Hello all. So a little back story, in January the car kept going in restricted performance randomly. Got it checked by my mechanic and said it was a faulty supercharger coolant pump. I got it replaced, but keep in mind I got all maintenance stuff including the pump, water pump, thermostat, etc replaced in 2017-2018. So I got the pump (Bosch 010) replaced again, and it didn’t make a difference. Gave him for further diagnosing and he couldn’t figure out. In March and April I took it to two difference jaguar dealers, one said to replace thermostat which I did and didn’t do anything. The other said to replace catalytic converter on driver side, which I did as well and of course it didn’t do anything. Fast forward this past week, I dropped it off again at my mechanics place he finally figured it out. It was a water pump restricting flow. Upon removal, he noticed radiator was disintegrating and plastic pieces from it were in the cooling system. I said go ahead replace it as well. So all together I got the water pump, thermostat, and radiator replaced. Picked it up yesterday and was fine. Today on my way home from work, I noticed it was pulling like it supposed to (nothing dramatic), I ignore it and keep going. I stop at the bank and when I do my same issue starts again, fans blowing high speed. So I get home let it idle and fans start blowing on high again. Pull out my OBD scanner and no codes, but the engine coolant temp was at 240 DEGREES! The only difference now is it doesn’t go into restricted performance. I’m really fed up of this issue and it makes the car undriveable obviously. I’ve spent too much money to give up, but after giving it to multiple dealers and mechanics, I’m really giving up. Just now I’ve spent $1,100 on the new water pump and whatnot. Anyone know what could be the issue?

I just honestly feel it’s the thermostat because when I accelerated to 2-3k rpms while idle my temp dropped from 240 down to 205. I kept accelerating for a solid 5 minutes even on and off and I heard the thermo click once and it dropped down to 203 right when it clicked, but that’s it. It wouldn’t budge down 205. Overall during the whole 15-20 minutes it was idling and overheating I heard the thermo click Twice total, once when it dropped to 203 and once a little while before that.

Thermostat is Murray brand
Water pump is Import Direct brand
Radiator is Original Jaguar brand, ordered straight from dealer

Also I’ve got almost all major stuff completed within the past 2-3 years including the cross over hose and other pipes, spark plugs, supercharger oil change, water pump replaced 2x, thermostat replaced 3x, supercharger (Bosch) pump replaced 2x, and much more stuff.

 

My advice: Go OEM for the thermostat. I had a non-OEM one (MotorRad?) and it leaked around the joint. Tighened the screws which stopped the leaks there but found others at hose joints. Swapped for OEM and I noticed my engine oil temp runs a good 20-30 degrees cooler now.

 

The one I replaced 2-3 years ago was OEM, it was due to the one in the car being stuck open. And then I just replaced in April again due to the dealership saying that’s the cause. I ordered that one from Suburban Auto Parts, and it was a Jaguar part but I’m not exactly sure it was an OEM part. And then one just replaced yesterday was by Murray, as I thought at this point it doesn’t matter.

Do you really think it might be the thermostat not being OEM? I mean I know you won’t know for sure, but according to my symptoms you think so?

Its cheap enough, and easy enough to replace. The only hard part was getting it put in, due to the tension from the spring. But it’s not that bad. If that’s the case I wouldn’t mind replacing it again with OEM.

i appreciate your help

 

Honestly, it's hard to say - I'd also wait for someone who knows the 4.2 engine/cooling system as my experience is all with the 5.0.

I know it's a nasty thing to think about but it's possble there's a piece of plastic that's made its way somewhere it shouldn't have, blocking a cooling galley in the block or something, but let's hope you're not at that point.

Is your coolant level staying fairly stable? I assume no obvious leaks/burning coolant.

 

It could be very possible, as I said earlier he found upon removal of the water pump that the radiator had disintegrated and he found plastic pieces in the cooling system. So it might be possible that a chunk is still in there and it’s blocking flow.

Also there are no leaks at all, no smell/burning or anything either. And surprisingly it doesn’t go in restricted mode or act silly this time either

 

Just another good car being killed by plastic components in the cooling system running at 200C its whole life.

The entire cooling system is suspect, there could be plastic trash anywhere restricting flow.

 

How many thermostats are there on this beastie?
On my old x-type there was an oil cooler thermostat which caused cooling problems

 

I think on your car there are two pumps one above the other. One is for the heater, the other lower one is for the supercharger. Are you sure he changed the correct one?

https://www.jaguarforums.com/forum/x...solved-172713/