GM 3.0 I6 Diesel

[IH Forever]

I've been dragging my feet but I really need to update my daily driver.  I'm just looking for a 1/2 ton truck.  I occasionally tow a trailer with lawn mower or skid loader but it's rare so a 1/2 ton is all I'm in need of.  I currently have an F150 with the 3.5 ecoboost and have been very happy with it.  That is what I've been looking for but saw a GMC Sierra with the little 6 cylinder diesel.  I haven't been looking at GM products just because I've never been overly impressed with the 5.3 in my very limited experience.  But I happened to see this GMC with the diesel.

Does anyone have any experience with them?  Curious about power, mileage, and also reliability.

[dale560]

35 minutes ago, IH Forever said:

I've been dragging my feet but I really need to update my daily driver.  I'm just looking for a 1/2 ton truck.  I occasionally tow a trailer with lawn mower or skid loader but it's rare so a 1/2 ton is all I'm in need of.  I currently have an F150 with the 3.5 ecoboost and have been very happy with it.  That is what I've been looking for but saw a GMC Sierra with the little 6 cylinder diesel.  I haven't been looking at GM products just because I've never been overly impressed with the 5.3 in my very limited experience.  But I happened to see this GMC with the diesel.

Does anyone have any experience with them?  Curious about power, mileage, and also reliability.

The only problem is the oil pump belt service at 100,000 miles or maybe 125,000 now. Belt is in oil pan and you need to remove trans to get to it. A few of them running around up here. 3 of them I know of in our hometown of 2500 people. All three were bought with a previous dodge or ram 1/5 ton diesel traded in. The dodges with the light duty. We’re having severe engine troubles at low miles.

 

[Lazy WP]

We have one. Bought it with 80,000 miles on it. Has 115 it now. They told us to change the belt around 150,000. Using it as a car, it gets around 30 mpg. Rides and drives great. Doesn’t turn as short as the 1 ton dually though. Ours is a 4 door with a 5 foot box. 

[Illini986]

My neighbor bought a Yukon XL with the little dirty in it for his wife. They're both happy with it. He seems to drive it almost as often as she does and hasn't had a bad word to say about it, to me at least. 

[Lazy WP]

I will say you need to drive it like a modern day diesel. No long term idling, no short on off with the engine, even though it has the auto start. It will cause the check engine light to turn on. EGR codes. Get it up to operating temperature every time you start it and you won’t have any issues. 

[jeeper61]

2 hours ago, dale560 said:

The only problem is the oil pump belt service at 100,000 miles or maybe 125,000 now. Belt is in oil pan and you need to remove trans to get to it. A few of them running around up here. 3 of them I know of in our hometown of 2500 people. All three were bought with a previous dodge or ram 1/5 ton diesel traded in. The dodges with the light duty. We’re having severe engine troubles at low miles.

 

That set up is a big no for me 

Why drive the oil pump with a belt?

If that snaps the engine is toast is seconds.

It is at the back of the engine to top it off so the trans has to come out 

And as it wears the debris goes in the oil to cause other problems

Ford’s 4-cylinder EcoBoost engines have the same type set-up

W- T- F 

 

[Binderoid]

2 minutes ago, jeeper61 said:

That set up is a big no for me 

Why drive the oil pump with a belt?

If that snaps the engine is toast is seconds.

It is at the back of the engine to top it off so the trans has to come out 

Ford’s 4-cylinder EcoBoost engines have the same type set-up

W- T- F 

 

Ford has a v6 in some car in which the water pump is used as an idler in the timing belt sysem... probably works OK for awhile, but the point is the same as your point.... being an interference motor, the water pump can take out the engine if it decides to lock up. Probably right after the warrantee expires.

[dale560]

2 hours ago, Lazy WP said:

We have one. Bought it with 80,000 miles on it. Has 115 it now. They told us to change the belt around 150,000. Using it as a car, it gets around 30 mpg. Rides and drives great. Doesn’t turn as short as the 1 ton dually though. Ours is a 4 door with a 5 foot box. 

They changed the specs a few times on the belt and change intervals. 

[dale560]

Does any body know what the issues with the little Cummins in the dodge? The guys that traded them off were all on replacement engines with low miles.

[Dmnstr8r]

I have a 2022 model with the LM2 that I bought new.  Zero issues thus far.  Best mpg is 36 with it...generally 28 to 32 at highway speeds.  Been a great truck for me.  It does drink DEF when towing if using in that capacity.

2025 and 2026 models are plagued with thrust bearing issues.  Have one at work that shelled it's first engine at 13k miles and was replaced under warranty.  Many of these failures are at low miles.  2024 and earlier models don't seem to share in the failure rate.

[Dirt_Floor_Poor]

3 hours ago, jeeper61 said:

That set up is a big no for me 

Why drive the oil pump with a belt?

