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I done the no removal of dash heater core removal today. I noticed the core I took out looked pretty good and didn't notice any cracks etc. I replaced It anyway and put it all back together. I hooked up hoses again, started car and let it run for a while and it still leaks. It is a small leak in passanger side footwell. I am guessing I am goin to have to remove whole dash now and replace pipes. Before I do anyone have any other possible reasons why it would still be leaking? And I have searched but could not find a guide
on removing dash, anyone know one?

if you replaced the core with a new one then it will not be leaking. The leak has to be identified but simple explanation is hose connection??

Hi flamo,

I dont know what year your car is but I found a pdf which tells you how to remove the dash for 89-93 MX5 if that's any help?

www.miata.net/garage/DashRmv_89_93.pdf

Cheers

AK

If your kinda lazy, you can bypass it, and just not have a heater core with flud running in it...

If it's leaking in the passenger footwell, it could be the air conditioning as there is a tube there that gets rid of the water that is pulled out of the air.

Lift the carpet on the passenger's footwell, and you should see a plastic tube with a T piece in it.
This tube can come undone, and when it does, it drips water into the footwell.

It is possible, but not likely, that the new core that you installed is faulty.

Not having used the method that you used, I do not know if this might have happened, but if you had to apply any force to position the core properly, you may have opened up a joint or something similar.

The air-conditioning drain is your best bet, for a cheap fix! How would you feel if that was the problem all along, and you didn't need to replace the heater core? I think that I can guess ...

Thanks for the help I ended up pulling the whole dash out and found that one of the copper pipes that run from the firewall to the heater core had a crack in it. Replaced it, and put dash back together (didn't test it until I put it all back) and than found that I had damaged one of the rubber hoses that connect the pipes to the core so it then started to leak from there. So I than had to pull out the core again and replace the hoses, lukily I did not have to pull the dash to do this.
So to fix this small leak and get my heater working again I spent 2hrs replacing core, 8 hours pulling dash and replacing pipe, another 2Hr to replace rubber hose.. After all that i guess it's still worth it, especially at 5am
on the way to work lol
Thanks for the guide on pulling the dash, it came in very handy!!

I've replaced a heater core - I feel your pain.

I recently had a leaky heater core and i replaced it via the drivers footwell but ended up snapping one of the heater core controls and had to remove the whole dash to plastiweld one tiny broken bit. While i was there i found heaps od dodgy wiring done by previous owners, almost as bad as the stuff i found on the loom at the computer when i wired in my Link.

Dann

flamo wrote:I done the no removal of dash heater core removal today. I noticed the core I took out looked pretty good and didn't notice any cracks etc. I replaced It anyway and put it all back together. I hooked up hoses again, started car and let it run for a while and it still leaks. It is a small leak in passanger side footwell. I am guessing I am goin to have to remove whole dash now and replace pipes. Before I do anyone have any other possible reasons why it would still be leaking? And I have searched but could not find a guide
on removing dash, anyone know one?

It could or could not be the heater core, but I know several similar scenarios and all of them pointed to a malfunctioning heater core.

Would love to know how to replace the heater core without pulling the dash? I did mine about two years ago and fingers crossed it lasts another 20 years.

NitroDann my ECU wiring thankfully is in good shape, but there's a real mess on the drivers side. I took out about a mile of wire that wasn't required. If I was doing it again I would have probably found a unmolested replacement loom.

I got mine replaced by a mechanic under statutory warranty.

For those interested to know, a heater core replacement in an mx5 will set you back around 2 weeks of no car and $980
The two weeks was most likely because I live in tassie and we have very little parts down here!

jerrah wrote:Would love to know how to replace the heater core without pulling the dash? I did mine about two years ago and fingers crossed it lasts another 20 years.

NitroDann my ECU wiring thankfully is in good shape, but there's a real mess on the drivers side. I took out about a mile of wire that wasn't required. If I was doing it again I would have probably found a unmolested replacement loom.

You look under the middle of the dash looking from the pedals towards the passenger side of the car, the heater core has a plastic cover over it. take it off, undo the clamps. Slide the heater core out.

Dann