2014+ radiator upgrade to fix cracking issues

kickass audio · February 5, 2023

I wanted to ask here and see if anyone has a legitimate fix for the wonderful GM problem of a small crack in the radiator. When I bought my truck 4 years ago it was under the service bulletin for the radiator crack where there is a small crack in the corners of the radiator and the fix was to replace the thermostat and radiator. That service was done and now yet again and of course after the warranty period for the radiator/thermostat is gone I am up again to replace the cracked radiator.

The crack both times was very small and never amounted to dripping on the ground but you can smell the sweet smell of coolant if you stick your nose at the top drivers side of the radiator and you can visually see the small crack in the housing where the top rail is welded to the side of the radiator. What I have noticed is during the winter if I am coasting I see the temperature gauge on the dash will sometimes go from 210 to 1 line to the left.

I have been trying to figure out if there is any actual fix that someone has found for these junk radiators/thermostats. I have new oil cooler lines I will have the luxury of replacing this spring and I have 4x4 so the front diff will be a joy to get around but wanted to ask about a better upgrade for the thermostat and radiator if anyone knows. I found an all aluminium upgraded radiator made by mishimoto but that thing is super expensive and there were complaints about leaks at the welds. I would hate to keep throwing my money out the window for this truck. It's already rusting out in the rear wheel wells despite constantly cleaning them out and removing the junk carpeted wheel liners to clean in there.

Doug Crumlich · February 6, 2023

I actually have a 2006 C5500 that we have put 4 Factory radiators in. After a year or so, when it sits more that a month or two, the radiator starts seeping out of the drivers side at the bottom. Sometimes just a little drip but mostly moist.

The current radiator is 6 months old and less than a thousand miles on it. When it sat and then the temperature in Georgia got colder it seeped than stopped. Havent' noticed it in the past month or so.

kickass audio · February 6, 2023

5 hours ago, Doug Crumlich said:

I actually have a 2006 C5500 that we have put 4 Factory radiators in. After a year or so, when it sits more that a month or two, the radiator starts seeping out of the drivers side at the bottom. Sometimes just a little drip but mostly moist.

The current radiator is 6 months old and less than a thousand miles on it. When it sat and then the temperature in Georgia got colder it seeped than stopped. Havent' noticed it in the past month or so.

I would say mine was from the cold but it had evidence of a micro crack in the top edge of the support on the drivers side. I'm just not wanting to keep tossing a new rad at this brown turd as I call it of a truck if I can avoid it but spending 3 times the OEM price for a rad seems high. I was considering a napa rad since it has a lifetime warranty so at least I can swap the rad out if it breaks again as usual.

Grumpy Bear · February 7, 2023

On 2/5/2023 at 4:26 PM, kickass audio said:

When I bought my truck 4 years ago it was under the service bulletin for the radiator crack where there is a small crack in the corners of the radiator and the fix was to replace the thermostat and radiator.

Chris, when they replaced the radiator did the new unit have a 3- or 4-inch squared piece of aluminum tape over the upper left hand (drivers' side) area of the fins? You can see it through the grill. GM's first pass at this issue centered on the thermostat sensitivity to cycling. Fix was a thermostat. The second was this tape fix. Thermo-shock was considered the primary issue.

Mines had that 'sweet smell' for years and I add a cup of fluid about every other summer. Could never find a wet spot anywhere.

On 2/5/2023 at 4:26 PM, kickass audio said:

It's already rusting out in the rear wheel wells despite constantly cleaning them out and removing the junk carpeted wheel liners to clean in there.

They rot, like they all do, from the inside out. Starts in the seam. Wool Wax, Fluid Film. Blaster Surface Shield. Some sort of lanolin sprayed between the panels that can seep into that welded area is a huge help. As is spraying the wheel wells on the tire side. That seam can be accessed from the box by pulling that plug above the inner wheel tub. Or a wand after pulling the tail lamp.

16LT4 · February 7, 2023

16 minutes ago, Grumpy Bear said:

That seam can be accessed from the box by pulling that plug above the inner wheel tub. Or a wand after pulling the tail lamp.

Or, just reaching an arm up with a garden hose to spray out the inside of the body panels. Every time I wash a vehicle, I start with the underside, nooks and crannies of the body seams, frame channels, etc. I'll even fill the boxed frames with water to rinse out salt and sand. One thing I learned as a teenager was to use a hose nozzle pointed back toward my face to clear the GM fender lips of debris, shooting water from the frame-outward. Just spraying out the inner fenders never removes the dirt/sand that traps moisture and sits above the fender lips. Forget about my '16 not having rust, but my '84 and '86 GMs that have lived outside their entire lives through upstate NY winters are also rust-free as well. It's a lot harder to repair rust than it is to prevent it.

Edited February 7, 2023 by 16LT4

customboss · February 7, 2023

5 hours ago, Grumpy Bear said:

Chris, when they replaced the radiator did the new unit have a 3- or 4-inch squared piece of aluminum tape over the upper left hand (drivers' side) area of the fins? You can see it through the grill. GM's first pass at this issue centered on the thermostat sensitivity to cycling. Fix was a thermostat. The second was this tape fix. Thermo-shock was considered the primary issue.

Mines had that 'sweet smell' for years and I add a cup of fluid about every other summer. Could never find a wet spot anywhere.

They rot, like they all do, from the inside out. Starts in the seam. Wool Wax, Fluid Film. Blaster Surface Shield. Some sort of lanolin sprayed between the panels that can seep into that welded area is a huge help. As is spraying the wheel wells on the tire side. That seam can be accessed from the box by pulling that plug above the inner wheel tub. Or a wand after pulling the tail lamp.

