I have a 2009 XF, with the 4.2 V-8 engine. The car is now 7 years old, but with relatively low miles, 30,000.


I've been "around the block" a few times, and I was raised on cars that had mostly metal parts, and as few parts as possible. My point being that the cars that I cut my teeth on had a "coolant hose network" that consisted of (1) molded, upper radiator hose; (1) molded, lower radiator hose; 4-5 feet of 5/8" heater hose; 4-5 feet of heater hose, and a metal thermostat housing.


If you kept the car more than 5-6 years, you most likely replaced the above items, did it yourself, quite easily, and it cost you no more than $50. As I mentioned, my XF is now 7 years old, which has me wondering about the overall condition of my cooling system's components.


Under normal circumstances, I'd simply replace everything, for the peace of mind. However, as I look up some of these parts, I find that the "multi-fanged, plastic kenorfus", that attached to the front of the engine, is well over $100. The rest of the hoses, when I can find them listed on parts sites, are a collection of $40-$50 hoses. I can see spending a significant amount of money, to replace this stuff.


This raises the question, what is the average expected life of these bits and pieces? I don't want to throw $$$ away, but getting stuck in some out of the way place, while on a road trip, isn't fun either......

 

Even with low miles time takes a toll, I'm just buying a piece at a time as I intend to do the wp, belt drives and hoses at the end of summer. Mine just hit 80kmi on its second wp and belts. I part # shop the Web and give my local Jag parts guy beer for the best prices.

 

My thoughts, exactly. I live in the northeast US, where temperatures range from (-) 10*F to 90+* F, and the car has been driven in both of those extremes. Because of that, I'm thinking of changing out some of these components, just to be safe. I swapped out the serpentine belt, a couple of years ago. I just don't want to be throwing $4-500 at the car needlessly...

 

Nobody else has any experience with the life expectancy of these plastic parts in the cooling system?

 

Mine were all replaced by the previous owners Jaguar dealership in late 2015 at a cost of nearly $2000AUD. I would expect that the extra plumbing under the supercharger would have added several more hours to the task than the NA engine.

 

On the normally aspirated AJ33/34, the water outlet containing the thermostat should be replaced every time the coolant is replaced as it can only withstand a finite number of cold to hot cycles before failing. The water outlet carries a JLR part number of AJ811793.

 

Thanks for the information. I've had the coolant replaced twice (on a 4 year interval), by the dealer, and neither time did they suggest changing this crossover/thermostat housing. I asked them about the hoses, and they said that they've seen them last a long time, so don't worry about it.

I found a write up on another Jag discussion site, outlining the replacement of this crossover piping. It appears that with this piece out of the way, there's easy access to the water pump. I've heard conflicting information regarding the life of the water pump, too. Is the 4.2 engine's pump also a "replace it while you're in there" deal, or is it just the 5.0 engines that have a questionable pump?

One other thing, when replacing the crossover pipe, are there specific torque values for the bolts, or is it simply tighten until snug? Thanks!!

 

If there's plastic pipes in your cooling system, they will break over time, and you're getting to that time when they will start breaking one by one. At 10 years, you are on borrowed time.

On the 5.0L those pipes do seem to break sooner, often 5-7 years, so I replaced all of them about a year ago on my 2011's so that I can buy another 5-7 years of trouble free cooling systems. After that, despite loving these cars, I will definitely sell them because they will just be too old to be reliable enough for me as daily drivers, and they don't make the cut to be in my weekend fun cars collection.

 

Unless there's seepage or a leak from the water pump, the 4.2 litre did not have the issues the 5.0 litre does.

The plastic parts of the cooling system should all be inspected for signs of cracking and replaced as needed. For torque values, refer to the Workshop Manual.

 

If only plastic gave you more warning. They go from looking and working just fine, to BOOM, gushing out your coolant and blowing your engine from the loss of pressure in the cooling system that causes the water at the heads to instantly boil and start warping heads and unseating valve seats. Look around this forum, and you'll see that's true. So this advice isn't going to help you.

 

Now I'm a little confused. I did some "online comparison shopping", yesterday, and found that if I use "2009 Jaguar XF with 4.2 engine" as a search term, the part number AJ811794 comes up. Is this an updated part number?

 

True, some what! My car (4.2 SC) has chomped through 2 water pumps in 67k miles....

 

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I don't happen to have a "workshop manual". Could some kind soul please post this information? Thanks!

That's what I'm afraid of. Looking at the pictures that I found on the other site that I initially referred to, the one showing how to swap the plastic thermostat housing/water crossover, it appears that without the plastic piping in place, the water pump is easily accessible. Therefore, if the water pumps are somewhat "fragile", it seems that when replacing the plastic parts, it would be a good time to do the water pump, if they are indeed an item prone to premature wear out. BTW, does anyone know if the OE water pumps have a plastic or metal impeller? That could be the point that makes the decision for me....

