My Jag overheated today. I noticed the A/C cutting out, then I heard fan belt squeal which stopped.....then it started to stall. All the while, the temp gauge stayed right in the middle :/

I drove for about 5 mins when it stalled again and I pulled over. Opening the hood, I had coolant coming out of the front of the engine (steam) next to the over flow tank and behind what looks like an intake. I let it cool, put in more coolant until it wouldn't take anymore and drove off. In 2 mins it overheated again and the temp gauge started going hot quickly and steadily. I pulled over and shut it off and called a tow truck. My questions:

From what I read, the most likely cause is the thermostat housing. How hard it is to replace? I'm fairly handy, I just pulled an engine out of my Saab 900 and rebuilt it and put it back. However, I replaced the headlight on this car and I'm REALLY intimidated based on that experience. I don't even know how to pull off the covers of the engine.

If it is a water pump, how hard are they to replace?
Lastly, how do you bleed the system of air?
I've done some searching but haven't found anything that is clear an pertains to my particular car.

Just a last thought, do they make a thermostat housing that isn't plastic?

I am still debating doing this myself or having it done. If it's not too bad, I'll try and save myself some money.

 

Your 2005 might have a metal replacement housing... I know I could not get one for my 2006, somewhere around 2005.5/2006 there's a VIN break point. They're drastically different looking housings.

It's not bad to replace the thermostat housing on this engine, everything is right up front. Really easy to remove the thermostat cover and check to see if it's broken internally (most likely is). The new plastic housings come with a new thermostat and coolant sensor, so it'll all be refreshed.

The water pump is not too difficult, just getting everything else out of the way. But from what I have been told these have a metal impeller and are not prone to failure. Your belt squealing could have just been leaking coolant dripping on the belt and causing slippage.

 

Though I haven't done this project on my XJ, the n/a 4.2 on my XK8 is fairly easy, and straightforward to work on...once some of the smaller stuff is moved out of the way, such as the radiator if you're going in front of the block. If you've done engine work on your Saab, you should only have to deal with the initial anxiety of the jaguar powerplant, but once you've started, your confidence will rise and it'll be the same operation, just a different patient...and a better looking one at that

I bleed the system on both my cars the old fashioned way...idle the engine and run the heat on HI, max fan for about 15 minutes. (I also leave the cap off the expansion tank so I can see air bubbles at times) When she cools down, I give the upper hose a few good squeezes, gives me a good idea if there's still any air trapped at the water pump...and then I do the same process again with the heat. After that, I've never had to repeat the process and all the air has been 'circulated' and released at the expansion tank.

The t-stat housing, at least for now, will remain a plastic version unfortunately. I changed my 4.2 housing at around 90k miles, its just one of those parts that is inevitably going to be replaced.

The JTIS should give you a step-by-step procedure to follow to pull the radiator...or a man of your DIY skill could probably just start unplugging connectors, removing hose clamps, pulling a few bolts/screws, and lift that straight out of there.

 

First you need to diagnose the problem and determine if it was a stuck thermostat, broken housing, bad water pump or something else. It sounds like a bad thermostat to me. I would buy a new thermostat and look in the housing for damage. Change the housing if it has any broken pieces in it. Check the water pump for weeping at the hole under the seal area. The pumps are cheap, if in question, just change it. Water pumps have a life of about 100K miles, thermostats and belts about 60K miles. When refilling the system, bleed it by opening the flat headed plastic bleed screw on top of the overflow tank while refilling ,close it when finished. Note that the overflow tanks have a 60K mile life as well and should be replaced around then to prevent nasty surprises. They break at the bleed nipple and leak.

 

Thanks for the info. My initial (real) worries are accessing the areas, how to move out the initial bits and the wild card.....the wild card is the unknown, can't anticipate piece of info that is specific to the car, isn't intuitive and if someone doesn't tell you, you'll break it.

 

Did some troubleshooting today. Visual inspection of the thermostat didn't show anything. One of the hoses going in does have sealant around it so I think the PO has some heating issues. Ran the car for 15 minutes with the over flow tank open. A lot of air came out, I replaced coolant as needed till it stabilized. Ran for 15 more minutes 86F at 80% humidity, no problems.

Decided to test drive.

After 100 yards, turned on the A/C got belt squeal and the temp started climbing quickly. Turned off the A/C and it went back to normal. Did this 3 times.
I'm thinking the A/C compressor is bad or the clutch is bad and it's causing drag on the engine.
Sound reasonable? If so, can the clutch on that A/C be redone in place? I can do it on a Saab but I don't know if I can on the Jag.

Also I want to pull codes off the car but can't find the port. It is supposed to be in the drivers kick well and by law it's supposed to be uncovered. I couldn't find it....

 

The AC compressor on X350s is a clutchless item. Operation is continuous via a PWM signal from the CCM to the compressor solenoid (that's what my Technical Notes say, anyway !).

Have you checked the auxiliary coolant pump, that is also a fairly key part of the cooling circuit.

It sounds like you need a check doing on the AC compressor, and also see if there is any gas in the AC system. In the meantime, you'll have to leave the AC turned off. A bit hard to endure in Dallas in summer, I'd think.

 

The first question was going to be whether you still had a belt.

Since it squealed after the refill, it seems that you do.

However, the AC compressor and water pump are on the same belt. If the compressor stalls the belt, the water pump will not turn. If the water pump does not turn, there is no coolant flow, leading to .... overheat.

 

FYI....I did the thermostat housing replacement on my 2004 XJ8 a few years ago, and as I recall, it took me a few hours, but it was fairly straightforward (dealer wanted $1K!!). As others have commented, it's made of plastic and prone to cracking/leaking. I vaguely remember the whole housing with the thermostat installed was about $200 from the dealer, but I found it online for less than half that. There's good news and bad news regarding the replacement. The good news is that there are no gaskets (to scrape) as all seals are "O" rings or rubber "donut" seals. I purchased replacements (for the intake elbows), but probably could've reused the originals. Note the housing comes with o-rings installed already, so you don't need to worry about those. The bad news is that I had to unbolt a lot of stuff to get all the housing fittings. I did not have to remove the radiator, but I did have to remove the intake manifold elbow and a few other hoses on the top/front of engine, and some of those were a bit of a pain. I actually spent the most time on the bottom radiator panel/cover that runs across the front of the car...some of my screws were stuck or broken. When I finally got the thing off, I had to spend a while "working" the radiator drain plug back and forth (since the radiator is plastic, you don't want to force it). I think the torque spec is 1 ft/lb or something. If you didn't want to remove this panel, I guess you could just unbolt the housing, but you'd have coolant flowing everywhere!

As to your A/C compressor, I've never messed with one, but I recall reading that (since it's down low), if you're going to remove it on this car, you have to lift the engine up to get it out from between the engine and the frame (I guess you buy one of those "lift bars" that straddle the engine...I've seen them in the Harbor Freight Catalog for ~$60).
Good Luck!!
Greg

 

Yes, the belt is on. It was difficult to start, once it started it ran fine and sounded normal. I dropped it off at the mechanic. I'll let you know what they find.

 

Well I'm up to $1200.....$600 of that is to replace the upper and lower radiator hose. It sounds a bit excessive to me.

 

This works out at £392. Not difficult to "achieve" with these cars. How much of that price is for the hoses ? Hourly charges at my independent are £59 an hour or $90.

 

About $170 for both hoses. The labor is the killer