WORD GRUMPY BEAR ....Ain't a decent heat exchanger made I know of. Worst ever EGR coolers for HD diesels.....total crap that nearly takes out trucking company fleets. Low level leaks from coolant over time make a big mess.

Grumpy Bear · February 7, 2023

16 minutes ago, customboss said:

WORD GRUMPY BEAR ....Ain't a decent heat exchanger made I know of. Worst ever EGR coolers for HD diesels.....total crap that nearly takes out trucking company fleets. Low level leaks from coolant over time make a big mess.

That true. They don't make parts anymore. They make money.

kickass audio · February 7, 2023

6 hours ago, Grumpy Bear said:

Chris, when they replaced the radiator did the new unit have a 3- or 4-inch squared piece of aluminum tape over the upper left hand (drivers' side) area of the fins? You can see it through the grill. GM's first pass at this issue centered on the thermostat sensitivity to cycling. Fix was a thermostat. The second was this tape fix. Thermo-shock was considered the primary issue.

Mines had that 'sweet smell' for years and I add a cup of fluid about every other summer. Could never find a wet spot anywhere.

They rot, like they all do, from the inside out. Starts in the seam. Wool Wax, Fluid Film. Blaster Surface Shield. Some sort of lanolin sprayed between the panels that can seep into that welded area is a huge help. As is spraying the wheel wells on the tire side. That seam can be accessed from the box by pulling that plug above the inner wheel tub. Or a wand after pulling the tail lamp.

The rad was not part of the foil corner, that was only for the condenser/tranny cooler at the very front. The rad sits behind that and is just your traditional GM radiator with the oil cooler and trans lines going to it.

6 hours ago, 16LT4 said:

Or, just reaching an arm up with a garden hose to spray out the inside of the body panels. Every time I wash a vehicle, I start with the underside, nooks and crannies of the body seams, frame channels, etc. I'll even fill the boxed frames with water to rinse out salt and sand. One thing I learned as a teenager was to use a hose nozzle pointed back toward my face to clear the GM fender lips of debris, shooting water from the frame-outward. Just spraying out the inner fenders never removes the dirt/sand that traps moisture and sits above the fender lips. Forget about my '16 not having rust, but my '84 and '86 GMs that have lived outside their entire lives through upstate NY winters are also rust-free as well. It's a lot harder to repair rust than it is to prevent it.

With the rot in the wheel wells, I wash the turd weekly at the car wash and every other week I flush out the wheel wells and frame rail. I tried treating the inside of the frame rail and the wheel wells including the area behind where the plugs are on the rear fender well with 3M wax coating and used the wands to get in there and it doesn't make a difference. Good old Western New York with the unnecessary shitload of salt all the time when it isn't even cold enough to freeze or raining/snowing out.

Grumpy Bear · February 7, 2023

39 minutes ago, kickass audio said:

The rad was not part of the foil corner, that was only for the condenser/tranny cooler at the very front. The rad sits behind that and is just your traditional GM radiator with the oil cooler and trans lines going to it.

Good to know. I was misinformed then. Thanks! :thumbs:

kickass audio · February 8, 2023

1 hour ago, Grumpy Bear said:

Good to know. I was misinformed then. Thanks!

no problem Grumpy! I actually changed my condenser with one from napa and it seems to be a better build than the OEM but time will tell on that. I don't know how the rad from them would work but it has a lifetime warranty so aside from the hassle of changing it out myself it might help.

16LT4 · February 8, 2023

15 hours ago, kickass audio said:

With the rot in the wheel wells, I wash the turd weekly at the car wash and every other week I flush out the wheel wells and frame rail. I tried treating the inside of the frame rail and the wheel wells including the area behind where the plugs are on the rear fender well with 3M wax coating and used the wands to get in there and it doesn't make a difference. Good old Western New York with the unnecessary shitload of salt all the time when it isn't even cold enough to freeze or raining/snowing out.

Car wash does absolutely nothing to prevent fender rot on these trucks. Nothing. Remove a tail light and shine a flashlight into the void, you'll see the upper surface of the fender well; THAT surface is what collects dirt sand sand, which retains salt and water, causing the rot. That area is impossible to reach with car wash, or even from inside the fender well; it is only accessible by shooting water around the fender well, either by reaching up with a hose, or by removing the tail light. I lived a decade in Livingston County, including daily driving my 442 through winters, so I'm no stranger to the salt out there. Rot occurs from the inside out, not vice-versa. Either way, too late now.

Oh, my truck also gets driven literally through salt water when I take it on the beach. Factory rust-preventive coating on the frame rails is still there, too.

Edited February 8, 2023 by 16LT4

Payton34 · March 3, 2023

I have been noticing a coolant smell through my grill and around the upper radiator hose for the past year but cannot find a leak and haven't had to add any coolant. I had to replace my thermostat last spring also. Where is the crack? Is this stress crack visible without taking radiator out. Also has anyone tried using something like a Blue Devil Coolant stop leak? Would a pressure test show where the crack is?

MikeBMW · March 3, 2023

I've had a coolant smell since I bought my 2017.
I've never had to refill coolant, as well.
I took it to the dealer and they couldn't find anything wrong so I just let it go and have had zero issues over the years (other than the occasional coolant smell).
I would refrain from adding any stop leak to the coolant system. If there is an issue, just fix that properly.

JimCost2014 · March 3, 2023

My 16 had the coolant smell, our 16 Tahoe has it, and my 18 is the same.

No visible leaks, just add 4-8oz, or so every 12-18 months. Coolant changed in all every 4-5 years. Think it just eveorprates because these engines run so hot.