- My model of MX-5 is: NC 3.5 2010
- I’m based near: Wales
- I’m looking for technical help or recommendations on: Identifying potential problem
Hello all,
Since I purchased my MX-5, I have noticed that there has been a coolant leak at some point - hopefully sometime within its 14 year lifespan. Forgive the naivety as I’m new to car mechanics, but I’d like to know if this looks like a current problem or a previous one from a past owner which has now been resolved.
The car still has a month of warranty left as I had a 3-month warranty from the dealership in September 2024. This is a photo I took of the engine bay around the time I picked it up. It displays the greenish coolant corrosion and blued cables from leaked fluid.
Is this something I should be concerned about? What do I need to do to assess?
On another note - I’m aware the coolant expansion tank should be replaced as a pre-emptive measure (as it’s yellow), but less confident I could swindle this one under the dealership’s warranty - any tips for this? Should I just get a new one and leave it with my trusted mechanic to replace or is it a straightforward job?
Regards!
Firstly, there is no coolant pipe in that area.
That isn’t a coolant leak in your first picture.
That looks to me that the previous owners/servicing people have been very sloppy and spilt brake fluid everywhere and not cleaned it up!
Hence the brake fluid has taken the paint off under the reservoir.
Those “cables” are the brake pipes. 
Edit- Just for your information. If you look closely you will see that the contaminated “blue” bits are additional sleeves put on the brake pipes. If you look further the actual brake pipe/s are black and not all is sleeved if that makes sense.
Reference the coolant.
Try and establish if it was changed at the 11 year interval with FL22.
All the expansion tanks go yellow (including mine).
The failures have generally been recorded in very hot climates, typically in the USA.
I changed mine at the 11 year point as got a good deal on a new one, but you don’t have to.
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Agreed. I’d definately have a wee Sunday bacon sarnie & tea removing the corrosion, apply some rust proofing that will act as an undercoat to take paint, and get it painted again. It’s been careless servicing a good while back. I had the same issue with my Mk1 when I bought it but I knew from a youngster from my Dad never to let brake fluid settle on paint. In fact it’s a favourite for thugs to ruin peoples’ cars. But do not worry…do it right…she’ll be good.
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