Just a story.......................I drove for maybe fifteen miles back to and back from my brother's house yesterday. No problems arriving there. Going back home I get in my driveway and turn the engine off. The radiator fan ran loudly for ten plus minutes. It has never ever done that in the past ever. I've driven in the deserts of Ca and New Mexico, Az and stopped at gas stations and the fan has never run on after shutdown.

So. No water leaks. No low fluid in the tank. Got up at 3am and tore the engine bay down to get at the outlet housing. The thermostat was in three or more parts and there is a little finger in length piece of plastic missing that was part of the outlet assy.

Jpg of the 'three piece thermostat' attached to this story. New outlet assy from Gaudin Jaguar coming in the mail next week. $114 bucks.

Chevy Vegas had a water temp gauge. The East German Trabant had a water temperature gauge. Jaguars don't have a water temp gauge. Sucks big time. Plastic on engines sucks also. Always has, always will.

A manual I read says that if the water temp gets too hot, a caution shows up on the dash. I see no caution/warning anywhere. Even when just turning the car on/engine off, I see cautions for the airbag, engine, etc but nothing that looks water temp related. So? Is there really a water temperature warning/caution light that is on YOUR XK??????????????????

A scanner I have says that the temp was up in the 218*-225* range, when the fan HOWLED. FYI only.

 

If it is like the earlier 4.2s. the warning will trigger above roughly 230 deg. F. Not great.

 

How many miles on the car and how many on the thermostat?

 

The gauges or lack thereof is really the only big gripe I have had with my XK, and I let Jaguar know it on the customer satisfaction surveys they have sent to me. I had gauges on my previous XK8 that looked good, but they did not register a problem until it was too late. They were just for looks.

 

81,410 MILES on the car. no idea of how many on the thermostat. Used car. I put 25,000 of those miles on the car since last July. Most miles I put on were driving from Ft Worth to Cotati Ca (3 times) or Arapahoe Ne (2 times), one trip to Winslow Az, and one trip to Carlsbad Caverns and last week a trip to the Grande Canyon in 100* plus temps driving thru New Mexico, Az and Tx. No problems noted when stoppin for gas i.e. there was no fan on when filling up with gas with the engine off.

The thermostat is locked into the housing with two plastic tabs (on the plastic housing). One of the two plastic tabs was broken off the housing, which would have caused the thermostat assy to get all cockadoodled inside the housing. Heat fatigue imho.

IF they make parts out of plastic, there should be a schedule for their replacement during the life of the car and the maint should be done by the mfg at their expense imho.

New Outlet Assy will be here by friday. I'll replace that and take a look at the temps and even if all is now well, replace the water pump assy later in the day for preventive maint. I know. I'm making almost double the work by not doing both at the same time, but I'd like to make sure which is the bad actor. Water pump is probably all plastic also with plastic impellers. Plastic screws also probably...humor, please.

Yeah, I expect things to last FOREVER and EVER.

 

MY 07 just clocked 45,000 miles. My instinct is to replace the thermostat at 50k miles. I have no idea what the recommended mileage for a thermostat is for our cars but a car without a heat gauge needs special care/precautions says I.
Maybe somebody will chime in on the Jag recommended interval.

 

I would be surprised if those impellers are plastic. Jaguar learned their lesson with those on early XK8s, and I believe they are all metal from the 4.2L on.

 

Two jpgs attached. The first one shows the area of plastic that was broken off which results in the fluid being bypassed directly back to the pump and imho not doing much if any cooling at all.

The result is a engine that runs hotter than it should especially at idle. In my case......the engine runs in the 198-205 * range doing 67mph on the freeway for ten miles in 95* heat.

I used a code scanner to monitor the engine temps. It's a INNOVA 3130 that does just basic things. Does show fuel trim, fuel pressure, rpm, ect, and basic things like that and basic codes. Not much of anything peculiar to Jaguar though.

If I come to a stop for a while, or drive slowly back to the house, the temps rise on up and result in the fan running much harder than it normally would and also results in the fan running after the engine is turned off for approx 10 minutes til the water gets cooled. From what I understand...........the ECU has a pulse width monitor that makes the fan run harder if it sees hotter temps. If the temps are not so hot....fan runs slower and quieter. Frankly in the past I was barely aware of the fan ever running. Must have had a cool engine prior to this minor disaster.

