i bought a 2000 jaguar s type 4.0 was told that it needed headgaskets, after the tear down there ended up being broken valves..long story short i ended up just buying another motor. put it in and is overheating. since then i have replaced the thermostat, checked water pump multiple times, secondary water pump, radiator, gutted the cats, checked all hoses, bleed the system multiple times. one night i thought we had all of the air out of the cooling system, drove it around wouldnt overheat but it still did not have heat. next day drove it down the road and it overheated. Has anyone had this problem, i mean what ever cause the last motor to overheat is causing this one to i just done know what the hell it could be!!! spent hours and hours on this thing, i have brought it to a few mechanics NO ONE KNOWSS!!!

 

i forgot to add that the headgaskets are good.

 

If you're sure all air was bled out of the system (heater core, etc.), thermostat is opening, then air may be sucking in from a coolant component i.e. loose gasket, hole in hose, etc. The problem is staring you in the eyes. Did you have the heat on whilst purging air from system? How does the coolant expansion tank look?

 

To add to brother bfgross - please explain exactly how you "bled" the cooling system - because on the 4.0 V8 - there is a specific procedure (as listed in JTIS) including utilizing the air purge bleed hose near the master cylinder. If you didn't utilize this air purge hose during the bleed process there is your issue.

Also, was the cap on top of the thermostat housing tightened up properly to 9Nm BEFORE bleeding the cooling system?

I can tell you from experience the cooling system bleed process on the 4.0 V8 is a lengthy one - keeping close watch of the coolant level in the expansion tank.

Finally - the expansion tank might have issues like a hairline crack or a break at one of the hoses leading away from the expansion tank.

Help us help you - good luck

 

Het htes311, i had a similar overheating issue I was getting no heat and my sensors were all fine so I thought it was the

 

sorry I pushed wrong button anyway as i was saying I thought it was my heater core but that was clear. well it was my heater control valve, so I removed it dismantled it and cleaned it out. one of the ports was stuck i got it to working again just by cleaning it. well I had to refill with antifreeze and purge the system and I still did not get any heat and then a few hours later it started over heating. i did not do it according to JTIS but used the basic fill while running but was told to jack up the car on the driver front side so that the elevation will cause gravity for the complete system to fill and I did that turned the car off a couple of times for a few minutes for settle and started it again while it was still elevated and the temp. gauge went down to normal and heart started blowing hot again. I know it may not be the complete correct way but it worked for me