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So there was this green-ish spotting all over my engine bay, I initially thought it was due to soap suds from washing the car...but I took it down to mania and they told me it coolant leaking everywhere

So we found a crack in the plastic which the radiator cap locks on to, asked mazda and they said it was $110 for the part...but 6 months back order

but apparently this is a very common issue in the NC.

Has anyone else have this issue? and does it mean replacing a radiator coolant box everytime?

Haven't had the problem yet at 4+ years and 63,000 km. I guess there will inevitably be cracks given that it's a plastic expansion tank. It will require replacement if cracked. What year and how many kilometers on your car?

kayye wrote:Has anyone else have this issue? and does it mean replacing a radiator coolant box everytime?

Yep. Replaced mine about 6 months ago. After about 120,000 kilometres, it gave up the ghost.
Initially I thought it was the cap as it only ever leaked during a track day when the motor got pretty hot.
I put a new cap onto it and it still leaked, then the top came away completely.

I got mine from Newell's. MX5 Parts in the UK had one on special but I missed that one by a week.
There's a bloke on Ebay wrecking an NC in QLD. You maybe able to get one off that car if you can't pick up a new one in AU, UK or the US.

it sounds like a design or component defect which should be fixable by Mazda. Plastics the same as oils are not all the same- the engineers define the material and the component maker must only the use the approved material. Substandard suppliers sometimes use regrind instead of virgin materials and the engineering performances suffers. It may be worth approaching Mazda spare parts and see if they are prepared to assist in some way. I do not understand a 6 mth back order. If its a non OE item and there cars off the road the car company normally pressures the component maker to make a production run.If the part is still in OE production it s/be readily available. Sounds to me like Mazda are being very dismissive- just not good enough.

The car is a '05 LE NC, only got 30,000kms on it tho..

Would you have a link for the part on mazdaparts? i couldn seem to find it on the site, or google...

Anyone got a contact who may be able to manufacture an ally version of the tank?
OR seen an ally version anywhere that would fit the bill?

I'm thinking I might do a little research and get a replacement on the shelf ready to go.

kayye wrote:The car is a '05 LE NC, only got 30,000kms on it tho..

Looks like it's an age problem and only good for about 7 years. Don't worry, BMWs have a similar issue with plastic cooling system components age deteriorating in 7 - 10 years.

Mine in the SE crazed and leaked at 7 years of age
Luckily there is a aluminimu aftermarket version available

Maybe with enough interest they will make an NC version

http://www.miataroadster.com/canton_racing_products/canton_racing_products_coolant_expansion_reservoirs/canton80276/i-464280.aspx

kayye wrote:The car is a '05 LE NC, only got 30,000kms on it tho..

Would you have a link for the part on mazdaparts? i couldn seem to find it on the site, or google...

Mine's a 2005 car also but you need to add 100,000klms.

US price is $70.43 for the tank described as a Sub-Radiator Tank found here: http://www.jimellismazdaparts.com/default.aspx
Part No. LFG115350C. Need to add transport cost.

Try MX5Plus http://www.mx5plus.com.au/ for a second hand one also as they bring in a few wrecks.

Also email Sales@mx5parts.co.uk to see if they have one.

Sailor wrote:Anyone got a contact who may be able to manufacture an ally version of the tank?
OR seen an ally version anywhere that would fit the bill?

I'm thinking I might do a little research and get a replacement on the shelf ready to go.

mmm and alloy one would be cool

and yes i might keep my eye out for one to sit on the shelf also

I wonder if that Durafix stuff would have a strong enough bond...

Durafix? It's a plastic tank under normal cooling system pressure.

Guys just an update, I ended up waiting for about a month for the part from mazda which also set me back $100.

However as I was searching yahoo auctions I found many of these sub-radiator tanks starting from $5. Just a tip to anyone that may need one in the future.