Water pump on order this day along with a new serpentine belt. Might as well do both now and not worry anymore. Everything is clear around the pump so it should be a easy remove and replace. The belt???? Never done one on a XK. Not sure how easy that is going to be. I see where to release the tension but I'm not sure if I can replace the belt with the car off stands (can't get below the car where it sits right now).

Ok, Maybe metal impellers hopefully.

 

Do you have a part number (price too) for the outlet assembly. I may need one.
My thermostat appears to be stuck in that it is heating past 220 while the radiator is comparatively cool.
BTW, Jaguar only offers a single temp thermostat as far as I can tell - 195F.

 

Attached is a email with the part number and the cost of it and shipping.

I order parts from this site 2007 JAGUAR XK Parts - Direct JPLV Porsche Parts.com

I''ve never dealt with my local Jaguar dealers. I've never even visited them except on Sundays when they are closed so I can look at the cars without being bugged.

I origianally order just the thermostat. After doing that I decided to actually go out and look at the thermostat. When I took the cover off, that's when I discovered that the housing for the thermostat was broken and I needed more than a thermostat. So the next day I ordered the whole outlet assy.

After I did that, I got a email from 'them' that the thermostat by itself was not available, so that order for just the thermostat got cancelled. Just in case........the outlet assy has the thermostat included. I got this part an hour or so ago and noticed it also had the waterthermo sensor included with it.

I put the new thermostat (attached to the outlet housing cover) into a boiling pot of water. It works.

Now when I get my new waterpump and serpentine belt friday, I'll be back in business.

Almost forgot...............remember the piece of plastic missing in one of the jpgs I attached in a prior post? I found it when I took the water pump off. It was just sitting there in front of the pump impellers. I'd say I recovered about 85% of that broken off piece.

And, sad to say............the impeller is made of PLASTIC. It's in good condition though. No chips missing etc. But I'm installing a new pump as a precaution and I'll keep the old one bagged up in the trunk/turtle for just in case. Hmmm. I put the wp back in the engine temp, but I remember from the look of the impeller that it looked plastic. I'll revisit this when I get the new pump and if it's not plastic, I'll say so.

 

REY.............if I were you I'd get out there and remove the cover off your thermostat housing (Outlet assy as 'they' call it). I see you live in the northwest and there is no call whatsoever for a car in that area of the country to be running anywhere near those temps.

It could be something as simple as a stuck thermostat or a cracked outlet housing (internal cracking as in one of my earlier pictures). A different temp degree thermostat isn't going to do you any good imho.

On a 2007 XK it's not too difficult to remove the cover off the outlet assy. Remove the engine cover by unlocking it's four phillps screws..........remove the two bolts (8mm wrench/socket size) from the power steering fluid reservior, and lift it up and put it to the side. Then remove the one 10mm wrench size bolt that holds the throttle body air duct in place. It's in the area of the power steering reservior you just removed..........then remove both band clamps off the throttle body air duct and set that duct to the side (it'll still be connected to some other ducts but it still can be set inboard and aft of the area)..................then get a mirror and look at the three torque headed bolts that hold the outlet assy cap in place (find the cover assy by following the large radiator outlet hose on the left side of the car, to the cover). Remove all three bolts and lift the cover to the side carefully (the large hose on it can be left in place if you want to leave it attached. Then just observe anything screwy with the thermostat located inside the cover and then look inside the outlet assy itself to see if that approx 1 1/4" plastic pipe is shattered or broken in any way. See one of my last few jps for what I found on mine.

You'll lose maybe a couple of pints of fluid. Buy a gallon prior to doing the work. Make sure it's the ORANGE colored antifreeze fluid and not some other type.

Check your fluid in your coolant expansion tank for being at the right level. If it is, then grab that upper radiator hose on the right side of the car, and squeeze it several times while watching the 'water' in the expansion tank. If there is air in the hose, then you'll see the level in the tank drop down as the fluid in the tank displaces the air you forced out of the radiator hose. Do that several times with a cool engine and top off the tank to the proper level (indicated on the side of the tank). Do this after you've put the outlet assy etc all back together, not while it's apart. Just my thoughts and nothing more or less.

 

Thanks Hailer. R&Red my thermostat. It is really easy to drain coolant. There is a special access port in the belly pan for the radiator drain. Wanted to check to see if the base housing was cracked like yours. Mine is intact.

