What To Do When You Break The Plastic Radiator.

Remember the RX8 that I have that doesn’t move in the winter?  Well, it totally makes up for all of that in the summer months, until I break it.  Well, I didn’t really break it, it broke itself first, then…oh fine, I will just start at the beginning.

Last Monday, I was sitting in a parking lot with some icy cold A/C pumping full blast on my face. It was rather nice considering there was 1 million percent humidity hugging the outside of the vehicle.  I then begin smelling the succulent smell of antifreeze.  “Oh Noes!” I exclaimed. (So what, I’m dramatic, don’t judge.) I hopped out of the race car into the sweltering heat, and found antifreeze fire hose’ing itself out of a crack in the coolant overflow bottle. Terrific, I thought, this is just what I was hoping to fix after my truck’s recent shenanigans. So there I sat, helpless, because honestly there isn’t much that you can do when this happens except for catching what you can with rags and hoping it stops before the engine is totally empty.

That night I hopped on the internet and searched around for a new coolant overflow bottle.  Much to my chagrin, my only option was to buy the exact same crappy, crack-prone overflow bottle from the dealer that had failed me in just 50K easy miles.  Great.  Not only was I now planning for failure in the future, but I also got to pay top dollar for it.  Reluctantly, out came the wallet.

On the following Saturday morning I had the bottle in my hands, and I had just gotten up early so that my wife and I could use her car again.  I popped the hood and began removing the items that were surrounding the old overflow bottle.  I removed the two 10mm nuts on the top and gently pulled on it so that I could get a look at where my pliers needed to sneak into (one hose clamp is buried deep). SNAP!  is what I got in return.  My heart then entered my stomachular regions and I had sealed my fate for the next 24 hours minimum.  That’s right,  I had just snapped the plastic tube off the top of the plastic end-tanked radiator.

RX8’s are great when they are driving, but when you need to take them apart, you are often hit with curve balls.  A great example is what I found shortly after breaking the radiator.  It was “Surprise! The radiator comes out the bottom!  … unless you disconnect the A/C lines, AKA…..not happening!.”  Yes, just imagine pulling the radiator out of any car from the bottom.  That is exactly what this job is like, except with 47 extra 10mm bolts to pull out, and 127 plastic shields.  My day was going really well by 9AM.

The radiator eventually fell out the bottom and soaked me, just as they always do after you “drain” them, and I could finally evaluate what I had just done. It was horrific because plastic is brittle, RX8 radiators are rarer than you think, and holiday weekends make auto part hunting extra challenging.  I called all of my local resources for a radiator because I knew that was the “correct” way to fix this problem.  It was a total failure.  Not only did nobody have the radiator that I needed, but they couldn’t even GET it.  Epic Fail.  It was officially time for Plan B, which was also known as the “Fix Your Plastic Radiator Tank and Hope Like Heck it Buys Me a Little Time” project.

I began by staring at the area and wishing I could turn back time.  Once that was complete, I dried the area with some kind of chemical I had around the garage.  It seemed to work.  Then I took a flat file out and smoothed the surface out because I was going to be screwing a steel fitting into this tank shortly.  For it to have any hope  of survival, it  needed to be against a nice surface.  I then grabbed a tap, and threaded the hole.

This was by no means a pretty  job, and wasn’t going to win an awards, but I just needed it to hold antifreeze inside until I had a new radiator in my possession.  I grabbed a 3/8ths fitting with 1/4 inch pipe thread out of my bolt bucket, gave it a nice helping of thread sealant, and screwed it in to its new home.  The problem was that 3/8ths of an inch was not the right size.  So I cut a hose fitting off of the old overflow bottle, and slid it over the steel fitting.  Nice.  But sadly, it needed more.  It needed… JB Weld!  I mixed up a fair amount of JB Weld, and poured the delightful epoxy over the whole entire area.  I wasn’t messing around.

I then reinstalled the radiator, the 47 10mm bolts, and 127 plastic shields, and let it sit for about 48 hours.  2 days later, the JB Weld was solid as a rock, and the fitting felt happy in its new home.  This morning was the RX8’s first test drive, and upon arrival at work, there was no leaks to be found.  I have my fingers crossed that the next week is equally successful.  I am currently still on the hunt for an all aluminum radiator for less than 1 billion dollars.  That way when if I break it again, I can TIG it back together instead of this sort of thready glueiness.

Jeremy Nutt

Hi, I'm Jeremy.

7 thoughts to “What To Do When You Break The Plastic Radiator.”

  1. I’ve used JB weld to fix many a laptop power jack. It also fixed the cracked fuel sending unit in Galant until I found a new one!

  2. I used JB weld 2 years ago to fix an 2001 Camry radiator crack across the top. I did a few nice things other than just slather it on. Short story, it lasted 2 weeks before leaking again. Better look for that radiator.

  3. I also did a Justice Bro. repair, the leak moved to a new place! Think of this as an opportunity to put your LS motor in there with a radiator to match! …after all an RX-8 needs an eight!

  4. I just had the EXACT same problem while trying to make the EXACT same repair. After examination, I realized there was nothing I could have done to keep it from breaking, the plastic nodule literally crumbled in my fingers form years of intense temperature changes.

    While I commend this repair tactic, I just got an all aluminum radiator on Ebay and my ‘8 will stay parked until it comes in the mail.

    Seriously though, who ever heard of a plastic radiator hose nodules?

    1. Gosh that was an awful feeling when I broke that. It would have been such a simple 7-minute repair, but nooooo – RX8’s have to have a stupid radiator. I will be getting an aluminum one too when this one starts leaking, but so far, it has actually held up amazingly well!

  5. I just experienced this exact same thing. Except that mine didn’t last 5 minutes… Once the car was warm, it started leaking again. By that time I was on the interstate and the front of may car looked like Old Faithful! Amazon had a replacement for not a lot of dough. Plus 24 hour delivery! Gotta say, I’m looking forward to the 47 bolts and 123 plastic shields. I had hoped to be able to wait for this fix until I rebuild my motor in a few weeks. Looks like Rex8 has a different idea.

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