XK8 / XKR ( X100 ) 1996 - 2006

Expansion tank woes!

Old 05-22-2019, 09:30 AM
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Default Expansion tank woes!

Have a small expansion tank is

sue. Found these parts when adding fluid to my expansion tank!? Looks to be parts for a pressure valve or a blown up radiator cap? Should I replace the expansion tank? No overheating but all of a sudden I have a low fluid warning and Iím having to add fluid everyday .
Old 05-22-2019, 11:51 AM
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It looks like thermostat parts, but how they ended up there is the question.
Old 05-22-2019, 01:20 PM
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Default Weird thing to find in coolant expansion tank

The coolant system is pressurised maybe someone tried to seal a leaky cap by putting a spring against it...on the inside??? As I said weird.

If the system is leaking, you need to find the leak. Buy new tank too? You donít want the aluminium engine block overheating.
Old 05-22-2019, 01:45 PM
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They don't belong in the Expansion Tank.

If you are losing fluid then you need to discover the cause and fix it promptly. The cooling system is low volume/high flow rate and you definitely don't want to risk an overheat.

Old 05-22-2019, 01:55 PM
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Looks like the cap separated. I believe the original cap is spring loaded as it is supposed to maintain system pressure, to a point, and then allow bleeding of air/coolant into the expansion tank in the wheel well. It is also supposed to let fluid flow back during cool down to effectuate "self" bleeding. Best a this point is to get a new cap.With the broken cap, the fluid is probably being pushed to the expansion tank, and not coming back. You might not have a true leak.

Best of luck, keep us posted.
Old 05-23-2019, 01:04 PM
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Going to rebuild the cooling system. New hoses , water pipe, water pump, 170 thermostat, all o’rings and gaskets as well as new expansion tank. Already have aluminum thermostat housing. ( found evidence and smell of a leak near thermostat housing)
I still don’t see how this system works compared to other systems . This has I small hose going to expansion tank and another continuing on to the heating system if I’m correct. Typically you have a pressure cap that releases pressure to a expansion tank that has room for expansion as pressure builds and siphons back when cools etc...As per jaguar bulletin fill the bock then fill expansion tank to filler neck then start car and let warm up slightly . If level drops then top off and install cap. Don’t see where the expansion of hot water can occur if the tank is full to begin with? This car also never siphons back . Always have a collapsed top radiator hose after every trip?! Never overheats but summer is here with 90-110 with heavy humidity. Can’t have this overheat.
Has anybody gone to Evans waterless fluid in their jag? Seems to be a no brained here in south Texas?
Thanks again for all of your input,advise and wisdom!
Old 05-23-2019, 02:47 PM
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hi there. I experienced exactly that. I had the collapsed top hose.. It was weak and had ballooned out, but also the Water Pump was leaking and you couldn't see the source of the leak. So change the top hose before it explodes on you, and change the water pump and thermostat at the same time.
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