I am looking for an all aluminum radiator that matches stock dimensions. Koyo makes one, R0181, but it has a filler cap on the top of the case. What is the use of that?
Anyone know of other vendors?
Thanks.

 

what do you mean on the top of the case?.you mean on top of the rad itself?..
well some setups have a pressurized rad cap and it will Relieve the presssure of the cooling sytem by that cap.The cap on the Thermostat housing is a Stationary cap.No spring.Just used to Fill the cooling system.
Now,here is an alternative Sort of,:http://www.corksport.com/corksport-p...r-for-rx7.html Corksport radiator.
You can always TEE the Coolant Overflow tubes(the one out of the rad and the one out of the Thermostat housing) and have them BOTH go to the overflow bottle.I did,
No issues doing your overflow like that, by the way.

 

Thanks. I considered putting a higher pressure cap on the filler on top of the radiator, welding the overflow closed and using my current 14.6 psi cap on the thermo housing. I does have a spring. However, I also have a clearance issue. Not enough room between my hood and the cap on the radiator.

 

I cut the extra cap location off the top of my Koyo, then had a round piece of aluminum sheet welded in its place. It looks nice after I used some metal polish to match the Koyo's finish. You can see it in this picture:

 

Thanks. I considered cutting off the filler tube and closing it off. I know this radiator is used for other vehicle applications but when they say it has the same as OEM specifications...

 

There is always the option of finding a portless filler neck for the thermostat housing and using the port supplied on the radiator.

All FC radiators that I have personally seen have a fill hole in the radiator. My 88 has its overflow line running from the radiator fill cap to the bottle, the fill cap at the thermostat is a capped off piece. When I had an 88 T2 the cap at the thermostat was made of aluminum and portless as well, the one on my NA is just the usual plastic that tends to break and then leak.

 

Thanks.I've seen dozens of '87 turbos and not one with a filler in the radiator.
I'll keep looking.

 

this is what i was going to suggest.

i hate the shitty plastic filler neck on the top of the thermostat housing too. you can replace it with a blocked off aluminum piece by ordering one for an FD. that ported style in that picture is actually quite rare of a style that mazda ever used. 90% or more always had the pressure port to the overflow tank directly at the radiator.

 

It's really not that uncommon to see the overflow line connect at the thermostat cover. Both of my cars were set up that way, and I've seen a many other S4s that were as well. There was just a thread on this, where a number of other S4 owners posted pictures of theirs too. It's more like a 50/50 mix of S4s that did/did not it, while no S5s did because the filler was moved near the battery.