I had installed a 180 degree thermostat this April. Wrote about this in the Engines Forum. Jaguar does not make such, so I went through the NAPA thermostat catalog (took a while) to find the best interchange. Settled on a $12 NAPA #166 thermostat, which I installed using the bridge retainer from an OEM thermostat. My modified thermostat is on the left in the attached photo. I should have included the dish-extension (sic) on the OEM thermostat, but its omission did not seem to affect coolant temps which were running thereafter and until recently at 185 or so.
A couple of days ago I noted the fans running on after shut down, an indicator of higher than normal shut down coolant temp. Checked radiator temp with an infared temp. "gun". It was cool indicating a thermostat stuck shut.
After reading your post, realized that I had made a stupid omission in my modified thermostat, so quickly removed the modified thermostat and reinstalled the OEM. I will test the modified thermostat; and will add the OEM dish-extension when I reinstall the cooler thermostat.

 

The way I see things..................in the base of the housing is that Tube. That tube was cracked on my outlet housing.

That 'Tube' lets coolant that has already been passed through the engine block and head, to return directly back to the inlet of the water pump without passing thru the radiator to be cooled. IF the tube is not cracked and the thermostat is working as it was designed, then that Tube is blocked off by the 'disk' on the aft side of the thermostat.

When that tube is blocked off by the aft end of the thermostat (where that disk is), then the water leaving the heads HAS to go thru the top hose of the radiator then thru the radiator and on to the open thermostat and then to the water pumps inlet (cooled water).

So the way I see it..........the water has two ways to get to the inlet of the water pump. If the thermostat is closed, then the water from the heads goes directly to the water pump inlet (no cooling being done). The second path is when the thermostat has closed the 'TUBE' and forces the water from the heads to go to the top hose of the radiator....thru the radiator........on thru the thermostat.........to the water pump inlet (cooled water enters).

So my problem, it seems to me, is the crack in the 'TUBE' was letting water NOT go thru the radiator but instead directly from leaving the heads and on to the water pump inlet with no real cooling being done. Some water was going thru the radiator though 'cause' I'm of the belief my thermostat was open to some extent even it it was laying crooked in the cover. I tested my old thermostat in a pot of boiling water and the 'shaft' of it extended and additional 0.9".

Waiting on my new water pump and serpentine belt, but I'm very tempted to just install the new outlet assy and do the pump and belt another day (the little boy in me I suppose wants to do it that way). I'll probably wait til the new parts arrive. Hate being a 'groatup'. Not as much fun.

 

Problem fixed by replacing the outlet assy. My new water pump and serpentine belt are still in the mail and will get replaced on my own schedule.

For preventive maint, I'd recommend replacing the whole outlet assy and not just the thermostat. It's my belief that my old thermostat was and is ok. It was the internal breakage of the 'tube' inside the outlet assy that cause the overheating. I put the old thermostat in boiling water and it extends as it should. The new outlet assy comes with a new thermostat and a new water thermo sensor or ECT sensor if you will.

It's hard to say if some of my problem didn't come from the previous owner/mechanic. When I got the car the engine cover had a hairline crack on the right side where evidently someone laid on it real hard or tried to remove the engine cover by pulling up on the edge without removing the four phillips screws that hold it in place. I'll never know. I paid a full c note for a new one of those a while back. Couldn't stand knowing it was cracked, even though nobody could see the crack unless they lifted the hood. Bye.

 

How difficult is it to get to everything in the front of the engine given that the hood opens the way it does...

I replaced a thermostat on the 2002 XKR I had without much trouble but getting to the center of the engine from the side would seem to be pretty difficult. Do you have to come up from the bottom?

I would not want to lean on the fender(s) trying to get at the front of the engine area...

 

After following this thread to its conclusion I became emboldened to R&R my thermostat. I went out to the car and took a look.

Dang! That ain't no simple job is it? There is a lot of stuff to get off before you can even see the thermostat housing. I'm reviewing the situation, as the old song goes.

 

I did this in close confines or a one car garage (they still exist!!!). Just opened the hood. Unbolted the power steering fluid reservoir (two small bolts) and set it aside with hose still connected.............Unclamped the throttle body air duct at both ends and disconnected one, one inch air hose connected to it, and set aside still connected to some hoses on the right side of the engine bay.

