After a few minutes of running, I'm getting some kind of smoke or steam rising from both exhaust manifolds. I think it's coolant because the coolant reservoir is a bit low.
I haven't driven the car much since I did the timing chains a year ago but I did drive it a bit right after the timing chain job and all was well. I was wondering if maybe oil was leaking from both cam covers but that seems unlikely and it would have shown up soon after I completed the timing chain job a year ago.
So I'm suspecting a coolant leak somewhere under the intake manifold. It's a 2001 XK8 convertible and I've never had the intake manifold off.
I've heard about some coolant lines under there so before I dig into it, can anyone give me some guidance on what tends to leak? If it's most likely one particular part, I'd like to have the part before I start.
Thanks in advance.

 

The valley hoses are suspect if they are of age. Parts 1 and 2:



The feed return hose seems to fracture where it connects to the block underneath the thermostat tower. It sounds the most likely if it is coolant leaking.
This is definitely a 'while you're in there' job, and I'd replace both hoses. Perhaps the tee-piece 9 (NNE3944BA), or either/both of the Norma connectors on the octopus. Consider also an aluminium thermostat tower upgrade, and the crossover pipe (AJ85885).

None of the parts are particularly expensive.

 

Thank you very much. Can you tell me a little more about the octopus?
I've already done the aluminum thermostat tower upgrade.
Everything under there is original so I'll get the parts and tear into it.
Just to verify, could this leak run down onto both exhaust manifolds?

 

It looks like this:



Not sure if coolant would get to the manifolds from the valley, but it can land on the cats, which may be what you're experiencing.
Also, if the the Norma connectors on the octopus are leaking, they can drip coolant on to the cats as they are cunningly located directly above them.

If it is just the RHS Norma leaking (that one is an engineering masterpiece), I'd suggest cutting it out and replacing with a short length of hose and metal pipe, as some have done. However, the assembly is getting on for 20 years old, so replacing it would be my recommendation:- particularly as you will have the TB and inlet manifold out of the way. Beware that OEM (MJA6728AC) is north of $150, though.

Do change the tee on the LHS. It's made of the same biodegradable material as the tstat tower & crossover pipe. It's also remarkably cheap at around $5.

You may need a hose clamp tool to get the connections off the heater water valve. Look out for the zip tie hiding under the transmission tunnel, as you will need to cut it to finally free the octopus.

 

OK, thanks. You have been a great help.
It's very possible that, as you said, I have coolant leaking onto the cats, but both at the same time? I'll be finding out soon enough. I ordered the two hoses and the tee as suggested.
I was going to wait on the octopus until I got in there but it's 20 years old and I found one on Ebay delivered to my door for $147 so I ordered it. I'm going to replace everything in there that looks even the least bit suspicious.
I found the intake manifold gaskets on Rock Auto and they were so cheap, under $4.00 per set, that I ordered three sets. I'm paying shipping anyway so I figured why not. Now I'll probably never have to buy them again.
Again, thanks.

 

Stu46h,

What is the colour of the smoke and/or smell you're getting. It may be a combination of things.

Here's a few pics and figs that may help in case you have a coolant leak at the numerous coolant hoses at the bulk head. However I think this is only really relevant on the LHS of the car.


One hose of the octopus (part 1 above) goes to the bottom of the coolant expansion tank. Other forum members have had problems at this location, including reports of leaks at the plastic seam of the tank. Also the main feed/return connections seem to be troublesome. I replaced my octopus back in 2018.


The hoses to the water valve are directly above the LHS exhaust CAT and can be the source of leaks due to old hoses. The red circle above are the feed/returns to the heater core. If you want more pics check out this reference from fellow forum member RD who has done ALOT of work in this area.
https://racediagnostics.com/cms/uplo...eater%20motor/

For the RHS of the car, I would guess that it's the vinyl ester cam cover's gasket that is leaking oil. My replacement gasket (a job I did 2 years ago) has just started leaking again and I'm cleaning oil drips from the head shield below to prevent smoking from the exhaust manifold below . I'm starting to understand that's probably why a Previous Owner had tightened it up way past the 9-11 Nm torque specified.

 

Hate to ask this but have you removed your oil filler cap and checked for 'mayo' on the underneath of the cap? Just remove the oil filler cap. Turn the cap over and look underneath. If its not white then great.

