Coolant leak
 

Hi guys,

Have noticed a small leak coming from under header tank, appears to be coming from around electrical connection. The connector itself had a little play, as I can wiggle it a bit.

Haven't taken anything apart yet, do you think I'm looking at a new header tank or is there a "fix" that some one knows of?

Thanks for any advice

Small leaks of the expansion tank are hard to pinpoint. My '03 XK8 had one that ended up being an invisible hairline crack - ended up replacing the tank (think I paid around $165 but they sell near $235 recently). Anyway, probably should replace it. It's not hard to DIY.

Nothing will permanently seal a leak in the tank. I know, I tried. It is the tank, not the sensor. The sensor is external to the tank.

I buffed the leak area up with a wire wheel to the point of raising 'hairs' and then applied JB Weld. Held for about 8 months.

After all the expansion and contractions of daily use the tanks have a history of suddenly springing a leak in an area not compromised by seam or injury. An obvious design problem.

My 30 year old Volvo overflow tank has never sprang a leak.

Get a pressure tester on there. You can replace two or three parts before finding the culprit that might be something as simple as tightening a hose clamp.

As all pointed out: Pressurize the tank if you can borrow an adapter, and use a mirror and flashlight to look under the tank to find your leak. Most likely, you will find that hairline crack in the bottom of the plastic tank. The sensor plugs into a blind hole, so that will not likely be your problem. Also look at the nipples on the tank where the small hoses attach. The factory clamps aren't enough to keep the aging hoses from leaking after a period of time. Coolant could be running off one of these, and looking to be from the tank itself.

Thanks for response guys, checked out tank and leak is coming from side under the "seam" so have a new one ordered!

Coolant refill procedure
 

New header tank not arrived yet, just wanted to confirm refill procedure. Run motor with cap off and heater on and add coolant as necessary when at operating temperature?

Thanks in advance.

'Burping' the system by squeezing the upper radiator hose also helps by forcing air out. It's also a good time to replace the thermostat if you are so inclined. I think the '03 retained the plastic thermostat housing tower. If so, careful about removing the cap as many have been broken and/or failed to seal on re-installation.

If you run it up to operating temp with the cap off you will have coolant all over due to expansion.

The idea behind 'bleeding' the system is to remove any air that might become trapped while filling it. When filling a drained system, I always remove both the coolant tank cap and the T-stat housing screw cap. Then slowly add the coolant/water mix, allowing time for any air bubbles to rise and vent from one of the two openings. After it appears full, cap off both locations and proceed as others have noted. I think using both locations to vent makes the venting quicker and more complete.