Hi:


I have a 2003 VJ8 VDP with 75,000 miles. I stored the car for the winter for about 4-5 months. I just took it out of storage (outside temp around 35F, sunny & dry). The engine started right up and purred like a kitty as it always does. I let it warm up for 5-10 minutes and noticed that engine temp was about mid scale. I then proceeded to take the car for a nice drive home (about 50 miles). I noticed that the temp wasn't blowing warm and when I looked at the temp gauge it was at the top of the blue range. It never warmed up the entire drive home. The car drove well, had plenty of power, got decent gas mileage, etc. just never warmed up. It was working fine when I put it to bed for the winter.


It seems to me that the thermostat must be stuck wide open (I have no idea of how old the original one is but the previous owner took very good care of the car). I'm a good mechanic but the Jag is new to me. Any thoughts. Should I just order a new thermostat as a first step? Are there other things that I should do at this time? Any comments, tips would be appreciated.

Thanks!

 

It sounds from what you say that everything is completely normal except you might have a partly blocked heater matrix, so you're not getting decent heat into the car. This is quite a common fault on the X350 series of cars and whilst people have succeeded in getting it flushed, a lot of them need a new matrix. However, as your car is a 2003, my question is - have you got the steel (X308 series) or the later aluminium car (X350 series) ? Reason I ask, is I am sure these weren't on sale in the US until early 2004, but I may be wrong.

If your car wasn't warming up I'd expect heavier fuel consumption, as the ECU main inputs are engine temperature and mass air flow.

 

Yes, stuck thermostat. The lack of cabin heat is an analogous symptom to the gauge reading.

 

I would also check coolant level. Low coolant can also give these symptoms

 

Are you by any chance having a CEL display? If so, a P0128 would indicate a stuck thermostat. That's what happened to my car a few months ago. If not, I would tend to think it's a heater matrix issue.

 

Hi guys:


Frasier Mitchell, I think you are correct, I have an X308 97-2003 version XJ8, not the newer X350 2004 on version. I will move my thread over to the correct Forum.


I did check the coolant level and it is fine. I will also check for codes indicating that the thermostat may be broken. I don't think it is the heater matrix (is that the same as the heater core, i.e. cabin heat exchanger?) since the engine itself is not warming up.


Best regards!

Tom

 

Hi:

I have a 2003 VJ8 VDP with 75,000 miles. I stored the car for the winter for about 4-5 months. I just took it out of storage (outside temp around 35F, sunny & dry). The engine started right up and purred like a kitty as it always does. I let it warm up for 5-10 minutes and noticed that engine coolant temp gauge was about mid scale. I then proceeded to take the car for a nice drive home (about 50 miles). I noticed that the heater air temp wasn't blowing warm into the cabin and when I looked at the coolant temp gauge it was only just at the top of the blue (cold) range on the scale. It never warmed up the entire drive home. The car drove well, had plenty of power, got decent gas mileage, etc. just never warmed up. It was working fine when I put it to bed for the winter.

It seems to me that the thermostat must be stuck wide open (I have no idea of how old the original one is but the previous owner took very good care of the car but it's possible it could still be the original unit. I will say that the coolant looks clean/clear). I'm a good mechanic but the Jag is new to me so I wanted to get the advise of you all before doing anything. Any thoughts. Should I just order a new thermostat as a first step? Is the thermostat replacement a straightforward process or are there special tricks I need to be aware of?


Are there other things that I should do at this time? For example, I have heard that the transmissions are prone to having problems on these cars and was thinking of changing the transmission filter & fluid as a precaution (an old transmission specialist told me to change the tranny fluid in my cars every 50,000 miles which would make a big difference in transmission life. I have also heard that the timing chain tensioners can wear out but that the 2003 model had the latest 3rd gen tensioners that have solved that problem. Is that accurate or do I need to look those over?


Any comments re the coolant temperature and other tips would be appreciated.

Thanks!

 

Dupe

https://www.jaguarforums.com/forum/x...arm-up-139735/

 

While you are in there anyway, it would be a good idea to also replace the plastic thermostat housing, since they routinely deteriorate and begin to leak.

 

My XJR did that last year. It was the thermostat. Cheap and easy fix.

 

There is a good chance you will crack the plastic thermostat housing, brittle with age. Replacing with aluminum is a good idea.

Just break the old one up using vise grips to make it easier to remove the rear screws and replace with socket head screws which can be tightened with a ball driver. Harbor Freight has a reasonably priced set.

Stuff a rag down the water passage to keep pieces out but don't forget it. Replace those old hoses while you're at it, and the cross pipe.

 

SNG Barratt has the aluminum housing at a new lower price of $39 shipped without thermostat. Paint it black. If left shinny aluminum it will corrode like the other aluminum.

Jaguar XJ8 XK8 uprated Aluminum Thermostat Housing Kit AJ82217 100 Feedback | eBay

Once opened and the coolant drained all the replaceable parts in the cooling system should be replaced on a 12 year old car.

 

Much appreciated! I'll give the thermostat a try and install the new housing & hoses as needed.


Best regards!

Tom

 

Tom,

I have moved your thread from the forum for the X350 to the forum for the X308, and merged both threads into one.

Cheers,

Don

 

If the engine isn't warming up then the thermostat is staying open and it is cold outside.
If you don't get heat after changing the thermostat you can have a blocked heater core
or the aux heater pump may be bad or the heater solenoid valve may be stuck. It is good to exercise these regularly or they stick. All these are located near the left side
firewall. Not easy to get to, but not impossible.