Thermostat Replacement and then some.

Waterndirt

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My 60K mile 2015 sprung a small coolant leak last week and after investigating I found the thermostat body was weeping coolant. I began looking into parts and after a few hours I thought, if I'm going to do this right by landroverforum.org standards, I'm going all in for a thermostat, front / rear coolant pipes, water pump, etc. After another few hours of tracking down all the necessary part numbers, I thought to myself, I don't have time for this repair, mainly because I don't want to pull the supercharger, so I brought it in to a local reputable independent LR shop for the work. They pressure tested and had the same results, leaking thermostat.

A day later and $2300 gone for the service I drove her home with no problems. She sat overnight and when I went to start it this morning, it had a rough go for a few seconds, felt like the engine was mis-firing, after a few seconds it all evened out and it ran as usual. As I was backing out of the garage I noticed a plume of white water vapor filling my garage. Ugh. I promptly called the shop. After going back and forth with symptoms and its current condition, there was no loss of coolant and the engine temperature still cold, we agreed that I'd start it back up up and see what happens. The symptoms had ceased so I brought it back to the shop, they ran codes, found logged mis-fires on cyl 5 and 6. At that point we went back and forth on possible causes, with a glaring faulty head gasket being the most likely. Their first cautious diagnosis was that while sitting idle overnight, excessive pressure due to an air-pocket in the cooling system found its way into the cylinder through some sort of anomaly in the head / block / gasket. Next on the list is for them to bring the engine up to temp and then let it sit overnight at their shop. They'll connect it up and start it in the morning, cold, and see what they find.

I'll take your guesses now...
 

ryanjl

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Intake manifold gasket got torn or is otherwise not installed correctly.
 

greiswig

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"...while sitting idle overnight, excessive pressure due to an air-pocket in the cooling system found its way into the cylinder through some sort of anomaly in the head / block / gasket."

Not buying that one. If anything, an air pocket in the cooling system will absorb excess pressure, not cause it. And if there were an anomaly in the engine that could cause it to weep into the cylinder, that would have revealed itself before this last repair, wouldn't it?

Wouldn't hurt to check the pressure release cap for proper function, though. But it sounds to me like they messed up the manifold gasket.
 
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jlglr4

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Was the plume of white vapor coming from the tailpipes or the engine bay? I assume tailpipes since you suspect a head gasket, but just wanted to be sure. And the shop replaced the crossovers, water pump, etc. in addition to the thermostat - correct?

I think the cylinder numbering is odd and even for the two banks. That makes Cyl 5 and 6 opposite one another on different banks, not adjacent. If that’s correct, seems odd you’d get a misfire on the two rear cylinders in different banks with a head gasket problem, right?

Intake manifold gasket could easily cause the misfires, but not sure why the white exhaust.

I’m trying to think through the procedure in my head - what things could go wrong. I remember someone on here ended up with the supercharger bypass valve getting stuck open - sucked a bunch of oil through the intake as I recall. And it didn’t show up immediately. I think it might have been @Fuji4. Maybe someone else has a better recollection. Could that white plume of vapor actually have been oil smoke by chance?

The other thing that I remember thinking when I pulled the supercharger is that the charge air cooler looked a bit delicate. I took care to set it aside well out of the way so no one would kick it, but it looked to me like it could easily get punctured. If I remember the way everything sets in there, a small leak in the charge air cooler might cause some coolant to be accumulated in the intake overnight, with a misfire and some vapor in the morning. But, again, I’d expect it one side or the other, not both.

Another thought - the throttle body gasket. We have heated throttle bodies with coolant running around it in a jacket. The throttle body gasket seals the jacket against the intake and is supposed to be replaced if they took the throttle body off. I’ve heard of them leaking - not necessarily causing this symptom - but seems like it could if it leaks into the intake.

Really hoping it’s something minor. Seems like it should be.
 

Waterndirt

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I appreciate all your responses and will forward them onto the shop.