If that snaps the engine is toast is seconds.

It is at the back of the engine to top it off so the trans has to come out 

And as it wears the debris goes in the oil to cause other problems

Ford’s 4-cylinder EcoBoost engines have the same type set-up

W- T- F 

 

It’s great. You can take it to the dealer that doesn’t have any techs so the parts guy can order the parts that are on back order. The timing chains that are 1/4 mile long with the plastic chain guides are another pathetic idea. Save a thimble full of gas to get saddled with a thousand dollar repair later. 

[jeeper61]

That 3.0 engine was a Opel design.

Why GM didn't get Isuzu involved like they did with the 6.6 is beyond me.

GM had a 4 banger 2.8 turbo diesel in the Colorado that was a troublesome too and once again no Isuzu involvement.

The LS V8s and Ecotec 4 cylinder both have front mounted crank driven oil pumps which have been very reliable why they wouldn't specify a sure thing instead of taking a chance on a unproven design is beyond me.

[dale560]

26 minutes ago, jeeper61 said:

That 3.0 engine was a Opel design.

Why GM didn't get Isuzu involved like they did with the 6.6 is beyond me.

GM had a 4 banger 2.8 turbo diesel in the Colorado that was a troublesome too and once again no Isuzu involvement.

The LS V8s and Ecotec 4 cylinder both have front mounted crank driven oil pumps which have been very reliable why they wouldn't specify a sure thing instead of taking a chance on a unproven design is beyond me.

There was some vibration or other issue with front crank driven pumps that the belt drive offset was to correct. Other mfg went to chain driven or belt pumps I think also

[Dirt_Floor_Poor]

Mickey Mouse must be the head engineer at multiple auto companies if this was the solution. 

[Sask466]

I feel mixed about belt driven oil pumps…. I have also heard mention about torsional/vibration issues the belt corrects.  That seems like an excuse to a minor problem that could probably have been corrected? 

The dumb thing to me is where they put it.  Pulling a transmission on a 4wd half-ton isn’t a small job, and not a shadetree job.   

So many cars have cam belts or chains.  If they fail, it’s a catastrophic failure.  And those belts are much longer and the cam/valve train has much higher load/inertial mass.  They really don’t fail all that often.   

 

 

[stronger800]

I had a ‘15 ecoboost 3.5, then got a GM 5.3 with the 8 speed, or was it six?, the denali “fancier” trans that the 6.2s have, in ‘19, had wanted a 6.2 but couldn’t find one, anyway..,back to ford 3.5 after that.   Idk how much power the diesel has, or if you need it at all, but I feel like it’s can’t be 3/4 the motor the ford is.  
 

I know two guys with those mini diesel dodges, the first generation ones though, from ten years ago, and they have had no issues.  One has over 200k on it, but it’s no powerhouse. Hooked my 29’ sled trailer to it one day and it said ouch.   The ecoboosts toy with it, the GM did ok 

[TroyDairy]

The belt change interval is 200k miles today.  26 models have neen having a bearing problem.  Alledge was a run that has worked though.  Do not know serials.

My nutritionist had one.  150k and didnt want to spend money on belt etc so bought new truck woth 5.3 instead.  Mid 30s mpg with 3.0 all day.  Pulled 24ft camper with ease.  Regrets not getting another one he told me recently.  I also would like one.  Lady friend of ours has a Suburban with it and loves it.  Fastish and mid 30 mpg too.

 

The belt ia 100% noise vibration issue.  People now general wont buy a diesel if it's noisy.  A chain would been better but people wont accept the sound.  The 3.0 is hard to tell its running frankly.

For 2027 gm.now allows the 3.0 in base models and all the way to High County.  I see more being sold quickly.

[Sask466]

Yeah they are notably quiet, now that you mention it. 

[jeeper61]

If they were worried about NVH it would make more sense to put the pump farther a way from the the passenger compartment.

[MCC]

12 hours ago, dale560 said:

Does any body know what the issues with the little Cummins in the dodge? The guys that traded them off were all on replacement engines with low miles.

The eco diesel is made by VM Motori.

[jeeper61]

VM Motori designed the 2.8 Duramax for GM.

And GM has since sold the engine and the factory in Thailand that built it to China  

[jeeper61]

Looks like Ford moved to a belt driven pump on the 5.0 Coyote 

 At least they made it assessable 

 

[stronger800]

When did that start?  Gawd.  All seems silly.  Tell me my ecoboosts are like that too and I didn’t know it 

[stronger800]

Actually I remember now, ecoboost have them up front, structural looking, chain drive under the front cover 

[Cattech]

It's kinda weird, the Ford 5.0 v8 and the 2.7 EcoBoost went to an internal timing belt that also drives the oil pump. At the same time, they went to a double timing chain and improved tensioners/cam phasers on the 3.5L EB.