 

Bringing this discussion back to the top.....

I finally "bit the bullet", and changed out the plastic crossover pipe and thermostat housing. I did this yesterday. I don't know exactly how to describe the job, as on one hand it's sort of "straightforward", yet on the other hand, it's a ROYAL PITA. It's a case where you need to remove the front belly pan, in order to drain the radiator, which is an awkward task, then a lot of peripheral stuff, in order to get at the crossover itself. Along the way, you're faced with a couple of "hard to get at" bolts. I was thinking it would take 2-3 hours. It took closer to 6, by the time all was said and done.

This task brought up two rather important points. First and foremost, Torx headed screws are rather cool inventions, HOWEVER when used in an application such as the crossover pipe, they're NOT practical. I spent WAY TOO MUCH time just trying to extract the lower, passenger side retaining bolt. Why? A) because it's completely obscured by the pipe assembly itself. You're either flying blind, or awkwardly using a mirror, getting the Torx bit seated in the head of the bolt; and B) when used in a location such as the crossover pipe, which is behind a rubber belt, that sheds "rubber dust" over time, which fills the "hex" of the bolt, getting the bit to engage the hex is quite tricky. In this location, a regular hex bolt would be better suited, since slipping a socket over the head of the bolt, scrapes the accumulated crud off the head, and the socket easily engages. The torx bit simply tries to pack the crud in further.

One other thing....while I prefer to use a torque wrench as much as possible, several of the fasteners are in such cramped quarters, that it just wasn't possible, so I gave it my best and practiced feel. I took a very quick look under the car, a few minutes ago, and didn't see any puddles, so I think I'm "good to go". An extended drive "around the neighborhood" is scheduled for today, just to make sure that I have 100% of the air out of the cooling system. The other thing is, we're having an unusually early cold front that's supposedly "just passing through", but it might contain a little snow. Even though it's still only mid-October, I may put the winter tires on.

EDIT...…..one other thing I learned, yesterday, or should I say, today. I'm not as young as I used to be, or thought I still am. All that reaching, stretching, and crawling around under the car, and I'm pretty stiff and sore this morning.

 

My 2005 STR lost the water pump at 122K miles. Good thing is the 4.2L shares the water pump with the 3.9L Lincoln LS so the pumps are easy and pretty cheap to find in the aftermarket.
So the 4.2L ones seem to last better than the 5.0L which are very failure prone.
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That's good to hear. Prior to our 2009 XF, we had a 2000 Lincoln LS, and we put about 70,000 miles on it, and it was still running well when we traded it off for the XF.

I hate to admit it, but I took the XF out for a "test ride" this AM, and it brought to light a "screw up" on my part. While swapping the crossover pipe, I slipped back the clamp on the upper radiator hose, so I could rotate it a little, and get a better shot at the lower bolt on the crossover. Well, I forgot to slip it back in place. What really shocked me, is that it took quite a while for it to blow off, and start dumping coolant. I initially ran the car for about 10 minutes, last evening, to bleed out the trapped air, and the unclamped hose stayed in place. Then I shut it down for the evening. Fortunately, my "test ride" this morning, was up and down my street a couple of times, "just in case", and "just in case" happened. I'm just annoyed that I took the time to do a thorough job of cleaning out the belly pans, yesterday, and I'm sure they got a good dose of coolant by this miscue...

 

>So the 4.2L ones seem to last better than the 5.0L which are very failure prone.
Ok, here's a waterpump question no seems to have considered: do the 3.0 engines have a similar problem as the 5.0? There's been lots of talk about 5.0 problems by nary a note about the 3.0.
Is it, perhaps, because 3.0 owners don't participate on the list as much as 5.0 owners do?
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You dreamed of a big star -
He played a mean guitar -
He loved to drive his Jaguar...

So welcome to the machine

 

I believe the 3.0's have similar cooling issues. I replaced my water pump ~45k (at the suggestion of the dealer while under warranty), and recently replaced all plastic coolant hoses and crossover pipe ~75k, I had a small leak starting on one of the hoses and knew I was on borrowed time with the others.

 

Yep, I'm pretty sure the whole coolant system and most if not all of the plastic pipes are exactly the same on the 3.0.
A member on the UK XF forum just reported that his 3.0 has a cracked rear heater pipe, see here: https://www.jaginfo.org/showthread.p...=1#post2671484
On my 3.0 F-Type (same engine) I had a crack in one of the small pipes across the top/front of the engine a few months ago.