1999 XJ Thermostat change.

Does the 1999 XJ have a radiator drain plug? If so, where? If not, is disconnecting the lower radiator hose the only way to drain the radiator? Also, any advice on changing the thermostat. Thanks

if your just changing the tstat then no need to drain all the coolant, ive just put the drainpan under the frt of the motor and just pulled the tstat housing

The drain is on the bottom, passenger side of the radiator, on the actual side of the radiator itself. It's in a pretty stupid location, IMO. I find it easiest to get to by removing the front passenger turn signal and taking a set of long needle nose pliers. I also have a long piece of hose I attach onto the drain that runs into a bucket to minimize mess.

It can be done by just removing the tstat (you'll only lose a bit of coolant). Just make sure to atleast take the radiator cap off to release any pressure. However if your coolant hasn't been changed in a while, now is a good time to atleast do a good drain and refill on the whole system.

One other thing, drill a small (1/16") hole in the 12 o'clock position of the lip that goes around the thermostat. This will help the air work itself out quicker when you go to put coolant back in it!

Attempting to open the radiator drain plug most often results in breaking it and then installing a new radiator. The opening is tiny and it take forever to drain.

Removing the lower radiator hose to drain the cooling system is faster and safer.

UNCC_99XJ said:

One other thing, drill a small (1/16") hole in the 12 o'clock position of the lip that goes around the thermostat. This will help the air work itself out quicker when you go to put coolant back in it!

Click to expand...

Or just go to the dealer and get the proper T-stat, with the check-ball in it.

No need to do a total drain for a thermostat installation. However, that may be a GREAT time to freshen the antifreeze. So unless the coolant is relatively new, I'd recommend draining it. And the ONLY way I do it is to remove the lower hose. Forget that stupid petcock. Terrible design and location. Use a 50-50 mix of coolant to distilled water, or buy premixed. Use conventional (green) coolant.

I like stats from Jeep and also the Stant SuperStat. 195 degree only.

Also a good time to review all other cooling system components. Radiator, radiator cap, water pump, fan clutch, serpentine belt, all coolant hoses.

birchlakeXJ said:

No need to do a total drain for a thermostat installation. However, that may be a GREAT time to freshen the antifreeze. So unless the coolant is relatively new, I'd recommend draining it. And the ONLY way I do it is to remove the lower hose. Forget that stupid petcock. Terrible design and location. Use a 50-50 mix of coolant to distilled water, or buy premixed. Use conventional (green) coolant.

I like stats from Jeep and also the Stant SuperStat. 195 degree only.

Also a good time to review all other cooling system components. Radiator, radiator cap, water pump, fan clutch, serpentine belt, all coolant hoses.

Click to expand...

I can not express how important it is to use steam distilled water in the cooling system. The only way to prevent scale buildup is to use distilled water as all of the minerals are out of it.

A 195 T-Stat for the stock cooling system. It must have an air bleed so either buy one from Jeep or drill a .125" hole in the T-Stat. Be sure to install it with the bleeder at the top.