The original coolant bottle on my 89 XJ (4l, I6 with tow package) developed a crack and is leaking coolant. I stopped the leak with some JB weld but today I picked up a nice shape tank from the junkers. Not sure what year the donor tank is from, I think maybe a 90? In any case, the tank looks the same as mine (the 'round, oblong one) but I notice it doesn't appear to have the tiny pin hole vent on the flat area of the tank next to the cap. I've read various posts suggesting the tanks are pressurized but my 89 (owned since new) definitely has a pinhole vent and is not pressurized - maybe it's a 'tow package' thing?

 

JB weld isn't going to hold. The new tanks and caps are poor quality, btw. They tend to deform and let the cap pop loose, which causes a loss of pressure and a boil-over. I believe it's a cap from a Volve 970 (?) that fits and stays on properly. Are you looking at the threaded insert in the top? That's mean to hold the strap. It's not a vent.

 

The flat spot on the top of the tank - between the cap and the metal strap 'locator' thing - my tank has a very tiny pin sized vent hole. Will try to post a pix tomorrow if I can find a camera that has enough 'macro' functionality to show it.

 

Should not have a hole. Use the new bottle with a Volvo cap. Napa 703-1396.

Now, before we go too far. does your radiator need replacing by chance? Is it original?
If so, there's another route to take.

 

What they said. No hole. Since it's as closed system, the tank maintains the pressure, like the radiator so there's no "vent".

I run the Volvo cap on my '88.

 

On these new tanks with bad caps, does the stock xj cap fit them, or is the volvo cap the only alternative to the bad cap?

 

Ya, I'm on crack: there is no hole on either the old or the new tank.

 

The volvo cap fits both the replacement and oem bottles. It's sturdier with better formed threads.

 

Many times a leak around the cap can be fixed with just the Volvo cap. FWIW.

 

there is never a bad excuse, no matter how small to convert the renix system to the new style.