Help! Coolant Leaks But Only Sometimes and is fast when it does!
 

Hi Everyone,

I tried looking everywhere on the site before starting a new thread.

I recently purchased a 2004 XJR with only 77k miles on it. I have put 2500 of those miles on it in the last 2 months since I purchased it.

I was driving and the coolant low sign came on so I put 3/4 of a gallon of antifreeze in it. Car ran great couldn't find any leaks, I drove it another tank and had no problems. Then last week I took it to the store a mile away from a cold start, came back 15minutes later to see a lot of coolant coming out of the bottom grill valance (Downward slope parking space). I drove it home and checked and couldn't find the leak. I have now gone another 300+ miles with no problem. Today, I drove it city driving for about 30 minutes (including 10 minutes of idleing in a parking spot. I get out and notice a ton of water coming out under the car(I previously removed the skid plates to find the problem and was parking on an upward slope) I was dressed in professional clothes about to meet a client so I couldn't get under the car. The low coolant light comes on and I drive home to try and find the leak. Again it will not leak and it never started to overheat. I slowly opened the coolant reservoir (Which is new the old owner put it in about a year ago) and all of a sudden the tank is filling up with water well over the full section. I then put the cap back on and start the car. I noticed that air bubbles were coming into the reservoir from the starboard side of the tank. Any idea what this can be? when it leaks it leaks a lot and it's bad but it almost never happens and I cant make it happen on demand so I'm afraid of what I would be charged if I brought it in to a shop. I also noticed this weird coloring in these pictures that I have not noticed before.

Thanks in advance everyone!
https://cimg0.ibsrv.net/gimg/www.jag...cf68d507f0.jpg
What is the orange / multi color stuff could it be related?
https://cimg1.ibsrv.net/gimg/www.jag...9ff9fe2901.jpg
Can this stain be related?
https://cimg2.ibsrv.net/gimg/www.jag...7ebab0be9a.jpg
https://cimg1.ibsrv.net/gimg/www.jag...ae71c4eaac.jpg
where these hoses are is the area I saw the main leak from today. These look like possibly power steering hoses and I couldn't find a leak. Also are these supposed to be taped up?

Orange stains look to be coolant, is that on the bottom of the overflow tank?
Over flow tank hose connection in good shape?
An air bubble can cause issues if not bled out properly.

I just came out to check again and the coolant tank is almost empty and this hose looks almost collapsed It is weird that their are not any obvious signs until it just floods outhttps://cimg7.ibsrv.net/gimg/www.jag...747d02b305.jpg
Came out right now after the car cooled and this hose is almost collapsed.
https://cimg0.ibsrv.net/gimg/www.jag...80ada2da1c.jpg
Supercharger pulley has coolant stains too

Upper radiator hose should be flush to the radiator. Looks too far out to me. Your sucking in some serious air somewhere or you have combustion leaking into coolant system for that hose to look collapsed.

Would that be a head gasket issue? I don't see any water in the oil. Also it runs great until it has this problem then runs great again for a while until it does it again. luckily we have the low coolant warning on the dash when it happens.

I spoke to a foreign auto repair shop and they said it could be the water pump, does that sound accurate? I don't know how so much coolant could leak from the water pump sporadically

Water pumps are an easy fix, both types on mine, have been replaced.

Do you think it could be the water pump?

When I come across intermittent cooling problem like you have described I usually suspect a sticking thermostat. I am addressing a similar issue on my son’s motorcycle right now. Then I will change the water pump. (Not because it is bad but because it will probably go next with my luck,) It is too bad we don’t get real temp gauges anymore to see what is happening with the cooling system as you may be overheating more than you know.

If you get to the point of eliminating exhaust gases escaping into the cooling system; your symptoms could be explained by loss of cooling system pressure.

The cooling system pressure cap raises the boiling temp of the coolant. When you removed the pressure cap and observed coolant back filling into the tank you are likely seeing your coolant boil down in the engine where temps are higher. The water vapor from the boil pushes coolant away from the vapor bubble.

