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The octopus' hose doesn't go through that area, so just the heater hoses. Not good.
You don't have the turbo, so that's good but doesn't take away the pain getting them replaced.
Do a search. Lots of good writeups on this job.
The heater feed and return AKA valley hoses are what he's referring to. The intake needs to come off so finding your leak will be pretty obvious good luck it's on my list for the future.
So number 1 on the diagram? XK8 has 105k miles so thinking I'll replace all while I'm there. Also will do short thermostat housing to engine hose becase mine looks like bulging. Found it at autohausAZ. They call it a "spider" hose. I pulled the intake on my XJ8 to change to the metal thermostat tower so been there before, Will also order new intake gaskets and injector o-rings.
You'll also want to replace a number of other parts, such as the plastic 3-way connector (Part 9 in the diagram), the intake manifold gaskets, throttle body gasket, and any other seal or hose you have to disturb. Lots of DIY info in the forums.
Does it need to come all the way off? I remember when replacing my thermostat tower on my XJ8 it rotated enough to allow bolt access for tower and room to replace intake gaskets. Did not have to disconnect from throttle body.
Last edited by pcolapacker; Feb 22, 2025 at 10:13 PM.
Spent a lot of time reading other posts on replacing valley hoses. Everyone was removing throttle body and the intake manifold. Found some one else who tilted manifold up. @galearmstrong in a 2021 thread wrote, "I changed the hoses on my 1999 XK8 and stumbled on a much easier/quicker replacement procedure. If you remove the 10 bolts to the intake manifold and lift up on the front of the manifold (throttle body still attached) it will lift/tilt up enough to remove and replace the hoses. I used a block of wood to hold the manifold up while replacing the hoses."
I removed my intake but you don't have to disconnect the fuel rail from the injectors. Saves a couple bucks in o-rings.
Yep, I realized that after I posted. I had replaced them all on my XJ8 when had lean codes because a couple were sucking air. Conflated that repair with the thermostat tower.
It could be running back from the thermostat tower, so don't rule that out. I had a leak from the thermostat tower because my aftermarket thermostat came with a gasket that didn't fully full the channel that the thermostat fits in, and the coolant ran all the way back through the valley.
It could be running back from the thermostat tower, so don't rule that out. I had a leak from the thermostat tower because my aftermarket thermostat came with a gasket that didn't fully full the channel that the thermostat fits in, and the coolant ran all the way back through the valley.
Possibility. I’ve got a new gasket for when I remove to replace the short connector hose.
Spent a lot of time reading other posts on replacing valley hoses. Everyone was removing throttle body and the intake manifold. Found some one else who tilted manifold up. @galearmstrong in a 2021 thread wrote, "I changed the hoses on my 1999 XK8 and stumbled on a much easier/quicker replacement procedure. If you remove the 10 bolts to the intake manifold and lift up on the front of the manifold (throttle body still attached) it will lift/tilt up enough to remove and replace the hoses. I used a block of wood to hold the manifold up while replacing the hoses."
Yes, you can replace the valley hoses with the intake manifold just tilted up. But you definitely want to replace the intake manifold gaskets.
While you are there, consider replacing the heater valve and motor. There are many of them on eBay at reasonable prices. My pump went belly-up and replacing it was a real pain in the rear. But having a functioning heater in sub zero Fahrenheit temperatures was critical.
I replaced the valley hoses on my 2006 XK8, 100K miles.
One of them had a split, but both were soft and swollen.
Long and tedious more than difficult.
I removed the inlet manifold.
Replaced several other small hoses in and around the throttle body, plus the T piece mentioned above.
I reused the hose clips.
The octopus hose seemed in good condition so I left it in place.
There's also a vacuum line that runs in the valley, fuel pressure sensor to throttle body, I think.
One thing that slowed me down was disconnecting many sensors and vacuum lines.
They all seem to have different connectors with a different trick to release each one.
Plus they are all plastic and brittle with age and heat.
But it's very doable, especially if there's no hurry.
Good luck, hope you find the source of the leak.
