Hi, guys I see that many people have been having a problem with the Coolant reservoirs cracking on the top. Recently it happened to me, I did some research and saw that the going rate for a new coolant tank is about 100-250 buks price range. Its a bit excessive for something that can be repaired fairly easy. Hence why I am creating this DIY thread, I hope it helps many of you guys out.

 

You need to have one of these

 

Clean the part that you are going to patch with some of this stuff, I choose MAF cleaner because its safe for plastics, make sure that no spray gets into your coolant tank.

 

Because of the high temperatures in your engine bay, Few epoxies can withstand it. I choose JB weld, its good stuff and I have used it many many times. So after thoroughly cleaning the spot that you are about to Glue, mix some of this stuff up.

 

Apply to the broken area on your coolant tank.



*note-JB weld take a really long time to dry so make sure you have 5-10hours free.

 

If your tank is cracked at the same point that mines was then you will need to apply weight to ensure 1 that it seals, and 2 that the cap will go on flush when the epoxy has dried. I used some of my weights, 13lbs did the trick.

 

Thats it your done!

 

So I know this is a new DIY, but how long has the JB weld fix been applied?

So hopefully it will stay for you.

 

Its been on for about a week now. This for me is just temporary until the expansion tank i ordered from Mazda comes in. But so far so good.

 

mine is broken in the EXACT same spot, but my piece has broken completely off... I wasn't sure if JB weld would hold to that plastic... superglue held for about 2 weeks the first time I tried it, then an hour the second time... I tried high heat plastic weld but it fell apart as soon as I secured the radiator cap... I'm picking up some jb weld tonight!

this is a temp fix for me too... I'm going to order the Billet Aluminum Weapon-R Universal Coolant Catch... it's only $50 off the Weapon-R website...

 

so, I tried the jb weld... sanded, cleaned it thoroughly, let it dry for 15 hours, and low and behold, it held for almost 30 minutes before shooting off and spraying coolant everywhere... yay for overheated rotaries! I'm seriously pissed about how unreliable my car has been lately... 75k miles and all of a sudden EVERYTHING is breaking... in the last month I've managed to replace my ENTIRE cooling system... Weapon-R universal 18oz billet aluminum coolant catch ordered and in route! I'm losing heart in my RX8...

"EDIT" have now also ordered a universal Radiator breather tank... since the coolant catch is insufficient for our money pits, er, cars rather...

 

Bringing this back to life, Lead what do you mean your entire coolant system? What have you replaced so far?

 

ok

i made all the steps but the glue didn't was very strong ...it only hold for a few days

so i made the next step

1) i cleaned again
2) i sand it a bit outside-inside
3) then i use fiberglass resin
4) put some small layers inside and outside
5) resin again
6) a lot of rocks on it till it ready
7) next day sand it again
and now is stronger than the original.....now i am thinking that will broke the other side

 

why cheap on a part like this?

I'm sure its cheaper to buy a new one than try to glue/fiberglass it than when it breaks car overheat kills engine.

 

It's pressured up to 15psi, and you are trying to fix a leak from the OUTSIDE!

Don't you see the inherent problem?

 

Agree..

why take this risk...sorry mate, but a fail DIY..

I can see it now...hot summer day, middle of nowhere and bang there goes the JB weld, gee that excessively costly $107.30 new tank seems cheap.

N3H1-15-351G

 

Well, I did something like the original DIY before actually looking at this topic: just superglued the plastic (the cut is less than half an inch), this was at least a month ago and I haven't had issues so far. Coolant levels are exactly the same.

Of course I'm constantly checking with Torque and under the hood to make sure nothing is bad, but as of today I can't say this DIY doesn't work.

 

heheh sorry guys ..but i got a lot of fiberglass a lot at my house and the cost was 0 E

 

you can successfully repair it by plastic welding it. Do Not try to plastic weld directly on top of the crack, the weld will be unsuccessful. You need to make a deep groove into the crack with a soldering iron. You then get some zip ties as they are made of nylon and use them as solder to fill in the deep groove melting the zip tie into the groove. You then mix the new plastic with the old plastic using your soldering iron thus making both 1 new surface. It takes about 15 minutes total and it is extremely strong, you don't have to wait for anything to dry. No Epoxy will work, you either buy a new tank or plastic weld it properly. You can fiberglass it but that is way more tedious than the simple fix I have given here.