XJ XJ6 / XJR6 ( X300 ) 1995-1997

Replacing the thermostat on an XJR

Old 04-02-2019, 05:13 PM
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Default Replacing the thermostat on an XJR

Hi there,

I've got an 95' X300 XJR that I need to replace the thermostat on, however I can't find any instructions for the procedure online. Can anyone help me out?

Thanks in advance!
Old 04-02-2019, 10:46 PM
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Lots of writings here. The most recent ones are
Nothing special, just buy the right thermostat with the gasket (sold separately), tighten slowly and evenly without breaking the housing; the procedure might take five minutes.
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Don B (04-02-2019)
Old 04-02-2019, 11:24 PM
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Hi Shinda's XJR,

Here are a couple of images that may help. First, the parts diagram:

And here's a photo showing the location of the thermostat at the front left corner of the camshaft cover, just above the supercharger belt idler pulley:

A few tips:

The thermostat spring goes into the housing, not the cover.

The jiggle pin or small hole in the rim of the thermostat goes up at the 12 o'clock position.

If the thermostat will not sit in the housing while you install the cover, you can apply three or four small dots of RTV silicone sealant on the rim of the thermostat and hold it in place for a few minutes until the sealant will hold it in position while you install the cover and gasket.

If your new thermostat comes with an O-ring, do not use it. Use only the flat gasket shown in the parts diagram or the thermostat cover may crack when you tighten the screws.

While holding the cover in place, alternately tighten the screws a little at a time to keep the pressure even, then torque them in two or three steps to 21.5 - 28.5 Nm or 16 - 21 ft. lbs. per the factory Workshop Manual. I personally aim for the middle of that range, 18 ft. lbs., which is plenty. You don't want to strip the threads in the thermostat housing.

If you have trouble getting the cover and gasket aligned while installing them, you can either put the screws through the cover holes, slide the gasket onto the screws, then offer up the whole group to the housing, or you can apply a few dots of RTV silicone sealant around the outer edge of the gasket and "glue" it to the thermostat cover to hold it in place while you carefully place the cover in position and install the screws.

When you disconnect the thermostat cover, some coolant will spill out. If you'd rather not have coolant spill all over your drive belts, you can place a catch pan under the right edge of the radiator, disconnect the upper radiator hose from the radiator and aim it into the catch pan while the coolant drains. Now only a minimal amount of coolant will drip out when you disconnect the thermostat cover. If you want to drain even more coolant to do a partial coolant change, you can disconnect the lower radiator hose instead.

Of course, be sure to top up the coolant once you have the new thermostat installed.



Last edited by Don B; 04-02-2019 at 11:33 PM.
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MountainMan (04-04-2019)
Old 04-03-2019, 01:10 AM
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The attached PDF document may assist.

John Herbert
Attached Files
File Type: pdf
Thermostat Replacement.pdf (1.62 MB, 4 views)
Old 04-03-2019, 02:44 AM
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Hi guys

Thanks for the replies, some great information there. I’m loving being apart of this forum, so much knowledge from so many people! I’ll let you know how I get on. Just one other thing, does anyone know where the radiator drain plug is? I want to give it a flush.

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