My 2018 Range Rover 5.0L Supercharged LWB recently developed a coolant leak associated with the plastic coolant bypass valve assembly under the supercharger. My intent was to replace all of the plastic pipes with aluminum, including the rear crossover. Unfortunately I learned that this "bypass" plumbing which sits in place of the traditional "Y" pipe at the front of the block is unique to 2018/2019 5.0L models in the Range Rover series. According to the dealer it was a short-lived design, never appeared on Jaguar platforms, and was reverted back to the "Y" pipe configuration for the end of the 5.0L production run.

I'm inclined to eliminate the bypass system and revert my motor back to the original "Y" pipe setup using all aluminum plumbing because it doesn't seem like there is anything unique about the block or heads on my 2018. I've seen several forum posts where users report good results converting to the traditional plumbing setup.

Does anybody know anything about the intended purpose of the bypass valve and pipe? I've heard everything from "mitigating hot spots at the rear of the heads" to "emissions control during warm-up." I'm going to pay for access to TOPIX to see if there is anything in the literature for my 2018 that would better document this short-lived system.

Thanks

 

Many owners have reported successful conversions. Your existing setup was short lived, and your reasoning for the conversion is solid. I would let a competent indy service tech do the conversion and replace with all aluminum components in order to eliminate the plastic failure points. Just make sure the system is properly bled during this process.

 

I appreciate the feedback. During my investigation I subscribed to TOPIX and got confirmation from the JLR literature via the following statement in the "description and operation - engine cooling" section:

From TOPIX:Confirmation that this secondary thermostatic valve located under the supercharger is solely focused on reducing engine coolant warm up time.

I've already disassembled everything and removed all of the components associated with this system. Prior to ordering replacement parts I wanted to feel fairly confident that I won't hurt my engine by converting to the more traditional setup using factory aluminum pipes in the front and an aftermarket aluminum rear heater manifold crossover pipe.

I'll order everything I need to replace and report back on results when I have the car up and running. I'll use a vacuum fill system to replace the coolant. I have a lot of work to do because the prior owner replenished the leak with standard green coolant against all common sense, ignoring the clear warning label on the expansion tank next to the fill cap. I need to thoroughly flush all of the lines with distilled water. I'll likely replenish the system with Zerex G-05 which I believe offers the best combination of protection for aluminum parts as well as longevity. Plastic parts and EPDM o-rings just seem to hold up better when exposed to HOAT G-05 vs Dexcool / G30 OAT.

 

Sounds like you are on the right track and know what you are doing. Good job and best of luck.