Water leaks in 2011 MX5 NC - summary with photos

  1. My model of MX-5 is: __2011 NC
  2. I’m based near: __Aberdeen
  3. I’m looking for technical help or recommendations on: __Water leaks - solved hopefully

Bought my car six months ago and managed to have a bit of fun between lockdowns.
Had a number of water leaks in the boot and in the cabin, not unusual given comments on the forum. Lots of help on Youtube on how to fix the issues.

1/ Leak into boot through an incomplete or cracked weld. Used automotive seem sealer on the inside of the boot to fix it. The weld is the short one inside the circle which starts under the boot seal and then come down the back of the car for 30mm. Bottom picture shows the underneath of the weld. Made a poor repair using silicone sealant but proper automotive seam sealer did the job.

2/ Someone had had the cable out of the boot lid at the car end, put it back in 90 degrees out and hadn’t sealed it. Siliconed in.

3/ Another cracked weld again sorted using seam sealer, took an age to find this. Right hand side of boot just in front of the hinge.

4/ Aerial dripping from underneath. The edge of the aerial at the bottom was missing part of it’s sealing lip. Siliconed underneath and screwed back on.

5/ Passenger footwell leaking in. Lifted seat and carpet to dry out underneath. Followed Youtube video on how to fix. The plastic grommet which takes the screw which holds the trim down in front of the windscreen had a felt gasket underneath which had long since disappeared. Bought new grommet complete with seal, put back in with uPol sealant. You can check for this leak by opening the glove box and looking forward and left towards the bottom of the windscreen, the rust from the leak is evident.

Youtube link https://www.youtube.com/watch?v=_zvNwzxIKCw

6/ High level brake light. The car is a folding hardtop. Again the problem seems to be the use of felt gaskets which have perished over time. On the photo, you can see the gaskets have disappeared around the bolts. Cleaned all the felt off and put silicone sealant around each of the bolts and where the felt seal was around the cable entry. Suspect that the right hand felt seal was the one which was letting the water in given the look of the roof panel before I cleaned it. Used Duck Tape Ultimate to replace the black tape shown on the bottom photo which holds the brake light cable in place. Not sure if there is something better. We’ll see how it holds.

Hope all that helps.

Hopefully that’s that, just driver’s side central locking actuator to change now. New one received yesterday…


Thanks for showing the problems areas, especially the seam leaks, good for others to check if leaks occur.
Got mine pretty much sealed (famous last words) with the scuttle grommets and any boot leaks of which mine were minor just in the boot.
The door lock actuator too I’ve had to replace (driver side) like hens teeth now to obtain second hand, I managed to get one for £25 posted some 3 years ago off ebay.
That top picture reminds me to remove the bumper again, I did around 18 months ago to treat some rust but never took the reinforced bar off to see how much rust is hiding behind the brackets.

I bit the bullet and bought a new one, didn’t want to go through all the work and then find it didn’t work. Any tips for that job?

Ta for that:)

Looks like you have had a similar time to me lately luengonigel. I to had wet boot carpet so took the back of the car to bits sealed the aerial and where the wiring goes through the gromit into the boot as they were letting a little in . Done the high brake light ,just done scuttle gromits today. What you may find is if you have more problems empty all the boot plastics ,fold the roof down half way then take all the plastics and carpet out from the rear shelf . I noticed water coming in over the back two corners of the rubber seal in which the third brake light panel sits down on. This was when parking the car on a hill ,water would sit there then seep over the rubber then trickle down through inside into the boot . If you check that rubber seal I bet the corners will be flattened and the rest will be supple ,I adjusted the panel to squeeze down onto the rubber a fraction more . Just something to keep in mind if you have more issues .

Thanks for that. Interesting what you say as my car is parked on a hill outside all the time with the front pointing up the hill. Any chance that you can take a photo of where you are meaning please then that will complete the MX5 leak story in the one post…hopefully.

I’ll pull her out in the daylight tomorrow and take a couple pictures of where I mean . Thats what mine was parked facing up hill on my drive,I’ve since built a carport to keep it under,

Thanks again for that, will check. Doing the high level brake light seems to have sorted it after the last few nights rain but will keep checking.

Just ben to check the car, the boot is dry now. The inside of the windows was very wet. Partly raised the roof. And did indeed see that the the corners and then running on towards the back window were wet across the width of the seal. Not much water ingress to be seen in the well where the roof retracts into though.

This is the seal in the middle of the car showing a good seal.

This is the driver’s side at the back corner, you can see it’s wet across the full width as opposed to the photo above.

The seal further forward towards the back windscreen is dampish rather than wet as per the above photo.

Where it seems to sit or get in over the seal on those corners look down inside ( back towards the rear inner quarters it makes its way back i belief then eventually into the boot well. Underneath the brake light panel there are bump stops i adjusted them a little to make the panel pull down on the seal a bit more . Try that let me know how you get on . I think this is a area people have been missing

Don’t keep on putting the roof up and down to much without the engine running and get a flat battery like i did .

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Bit of luck and we might be able to get out a bit to charge the battery up!

Also thinking of buying a new seal. I was just going to try and find a picture of a new seal on the inter web to see if it is supposed to be flat from new or it goes flat over time.

Will look into the bump stops thanks. Did that cure it for you or was the car port the answer?

Its been sat out in the rain a couple times and so far so good but time will tell. Glad I done the car port though. I looked into a new seal but I think they are £130 ish as I wasn’t 100% if a new one was the answer I thought I’d hold fire. I love mx5s I’ve had a few but they don’t cure any problems they just keep making them the same ,rubbish really not impressed with that side of it

@Luegonigel How did you remove the high level brake light?

Thankfully I’m not leaking but want to do it as preventative maintenance.


If you open the roof a little so that the rear deck with the brake light is up in the air ,peel back the material tape underneath the brake light and you will see .

@Reg Thanks, sounds straightforward.