1998 XJ8 Im having a problem when I shut the car off it overflows into the expansion tank then all over the ground. It does it weather I drive it far or short distances. Its not getting hot as my scanner and temp gauge say the say thing and the fans are kicking on. The only thing I have changed on the coolant hoses that I could think would cause a problem is the one from the radaitor to the coolant tank. The little fitting broke so I just put a heater hose with hose clamps on it. Its not leaking or anything but Im thinking that maybe there was a check valve or something in the factory one. Does anyone know if this is the case or could think of anything else that would cause this? thanks in advance Jeremy

 

Either the rad cap is defective and not holding pressure, or you're overfilling the expansion tank.

 

Hello Smitty,

The overflow to ground is from the atmospheric catch tank which is situated down the front left of the wheel behind the splash guard.
Your repairs won't have anything to do with this problem.
These lines had no check valve.
Just check to make sure you haven't crossed the connections which can happen quite easily and will cause the coolant to dump.
If your connections are right, start looking at other possible causes.
The pressure tank cap should be replaced every two years when the coolant is flushed and replaced.
So should the thermostat.
These are both classified 'service' items.
It's an easy job to check/replace the water pump, which on your model should be the latest spec.
Correct coolant level in the expansion tank at dead cold is just the bottom of the filler neck and no more.....over fill and it just goes tot he catch tank which syphons back into the expansion tank as the system cools.
The expansion tank has three connections:
1. Inside one facing the throttle body has line leading to thermo tower.
2. of the two connectors on the front edge of the tank, this is where it's quite to mix up connectors......I have added a dap of paint to mine, blue to catch tank and red to rad.
The line from rad. to tank is the outside one.
3. The line from expansion tank to atmospheric catch tank is the inside one closest to TB.
These are a well designed system and if serviced correctly at the prescribed times will give no trouble.

Cheers,
Maximus

 

The lines at the rear of the reservoir need to CROSS. It looks wrong and most people install them backwards unless it is noted beforehand.

bob gauff

 

Thanks everyone I will check the lines tonight and let you know thanks again.

 

It's a daft idea Bob and easily confusing

Maximus

 

I agree Maximus

I saved the shop foreman's *** one time at the dealer when I was working late. He worked on a customer car for cooling system faults and he went home at 5 PM. I was not ready to go home that night and the customer came back with coolant spilling from the atmospheric catchment tank and the reservoir indicating 'coolant level low'.

I pulled the car in the shop and noticed that the reservoir lines were not connected to the proper places. The bleed line was attached to the overflow port and the catchment line was attached to the radiator air bleed port. Coolant was flowing freely to the catchment tank making a big mess.

I connected the lines correctly and topped up the system. I told the service writer that the system had an air pocket and simply 'burped' some coolant out of the system.

The customer left and I never told anyone. He owed me one but I never needed to collect!!!!!!!!!!!!!!!!!!!

bob gauff

 

Bob.....ain't it always the way!
I can empathise with that!

Maximus

 

im with Bob. I bought an 03 XJ8 at a much lower price from a used car lot, came home to coolant spilling everywhere. Joined this site, used a small flathead screwdriver to wiggle hoses free and put them into the correct spot. runs great now.

 

If you use my little trick of blue for atmospheric tank and red for expansion tank, you can't go wrong

Cheers,
Maximus