Car Analogy

Stock radiator end tanks leaked (150k miles, no surprise). Good time to upgrade to more durable all aluminum aftermarket (koyo). But I don't like the bare aluminum look, nor the maintenance involved in keeping it from corroding.

So I wanted to paint it a satin black that would blend in and look more stock. I used SEM Trim Black. They make two versions, one that is a closer to USDM cars black trim, and the other for foreign (mostly Euro) cars. I went with the foreign color.

SEM 49143 Trim Black Ultra is the version for foreign cars. The USDM version is 39143.

Trim Black is made to paint over bare metal, including aluminum. Its rated to 200F, but the SEM tech rep I spoke to said it'll easily handle 220F or more. 250F not so much, but you'd have bigger problems at that temp. My car is street only, so this paint should be fine.

Eastwood makes a radiator specific paint, thst is super thin so won't interfere with heat transfer. But I was only painting the end tanks, left the fins unpainted. So actually a paint that blocks some heat would be welcome (to keep heat away from intake and from me when I'm under the hood.)

Cleaned the end tanks thoroughly with acetone. Used a grey scuff pad to scuff up the end tanks, making sure no shiney metal left. Then cleaned again, and again, until white rag didn't pickup any more black aluminum debris.

Painted two wet coats, as instructed by SEM tech rep.

It looks amazing! Really a good match for the stock black fan brackets. Doesn't draw attention to itself. Exactly what I was looking for.






I also added foam rubber to seal off radiator and prevent air flowing around it. I replicated the stock foam strip at top of radiator, but also added a similar strip along bottom end tank. Also added strips to seal off the sides.

I wanted it to look clean, almost like it was stock. Used an in widow AC sealing kit from home depot.




Kit has two long, skinny pieces. An L shaped cross section, and a rectangular. The foam is a bit stiff, not floppy. There is no adhesive on them.

Used a straight edge and razor knife to cut. Cut the rectangular piece lengthwise, in half. Then cut to length of end tanks. One piece at top of radiator, other bottom.

Also cut L piece lengthwise, to cut off about 2/3 of the thinner leg of the L. The wider section of the L is an absolute perfect fit into the slotted channel that makes up the Koyo side rails.




I used spray adhesive to hold the foam in place, glued to radiator. I carefully lowered radiator into place, as it was a little more awkward making sure foam didn't get pushed out of place as radiator was lowered. But very doable.

The only thing not perfect is the foam color is gray, not black like original. But at least on my car it blends in with the Silverstone paint of radiator support. I bet a can of flexible black spray paint, the kind meant for recoloring interior, etc, would work well on the foam. Easy to try out, as you'll have several small leftover pieces of foam.

Zer0ne

The black looks great! I've been meaning to redo the foam I did on my koyorad since the adhesive on the foam I got wasn't strong enough. Which adhesive did you use?

Car Analogy

3M spray adhesive. The kind of stuff used for interiors, like headliners. Thats what it seemed like was used for the stock foam on the stock plastic radiator.

Hopefully it holds up. Its mostly held in place on its own once radiator is in place. So only an issue if radiator needs to come out again, the pieces might fall outta place.

B serious

Looks good my brü