Just bought a 1999 XK8 ragtop with 60K miles. After getting comfortable with it, I took it up to around 160 m/hr. Shortly after starting having the coolant problems. first noticed a white chalky substance in the coolant, and then noticed the prev owner had added green coolant on top of the orange. Later we determiined the chalk was engine sealer and suspect there had been some undisclosed trouble before they sold it. Saw a spray of white chalky near near the water pump, changed the pump, changed the thermostat housing to aluminum, new thermostat, new thermo sensor, new coolant sensor, new radiator hoses, new pressure cap... Now car runs fine, but continually looses coolant through the overflow. Checked the pressure on the cylinders, 180 on each except for the #5 has 130, figure there is a leak in the head gasket, no water in oil, as I fill the cooling system from the thermostat housing cap, it appears like circulation is good, nbo excessive bubbling, then fill the pressure tank and at idle no bubbles just mild circulation, then if I apply the throttle and watch, small bubbles enough to create a fine foam. Is this normal?? should I apply engine sealer to this problem like the prev owner must have done?? How much would a new head cost?? How much does a new block cost?? Please let me know what you think.
thanks in advance,
Passout Pete

 

No offense but you may have better luck in the XK8 section.

Just at a glance you say your losin it thru the overflow? Thats not a bad thing. Sometimes that happens. The bad is coolant in your oil or exhaust. Or if you have a leak somewhere it may need resealing. That about sums up coolant.

As long as your not overheating or seein odd temps, I dont see a major problem.

Also may be because of the coolant mix by previous owner. Not sure what that exactly does. But could be your problem. Worst case is a head gasket leak. But so far it doesnt sound like it.

 

thanks, I thought I was in the XK8 section. It wouldn't bother me so much, except after the Low Coolant light comes on repeatidly it starts to do the restricted performance thing, and then later the engine light comes on. The resevoir becomes low, and then the sensor actually burnt, I guess from triggering repeatidly. I will check the sealing again, and research mixing green and orage coolants.
thanks again,
Pete

 

Well if your losing that much coolant its goin somewhere. I thought you meant its just spillin some out of the overflow. If its going below the cold level theres a problem. Check all the coolant passages first. Line hoses, water pump, thermostat housing, bleeder if it has one, anything to do with keeping the coolant from escaping. If you find NOTHING then check your oil. You say there was no milky substance in the oil correct?

Thats a tough one. It has to go somewhere. Obviously.

Check it out more.

 

I really appreciate your help, looks like it is OK now. We sealed the motor with liquid glass, stopped the leak, then cleaned the sensor and everything seems fine. Time will tell.
thanks again.
Pete