Is this normal or should I think I have an issue?
My 99 XK8 convertible is in South Florida now where Temps average the past 2 months 92 - 96 degrees. I am loosing anti freeze, about 2 inches off of the filler neck every 10 days. I checked all hoses and no leaks. Also no white color from exhaust. Is this normal or should I be concerned?
thanks
jack
1999 XK8

 

It is not normal. Check the underside of the plastic coolant expansion tank for cracks.

The easiest/fastest way to check the cooling system for leaks is to have it pressure tested.


Stu

 

It definitely is not a normal condition. Pressure test is the best way for leaks. It might be that the radiator cap on the coolant tank has gone bad and your missing coolant is in the overflow reservoir. Do you have have any puddles near the fender on the left side?

 

Also check in the valley and behind the throttlebody. You have two hoses connecting to the throttlebody.

 

Isn't the overflow on the right side in the fender well?

 

Yes that is correct.

 

My 97 was losing about 4-5 ounces every 5 days and I could smell antifreeze but could not find any leaks/drips. Hoses and evap tank were new. Turns out; the metal tubes going to the heater at the back of the motor were leaking a little (pin holes) and the fluid was boiling off on the hot motor. Really difficult to see even with the engine running up on a rack. Good luck!

 

My 1999 XK8 convertible went through the same thing. Every week or so I had to put more coolant in, but I could not find the leak, and I could not smell antifreeze while driving either. Turns out that my crossover pipe was the original to the build and was failing at the ends.
1) Couldn't see the leak because the coolant was "soaked up" in the micarta material used in the crossover pipe (think of how a garden soaker hose works)
2) Couldn't smell the antifreeze because it was only happening while the engine was hot & running. Being so slight, the fans and road wind blew the smell away.
3) I didn't know it was failing until I had the huge rush of steam from the hood. I thought it was the radiator hose, but a new one didn't solve the issue and it still over heated.
4) When it was hot I spotted three or four coolant drops "form" on the crossover pipe near the bend by the thermostat. I removed the pipe and both ends and the temp sensor locations were soft and I could pull it apart with some pliers.


If you don't know what the cross over pipe is, and some people don't, look at the front of your engine. It's the pipe that passes by the thermostat. If it's dark brownish with goldish spots, it's the original micarta material and it's probably doing what mine did. A replacement is only $35.00 +/- from amazon and is super easy to replace.

 

Every hose and pipe, thermostat housing now aluminum, belts, water pump, all done. I just did a contortion to my body and found a tiny drip under the radiator reservoir. Has anyone here ever used POR 15 Epoxy putty to seal things like that?
I was thinking of using it to stop the leak. Looking also for another reservoir tank.
thanks
Jack
1999 XK8

 

"I just did a contortion to my body and found a tiny drip under the radiator reservoir".

An inspection mirror should be a part of every toolkit.

As for the Epoxy, it needs to be both waterproof and heat resistant. Still, I figure it is only a temporary fix.

A new expansion tank (part #MJD4400AB) is the ticket.


Stu

 

I recently moved to South Florida from New York and my tools are still in boxes. It's been too hot to unpack my garage, I hope by end of Sept.
I just bought a new reservoir/expansion tank unit from SNG Barratt. Should be here by weekend and that will be one more repair done. Glad it's on top, a bit easier than others I have done on this car.
thanks
Jack

 

Jack - Where are you in South Florida... if you're near Boca at all let me know and I can help you out with some toolage and help...

 

hi,

i just received a new expansion tank but before i remove old one i need to know something. On the top 2 outlet for the hoses that go towards the thermostat and water pump, is one out let closed and one open? The new one is like that.
also, is there a special tool to remove the rubber mounts on the rear, or do they just slide on ?
thanks
jack
1999 XK 8

 

Yes, one closed and one open. No special tools needed. Just undo the one screw on top and it slides off.

 

I concur with johns55, the closed port is not used on the 1999 XK8, just make sure you don't put the only hose on that port by mistake. Your engine compartment would get really wet, really fast...