 

I just replaced the valley hoses on my 2000 xk8. My leak was also hard to find and it appeared to be the valley hoses. As it tuned out the leak was at the throttle body, the lower hose. It was impossible to see and even using a pressure tester didn't help. Anyway once in there I replaced the valley hoses and the plastic tower as preventive medicine. Prior to this I had to replace the radiator so it seemed like it was just a matter of time that the rest would fail. Most likely the spider / octopus hose is next to go.

 

My xjr’s octopus hose just broke a couple days ago. It sheared off at the T junction behind the engine, broke the t-junction in half. It’s made of plastic, so it’s only a matter of time.

Rather than replacing that crazy expensive hose (which is hard to get entirely out in the first place, and costs altogether too much money), I just cut the t-junction out and replaced it with a cheap t junction and three hose clamps. Sadly, Jaguar didn’t use hose clamps to begin with (they have metal belts on the T that can’t be removed) so cutting was necessary... but it was easy enough (I just cut just past the T). I did have to replace one of the short hoses (one that went toward the driver side), but it was less than a foot of hose and was hose clamped on so that was no big deal.

I think I spent fifteen dollars on hose clamps and hose, and maybe an hour removing and moving parts above so I could pull the hoses up and get the t-junction on. There isn’t much room back there. You have to remove some stuff (and unplug some stuff) to get a hand down there. Thankfully mine wasn’t leaking at any of the connectors, so I’ll save that harder job for another day .

The hoses under the supercharger are famous for blowing out at bad times, so that might also be a cause... but taking off and replacing your supercharger is a pain so I’d probably check behind the engine before I went about yanking the supercharger.

If the hose goes out, it is leaking straight down onto exhaust pipes, so yeah, it’s definitely going to smell .

 

I believe that I don't have an oil problem, and that I have a coolant problem. I recall a puddle of coolant under the car, and I have the exact same vapor coming off both sides, whether it's the exhaust manifold or cats. With the age of the car, I need to address the valley coolant hoses anyway, so I'll see what I find.

 

Yes very much so. Both the valley hoses that run under the intake manifold AND the Octopus hoses can drip on the exhaust manifolds and not even hit the ground. I was losing coolant slowly without a puddle, but I could smell the sweet smell of antifreeze. You really should do the whole job at once to save money. If you have the funds, it will be cheaper in the long run to do valley hoses (intake manifold must come off), water pump (esp if you have never changed; my 2001 had the old plastic design impellers that will break off), octopus hose, upper and lower radiator hose, etc. This way you know the system will be stout, and you only have to pay for coolant flush once for the next timeframe instead of losing it on the ground due to a blown hose or other failure.

Also, if you've never done the tensioners, this also may be a time to bite the bullet as the front of the motor/intake can easily be cleared while the engine is drained. Just food for thought.

 

Don't take offence. Non intended. But are you sure its not just water from the Aircon? Most car makes, including Jags, get water as you describe under their cars from that.

 

No worries. Everyone is here to help and I appreciate it. This isn't air conditioning condensation. It's a new problem and I'm quite sure that it's coolant. Both sides have the same symptom, steam/smoke from the exhaust at the back of the engine compartment. And the coolant reservoir is low. It makes sense because I've owned the car since 2005 and I've never replaced anything under the intake manifold. I replaced the tensioners, guides, and timing chains a year ago. I replaced the upper and lower radiator hoses, water pump, and thermostat and tower prior to that. So now I'm going to give the heater/coolant system new life. I'll replace whatever I can with the intake manifold off.
I don't recall any milky stuff on the oil cap but I'll check since it's so easy. I don't expect to find anything there because if I had a blown head gasket that would have showed when I checked compression a year ago (I haven't driven the car much since then) and everything was OK.
Thanks for all the suggestions and I'll keep everyone updated.

 

Please take a lot of pics when you do the work Greg.

There are not many pics of this work on a 4.2 engine. A comprehensive set would be useful in the future.

 

When I do this job I will take pictures and post them. I'm curious to see what I find when the intake manifold comes off. I hope the problem (leak) is obvious. But right now I'm working on building a deck to try to get it done before the weather gets hot. And for the record, I have a 4.0 engine, not a 4.2.

 

Stu,
One thing I forgot to mention is that your part load breather (2) may well fall apart when you wrestle it off the TB:


The connectors are reasonably robust but the convoluted plastic hose isn't. Part # is now AJ84880. I used fuel line as a temporary measure (~5 or 6 years) without issue.

 

OK, thanks. I'll watch for that.