Coolant Reservoir Install

After 20 years of being in the engine bay of an e30 any kind of plastic starts to… look like a cross between dried snot and old cheese. The coolant reservoir suffers the worst because without regular flushes the contents turn slimy and seep into the plastic.

Of course this in no way impedes functionality so replacement ranks low on the priority list. I’ve read that some (ABS) plastic can be bleached in peroxide and regain some of it’s original appearance but that can take weeks and produce marginal results. In most cases DIYers choose paint over replacement.

I’ve collected the following example photos of painted engine bay plastics for example:

My e30’s own coolant tank was especially pathetic. In addition to being cat-vomit brown it had picked up some overspray from the PO’s paint job and accumulated a thick layer of sludge in the bottom. The washer fluid tank suffered the same overspray but I painted that blue which I think really sets off well against the rest of the engine bay. I decided not to paint the coolant reservoir because I don’t have a space to paint in right now and it’s impossible to read the coolant level once painted.

During my engine swap I needed to fill out an order for some small parts and decided I’d add the tank to the order. I didn’t take any photos during the install but it was pretty straight forward and I think the results are nice.

IMG_7061

1989 BMW e30 325i Clean Engine Bay and new Coolant Reservoir

e30 Coolant Reservoir

Coolant Reservoir Replacement


  1. Disconnect the Air Flow Meter and remove it along with the air box that holds the air filter.
  2. Put some cardboard and catch pan under the radiator and remove the lower drain plug.
  3. As coolant drains remove the cap from the overflow reservoir.
  4. Disconnect and remove the coolant level sensor by loosening the large black nut that connects it to the reservoir.
  5. Remove the coolant return hose from the bottom of the reservoir and immediately move it over the catch pan to drain.
  6. Cut off the radiator to overflow reservoir hose very close to the hose clamp, or cut the hose clamp off.
  7. Cut off reservoir overflow hose that runs to a hole in fender.
  8. Remove the old reservoir by pulling up to release it from the clip holding it to the frame.
  9. Put in the new tank, reconnect the hoses.
  10. Use either a very small worm-gear hose clamp or use the OEM “Oetiker Clamp” and end nippers (in lieu of the proper pliers) to connect the high-pressure radiator overflow to overflow reservoir hose.
  11. Refill the system with coolant and bleed it of any trapped air. This is well covered elsewhere in more or less detail.
  12. bmw e30 coolant reservoir

    Parts List


    Radiator Expansion Tank 17111712641
    Hose Clamp 32411712735
    Oetiker Clamps and Pliers on Amazon

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    Tags: , , ,

    May 26, 2013 cosmetic, mechanical