Howdy! I am the proud owner of an 03 XJR, but recently have had an issue with what seems like overheating. After driving/idling in town for about 15-25 minutes, the temp gauge goes from normal, and slowly climbs up to red, then will drop back down to normal and stay stable. From what I can tell it seems to tend to only do this at idle, though the first time i noticed this behavior it happened while i was cruising at about 45mph. Not sure whats going on, i dont get any check engine lights. No warnings or shutdowns, no limp mode activation. Though i have noticed what i suspect is a coolant leak from the front of the car. It must be very slow because i dont see it drip after watching for about 10min, but overnight a small puddle will form near the front of the car. Im going to try and scope out the leak, but i also took the liberty of ordering a new thermostat which i have read can be an issue in these cars. Beyond that what could be causing these odd spikes in heat? Im thinking maybe a water pump issue? Beyond that, maybe fan problems? Im praying its not a head gasket but I have read that those can cause temp issues as well, but my oil looks normal, if a little low, (its about time for a change anyway) and I havent observed any steam/white smoke from the tailpipes.

Any suggestions or similar experiences? Any tests or other things i can check to pinpoint this issue? Any help or ideas are appreciated, thanks!

 

Before I got to the suspect coolant leak, I was thinking the water pump. Especially with it only doing it at lower RPM.
But I am more suspect of the 2 coolant lines running under the SC. They are notorious to make you scratch your head figuring where the leak is coming from. If it is these, its remove the SC time.
Be sure your reservoir is topped off and how much your putting in.
Check your oil to see if water may have gotten into it. This would be the telling sign of a head gasket, but I'm seriously doubting its the issue.

 

Thank you for the input! Seems like m odd choice to run coolant lines under the SC, but I will check it if it comes to that. I think I might just do the water pump too anyway since they’re not terribly expensive.

 

Just keep in mind, she is 17 yrs old....barring regular maintenance.

 

After replacing the thermostat the overheating issue continued to persist and I found out that the leak was not, in fact, coolant, but oil. So i elected to take it into a shop to get it diagnosed. Turns out there is indeed a coolant leak from the water pump, an oil leak from the hoses in front of the vehicle, and another coolant leak in the back. The shop wants to charge me $1600 to replace all the hoses and the water pump, quoting me $400 to buy the water pump...Ummmm is that the same as the water pump i see on Rock Auto and PartsGeek for $20-$80???? I asked him if these fixes would solve my overheating issue and he said he didnt know, so I kindly requested he see if we can patch those leaks without ordering and redoing all the hoses, and that I would source my own water pump. So now I find myself asking, are these cheap water pumps what I need? or do i need the OEM one from jag he was telling me was going to cost me $400?? And about these leaks, how difficult is it to get to the hoses in the back toward the firewall? are these things i can swap out myself? Im no stranger to turning wrenches, but if its a matter of pulling out and putting back a bunch of parts rather than pulling and swapping a hose, id rather have the shop do it in a much more efficient manner. Anyone have experience with this? anyone have experiences with getting shops to charge what at least seems like an exorbitant amount for parts that appear to be cheaper?

 

Also I think i should note the shop did not seem to think the head gasket was an issue so that is a positive...no telling if they actually tested the oil or coolant tho.

 

They probably tested the oil,...pulled out the dipstick to see if there was any white residue on it...tested.

The water pumps are pretty much the same. Places like Autozone, O'Reilly's, etc...charge extra for a longer warranty and they are probably sourcing from the same places your looking. As long as it has the metal fins in it, your good. OEM came with plastic fins and were notorious breakers.

For the oil leak, you need to be a bit more specific on where the problem is...a pic would be nice.

Now for the $1600 for all...and that's if its "all" the hoses. That's gonna be mostly labor to remove the SC to get to the 2 lines running under it.

Yes, you can do any and all this if you have the mechanical ability. I suggest you find and download the... X308 Workshop Manual. Its too large to attach here, but there's a link or 2 to someones Dropbox or the like.

 

Well I have ordered a new water pump and we will see what i can do about the leaks myself. Should be interesting, but at least I wont be dropping the $1600 they wanted to MAYBE fix the problem haha Hopefully with the water pump and and thermostat replaced i wont be overheating at least.

 

Meant to ask before...is your thermostat housing plastic? The replacements are metal because the plastics tend to crack.

 

No its the metal housing, it looked to be in great shape, no cracks or anything so I just swapped out the thermostat only. The shop quoted me $100 for that job I about fell out of my seat. Its 3 bolts in open air....

 

Yeah, some techs think they have you over a barrel. Heck, my tech is a full blown Inde' Jag Tech and doesn't charge that much.