1998 Jaguar XJR

1998 Jaguar XJR

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Discussion

LeBlanc

Original Poster:

2 posts

1 month

Friday 3rd July
quotequote all
Hey! I have an overheating issue 98 XJR. Suddenly after driving temp rises quickly into red. No hose leaks, changed thermostat. Coolant flowing through rad, both fans coming on. Rad hoses are both 2/3 way up on rad not top and bottom. Should I rad flush? Where is a drain plug? I suspect sludge so not circulating properly. Can’t find drain plug and what’s best method to flush?

Jaguar steve

6,453 posts

166 months

Friday 3rd July
quotequote all
Rad drain is small plastic key on bottom left of rad. Remove expansion tank cap remove thermostat housing cap (carefully very delicate), and drain open key and drain.

Remove water pump and check impeller is intact. Replace or renew. Remove feed and return pipes and flush through radiator with running hose and drain. Remove heater matrix feed from aux coolant pump and flush through and drain. There is a plug on the o/s bottom of the engine block. Remove and drain.

Reverse flush everywhere where you can with the hose. Connect everything back up.

Fill through the thermostat cap with 50:50 mix of orange long life coolant until full. Fit cap. Continue filling through expansion tank till 2.0 cm from full. Squeeze hoses to expel trapped air then top back up.

Start engine with expansion tank cap off. There should be a steady stream of bubble free coolant from the small radiator return hose into the tank. Run engine with heater on max 'till there is then replace cap.

Continue running engine. Heater should increase temp very quickly. Check thermostat opens by sudden increase in temp of top hose and continue 'till fans kick in - there's two speeds - and heater is really hot.

Allow to cool then check for leaks and expansion tank level.

If overheating continues suspect rad blockage or head gasket failure.


EddieJT

35 posts

67 months

Saturday 4th July
quotequote all
Now that's what I call a response!

I'm going to make note of this myself if ever needed.

groomi

9,239 posts

199 months

Saturday 4th July
quotequote all
Jaguar Steve has covered it comprehensively.

The water pump impellors were known for failing.

Jaguar steve

6,453 posts

166 months

Saturday 4th July
quotequote all
groomi said:
Jaguar Steve has covered it comprehensively.

The water pump impellors were known for failing.
On earlier engines especially.

Engines were revised in late 1999 for the 2000 MY from AJ26 to AJ27 spec which included an upgraded pump. If your VIN number ends in five and not six digits you have the later engine. In any case it's simply drain cooling system, belt off and six bolts to remove the pump so still worth checking.

Temp gauge on the X308 is software driven for consistent readings and is not a true reflection of actual engine temperature.

LeBlanc

Original Poster:

2 posts

1 month

Sunday 5th July
quotequote all
Jaguar steve said:
Rad drain is small plastic key on bottom left of rad. Remove expansion tank cap remove thermostat housing cap (carefully very delicate), and drain open key and drain.

Remove water pump and check impeller is intact. Replace or renew. Remove feed and return pipes and flush through radiator with running hose and drain. Remove heater matrix feed from aux coolant pump and flush through and drain. There is a plug on the o/s bottom of the engine block. Remove and drain.

Reverse flush everywhere where you can with the hose. Connect everything back up.

Fill through the thermostat cap with 50:50 mix of orange long life coolant until full. Fit cap. Continue filling through expansion tank till 2.0 cm from full. Squeeze hoses to expel trapped air then top back up.

Start engine with expansion tank cap off. There should be a steady stream of bubble free coolant from the small radiator return hose into the tank. Run engine with heater on max 'till there is then replace cap.

Continue running engine. Heater should increase temp very quickly. Check thermostat opens by sudden increase in temp of top hose and continue 'till fans kick in - there's two speeds - and heater is really hot.

Allow to cool then check for leaks and expansion tank level.

If overheating continues suspect rad blockage or head gasket failure.