- My model of MX-5 is: __na6
- I’m based near: __ Hertfordshire
- I’m looking for technical help or recommendations on: __chassis panel and makeup
Really odd one, I’ve owned every single Schassis and most Honda Type R’s (jdm versions only) and never had this issue…
My mk1 seems to be holding water, it leaks out of a very specific location too as I found out while recently doing a fuel filter!
The two expanding plastic screws that hold the cover on (underside, flat part) seem to have a torrent of water pouring out of them for days after it rains.
Does anyone know what areas I need to be looking at to address this? It’s driving me mad!
Also, hard too fitted and no damp inside the car atall
I remember driving my mums one that used to occasionally slosh as you drove it. The sills were completely filled with water. Could be that this is what’s happening and water is gradually finding its way out over time or depending on the ground level etc…
I’d start by checking the the roof drain tubes are clear and actually connected and routed correctly.
Edit: Just seen that you say that you have a hard top fitted so ignore the above.
It was a long time ago but I seem to remember either clearing some holes out under there or taking some rubber body bungs out. When I say sloshing I mean there were litres of water in them. You’d hear it if yours had the same I’m sure.
Ideally I’d like to find out how it’s getting in, I don’t mind adding some holes or clearing the ones Mazda put in but it seems madness to allow water into the chassis cavities in the first place.
If anyone knows the panel layup on a mk1 well enough to say it’s a particular seam il just seal it up.
Save me going mad and doing the whole car… even if the extra stiffness would help the thing flex!
I admit I can’t picture the area described but I just wondered if you could remove the cover, let it dry/go over the whole aea with a towel, then after the next rain storm (or hose pipe spray?) go underneath and look for wet patches/trickling water to locate where the water is coming from.
The water is coming out of the cavity above/ behind the filter. It’s not accessible unless I literally start cutting holes in what is currently not a rusty car.
While it’s a tidy early mk1 I want to keep it that way 
With a hard top on, the only place I can think of that the water maybe getting into that area would be under the chrome deck plates where the hard top mounts. But that’s a bit of a guess.
I’ve looked at a video online to get a better idea of the cover (I admit I’ve never changed my own fuel filter as when I jacked the car up my rear sills collapsed due to rust so it got replaced at the same time as the garage did the welding) so I didn’t realise it clipped into the car in that manner.
I do wonder though whether if there’s any form of cavity up there that water could sit in whether viewing inside with a boroscope might be an idea to check the internal structure and consider cavity waxing once you sort the leak out.
I have a car (not an MX-5)with sill inspection plates (meaning you can look inside the full length of the sills). Externally the sills are good and solid looking (you can hit them and they have strength to them).
Internally I found water had been getting in through the B pillars and I could pull out large hand-sized sections of the sills and crumble them with my fingers.
I hope the above isn’t a possibility with that area on the MX-5 and that the water hasn’t ever been sitting, but if it is a possibility, I’d be worried since I’ve had too many bad experiences with rust and cars.