Another LR4 Saved from Coolant Death

[ScottK]

@jlglr4- in hindsight I definitely should have done then. I had that done at the indie. When I discussed replacing the front with the dealer they recommend or more like insisted
that they replace the water pump at the same time. I’m sure that is probably a good idea seeing that is a key component and the high mileage. Your thoughts? Anything else glaring that I should replace at 100K? Thanks.

 

[jlglr4]

Lots you can do, but it adds up when you’re paying someone to do it.

Definitely do the water pump if it hasn’t been done. I’d do the thermostat as well.

If the PCV valve diaphragm hasn’t been changed, easy and cheap to do that while the supercharger is off. Maybe have them check for oil leaks around the valve covers - especially the passenger side where the leaking oil can eventually take out the alternator.

These cars also develop a problem with the supercharger coupler. They start to rattle because the coupler gets worn. I haven’t yet seen any reports on the things coming completely apart (failing), but when you’ve got the supercharger off, its a pretty easy fix. Still...not sure what an indy will charge for it. I’d say it’s probably not essential if you don’t have too much play in the pulley wheel.

With the supercharger off, you’ll have easy access to the intake valves, which tend to get caked up on direct fuel injection cars. You could have the intake valves cleaned. Again - no idea how much extra that would cost.

If you haven’t had the belts changed, might do that as they’ll be off anyway.

I’m just trying to think of things to do while that supercharger is off and the coolant drained. Nothing else really comes to mind. The cooling fans tend to fail on these cars - makes a clicking noise independent of engine RPMs - but those are pretty easy to change independent of everything else.

Maybe others can chime in if I’ve forgotten anything (I’m sure I have).

 

[ScottK]

@jlglr4- thank you so much for taking the time to put this together. I plan on getting these things done in the next couple of weeks when I swap out my winter tires as I’ll be taking a road trip from Michigan to Alabama next month. Sorry to the rest of you...I didn’t mean to hijack this post.

 

[ryanjl]

@ScottK - if you’re rear manifold was already leaking, that’s probably a good indication that the front needs to be changed. Both are plastic pipes that suffer from the same problem. When I changed mine (preventatively, 2016 model), the front was clearly degrading faster than the rear.

I’m actually really surprised they didn’t do they front and rear together. They’ll usually pull the supercharger for both, and I would think they’d do both while they have it apart.

I talked to an indie a few months ago who's worked on what he called "countless" 5.0 engines. He said he's replaced more front crossover pipes than he can remember, but has never replaced a rear one.

I'm obviously not saying the rears never go bad, but I am saying the front ones go bad a whole lot more often.

 

[AGLR4]

I talked to an indie a few months ago who's worked on what he called "countless" 5.0 engines. He said he's replaced more front crossover pipes than he can remember, but has never replaced a rear one.

I'm obviously not saying the rears never go bad, but I am saying the front ones go bad a whole lot more often.

This is explained by fluid dynamics. The rear crossover is small in diameter, maybe 1cm or so. The front crossover is much larger in diameter, maybe 3cm or so.

LaPlace's Law relates cylinder wall tension to pressure and radius.

Pressure x Radius = Tension

Our LR4 radiator caps are rated 200 kPa. When the whole coolant system reaches that pressure the front and rear plastic crossovers are experiencing vastly different levels of stress even though the internal pressure is the same.

Example:
Rear: 200 x 0.5 = 100
Front: 200 x 1.5 = 300

The pipes are degrading at the same rate. The front is simply under 3x more tension due to its larger diameter and therefore typically gives out first.

So, basically, science supports the anecdotes that suggest the front is the one to replace early. The rear can go longer in most cases. How long? Lol, who knows, i haven't seen a formula for that...




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[ryanjl]

This is explained by fluid dynamics. The rear crossover is small in diameter, maybe 1cm or so. The front crossover is much larger in diameter, maybe 3cm or so.

LaPlace's Law relates cylinder wall tension to pressure and radius.

Pressure x Radius = Tension

Our LR4 radiator caps are rated 200 kPa. When the whole coolant system reaches that pressure the front and rear plastic crossovers are experiencing vastly different levels of stress even though the internal pressure is the same.

Example:
Rear: 200 x 0.5 = 100
Front: 200 x 1.5 = 300

The pipes are degrading at the same rate. The front is simply under 3x more tension due to its larger diameter and therefore typically gives out first.

So, basically, science supports the anecdotes that suggest the front is the one to replace early. The rear can go longer in most cases. How long? Lol, who knows, i haven't seen a formula for that...




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Hey, I understood some of those words!

Haha. j/k Thanks.

 

[16FujiDisco]

Has anyone with a warranty had theirs replaced preventatively instead of waiting for the failure? 65k miles on mine and no documentation it's been done prior.

 

[AGLR4]

Has anyone with a warranty had theirs replaced preventatively instead of waiting for the failure? 65k miles on mine and no documentation it's been done prior.

What kind of warranty do you have? In my experience a warranty rarely will cover "preventative maintenance" other than maybe a courtesy oil change. That's one reason why I prefer to pay for my own maintenance at the pace I choose rather than paying for any kind of extended warranty.

Please provide feedback if you have a warranty that covers it, as I am sure others may be interested in doing this early if you find that it is covered.

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[16FujiDisco]

I have a warranty through Carmax; they've done well at covering everything I wanted repaired so far, and its already paid for itself in less than a year and a half. It would make sense to cover known issues or very common ones instead of paying more for the pricey repairs, but I know those types of companies don't always do what makes sense.

 

[ryanjl]

My front coolant pipe was covered under my certified pre-owned warranty. I made sure to bring it in and complain every time I caught even the slightest hint of coolant smell, which meant I bought it in once or twice with them saying they could not find anything before the time I bought it in and they replaced the coolant pipe.