Heater Core Swap

[Icedawg]

My 1994 MX3 heater core is leaking coolant, and I am tired of smelling it all the time, and tired of the film of coolant on the windscreen. So it is time to try to replace the core. Has anyone done this? The on-line service manual does not have enough information. It shows the dash parts, and how to connect and disconnect the heater control leads, but no more than that. So, any advice?

[onlytrueromeo]

You will need to pull out most of the dash, and disconnect the lines in the engine bay. It is easier on a 4banger than a v6, if I remember correctly...there is more room to get to stuff in the 4 cyl. engine bay. Either way, be careful not to damage the connections in the engine bay, they aren't the easiest pieces to find replacements for. I think I can find you a part number if you do break them, because someone got the # for me! (for v6 at least, think they're the same for 4 cyl as well)

This is a bit of a PITA just to let you know!

[Mad Cow]

I replaced a heater hose on my car and it didn't have the dumb connectors that everyone complains about, it just had clamps like what you use to hold the coolant lines to the TB, the kind you squeeze with pliers and slide down. So I'm sure you can work something out if you break them.

[Icedawg]

A PITA. Yeah, I had that part figured out. I was hoping I just had to take apart the console region between the seats, and not remove the dash too. It is a V6, and I was noticing the other day that the cross member underneath prevents you from getting at almost anything from underneath at the backside of the engine. And there is soooo much room to get at it from the top too. Ah well. It turns out a new heater core is $660 from a Mazda dealer, so I may just go on breathing fumes for a while.

[onlytrueromeo]

You can find heater cores on ebay from time to time, and I actually have a used one I can sell ya when I get back home after I leave my parents house for mothers day.

Take off the manifold and shove terry cloths in the intake ports on the head. This is THE best way to change it from the engine side...alot less stress, and it ain't too hard to take the manifold off!

You might be able to get away w/ just taking out the center console/radio surround and glove box, but it will still be a PITA. rather than fighting with everything, taking nearly everything out will be the easiest way to get to it...also a good time to clean out all the vent pipes/fans.