That takes approx 20 minutes and maybe thirty, but closer to twenty or so. Max.

Now you have all the access that is needed for removal of the complete plastic outlet assy with thermostat included.

Now you have to remove just four high torque bolts. I used a mirror and a short extension with 1/4" drive. The four bolts are at the area of the outlet assy that connects to the left head water outlet and the right water outlet.

I forgot to mention the five water hoses. Two large and the others small. Also you have to disconnect the ECT sensors two wire plug. Big deal.

Once I got those four bolts off and the five hose........I thought that the thing would just drop off. Nope. There is an approx three inch in dia outlet at the rear of the assy that fits over a large o'ring that's on a u shaped duct. So just gently pull and slightly twist back and forth in a fwd direction to release the outlet assy from said duct. Easy peasy as they say.

Personally I'd suggest having the car on ramps in the front and the removal of the undertray. I suggest this in case you drop the high torque tip or one of the bolts/screws. I was very careful and did not drop any.......'cause I knew I had no room to jack the car up to get under it to remove the tray.

Reinstall is the reversal except be sure to use vaseline on the o'rings or kyjelly on them, one.

If you look at my post number one, I attached a jpg from Gaudin Jaguar that shows this U shaped duct that the assy attached to. I did NOT replace this u shaped duct. I even left its original o'ring on that duct. I have no fear from doing this although I know it's not a good practice out there.

I got up at 4am saturday and was through with this job before 6am which included reinstalling the water pump that I'd removed earlier for inspection and adding water and starting the engine. The water pump does not need to be removed to do the outlet assy replacement. I now have a spare/new water pump that arrived late Saturday care of UPS, and it now sits in the turtle/trunk with my spare drive serpentine belt.

I'm sure that is no record for replacement of the assy. Just was being careful and working in a very confined place.

I have no idea what I'll do with those parts when I break down in Canada. I think the belt has to have the undertray removed for replacement although I think if one is sneaky he can do it from the top with the throttle body airduct removed and maybe the return hose from the radiator disconnected. Maybe. And you'd need a breakover or long ratchet to remove the tension from the belt.

I'm going to remove and replace those parts in the fall when it's cooler. They won't break before then 'cause', I feel lucky.

From my observations this car runs at 197-200* at 67 mph in a 60mh zone (safe ticket speed on my loop 820 in Ft Worth. Can drive right past a radar guy and he won't even notice). Idles at 203* sitting in my driveway and the fan does not come on anymore when I park it after a drive. I've driven in the deserts of Ca/Az/Nm and stopped to gas up in the past and the fan NEVER ever came on. I don't expect it to come on in the future.

So I know for sure it was the busted plastic piece inside the outlet assy that cause the problem and not the water pump (still using the old one for now). And I know why the busted piece cause the overheated condition in the driveway. Not guessing.

And yes, the water pump impeller is indeed plastic. They never learn it seems.

 

How did you get the thermostat housing out ?? I have been looking at this for an hour with only option to get to the bolts would be removing the intake manifold .And I dont wanna do that .. Any suggestions or a diagram on what must be removed ???

 

The pictures are from the manual for non supercharged cars. I'll add to this in a few minutes. I sure as heck did not remove the intake manifold. I used a mirror and sockets with and extension. I did remove the intake duct. I'll go look at my car. Later.

I added a phot called SIX. You have to remove the large black duct. When you do you need to lift the ?? fluid reservior on the left out of the way so the duct can be removed. You also remove the metal intake part on the inboard end of the black duct. Just three long bolts and move it out of the way.

On the right side of the coolant intake manifold there are a couple or three small vacuum tubes. Do not abuse them like I did and have to repair the one I broke. I worked with a mirror a lot doing this and feeling with my fingers.

I DID A NON SUPERCHARGED CAR. NON SUPERCHARGED. SUPERCHARGED IS DIFFERENT IN MANY WAYS.

TWO OF MY PICTURES ARE OUT OF ORDER TOWARD THE END OF THEM.

I'M LAZY AND DID NOT DRAIN THE COOLANT. I LET IT FALL WHERE IT MAY. IT'S NOT THAT MUCH FLUID TO BE LOST.

 

Hailers, Thanks for the post. This was exactly what was going on with my XK - I replaced the water pump and the outlet assembly. We found the broken piece lodged against the water pump impeller.