Please HELP! Sudden coolant loss after hard acceleration
 

I mentioned this is another thread where I was griping about the car, but I'm hoping someone can offer some specific advice about this issue and save me a thousand or two thousand dollars.

I floored the car to pass someone, which revved the engine up to about 6000 RPMs. As that happened I noticed the air coming through the vents immediately got warm and humid, and I could kinda smell the coolant. As I was slowing down I thought all would go back to normal, but the air stayed warm. I turned the air conditioning down a few degrees and things started to cool off.

About this same time I got a low coolant indication on the dash. I already had the Torque app running, so I glanced down at it. The temp was normal. I was a few miles from home so I kept driving.

As I was getting closer to home the coolant temp started to rise. As I pulled into the garage it was indicating 224 Fahrenheit. I immediately killed the engine. The radiator fan continued to run for a couple of minutes, which has never happened before.

When I got out of the car, coolant was slowly draining out, spreading out across the floor. It wasn't a fast leak. I drove 8 miles or so from the time the leak started until the time I got home, and the temps stayed in the normal range until the very end.

Here's a diagram of the cooling system. The pump is circled in red and the heater core is highlighted in yellow. The heater core is the very first thing in line after the pump. That means all of the pressure is concentrated right there where the coolant enters the heater core.

https://cimg6.ibsrv.net/gimg/www.jag...f80e463623.jpg

Clearly something burst. If it happened anywhere downstream of the heater core I wouldn't have felt the rush of warm, moist air right after the burst. Or maybe I would have. Any of you who have ever changed the cabin air filter know that it's totally open and exposed to the engine bay. I suppose a coolant leak in the engine bay could suck in that warm, moist air.

But It kinda makes sense that the heater core would take the brunt of the pressure if the engine is spinning at 6000 RPMs and the water pump is spinning at some multiple of that due to the effect of the pulleys.

By the way... #5 in the diagram about is the throttle. Some of the warm coolant goes to the throttle, but that's probably just a thin line used to keep the throttle from icing up.

I'm thinking either: 1) the heater core couldn't handle the pressure and it popped. or 2) the hose going to the heater core couldn't handle the pressure and it popped, or 3) the hose coming off of the heater core popped.

Thoughts?

For those of you wondering what all of the numbers mean in the diagram above, here's the breakdown:

https://cimg2.ibsrv.net/gimg/www.jag...09adbe69d2.jpg
https://cimg6.ibsrv.net/gimg/www.jag...b62c7fd031.jpg

I doubt the heater core is the issue. If it were then you would see coolant deposited on the passenger side carpet.

At least with the normally aspirated model, it is easy to see the heater hoses in the engine compartment so you can validate that theory about a loose or failed heater hose.

I would say it is more likely that another hose, like the engine valley hose which connects from the rear of the coolant pump to the throttle body, has failed. That is not easy to see unless you remove the intake manifold, however if it leaking then coolant would flow to the rear of the engine and exit over the transmission bell housing.

My suggestion is that you refill the coolant reservoir, remove the black plastic cover over the engine to improve your view, start the engine and look around to narrow down where the coolant leak is occurring. Good luck.

Hook up some static pressure from a compressor or something to pressurize the cooling system, then wear a pair of those UV glasses & a black-light so you can see stuff better.

I just went through a low coolant warning issue too on my XK MY14. As it turned out, two things happened. One the infamous water pump failed, coolant leaking out of the seals in the front. Also at the same time according to the service rep, the outlet pipe where the coolant comes off the engine also developed a leak on one of the plastic nipples that the hose clamps to. The water pump was repaired under warranty, but the outlet pipe which sits underneath the engine cover and the manifold near the rear of the engine was not covered and had to be replaced. This little cutie, has 5 hours of labor involved just to get to the pipe and then reinstall the new piece. the heat from the engine gets the plastic hard and brittle over time and they just break. on the older XK8s this piece I believe was made of metal. Cost will be about $1100.00 at the dealer. The dealer can run the pressure diagnostic and let you know. Sorry! Jaguar should have put a recall on the waterpumps and swapped out these plastic pieces that seem to be so troublesome.

Isn't the heater pump electrically powered, in which case revving the engine wouldn't cause the water pressure in the heater circuit to increase?

Guessing and speculation aren't going to get you closer to the sourse. I'd follow what Patrick and/or Cee Jay offered to trouble shoot. Though it does seem reasonable that it could be the valley tube you just won't know without some investigation. I wish these plastic parts were more bullet proof but they are not and we have what we have with little hope to avoid inevitable failures.
I hope this works out ok for you but keep us informed what you find.

MY suspicion is something popped out front and sprayed hot coolant on the condenser causing it to lose efficiency.

If it's leaking it shouldn't be too hard to fill it up with water and see where it leaks out. There's a ton of coolant lines on these critters and the system is very convoluted in how it works.

That makes a lot of sense. I hadn't considered that possibility.

Well, it's a 2010. The first year of the worst water pump design in history (exaggerating ;) ) I'd start there. The pump and it's plastic outlet tube (that must be installed perfectly when installing the pump) are likely suspects. If so, prepare to shell out ~$1500 to the dealer. Or... make your first video!

Good luck!

Try doing a pressure test to find the leak/s. Thats what i do to diagnose leaks at works and pressure test when done because with big leaks you'll never see a smaller leak that will still be there after the big leak repair. Again lots of plastic which outlet pipes are and the seems can split when old. Don't go to snappy oil change for the work :)

Just one piece of advise. Ignore that there is any connection to you flooring it and the coolant leaking.
There may be a connection- but to start there will completely obscure your view by sending you on a wild goose chase.
Start fresh like any good mechanic would.

There is a bit of psychology involved here. Every time something goes wrong the human mind wants to think 'what was I doing that caused this'.
Majority of the time its nothing you did.

Depending on where the leak is, you might want to check the engine mountings. My understanding from reading the forums is that the engine can move quite a bit under load and that could have stressed some of the pipe work. Obviously if the leak is from a fixed part on the engine like the water pump then it’s probably not a factor. I recall some postings with simple checks for mount failure so maybe do a quick search or someone experienced with the failure can chime in. If it is your water pump, I recently did the change on my 2012 XFSupercharged so search under my name and it might help if you do it yourself. I also changed out some of the older crimped style coolant ducting for the newer one piece stuff. PM me if you need any help.

I faced a similar scenario with my XK back in September -- I floored the throttle and broke the plastic connector on a coolant line. In my case it was one of the lines between the engine and heater core and was due to a combination of a broken engine mount and a heat-fatigued coolant hose. https://www.jaguarforums.com/forum/x...d-part-208225/

If you top-off your coolant with distilled water then let the car idle, you should be able to pinpoint where the leak is--this could be an easy DIY fix. In any case, it's also worth checking the condition your engine mounts as excess movement will put extra stress on the connected plumbing.