If you then cap the tank, the pressure will drop as the coolant cools, causing hoses to collapse. ( does anyone know if there is a pressure relief valve that allows air to flow one-way into the cooling system?)

A water pump issue, or other flow restriction (thermostat, etc) could be causing the coolant to get heated above the desired, regulated, temp.

Best Regards, William

Hi scotster9822,

It's late here and I have to get to bed, but the first thing that occurs to me is that perhaps your leak is in a section of plumbing that is not always connected to water pump pressure. I think coolant always flows through the heater core when the thermostat is open, but is there some other component or section of the system through which coolant only flows some of the time? Maybe the diagram from the Technical Introduction manual will give you and other members some ideas:

https://cimg7.ibsrv.net/gimg/www.jag...eca44c6ab0.jpg

Cheers,

Don

I read through this thread with great anticipation until the end, where the issue was not resolved. Oh well, I have the same exact thing happening as of yesterday. Intermittent leak...sometimes none, sometimes enough to make me nervous. Coming from the bottom of the expansion tan or one of the hoses I presume. Upper radiator hose is collapsed in after cool down.




Thermostat and housing are new as of 1.5 years ago. Just replaced the water pump last month. The 04 XJ8 is due for a radiator and new hoses, so will probably just replace them all.

Consider replacing the expansion tank cap as your collapsed hose is a tell tale sign of a failed or intermitient failing cap.

Thanks for the tip, that is what I, too, came to the conclusion of with the collapsed hose. I suppose I will replace the entire expansion tank too, as I suspect it is leaking from the seam when hot. Unfortunately I replaced the expansion tank nipple with a metal one not too long ago, but it seems the rest of the tank will not hold up.

Being that you only recently purchased the 2004 Jaguar XJR, the first thing that ran in my mind was that the head gaskets may have been compromised. If that was the case, then it was likely due to the former owner driving the car with an overheated engine (which might explain why he decided to part with it). Unfortunately, that type of intermittent coolant leak is difficult to spot. If the leak was due to a water pump, I would imagine that it would be leaking consistently. This is just my two cents for what it's worth.

Replace expansion tank cap and see how you go from there.

+1 exactly

And my :icon_twocents::

Meantime, while you are at it, to eliminate a head-gasket problem, go ahead and do a compression test.

Compression test will let you know where you are with your head gasket.

As 67ECoupe said in the previous post.

Here is an update on my Jaguar.

I went to pressure test the old girl and when I went to pull off the small hose on the expansion tank, the metal bung I had put in there 1.5 years ago came out, too. Seeing that I needed a new cap and suspecting the temp sensor was on its way out, I opted to purchase a new tank. Surprisingly, the local Jag dealer had one on the shelf, so I purchased it 30 minutes before closure on Friday.

The new cap seems to have cured the upper hose collapsing on cool down, but did not remedy the main leak. After pressure testing the system I found the upper radiator hose heater line had a pin hole leak. I am guessing it only leaked when the pressure built up the most when the car was fully warmed up...but it didn’t do it all the time, which is what baffled me. I assume it was a small enough hole that it didn’t open all the time.

Seeing it was a weekend and I needed the car back on the road by Monday, I made a quick trip to the auto parts store to purchase 3/4” heater hose. They didn’t have the corrent bends I needed, so I just purchased inexpensive unmolded hose. I cut the factory steel bands off the old heater hose with a dremel, and replaced the leaking line with the new hose and clamped it on with hose clamps. I also had to replace the O ring inside the lower spring clip fitting. I refitted it and it worked! The hose is not as straight of a flow as I’d like, but not kinked enough to block off flow. Seeing it goes to the heater core, I am not too worried about it until I properly fix it. I still have hot heat after the fix. Just thought I’d post to give others with similar issues a clue as to what it might be, and an alternative fix if parts aren’t readily available.

https://cimg1.ibsrv.net/gimg/www.jag...544fe4ace.jpeg

Looks like a success to me, nice work.