Waiting on a new OE radiator to arrive for my '06, what have you all used to replace the foam fillers on either side and top of the radiator? The Jag parts for these are long discontinued. I was thinking maybe some foam weatherstrip from the hardware store. Or is there something better? I know it's a pretty wide gap to fill.

 

https://www.mcmaster.com/foam/

Measure the stock stuff and scroll down under the tape section. Match one up based on material choice(temp range, UV resistance, color) and size.

 

Go to Lowes or Home Depot and use thick insulation. Not a deal breaker if there is a slight gap. A new radiator will gladly compensate for a bit of air gap.

My insulation crumbled and I did that and all is well on my XJR. Runs about 8 - 10 degrees cooler with the new radiator fitted.

198F with car moving in mid 90 Temps w/ AC on...

 

every manufacturer uses these and they all crumble away.

if temps are good just let it slide

 

I've used this to fill the gap beside the radiator Air Conditioner Foam Weather Strip

 

Just to wrap up this thread, I got the radiator replaced last week. I wasn't able to find any adhesive foam that would fill the gap, but Home Depot did have 2.25" square similar to what hafren suggested above, and abonano as well. This fit very snugly in the gaps and so far is working exceptionally well. I'd say the ac is working more effectively so far without hot air circulating back around.