Troubleshooting coolant vacuum fill failure

[Rover Range]

If the head gaskets were leaking that bad, the engine would be billowing white smoke on start up.

 

[greiswig]

If the head gaskets were leaking that bad, the engine would be billowing white smoke on start up.

Probably, or hydrolocked on startup. When you have coolant in the cylinders burning, you'll know it. White smoke (doesn't dissipate like steam does) that smells kind of sweet. I suppose another possible escape path (less likely) that would avoid the white smoke is into the oil reservoir. There are telltale signs of that, too, which you can check for.

 

[Rendak]

@ Rendak - what is the service history of your vehicle?

In other words, How many miles do you have, are you the first owner (who owned previously), what has been done with the engine and cooling system already, how often do you change the oil, what kind of fuel is used, etc?

Those details are going to be important in figuring this out.

I can tell you that the fluids changing business is super important. I have been pretty fastidious with my oil changes (around 5,000 miles or one year between changes) and in going over the engine after my recent tear down (still a work in progress)...my OCD must have made a huge difference. I have 90,000 miles (some tough) and 15 years of wear on that engine and things inside looked great - no issues and no issues even developing. But...There are a lot of folks who don't change fluids (particularly engine oil and transmission fluid/oil) and wreck things. In fact, Land Rover said that we were supposed to change the oil every 15,000 miles with the V8 (AJ133) I have...which is completely ridiculous and insane. There are a million spots in that engine where gunk can block oil passages and whatnot which will destroy the engine and can easily cause problems with the heads which could cause symptoms like yours.

So to put it simply - if you are at a fairly low mileage (less than 150,000 miles) and have been good to the engine, then I would guess that this could be tricky or strange...but totally doable. If, on the other hand, the engine has not been well maintained, then this could easily be the head gaskets or something else similar regardless of mileage which will be ugly. As I am sure you know, these aluminum engines can warp easily from heat and those heads, and potentially the block, could be way out of tolerance if warped. That situation would indeed require a new (or reman'd) engine (Yikes).

I doubt it is the expansion tank and from your description this sounds like something more complex, potentially very bad.

@Land Rover Joe thanks for the detailed set of questions / comments. I'm the 3rd owner (first two being a father and a son) and the LR4 has 86k miles on it. Oil changed about every 8k miles (higher than I'd have liked) at a local indy JLR shop, and since I bought the vehicle in January of this year, I'm running Liqui Moly OW20 I think (or whatever is recommended in the manual that's in the glovebox). Always premium fuel -- I tend to use BP or Shell, given what I've heard about the quality of the additives. As for other service history, I have comprehensive records from the previous owner, and there aren't any red flags to the best of my knowledge. The previous owner had the cooling system repaired by a seemingly reputable shop (I've posted about this prior cooling system work here: https://www.landroverworld.org/threads/2015-lr4-coolant-leak.45846/)

That said, I suspect the engine’s been running hot for a while. I found out by chance—plugged in my GAP tool just to see what was going on. Temps would regularly hit 220°F and briefly spike above 230°F, but the dash gauge never moved past center. As I've learned, this is an infuriating design choice by JLR; only truly emergency-level temperatures will get the instrument cluster to register elevated temps.

For instance, I went on a 20 minute drive where I went no more than about 40 mph, had very little traffic, and only went up one small hill which made the RPMs go above about 2400 and the temperature peaked at 230 (going up the hill) before going down to 219 or so by the time I pulled in my driveway. However, if I turn the heater to max, it blows strong, hot air and the coolant temp would never get over about 215 or so.

Between that observation and watching the “engine coolant temperature 2” metric on my GAP tool (which I believe is measured just below the thermostat housing) stay under 100 degrees F when engine coolant temperature 1 was reading 220+, I narrowed down the list of problems to water pump underperformance, trapped air somewhere around the radiator inlet, or the thermostat not opening at all / or fully.

Again, all of this is happening without a single trouble code. Anyways, my theory is that the head gasket was fragile after all the heat cycles, and perhaps a higher pressure with a truly sealed system + the adventure I had on the highway made the head gasket the weakest link.

 

[Rendak]

I decided against getting the new expansion tank. Talked to an experienced mechanic at my local indy JLR shop and he recommended that I do 2 things:
1. Drain the oil and see if coolant comes out with it
2. Pull the spark plugs and use a borescope to look for coolant in the combustion chamber of each cylinder.

I'm gonna do those things and report back. If I find coolant in either place, I think it's basically cooked. The mechanic said he sometimes buys Land Rovers that need new engines, so I'm ready to sell for $5k or $6k and just be done with it if need be. However, if I don't find coolant in either place, I'm getting the car towed to the shop and will see what they say -- at this point, even a $5k repair would be infinitely better than selling at a $12k loss.