A numpties guide to replacing the expansion tank

[Obiwonkeyblokey]

Evening,

following the detonation of my expansion tank last week during the MOT, the replacement AUDI part arrived today.

I stripped down the top valance to get to the tank and removed the old one.

I then took a hacksaw (TVR style) to the new one to lop off the two unwanted corners and fitted it into place replacing the jubilee clips at the top and bottom.

I then rebolted the new tank into place topped it with water and referred to the web for the next part.

As a complete mechanical numptie, whats next? the tank is full of water and I cant find the bleed valves on the coolant pipes as described in the handbook.

Do I need to remove the larger engine cover to get access to the rad and bleed from there? I thought I would check here first before proceeding.

How much coolant should I be adding and when?

Sorry for the apparently silly questions, but I would rather ask than guess, then cook my engine.

Thanks.

[C3BER]

Drivers side of the rad you will see a brass bleed bolt at the top. Bleeding is an art but first step is fill until it pours out of the bleed bolt.

[C3BER]

Not sure on the 4.2 but the bleed nipples are on the water rails under the air boxes.

[Supateg]

Did you just pull the expansion tank off and didn't drain the main system?

If so you might just get away with topping the expansion tank back up?

Or at least just bleeding the water rails either side of the engine with the brass body and wing nut type bleeder at the front of the rail tucked under the airboxes. You can just see them if you peer under the airboxes at the front .

[ukkid35]

If the car is on an incline (or axle stands) with the front raised, then bleeding will be significantly more difficult.

Try to avoid using tap water if you are in a hard water area. Water from a dehumidifier my preference (or ready mixed coolant if you are feeling flush). Ideally you will be adding antifreeze if you are topping up with water, the owners manual says use a rather weak 3 to 1 mix.

[Obiwonkeyblokey]

Thansk for the tips. I can see the bleed valves on the coolant pipes but not sure how they operate and dont wish to force them. Ill take a closer look this evening.

[C3BER]

Fill until it pours happily out of the rad. Don't overfill the tank and keep the water level lower than that line. I have mine just over the hole at the bottom. When its warm just twist the air bleeds. Water eventually will come out and tighten. Let to cool and re check your water level.

[ukkid35]

If you have silicone hoses you will need to retighten the hose clips on the expansion tank after a heat cycle (possibly two).