1st Gen "How To" How To: Replace Coolant Expansion Tank (Gen1)

I want to replace my coolant expansion tank, which has finally split along the seam.

I've searched around and there doesn't seem to be a how-to. But I've inferred from threads here and there that you simply siphon off the coolant in the tank, unclamp hoses, replace tank, and refill. Is that all?

Oh, and I am guessing the clamps cannot be reused, so will proper size generic clamps from the auto parts store work fine? Other tips/advice is appreciated.

(I'll take pics and post the step-by-step when I get around to it since there doesn't seem to be a diy for dummies that I can find.)

 

OK, thank!

I'll let you know what I broke. :lol:

 

^ Cool. Thanks. I recall that you had posted something on clamps on the sewing site---just couldn't find the thread.

Where can I score these?

 

Thanks for the tips, guys.

The aluminum tanks look great. Unfortunately I already have a new replacement oem plastic tank. It is supposed to be sealed better than the older ones. We'll see ...

 

Yeah!

 

Keith and others, just curious, it's not clear to me how the stocks clamps work. I don't see what's holding the clamp tight (except for the the rigidity of the clamp itself). Is that right?


Oh, and is there a special tool needed to get the clamps on? Thanks!

 

I see. That makes sense with what Keith said about the clamps being able to expand. Thanks!

 

Got around to replacing the tank this evening. Here is the DIY "for dummies" with pics! Maybe it will help someone...

First, make sure the engine is cool. Let the car rest for an hour or so to be sure the coolant isn't hot.

Remove the coolant from the tank. I used a cheap "turkey baster" from a hardware store:



Remove the upper hose from the expansion tank. The oem hose clamp is loosened by squeezing the two tabs together with pliers. You can slip the clamp down the hose then pull the hose off:





Next, remove the nut holding the tank to the car:



Now, you need to lift the tank off of two holders underneath and remove the lower hose attached to the tank. The tank has two "nipples" just sitting in two holes of the holders (see picture further down when the tank is removed).

The ignition coil pack is kinda in the way to remove the tank and work on the hose, so I removed the coil pack. I first unhooked the battery. Maybe this wasn't necessary, but I didn't want to be screwing with the electrical components while the battery was attached. Since this is "for dummies" the battery is in the boot (for the Cooper S) :lol::



To remove the ignition coil, remove the four bolts on the top:





As you remove the ignition coil, be careful not to lose the four rubber gaskets underneath. They will probably be stuck to the base or to the engine:



If the gaskets look cracked and worn, they should be replaced. Mine looked OK after cleaning them up a bit.

Put the ignition coil to the side and out of the way:



With more work space, you can work on the lower clamp. Loosen it by compressing the tabs again, and work it down the hose. Twist the tank free of the hose:



This is what it looks like with the tank removed:



Attach the lower hose to the new tank and re-clamp it. Insert the tank into the two holes and reattach the upper nut. Reattach the upper hose:



Reattach the coil pack. Don't forget the four rubber gaskets at the base. Recommended torque for the four bolts is 9 foot-lbs:



Reattach the car battery.

Refill the coolant expansion tank with coolant (I used the MINI coolant from the dealer mixed 50:50 with distilled water).