Painting the Engine Coolant Overflow Bottle

[TP, GM] I painted my coolant overflow bottle Sunday and reinstalled it last night. It looks terrific, much better than the stock white plastic.

1. Remove cap. Remove the two 10 mm screws holding the horizontal flange of the bottle to the mounting plate. Loosen the 10 mm screw holding the vertical flange to the firewall bracket, but leave the screw in to stabilize the bottle. Snap out the vacuum hose that is
   supported by a metal bracket fastened to the side of the bottle.
2. Slide back the squeeze clamps on the two hoses (overflow and return) and wiggled them off. Only a few drops of coolant will drip from these hoses, however, the bottle has about a quart of liquid in it so get you thumb over the large (return) tube in a hurry! Leave the small drain hose attached to the pressure cap fitting, it will come with the bottle. Carefully lift out the bottle and drain the coolant into a clean bucket
3. Remember pets are attracted to the smell/taste of antifreeze but it is fatal to them even in small doses.
4. Remove the drain hose and vacuum hose bracket (10 mm screw.) Thoroughly clean the outside of the bottle, removing all dirt and grease. Let dry. (I used denatured alcohol as it leaves no residue)
5. With the bottle removed you can wax the painted bracket on the side of it and polish the cap on top of it. A must for those with exposed engines!
6. Tape the brass refill neck and the two molded-in tubes. Spray two light coats of Plastic Bumper & Grill Restoring Spray, #20241 – Dark Gray, from Griot’s Garage ($11.95 plus shipping). Let dry overnight.
7. Reverse the procedure. Add the saved coolant. Add a bit more to restore the level.
8. Stand back and enjoy a fully color-coordinated engine compartment!

[LL] You’ll be looking for a flexible bumper paint. Some owners have had success without a primer, but the paint mfgr’s will tell to be sure to use a plastic primer first. You should also rough up the entire surface first with 400 sandpaper, no coarser.

The particular brand I used was by SEM products, inc. of Charlotte, NC. It’s called "urethane bumper coater" and their sand-free primer. It worked very well and is available in about a dozen colors. The smoke M #39163 I used is a very dark grey. I purchased it at a local paint supply house, the products these folks sell is a better bet IMO than something from NAPA or Wall-Mart.

You can take a strip of pin-stripe tape and run it down the side vertically leaving a natural stripe which will allow you to still ascertain your level.

I’ve recently looked into the heat capability of urethane paints like these. The mfgr’s don’t have exact numbers for an application such as this, but their guesses run in the high 200’s F. There is most always risk involved in customization.

[DLJ – 99/2/27] I was determined to get rid of the garrish white color, as others have done. I was surprised to find, in the auto parts store, a spray can of "Bumper Black" which is a "flexible acrylic" that is designed to stick to all types of plastic! It sprayed on very easily, and is a semi-gloss.

So the solution isn’t as exotic as I had feared (or as the car).

I was a little concerned that I wouldn’t be able to see the water level, though I could never do it with the white, either. THEN I REALIZED that most of the cars I have owned, the only way to see how much water in the radiator was to take off the cap! So now I don’t feel so disadvantaged.

[KJ] I used gray bumper paint, rather than black. Also, I taped a vertical stripe about 0.5 inch wide, both above and below the center line. This stripe remains white plastic. To check fluid level, wait until dark and shine a flashlight down the open top. Or just look in the top and see whether the level is above or below the center line.

[MBA – 2000/1/13] If you’re careful, you should not end up with any air in the cooling system or need to bleed it. By careful I mean, don’t bend the hoses that you disconnect below center. They will not leak below the need to bleed range if you keep them upright.