I have a 2000 Vanden Plas XJL. I'm the second owner and it has 80,000 miles on it and it's in mint condition. LOVE the car as I always wanted a Jaguar and now that I own one life is GOOD. I've replaced the thermostat, waterpump with new metal impeller, new improved timimg chain tensioners, and radiator hoses. All preventive maintence. Now recently I've developed an "Engine coolant low" light coming on after about 50 miles. I'll put in about a two to three cups of coolant in the coolant tank, but then 50 more miles the SAME THING happens. I've checked and checked for leaks but I can't seem to locate any. I can smell coolant but no leaks. The car does not overheat but I can't trust it on trips longer than 50 miles. Any suggestions for a newbie? The dreaded octopus?

 

testpoint will recommend at this point that you pressure test your system if driving it and/or running the car in the garage cannot help find your leak.

If its leaking that much, you should be able to see a visible leak.

feel under the reservoir tank, is it wet? look at the rear of the throttle body...there are several points that the engine block lines connect to the heater hoses (your octopus). Green or orange colored residue should be present somewhere on the manifold/engine where it has been burning off, depending on which type your car is using. check the thermostat tower and around the water pump that you replaced (and under)

keep us informed of your progress!

Welcome BTW, and I'm moving your thread to the XJ subforum, as its a tech question and the new member area won't get you the kind of responses that you're looking for.

 

I suggest you check the archives for the post with pictures of the corrct placement of the small pipes leading to the pressurized resevoir. Basically, the one leading to the overflow tank in the wheel well can get crossed up with the one leading back to the engine. The higher one, one the front side of the tank that leads from the tank neck area goes to the wheel well. It crosses over the other port on the front and is easily swapped. if that is OK, then a frequent leak is a deteriorated riser/ thermostat housing. There are metal ones available online to replace the plastic one that is from the factory.

Oh, AND WELCOME TO THE FORUM.

 

welcome aboard looks like you're in great hands

In the meantime I've manually upgraded you to full forum access so you can better view the site

 

This forum is a Jaguar owner's gold mine. Thanks for all the tips. I'll keep you posted.

 

Okay, I took it a reputable local import mechanic to get a pressure test done on the coolant system to try to find the leak. The hoses were all in the correct place and no leaks were found. However, he did a check for exhaust gases in the coolant and sure enough it turned from blue to yellow real fast. So I have a blown head gasket. Now just for everyones benefit of my experience the symptoms were loss of coolant with no obvious leaks and no overheating. The car ran great with no steam coming from the exhaust. I did notice some bowing of the top of the cap on the overflow reservoir and the bottom of the holding tank by the front drivers side bumper was wet with coolant. I now know most of it was going out of the exhaust but some of it was going into the holding tank and then overflowing due to the pressure building up inside the coolant system. The mechanic said it looked to him like a previous owner or mechanic had put some temporary sealant in it in order to try to "fix" it and now the sysmptoms have returned. Thanks to all who responded and I hope this helps another Jaguar owner with a similar problem.

 

Hi RON WMS.

I have a Jaguar S-Type, and I had the exact same problem. I think I know what might be happening with the loss of your coolant. Check the cooling resivior bottle. Is it make of Plastic? You can check this by removing the fill cap, and just looking at the top of it. It would be a lite colored hard plastic. These bottles are notorious for cracking, and leaking coolant. The coolant cycles thru it, and your engine. IF you fill it, it seems to hold the fluid. Rather deceiving. WIth the pressures from the engine running, and the cap closed shut, the crack opens up, and dissipates the fluid rapidlly.

Give it a check, see if thats what is causing it. Worth a shot.
David Sepulveda
San Antonio, Texas

 

Thanks David. I did check that because that would have been a really easy and inexpensive fix. Believe me I WANTED that bottle to be cracked. Unfortunetly that was not cause of the bottom of it being wet. What was happening was pressure was building in the coolant system from the exhaust gases leaking from the blown headgasket and that would cause the coolant to go into the reservior tank and leak out of the hole in the side. This was then dripping into the driver's side wheel well. But with the excessive heat from the Florida roadways most would evaporate before I got it back to my garage to check it. No milky oil, no foam on the oil fill cap, ran smooth, no steam from the tail pipes, just coolant loss with no obvious leaks. Apparently it's small enough to cause coolant loss but not big enough to make the engine run rough. I think I'll have him fix both sides just so I don't have trouble with the other side in the future.

Ron Wms
2000 Vanden Plas

 

Ron, our 2005 S-Type 4.2 has similar symptoms and I am guessing we have similar coolant components based on your description. Dealer replaced a leaking reservoir in March, under warranty, but we recently got the warning light again. This time we see the repeating loss of coolant, the smell, no discernible leaks, liquid/moisture in the passenger side tailpipe (but not the driver's side), and no foam in the oil.

So, from your post, I assume ours has a leaking head gasket on the one side.

Any advice, or useful comments from your mechanic, based on your experience getting it fixed, after your August post? Cost?

We have about 70K miles.

 

The S-type has a plastic thermostat housing with a bunch of hose connectors that is prone to tiny hairline fractures. That is more likely to be your (much less serious) problem. See https://www.jaguarforums.com/forum/s...ak-help-46770/

You should have a pressure test done before replacing parts, however...there are many other possible leak points also.

 

That is a real bummer Ron. It sounds like somebody put some stop leak in it and dumped it on you. It may have suffered from the plastic water pump and overheated to the point of no return. Best of luck.

 

Unfortunately, the early cars suffer from the plastic water pump vane problem.

The dealers recommended replacing them years ago. Those not taking that advise could easily have a pump not supplying proper flow but also not being bad enough to elevate the coolant temp sensor -- you get hot spots that stress all the components.

While the later cars do occasionally suffer from hose/ plastic component problems -- it is the early cars -- not properly upgraded that make up the bulk.

And you absolutely don't want to have an overheat situation.

 

Srry to hear about your car, im going through the same thing right now. Pretty bumed out and not sure what to do since i cant afford the repairs right now.

 

White XKR, thanks. You were right on target. As info for others:

Thermostat housing replaced by dealer (~$500). I could see the hairline crack after you commented, but it was not obvious. Unfortunately, the dealer puts the OEM back on. I'm surprised there is not a TSB on this.

I'm still not clear why I was seeing moisture in one tailpipe (fully hot engine). That has not appeared as I've rechecked, however.

 

303-54
V8 XJ Series/XK
DATE: 06/02
MODEL
1997-2002 MY XK Range
1998-2002 MY V8 XJ Series
VIN
001001-A30161
812256-F55733
Overheating - Thermostat Stuck Closed - Revised Thermostat Available
Issue:
Some V8 engines in XJ and XK vehicles within the above VIN ranges (prior to engine number 0203230140) may experience overheating due to the thermostat sticking in the closed position. A revised thermostat with a more robust wax bulb is now available.
Action:
On a customer complaint basis only, follow the workshop procedure outlined below.
WORKSHOP PROCEDURE
1. Open the hood and place protective covers over the fenders.
2. Raise the vehicle on a lift.
3. Place a suitable tray under the front of the vehicle to catch spillage.
4. Drain the coolant from the radiator.
5. On normally aspirated vehicles only, remove the engine covers.
6. On all vehicles, release and reposition hose clip from thermostat housing coolant pipe.
7. Disconnect and remove the coolant hose from the thermostat housing.


This was taken off of all data, jaguar recall ..