driving everyone away from learning anything. way more people in shops have been injured from a 12v lead acid battery exploding in their face than ev batteries ever will and we don't tell the average person to go run and hide from their 12 volt battery

here's pics of the stuff I deal with almost daily. new pack came with a random fault in the wiring in the bottom of that rats nest. that's 26 cell 1000lb pack with 2 bms's slaved together. it's a cluster to work on, you're not pulling all the cells out to work on it. it's not practical. you disconnect circuit and then don't cross the individual cells like you would any other battery. reach down and start pulling harnesses out.




like with all batteries, even your 12v car battery. don't complete the circuit by touching pos and neg together with anything.


as for the oil pump, yes I'm talking about an ls engine, not a LT. they did put a variable displacement oil pump on a ls engine( specifically the Hybrid engine being talked about in their thread) and it can be installed on any ls engine across the board, it is completely different from the one used on LT engines. Just like with batteries, just because you don't know it doesn't mean lock down and run away. do some research and don't be scared to work on your own vehicles.