Well I've ALMOST stopped all my coolant leak problems on the 1997 XK8 convertible.

Replaced cap up by the thermostat housing $10 (Previous owner must have lost the rubber gasket and then tightened it until the hex hole fractured through the cap.)

Replaced the thermostat housing $30 (The nipple disintegrated until there wasn't enough left to hold the hose so it popped off.)

The coolant level sensor dropped out of the bottom of the res tank. Snapped it back up into position $0 (It didn't leak, but gave me a false low coolant light)

But she still leaves a puddle overnight. Not huge, but about 4" diameter. The wife told me the big cat was just marking it's territory. LOL

What baffles me is the location. I haven't jacked it up to get under it yet, but it seems to be centered, left to right, on the vehicle but about 6 or 8 inches behind the front tires.

What's back there that could leak antifreeze? Freeze plug? Hose above the engine dripping towards and off the back of the engine? Seems like either one of those would favor one side or the other instead of centering.

Anyone give me a hint before I go blindly hunting?

 

That may be the air con evaporator drain location?

 

+1, the drains are either side of the gearbox around the position it mates to the engine.

 

+1

I agree, AC drains is the likely culprit in which case it will be plain water.

If it's coolant, then a possible cause is the 'valley hoses' (see 3)



Find out first from the colour if it's water or coolant.

Graham

 

First you have to establish if it is clean water from the airconditioning, or anti freeze fluid.
Antifreeze fluid has a red/yellow or green/blue color and a particular smell. It is poisonous.

A leak from the thermostat housing may follow the "V" between the cylinder banks and drip down where you indicate.

At the rear of the engine you have multiple leaking sources: Hoses to throttle body, header tank with hoses, heater pump/valve with hoses and couplings.

All these will probably give you a drip at the same place.

 

HI Place a piece of tissue (so you can see the colour) under the car in a tray.. Then you might get a definitive answer. But my guess is that the guys are probably right with AC water condensation. Which is normal, and no worries, else your coolant would be going down.

 

For tracing purposes if have added florescent die. It is positively antifreeze that is leaking.

Thermostat housing is new and is sealing well.

Valley hoses sound like a possibility. (a pain to access, but a possibility) I can't find "valley Hoses" or that diagram in my workshop manual.

Where do these hoses labeled 3 go? I found the throttle body coolant hose but not heater pump/valve. I can't definitively figure out how the heater core, and the throttle body get fed with only 2 hoses.

This gives me starting point to probe around. This looks like a good place for me to deploy my bore-scope toy since there isn't room for light to even escape from back in the "bowels" between the firewall and engine.

Thanks!

 

Jay, +1 on Oyster's note about poisonous - Be especially careful with dogs, apparently this stuff tastes great but . . . well you can imagine.

 

Just went out to take a look like you folks suggested. I found a couple of questionable hose connections. Took some pictures.

This is the passenger side leak. There is corrosion from prior leaks, but there was no tracer dye showing so that's not my current problem. Checked and tightened a bit to preclude future leaks.



Passenger side leak. I see tracer dye here and some below where it has dripped.



My camera didn't pick-up the glowing dye very well, but the bright green at the tip of the arrow is the dye. tightened the clamp a full turn.

Now I clean off the dried dye and run it a bit and recheck.

Thanks for the pointers as to where to look.

 

Looks like the octopus hose Norma connector.

 

When it's leaking from where you pointed it out in the picture, it's the 3-way connector of the heater return hose (which is one of the valley hoses).
For detailed info see attached picture.
The connector is made of plastic and can get brittle with age, since it's positioned right above the LH cat. When changing it, I'd definitely recommend changing the two heater hoses (return and feed = valley hoses) as well as it is likely that they'll - sooner or later - fail too. Because of their location right on top of the hot engine block, they're prone to fail when ageing.
And as they're not expensive (<20 € in Europe), it's not worth taking the risk as soon as you're observing other parts of the coolant system deteriorating.

 

@AC0FC: Mhhh...rechecking the second to last picture in #9, isn't there a small amount of tracer dye on the coolant outlet of the throttle body, too?

 

here's a picture of the valley hoses, the arrow shows where mine was leaking.

 

Yes xjr2014_de, that is dye. The last time the hose blew off the thermostat housing it showered the entire engine compartment with dye enriched antifreeze. It took quite a bit of cleaning, but almost all of the tracer dye is gone now. This got adsorbed into the cotton threads embedded in the hose and hasn't come out yet. Good eyes!

A week + now and no drips and no sweet smell. Yeah me!

 

you're skating on thin ice. all the hoses and plastic pieces need to be replaced. its only a matter of time and wont happen when its "convenient" . under the intake. the heater matrix above the trans. the small hoses and the plastic pieces that connect them like the one under the throttle body and both hoses to the TB. After all the car is 20 years old and many cars would now be on the second set

 

Good to see you check in, Brutal. You're a rare sight around here these days....

 

I recently replaced both houses to the throttle body and the 3 way connector. Not a difficult job just a PITA.. I found that the 3 way was cracked and brittle and would suggest it be changed along with the other hoses.

Gus
www.jagrepair.com

 

Lol, well you know looking for new side work customers. my past base has slimmed down either from cars or owners passing. And well I can make a lot more money NOT being on the web and actually working