You all are a lot further along with your knowledge of the 3.0 than I am as I've never had one apart myself. Looking at the plenum and intake manifold gaskets I don't see water passages? Am I missing something there?

The other thing that I remember thinking when I pulled the supercharger is that the charge air cooler looked a bit delicate. I took care to set it aside well out of the way so no one would kick it, but it looked to me like it could easily get punctured. If I remember the way everything sets in there, a small leak in the charge air cooler might cause some coolant to be accumulated in the intake overnight, with a misfire and some vapor in the morning. But, again, I’d expect it one side or the other, not both.

The intake cover has a pair of inlet / outlets on each front side and coolant circulates through a closed exchange cooler on each side, right? Is that what you're referencing too? As a side note, when I took off my black plastic engine cover I noticed my intake cover was dirtier than I recalled with some odd green marks on the left side. They had another LR4 in the shop for the same type of work at the time. hmmm. Wondering if they accidentally swapped in another intake cover. Just thinking out loud here...

Was the plume of white vapor coming from the tailpipes or the engine bay? I assume tailpipes since you suspect a head gasket, but just wanted to be sure. And the shop replaced the crossovers, water pump, etc. in addition to the thermostat - correct?

The plumes were white, wispy and evaporated steadily with a sweet smell of coolant and coming from the tailpipes. Correct, along with some other misc hoses and parts. I attached the itemized list.

I will pull codes this weekend and double check misfires, assume IIDt will tell me which cylinder?

The shop gets it back on Monday morning first thing.
 

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jlglr4

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Yes - the exchange coolers inside the SC cover are what I was referring too. Delicate fins/tubing - like a radiator. I believe a leak there would drip straight into the cylinder intakes.

I notice they didn’t have the throttle body gasket on the parts list. Possible they didn’t remove the throttle body - just pulled the whole thing out as one piece (which is what I did), but if they did remove it and just reused the old gasket, it could be leaking inside the throttle body. If you’re so inclined, you might just pull the plastic intake plenum off and take a peak inside the throttle body after the car has set a while and see if there’s any coolant.

Other than those two spots, I can’t think of anyplace the coolant could get into the engine aside from the heads. But it just seems a little bit too much of a coincidence that a head gasket starts leaking right after they didi this work. And, really, I haven’t heard of many head gasket leaks on these engines outside of the overheating situation.
 

txfromwi

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A bit off topic, but I have an incredibly tiny, slow, slow, slow coolant leak in the 2013, 85K miles. Rather than just jump in whole hog and just do the entire project, I would like to UV test the coolant system first.

ANY UV dye, or, being Rover, do we need something "special"?

Thanks...
 

jlglr4

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You need the stuff that is dexcool/OAT compatible, assuming you’re still using that kind of coolant. I think AC delco makes some, but there are others too.

If you do this, let us know how it works. I made a half-ass attempt to use a UV dye once and didn’t find it easy to do - lots of things seem to fluoresce in the engine compartment and I wasn’t able to find a tiny leak (different car - maybe a crappy UV light or something). One tip - put a drop of the dyed coolant on something and shine your UV light to see what it looks like (both wet and dry), which might help you distinguish the coolant from everything else that seems to fluoresce.
 

txfromwi

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I will report back, but as the leak is something like 15mL over a month, it might take a while to diagnose...
I can smell it, but it's clearly a very small leak.
I will pressure test it tomorrow...

I use OEM Rover coolant, LRN2279 from AB.
 
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txfromwi

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UV penlight and Yellow safety glasses in hand ($15 on Amazon), I find that the Rover LRN2279 coolant already has UV dye in it.

Unlike others, I find nothing UV active except for a zippy tie that I installed myself on an earlier project - and the leak of course....

I find sticky thick red-brown UV active material, that seems to smell of cooked coolant on the flat surface directly below the water pump, (as per the attached photo I shamelessly copy from another forum) so it's either the pump itself or the gaskets.

Additionally, I see a pressure drop from 13 psi to 12 psi in less than 5 minutes.

So it's a grand case of "you might as well" in the near future.



Capture.JPG
 

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