2016 LR4 Coolant Crossover, Water Pump, Thermostat Replacement

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jlglr4

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Just reading back through, it looks like you have not yet replaced the crossover. In my mind, it is much more likely that your crossover is leaking than your newly replaced water pump. That might have been the problem from the beginning. If you stick a borescope down into the valley (just past the oil filter), you might see coolant down in there, which would indicate either the crossover or possibly the oil cooler pipe. There’s also a soft rubber coolant tube that runs from the coolant-heated throttle body under the intake manifold to the rear crossover, but I haven’t heard of that one leaking before.

The other leak that’s been reported at times is the thermostat housing, so maybe check that as well.

The pattern of drips looks like a front coolant leak, but with the skid plate attached, can’t be sure. It might just be pooling up and dripping out the front holes on the skid plate. Still, front engine area seems most likely.

Just my $.02, but I would stop driving this vehicle if I were you. You’ve probably read the horror stories on here about people running out of coolant and overheating. Almost every one of them says the temp gauge did not budge from center. I think the temp gauge just doesn’t work once there is a sizable leak - not sure why, maybe an air bubble gets in the area of the temp sensor or something. A liter of coolant inside of 20 minutes is a pretty sizable leak.
 

superty

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Hi Guys, I'm preparing for this in two weekend time. What's the consensus on replacing the intake gaskets that sit between the supercharger assembly and the engine?

Similarly I've read nothing about replacing the gaskets at the top of the assembly above/around the intercooler? Are these reusable or are replacements necessary, or should I be using liquid gasket?

While I'm in there the supercharger is getting a rebuild, with new bearings and coupler and a smaller upper pulley. Just bought an hydraulic press to do this rebuild... Pretty excited!
 

jlglr4

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You should replace the gaskets between the supercharger and the engine. You do not need to replace the gasket between the intercooler and the supercharger. That’s per the manual.

I haven’t heard of the supercharger bearings being a problem, but more power to you.
 

Arman

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Absolutely heck NO to liquid gaskets, this is not an oil pan in American or Japanese car...

Be careful with supercharger rebuild... there are special tools (a bunch of carefully machined spacers and rods) required to get spacing of bearings right, and to remove and insert everything without damage. There is someone selling these rebuild kits (and provides rebuild service) on ebay. I wouldn't recommend messing with it on your own if you don't have much experience with hydraulic press... If SC is below 100k it's unlikely for bearings to go bad, but YMMV
 

theegovernor

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I am in the middle of this job. For those of you who upgrade your intercooler pump I have the info to create your own harness instead of splicing in. I will also share some info for doing the valve cover gaskets.

Mercedes parts
230-540-00-81 Coupling x1
008-545-63-26 Plug x2
000-545-68-80 Rubber Ring x2

Bosch plug
 

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Copemech

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Been following this thread since my wife bought a 2015 RRS HSE. She came home from a short trip and mentioned the low coolant light. After a check it was leaking down the front like most of them with the crossover pipe issue. Removing the supercharger to get at it wasn't too difficult. I didn't remove it all the way as I was able to prop it up and replace the Y-pipe, gaskets, and then the oil cooler tube and o-rings on that. After putting everything back together I took the coolant cap off to fill for bleed and there was coolant flowing out like crazy. Same leak pattern as before. Assumption is at this point it is either the o-ring on the oil cooler pipe or the rear coolant pipe. Any chance I could have broken that rear coolant pipe when moving the supercharger around? How common is that failure point?

I wouldn't be surprised if it was the o-ring since getting they water pump back on was a major pain. Any suggestions are appreciated before I rip it all back apart again.
 
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jlglr4

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By the “rear coolant pipe” I assume you mean the rear crossover (heater manifold) at the back of the engine. I don’t know how likely it is you could have damaged the rear crossover, but there are heater tubes attached to the crossover, and a bunch of stuff tied to the bracket at the back. If you propped it up without undoing that bracket, I guess something could have broken. But that doesn’t seem to be your present leak if its coming from the front.

Still, if it were me, I’d pull the sc all the way off, check the connections, and replace the rear crossover. It’s plastic and if your front is going, good chance the back will eventually go as well. It also allows you better access to change the gaskets between the super charger and the intakes. With only propping it up, I’m guessing you were not able to change them, but maybe I’m mistaken. If you don’t change the gaskets, you can end up with a vacuum leak or a boost leak (or both).

Taking the SC all the way off also makes installing the water pump much easier and lets you examine the orientation of the oil cooler pipe to make sure its straight. Even if you’re not replacing the water pump, you should replace both o-rings on the oil cooler pipe.

Some people have had some trouble getting the Y-pipe of the front crossover all the way into the block, usually due to a piece of the old pipe still sitting down in the hole. Pulling the SC all the way off will also give you better access to check the seating of the pipe in the block.
 

Copemech

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Wow! Thanks for the quick reply even with my typo riddled first post. Thank you. Yes I did prop up the supercharger but I managed to move it up enough to get new gaskets and guide pins in and was mindful of those knock sensors you mentioned.

I was having difficulty getting the rear bracket off as I seem to be cursed with sausages for fingers. I have the L494 manual but it is of little use for that diagram. Any tips on getting that bracket and things attached to the rear of the SC off?

Ordered the rear crossover once I realized I would probably have to take everything off again anyways. At least it was easy enough to do aside from getting the stuff of the rear.
 

Arman

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Wow! Thanks for the quick reply even with my typo riddled first post. Thank you. Yes I did prop up the supercharger but I managed to move it up enough to get new gaskets and guide pins in and was mindful of those knock sensors you mentioned.

I was having difficulty getting the rear bracket off as I seem to be cursed with sausages for fingers. I have the L494 manual but it is of little use for that diagram. Any tips on getting that bracket and things attached to the rear of the SC off?

Ordered the rear crossover once I realized I would probably have to take everything off again anyways. At least it was easy enough to do aside from getting the stuff of the rear.
I didn't remove the bracket from the SC, but instead removed everything from that bracket (primarily plastic tree connectors to guide wires). I then had to (carefully!) maneuver SC to get it out since the bracket is in the way hitting hood/firewall. I don't thing I'd be able to do this without an engine hoist.
But it's all been described before, please read this thread fully before starting the job, a lot of helpful info here
 

Copemech

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Removing/manuvering the SC wasn't too difficult really, at least it's easier to work on vs my old ford diesel. I was able to get the pieces of the backet removed and the connections on the back (at least all I thought were there). I actually purchased the harbor freight engine suppor bar but didn't need it. Plan is to remove everything again and go back at it piece by piece until I find the new leak as well as just replace the rear coolant manifold while I'm in there.

I'd be curious if anyone has used a vacuum bleeder/filler instead of just running with the manual bleed process.
 

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