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98 2.5RS/95 GF8/01 LGT
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297 Posts
Discussion Starter #1 (Edited)
Project: Installing a turbo aluminium radiator in a naturally aspirated car.

Difficulty: 4/10

Benefit: Increased cooling capacity/ease of maintenance

Parts:
-Aluminium radiator
-1.5" Coolant filler neck (O'reilly P# MRY 85324)
-Dodge Dakota 4.7l radiator cap (Carquest was the cheapest brand)
-Phase II upper radiator hose (Can use others or make your own but this is what I used/it was free.)

Total cost:
$15.95+Cost of radiator

Prologue:
I was using a phase II radiator on my rally car, which worked well until the dinky radiator fill neck was worn out. After getting sick of looking like my car vapes at every stop light I decided to wrack my brain about solutions. I already had the GC aluminum radiator laying in my backyard and didn't want to buy a junkyard one in fear of having to replace it over an over. Eventually I was able to find that the filler neck from a 2004 Dodge Dakota 4.7l has the same 1.5" diameter as Subarus and the radiator cap they use is 20psi rated (~1.3bar) which is the same as STI caps. Oh, and almost every store in my area had multiple in stock so a hot swap down the road is easy.

Lets begin.


Here is the aluminium radiator I dug out of 2ft of snow.


Compared to the phase II radiator I was using, it's huge.


P#'s


Total contents


We're going to use these hose clamps cause we paid for them and they're shiny


Grab yourself a Towne Club and drain that coolant

One problem we have with the GC radiator is the fitting that is needed for the expansion tank. Since we don't have a turbo we're going to have to cap that off.


An easy way would be to just jam a bolt in and make threads with it but that's not how we roll. Plus, with such little material there is a very small margin of error. This is probably the hardest part of this whole DIY and it would be a 2/10 otherwise.


A timing cover bolt will be perfect for this cap.


This is a M6-1.0 tap since I couldn't find my 1.25 pitch, it worked fine. I went about at deep as the bolt I'm using.


A little Teflon tape wrapped around the threads will ensure a good seal and tighten to hand tight plus 1/4 turn or ~20-25ft-lbs
(Be VERY careful not to strip the threads.)


And plugged. You can see how little material there is by how the bolt bulged out the fitting ever so slightly.

Install the fans onto the radiator and once all the coolant drained you're good to drop in your new radiator. Now we get to have some fun making things fit.

I used a phase II hose here for the large straight section and cut it to my desired length with a reciprocating saw. You can use hand tools but I found a saw leaves the cleanest cut.


After you have a section from the radiator to the crossover pipe, mark where your filler neck is going to be placed.



This was a bit of a task to get everything lined up perfect, I should have left a little more hose on either end but it's able to grip and hold pressure as pictured.


Fill it up and burp all the air from the system (This should be easier than any Subaru since you're filling the engine and radiator at the same time.)


A quick shot of the whole system. You can use a stock overflow system with this set up, I just don't have a way to mount one.


All done!
 

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www.jackstalk.com
‘98 RS, 911 Cab, CT6 TT, Escalade ESV
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5,625 Posts
Doesn't seem like too bad of an idea, I'd be weary of springing a leak either from the screw or the four connections on the upper radiator hose. I like the fact that it's easy to burp.
 

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Registered
98 2.5RS/95 GF8/01 LGT
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297 Posts
Discussion Starter #3
I was worried about the engine shaking the fittings but the slight flex in the bend on the radiator side allows for enough movement and you're still able to pump the rad a bit there. As far as the clamps, I'm pretty happy with them and the filler next ports are slightly oversized so the hoses fit on very snug. The timing cover bolt used for a plug seemed to be a tight fit as well, if it leaks I have a longer bolt to use with more Teflon tape.

After burping out all the air I found a nice empty snow covered lot and did a pressure test. All systems seemed good and my engine was happier with the increased cooling.
 

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Registered
98 2.5RS/95 GF8/01 LGT
Joined
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297 Posts
Discussion Starter #4
Update: If the 20psi cap is too much pressure switch it out for a 13psi (.9bar) cap from a 1966 Ford Mustang 289 (P#10229)

I just did the same thing for a buddy with a turbo radiator in his Legacy. I'm pretty happy with how it turned out on a phase II radiator. We went with a more permanent solution of grinding the nipple flat and coating the threads in permatex.



 

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www.jackstalk.com
‘98 RS, 911 Cab, CT6 TT, Escalade ESV
Joined
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5,625 Posts
The coolant system is pressurized higher than a vacuum line. The best way to do it without any modifications is to run a short hose, block it with a screw/loctite, and a small hose clamp.
 
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