Well, this is interesting. My dealership service advisor informed me that he's seen a lot of 6 cyl Defenders with leaks at the upper radiator hose to the thermostat housing (mine is a 2022). Was surprised that mine lasted as long as it did with 65k miles. The repair included the replacement of the by-pass tube. No recalls on this but supposedly, the replacement part has been redesigned. For those of us who out of warranty like me, he suggested the best chance for relief is to be on the watch for a class action suit. He tells me he's seen this before when there are a lot of failures, but no recall.

 

It is a know issue and really a hit or miss with the Defenders. I had a 2023 Defender with a coolant leak that the dealer could never find. Finally, they did find a tiny leak around the water pump. I also had a 2020 Defender with no leaks. And my current 2022 never had a leak.

 

I have a 2020 HSE that I am waiting to bring in to get the o rings to the turbo replaced. They also said coolant is leaking from the inner cooler, but wanted $2500 to replace that. I’m going to see how the o rings improve things. These engines seem to be leaking coolant like a sieve.

 

I mistakenly assumed that coolant leaks were a thing of the past since I can't even remember owning a vehicle with a coolant leak. But our 2023 Defender had one coolant leak at the intercooler then another one developed where the radiator hose meets the engine block. I initially thought that whoever engineered the Defender coolant connections set us back many years. But our 2021 isn't leaking yet, so more likely whoever supplies these coolant system parts to JLR needs far better quality control.

 

https://www.caranddriver.com/news/a6...-fires-recall/

 

I had the same coolant leak about 65,000 miles- appears to be an issue- had an extended warranty so covered

 

This was interesting reading -
My 2022 LR Defender top radiator hose developed a sizeable split in it from rubbing as well.
It took 99500kms or 3.5 years to wear through the pipe allowing coolant to spray out over the engine. This resulted in a low coolant message.
It has been replaced under warranty, however the replacement will wear through too over time.
Not aware of any advisory having been issued either, but believe there should be as, looks like a design error and really should require a recall to check for wear and replace with the upgraded version of the pipe if there is one. Mine was replaced with the same pipe, but the issue of wearing still exists. I have placed a temporary fix by placing a rubber packer in thereto stop it wearing.

 

Any chance you could post a picture of your DIY fix?

Thanks in advance!
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For the V8 Lucky 8 sells a whole kit the replaces the thermostat and all hoses with aluminum to fix a bunch of these issues. I wonder if they make something for the 400.

 

To reduce wear on a hose, what I’ve done in the past when replacing a hose is to cut off a section of the old hose, slit it lengthwise and wrap it around the new hose and secure with zip ties. And no cost.