Cheers!

It looks like I have a coolant leak at the rear part of the engine. When we changed the oil I noticed that the rear of the engine was wet and thought it might be a bit of oil leaking from valve covers or such but this morning there was a small puddle of coolant on garage floor.

XJR goes to a specialist on Friday but I would like to ask if the AJ-V8 engine has some typical coolant leak issue this could be?

 

Probably valley hoses.
Be sure to check your knock sensors are not throwing a code, they do break down when flooded.
Easier to change at the same time.

 

+1 on the valley hoses.

 

+1 on valley hoses (= heater return and feed lines) + connections (e.g. part 8 = the 3 way connector of the heater return line is prone to fail too, since it's made of plastic and sits right above the LH cat)
Second possibility are the small coolant hoses going of the throttle body and/or EGR valve.
Another possible source of the coolant: Octopus hose (see this thread here https://www.jaguarforums.com/forum/x...nt-hose-75681/).

 

Thanks, gentlemen.

Is it usually so, that the lines/hoses themselves deteriorate or are the connections typically those that start leaking?

Can this small leak lead into a quick empty-the-whole-coolant-system-at-once situation or just keep leaking a bit? I'm thinking about the risk of driving XJR to the specialist or trailering it with my Grand Cherokee instead as the specialist is some 175 miles away.

 

Both deteriorate...connections and lines.
In my opinion, I wouldn't take the risk of driving it anywhere. Bear in mind that when the engine is warmed up the coolant system will be pressurized. This will usually make the leak getting worse. Once I had a very tiny tiny hairline crack in the engine outlet hose and couldn't even drive 2 km.
When sitting, the car wasn't leaking at all, but when up to temperature, it was. And in your case, the leak is obviously severe enough to leak even when cool and sitting.
And additionally, the XJR engine produces quite a lot more heat than the NA engines...overheating a SC engine is no fun at all..
So in doubt, get it trailered to your specialist.

 

Vielen Dank, trailer it is.

 

Ole hyvä!

 

Right choice.

 

Out of curiosity, are these hoses and other related parts something that have been revised through the years or are they still of original design/materials?

 

That depends...both...
Sticking to the heater hoses, you can see that there had been a revision of the heater feed hose from engine no. F07815 on (AJ87634). Thus the revised version has been replaced for the earlier engines too....
In case of the return hose it remained unchanged. It's the same for the connectors.
So best way to find out is to consult jaguarclassicparts.com in case you have any doubts about parts numbers.

Cheers, Alexander

 

Loaded XJR on trailer this morning and headed to Helsinki with my -96 Grand Cherokee 4.0. Despite of modest speed trailer started swinging left to right on two separate occasions - yikes!

At the specialist his quick verdict was leak under supercharger so I left the car there. They will change all necessary bits and pieces and then some. I'll get the car back within a week or so depending on if they need to order parts from Ol' Blighty.

 

Good job! I'm happy the specialist has found the source of the leak quite fast. Even if it's almost the worst location having a leak (at least for the SC cars, as the throttle body, the intake elbow, the EGR and the supercharger have to come off).
Dependent on what mileage your car has done and if you want to keep it for a long time, it might be worth considering to renew a few more things.
- supercharger coupler and oil
- the small coolant hoses of throttle body and EGR
- gaskets, O-rings and seals
- optionally the knock sensors

My MY 2000 XJR had ~170.000 km on the clock, when a knock sensor failed. For replacing them exact the same engine parts had to come off as with your car now. So I replaced both knock sensors, the valley = heater hoses, the small coolant hoses of TB and EGR, the supercharger coupler and oil, and almost all gaskets and seals of the air intake system which I came along.

And since your specialist has to disassemble it anyways, only the additional parts costs will add to the bill.

If interested, I can provide a list of parts (incl. Parts no) of al the replaced parts.
Best regards, Alexander

 

That shop must had been reading this thread, that's how they figured it out so fast....

 

According to specialist head gasket/gaskets are toast and top end rebuild is a must.

Luckily the car is under used car warranty and I don't have to pay for repairs so it is up to the dealer to decide whether they allow the repairs or if we cancel the deal. I'm OK with both alternatives.

As it hasn't overheated during my possession the damage has occurred with previous owner. Sucks big time, though.

 

Damn, that's s***. I feel very sorry for you! So it isn't necessarily the valley hoses which are leaking? By any chance, do you know how the specialist found out about the head gaskets? Is it leaking right from the heads?

Keep smiling and fingers crossed that this will work out for you!

 

When it rains it pours.

The valley hoses are leaking and it seems that head gasket and/or valve cover gasket is leaking also oil. He said that it is building pressure in the coolant expansion tank and that HC value is high so that's it.

Unless there is something extra wrong with the heads ie. cracks or such then it is a straight forward top end job including milling the heads etc. I have no idea how long this problem existed but now it will get done right.

I had a -91 Lexus LS400 earlier. Problems with that car was zero. Nil. Nada. Zilch.

But it did not produce the semi-boner the whine from XJR engine bay does.

 

So the decision has already been taken to renew the heads and to keep the car? Maybe you can take the opportunity and throw in some new parts for having an almost brand new engine top. What's the mileage your car has done?
And yes, the supercharger whine is one of the most exciting wolf-in-sheep-clothes-attitudes of this car - sometimes I can't hold back to floor the throttle just for the fun of it. Well...and to see how fast almost all other cars fall behind me

 

Yes, dealer is taking care of the cost so it's OK. Unless there's something funky to be found when heads come off. I'm on a work trip and will go past the specialist tomorrow so I should see how things are. Mechanic is an Englishman.

135k km on the clock. Engine is a factory new engine changed at 89k km because of...drum roll...overheating.

 

This means the replacement engine has only done 46k km? The preowner must have been heavy on the accelerator.
Since the engine is quite "new", it might not be necessary to replace the parts I suggested above. Except of the supercharger oil and if necessary coupler, if you ask me. Don't think they replaced the supercharger too, when they installed the replacement engine.
Ask your specialist to rotate the supercharger pulley back and forth by hand, when the supercharger is off. When the supercharger rotors respond the back and forth rotation without any noticeable delay or play, the coupler should be fine.
When I noticed some play when turning the pulley, I decided to change the oil and coupler of my supercharger (170.000 km on the clock at that time). When I disassembled the supercharger the coupler disintegrated in my hands.
The coupler is made of two steel springs embedded in a plastic housing, which deteriorates when ageing. Pic 2 is with the new replacement coupler (yes, it's a solid, oil filled nylon coupler).

Well, the SC engines produce a lot of heat and forgive almost no cooling issues. In particular when stuck in stop'n'go traffic, the heat under the hood builds up quite fast. That's the reason why I replaced the factory Hella intercooler pump with the more powerful Bosch 0 392 022 010. Helps a lot to run the intercooler noticeable cooler - so it's more of a sustainable improvement than a performance upgrade.

Cheers, Alexander