Solved! 'ish' Coolant Leak + Possible Engine Replacement

[BigAlBuilds]

Ok so here's the story.

I have a 2022 Silverado 2500 6.6 gas with 35kmiles  and I absolutely love the truck! Bought it for my slide in camper and I now have a 24ft rpod I tow with it.

Couldn't be happier.

 

At about 10k miles I started periodically smelling coolant. Also noticed a bit of oil consumption but I've owned 3 GM LS/LT trucks so I thought nothing of it.

 

At about 20k miles the coolant smell was persistent and I felt like the oil consumption was more than I was used to...even for my previous 250k mile truck. I looked online and couldn't find anyone with the same problem. I was planning a move from CA to CO with a few 12k lbs tows across the rockies so I took it to the dealer. They had it for three days and finally ended up replacing the passenger headgasket. I got the truck back and smelled coolant again a few days later.

 

Now in CO I smelled coolant regularly but ignored it. Summer 2024 I drove from CO to MA with my slide in camper doing about 75-80mph. After about 1500 miles i noticed about a 1/2" drop in coolant and about a quarter of oil burnt. When I got back to CO I took it to the dealer with about 28k mile. They did a pressure check and found nothing. Typical. They added dye to the coolant and sent me home.

 

 Drove for about a year and regularly smelled coolant but did not see the coolant level go down. Also my oil consumption was acceptable.

 

This fall I took a trip to Utah with my trailer. Maybe 5k in trailer weight and 1k in additional payload. I felt the truck was under powered. After the there and back 1k mile trip I burnt through 1 quart of oil and my coolant dropped by 0.75".

 

Took it back to the dealer right after the trip at 35k miles. I told the counter to come out and smell my truck, it reaked of coolant and they agreed. Finally, someone was on my side. 

 

They founds that my passenger head was cracked near the V and at the very back. However they cannot explain my oil consumption. They are pushing tk have GM replace the whole engine.

 

Anyway I do love the 6.6 gas and I think this is an isolated issue as I have not seen it elsewhere. I just got a dud. Posting this as a statistic really.

 

I will update on what GM decides to do.

 

Al

 

 

 

 

[Chuck FB]

19 hours ago, BigAlBuilds said:

Ok so here's the story.

I have a 2022 Silverado 2500 6.6 gas with 35kmiles  and I absolutely love the truck! Bought it for my slide in camper and I now have a 24ft rpod I tow with it.

Couldn't be happier.

 

At about 10k miles I started periodically smelling coolant. Also noticed a bit of oil consumption but I've owned 3 GM LS/LT trucks so I thought nothing of it.

 

At about 20k miles the coolant smell was persistent and I felt like the oil consumption was more than I was used to...even for my previous 250k mile truck. I looked online and couldn't find anyone with the same problem. I was planning a move from CA to CO with a few 12k lbs tows across the rockies so I took it to the dealer. They had it for three days and finally ended up replacing the passenger headgasket. I got the truck back and smelled coolant again a few days later.

 

Now in CO I smelled coolant regularly but ignored it. Summer 2024 I drove from CO to MA with my slide in camper doing about 75-80mph. After about 1500 miles i noticed about a 1/2" drop in coolant and about a quarter of oil burnt. When I got back to CO I took it to the dealer with about 28k mile. They did a pressure check and found nothing. Typical. They added dye to the coolant and sent me home.

 

 Drove for about a year and regularly smelled coolant but did not see the coolant level go down. Also my oil consumption was acceptable.

 

This fall I took a trip to Utah with my trailer. Maybe 5k in trailer weight and 1k in additional payload. I felt the truck was under powered. After the there and back 1k mile trip I burnt through 1 quart of oil and my coolant dropped by 0.75".

 

Took it back to the dealer right after the trip at 35k miles. I told the counter to come out and smell my truck, it reaked of coolant and they agreed. Finally, someone was on my side. 

 

They founds that my passenger head was cracked near the V and at the very back. However they cannot explain my oil consumption. They are pushing tk have GM replace the whole engine.

 

Anyway I do love the 6.6 gas and I think this is an isolated issue as I have not seen it elsewhere. I just got a dud. Posting this as a statistic really.

 

I will update on what GM decides to do.

 

Al

 

 

 

 

That is not good to hear when issues like that persist and yet can be hard to find as coolant evaporates off if not excessive and when it leaks only when hot, now if its literally streaming out and puddling on the ground then there is somewhere to trace it back to the source. Luckily and after a lot of effort on your part it was finally found but then there is your oil usage and you felt you were down on power. How much oil would you say it is using and I assume its varied according to being driven empty vs towing. 

 

Because you had it at the dealer multiple times, did they top of the reservoir to a specific line as I haven't spotted any markings on the plastic bottle or I am not looking in the right place as to what the operating range is even supposed to be, I've never had this issue with any other vehicles trying to figure out where the cold or hot level was on the tank. Is it supposed to be just at the top of the mold line where the two halves of the tank come together ?  

