2010 5.0L XK 45k miles,

Got the alert coolant low after starting my car today, popped the hood and noticed dripping coolant
from one of the upper fittings on the hoses in front of the engine passenger side,
could anyone tell me what this part is?

Is there any other cooling hoses/parts I should change while I'm doing this?

Thank you in advance.

 

I think this is just the upper radiator hose,

I wonder why there is the plastic piece in the middle,
It appears the clamps on both sides have weakened causing
the seal to leak, I will check tomorrow and possibly replace with
hose clamps.

 

So here is the hose that coolant is seeping out of the plastic part.
What is the purpose of the plastic part?

To keep the hose rigid and provide the proper angle?
or
To provide a indication of the condition of other plastics in the cooling system?

 

The two ends of the hose are different sizes, the plastic in the middle
serves as an adapter, I was able to find a similar hose and will stretch
one end of the hose since the dealer is out of this hose.

 

I'll add the relevant extract from JEPC for anyone with the same issue with the Radiator Top Hose in future:



NOTE: the above is for the NA engine. Here is the equivalent for the SC engine:




Graham

 

With the original hose, what is the condition of the plastic adapter? If you cannot timely obtain the correct hose, and the plastic is OK, it seems that it would be better to buy two hoses that have the correct inner diameters, and reuse the plastic.

Of course the best bet would be to obtain the correct hose from parts.com or your favorite US mainland Jaguar dealer selling parts at a discount.

In your original post you asked what other hoses should be replaced. I would say "all". I did that on my 2007 4.2 over the last year (82K miles on odometer currently), and no longer smell coolant in the engine compartment. I also replaced the coolant reservoir and the plastic coolant outlet assembly that holds the thermostat and coolant temp sensor. It's not easy - you have to remove the intake manifold for access to the hose that connects to the engine "valley", as one example.

None of the hoses were obviously leaking or bad, this is a peace of mind issue - not waiting for a leak to happen before taking action. The plastic coolant outlet assembly definitely needed to be replaced as the interior was discolored and the plastic around the thermostat was starting to break. (Of course your 5.0 engine does not have a plastic coolant outlet.)

What is the condition of the engine coolant pump bearing - any fluid leaking from the weep hole?

 

Ditto. Plastic cooling system parts age at a pretty consistent rate and I assume yours has spent it's life in a warmer climate that exacerbates the problem. Ten years or 100k due to heat cycles is about the same. The real question is do you want to replace them pell-mell or all at once? I chose to only replace those that are bad as they go bad. On my sons '05 Lincoln LS that turned into a three year saga of replacing anything plastic in the cooling system as it all failed. There is also a huge problem when using the wrong coolant (which I'm sure I did on the LS) which is not compatible with the plastic bits. The end diagnosis from a thread a while back is Ford / Jaguar used several different plastic compositions and none are compatible with one type of coolant. The pink Jaguar stuff is compatible with most and the green Wal-Mart / auto parts place stuff is compatible with very little. The orange GM stuff is horrible...

Google coolant types versus plastic cooling parts for an insightful read. You'll need to find the three letter code for the type plastic you have and see what's compatible. It's a design flaw and an engineers train wreck.

 

Ive beem searching coolant for a while,
and still dont know what coolant to out in
Oat, hoat, eg pg, dexacool?

 

It is leaking from the plastic not the hose,

the waterpump weap hole area is dry.

 

I think you'll find Dexcool fits JLR specs.

 

Not knowing the 2 different sizes of the plastic part I would measure them and consider making up a piece of copper pipe with hose fittings on each end . Seems like a fairly straight forward fix.

 

I had a T fitting on the Lincoln that I turned and welded up as it was cheaper than $179 for the hose and fitting. Plastic looked like gray wool on the inside from using the wrong coolant.

 

Where the plastic meets a hose, resist the use of a worm-drive hose clamp as the plastic must be able to expand and contract. Use the constant-tension hose clamps supplied with the OEM hose.

The plastic cooling system parts can only withstand a finite number of cold/hot cycles before failing. Given the age of many of the early production vehicles, the plastic parts should be replaced when the coolant is replaced.

DEXCOOL meets Jaguar specification for OAT coolant.

 

eeeeehhhhhhhh..... maybe Aluminum instead? No sense adding ANOTHER alloy to the mix.
But, this is probably what I'd do. No sense in spending MORE for an inferior OEM part that will undoubtedly just go bad again.

 

can DEXCOOL be mixed with the factory coolant?

Thanks

 

Yes, and it is easiest to use the pre-mixed blend.

 

Does dexcool eat at the plastic and silicone parts in jags? I cant find a definitive answer.

 

Any coolant conforming to specification WSS M97B44-D may be used.

 

Sooo.... 7 years later the same hose is leaking on the joint, upper radiator hose.
This part was designed to as an early indicator of when your plastic cooling parts need replacing.
the middle section is made of layered plastic that will slowly leak at first vs. causing a major leak
while on the road.

 

now at 85k miles.

The order of failure for me was:
Upper radiator hose -> Rear heater manifold -> Water outlet (under intake manifold) -> Thermostat housing