Hi, i have problem that i always get low coolant warning after some time of driving. When i open the expansion tank cap some water burst to ground in the right side if the car. So I think that for some reason coolant doesn't return from recovery tank and instead burst out. Anyone had similar problems?

I have also problem that obd2-app (torque) gives me very high coolant temperatures 205 fahrenheits when idling. I think that's bit too much. Car's own temperature gauge isn't showing any overheating, stays in center. Should I replace thermostat also? I think I should not drive the car in this condition..

 

The system is under pressure, and coolant will normally burst out of the tank when it is opened hot. If it is bursting out on the side opposite of the car from from where the tank is located, you have a leak somewhere. A pressure test kit can be used to locate a leak if your fluid level keeps dropping.

205 F while idling is normal. It should cool a few degrees when cruising. The fans should come on preventing it from getting much higher than 205 when idling.

The temperature gauge displays center scale from 185 F to about 235 F, so it is a poor indicator of true cooling system operation. There is a mod my company makes called RealGauge that remedies this problem. See XK8 / XKR / XJ RealGauge - TheJagWrangler

 

The atmosphere recovery tank is located behind the wheel on the right side. When you loosened the reservoir cap the above suddenly boiling coolant escaped to that tank and overflowed it.

I am also getting above 200*F readings on Torque and an IR thermostat when the 184*F thermostat should be managing the temperature lower. My V8 Volvo with a 180* thermostat reads 183 - 186*F on the head to thermostat metal and never gets above 190*F.

I have yet to come to an understanding of why this car should run at 205+*F with a 180* functioning thermostat installed.

 

I don't think this is necessarily mysterious. Even with the thermostat fully open, the coolant might have to reach a temp higher than, say, 180 in order to dump all of the heat the engine is making. The equilibrium coolant temperature would depend on all the parameters of the cooling system, the amount of heat the engine is making, and the ambient temperature.

Two different marques, both with 180 degree thermostats, same operating conditions, could have different equilibrium coolant temperatures.

If this equilibrium temp exceeds the boiling point (taking into account the pressure rating of the radiator cap) on a not-to-hot day, it is probably a 60s vintage British roadster.

 

Coolant burst out even tought I open the cap when engine is cool. I just checked and that tank is completely full. How much there should normally be fluid when engine is cold? I am starting to think problem is that coolant isn't flowing back from that tank. But why?

 

There have been some posts in the past where the pressure cap malfunctioned and coolant was not returned when the engine cooled. Replace the cap with a new one, they are not very expensive, and it's worth a try.

 

Agreed. Replace your cap as a first step. I had to replace the factory cap on my wife's car several months ago. Problem solved....

 

Building up excessive pressure ........ I'd also be thinking sticking thermostat.

Graham

 

Yep, sounds like the lower cap gasket: https://www.jaguarforums.com/forum/xk8-xkr-x100-17/what-why-gushing-118185/#post980401
Good luck