[BigAlBuilds]

On 11/7/2025 at 12:35 PM, Chuck FB said:

That is not good to hear when issues like that persist and yet can be hard to find as coolant evaporates off if not excessive and when it leaks only when hot, now if its literally streaming out and puddling on the ground then there is somewhere to trace it back to the source. Luckily and after a lot of effort on your part it was finally found but then there is your oil usage and you felt you were down on power. How much oil would you say it is using and I assume its varied according to being driven empty vs towing. 

 

Because you had it at the dealer multiple times, did they top of the reservoir to a specific line as I haven't spotted any markings on the plastic bottle or I am not looking in the right place as to what the operating range is even supposed to be, I've never had this issue with any other vehicles trying to figure out where the cold or hot level was on the tank. Is it supposed to be just at the top of the mold line where the two halves of the tank come together ?  

 

Yes, it has been hard to find. The second time they added dye to the coolant which they said helped find the coolant leak.

As for oil, I was towing 5k lbs and burnt 1 quart of oil in just 1000 miles. That is excessive IMO.

 

My understanding is that the cold level fill for the coolant is at the mold-line.

 

I have been approved for a new engine! Glad that GM and the dealer are finally working to resolve this....I wonder if it has anything to do with the fact that this is my third visit for the same issue and I fall within the Lemon-Law now.

[Chuck FB]

Presuming the engine does get replaced, the head work was somewhat of a waste but it also showed GM that there was an issue with the engine. At the time they replaced the head they would have seen if there was scoring in the cylinders if any coolant had been entering in that direction as well on that bank of cylinders. To me that 1000 mile/1 quart seems off from what some on here have experienced with their engines but the odd one has said they had an oil use issue. It would be nice to know what the reason is behind those engines out there that are using oil. I have few miles on my truck and have changed the oil a few times just to flush out break in metals as the filter doesn't capture them all and have not been working the engine either so have not noted any noticeable usage but its not a good example as I would have to be asked that same question after I had 100000+ miles !. 

 

I have been keeping an eye on my coolant level and so far so good as per not dropping but again just odd how GM designed that bottle to give no indication on it as to where "full" is. 

 

It will be interesting after they drop the new engine in, how it runs power wise in comparison and of course the oil consumption aspect. I know GM doesn't expressly say to change the initial factory oil early in so many words and yet says don't tow for the first 500 miles ... but then says change the oil before you tow. Some genius lawyer wrote that brain twister LOL but anyway I personally subscribe to the concept of changing the factory oil out after 500 miles and then after another 1000 or so miles accumulated on the second oil interval, it sure can't hurt. And beyond that, well I am one that tries to stick to that 3000 mile change interval with cars or pickups over the years but again that is what I am used to doing and not sending out samples that give the engine a chance to speak up and tell what the real picture is. 

 

Hopefully you will have the opportunity to give updates on here as time goes on after the new engine is installed to see how that has worked out for you. 

[GMCustomerService]

On 11/6/2025 at 6:15 PM, BigAlBuilds said:

Ok so here's the story.

I have a 2022 Silverado 2500 6.6 gas with 35kmiles  and I absolutely love the truck! Bought it for my slide in camper and I now have a 24ft rpod I tow with it.

Couldn't be happier.

 

At about 10k miles I started periodically smelling coolant. Also noticed a bit of oil consumption but I've owned 3 GM LS/LT trucks so I thought nothing of it.

 

At about 20k miles the coolant smell was persistent and I felt like the oil consumption was more than I was used to...even for my previous 250k mile truck. I looked online and couldn't find anyone with the same problem. I was planning a move from CA to CO with a few 12k lbs tows across the rockies so I took it to the dealer. They had it for three days and finally ended up replacing the passenger headgasket. I got the truck back and smelled coolant again a few days later.

 

Now in CO I smelled coolant regularly but ignored it. Summer 2024 I drove from CO to MA with my slide in camper doing about 75-80mph. After about 1500 miles i noticed about a 1/2" drop in coolant and about a quarter of oil burnt. When I got back to CO I took it to the dealer with about 28k mile. They did a pressure check and found nothing. Typical. They added dye to the coolant and sent me home.

 

 Drove for about a year and regularly smelled coolant but did not see the coolant level go down. Also my oil consumption was acceptable.

 

This fall I took a trip to Utah with my trailer. Maybe 5k in trailer weight and 1k in additional payload. I felt the truck was under powered. After the there and back 1k mile trip I burnt through 1 quart of oil and my coolant dropped by 0.75".

 

Took it back to the dealer right after the trip at 35k miles. I told the counter to come out and smell my truck, it reaked of coolant and they agreed. Finally, someone was on my side. 

 

They founds that my passenger head was cracked near the V and at the very back. However they cannot explain my oil consumption. They are pushing tk have GM replace the whole engine.

 

Anyway I do love the 6.6 gas and I think this is an isolated issue as I have not seen it elsewhere. I just got a dud. Posting this as a statistic really.

 

I will update on what GM decides to do.

 

Al

 

 

 

 

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