Cheap garbage RockAuto thermostat started leaking in less than two years after replacement. I barely even drive the car probably only about 2,000 km total on that thermostat. I knew I should’ve gone with the original OEM part for something this critical. At least the thermostat didn’t fail stay closed and overheat the engine. It's leaking exactly where the OEM was leaking from

 

Perhaps you should consider the aluminium aftermarket version along with the water outlet and heater pipe.

 

I buy a lot of stuff from Rock Auto, but I agree with you on the thermostat & some other parts that I'll only go with genuine JLR or the supplier to them if available.
Which brand was this? Rock Auto isn't the brand, just the sales outlet.
I think I've tried a Gates or Uro from Rock Auto, it didn't last long which is why I stick with JLR for almost all cooling parts.

 

JaguarXJL15, consider NBCat's suggestion and get an aluminum replacement thermostat for $74 off eBay and never have to mess with that part again. I replaced all the pipes and parts that are offered in the aluminum aftermarket. The peace of mind is worth it not having to worry about when those parts will fracture.

 

I would discourage the aluminum thermostat, I had one fail in less than a few thousand miles of usage and have seen other folks state the same. Stick with Genuine JLR for the thermostat, it should last you at least another decade, and you can buy it from FCP Euro who has a lifetime replacement guarantee.

 

What part failed? Was it the housing or the thermostat itself? If it was the thermostat, maybe the original thermostat can be moved from the old housing to the aluminum housing to have the best of both worlds.

 

I have the same question. The idea was to get away from the failing plastic housing. Good thought lotusespritse. I took care to replace sensors with JLR OEM in the other aluminum parts just because I didn't trust the aftermarket sensors. Could be the same case here with the thermostat.

 

Yeah, I don’t trust those aftermarket aluminum thermostats or aftermarket thermostats in general. I went against my better judgment and bought an aftermarket one. A small leak isn’t really a big problem. What would be a big problem is the thermostat failing to open and overheating the engine.

Is there an easy way to drain most of the coolant? I’d rather not mess with the radiator drain plug. I don’t want to lose a bunch of coolant just to replace the thermostat.

 

There is more to it than just a simple issue of being "plastic" (the genuine article isn't just "plastic", it's a specific composite) and metal (various alloys & anti-corrosion chemicals for the specific system & conditions).
But the main selling feature is that it's "metal" or aluminum. And although some vendors have been identified, I haven't seen anything clear on who makes them which can help with feeling comfortable about production control, quality control & the like.
I prefer to stick with the genuine article for now too, more because of the unknowns.
The aluminum aftermarket parts may be better or worse; I suppose time will tell.
And I am certainly grateful to those that are testing out these alternatives & sharing their experiences with them.

 

So, with all of us having similar concerns, can anyone advise what I should be watching for now that I have installed the aftermarket aluminum thermostat? Were the experienced aftermarket failures a stuck open or stuck closed thermostat or a leak related to the housing?

 

Smart move..

I have been very leery of aftermarket junk after 40 years in British cars,,,,

 

Interesting JoshMcMadMac. What failed and do you have any pictures? You are the first and only report of this and I would like to see what happened?
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It failed open, nothing to photograph. I have definitely seen others post the same problem with theses aftermarket thermostats, both on forums and Facebook groups.

 

Radiator drain plug is the easiest way to drain the coolant. Unfortunately it's a plastic part that usually breaks when you pull it out, I got lucky and the plug was still in good condition. I replaced it anyway with a Dorman part.

It's anecdotal evidence, but I've put 40K on the aftermarket aluminum thermostat with no issues. It replaced a URO Parts brand plastic thermostat housing that the previous owner installed, and was leaking. URO Parts have been poor in many categories for me.

 

So if it fails open the car does not over heat? But runs too cool?
Thanks for mentioning that radiator drain plug too! I found that when I mangled my OEM one.




Agree about URO parts too. But sometimes that is all I can find.
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Ironically, I am about to replace my slowly leaking OEM thermostat housing in my 2015 XJL V6 with 110K miles on the Odo. I am going with the aftermarket aluminium part purchased through Amazon for $60. Time will tell how well it will behave, but I am pretty sure it won't crack or leak. I reckon that even parts made in China and sold through US auto parts suppliers should have a level of quality ensuring their continued success in the market. If all were so bad, these manufacturers would not have a chance to stay in the market for too long. Amazon has been great about support for parts outside of their 30-day return window. Just as with anything these days, we will hear from one person whose part failed, yet we won't know about 99 owners who had success with these aluminium parts. Anyway, the price differential was only $40 more for OEM from a Jaguar dealership vs. the aluminium part I bought, but I just don't trust those OEM composite parts anymore, so will give the aluminium thermostat a try. I will report back.

 

[QUOTE=clubairth1;2893175]So if it fails open the car does not over heat? But runs too cool?
Thanks for mentioning that radiator drain plug too! I found that when I mangled my OEM one.




Agree about URO parts too. But sometimes that is all I can find.
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Thanks for the pictures. Do you have a picture showing where the radiator drain plug is located? Is it easy to access?

 

Here’s bad experience I had with aftermarket aluminum parts the gaskets turned into mush after just a few drives. I removed it and installed an OEM part instead.

 

That … looks like someone played FAFO games with RTV. The aluminum coolant pipes are a worthwhile upgrade, but definitely pair them with stock/factory O-rings.

 

It's not hard to find. Get under the car and look for it.