Toyota MR2 Message Board - View Single Post - not the heater core please not the heater core!

mrtwo1991 · 11-20-2009, 07:44 AM

I just replaced my heater core last year. My leak showed up on the passenger side. The coolant will first drip into the A/C coil plastic box(located behind the glove compartment) and then onto the carpet.

I was able to get a factory heater core from Toyota (since I could not find anyone who made an aftermarket unit). Cost was approx $250.

The original unit looked to be made of brass. Depending on your leak, a radiator shop MIGHT be able to repair it.

It took me approx 20 hrs to replace the unit. I could not find any writeups on doing this. If I had to do it again I think it would take 12 hours.

I found it easiest to also remove both of the seats to get access room.

Start by taking out the glove box, center console, radio. I also had to remove the air bag ECU located under the radio (be CAREFUL and follow instructions in the service manual for doing this). The AC coil box comes out as a unit (you will first need to evacuate the refridgerant and then disconnect the fittings located in the front trunk). Then remove all of the defroster ducting on the passenger side. Then start disassembling the heater core box from the bottom. Once you remove the bottom part of the heater core box then the heater can be removed with the top part of the heater core box. Dissassemble the plastic heater core box to finally get to the heater core.

When you're removing the top part of the heater core box from the dash it takes several contortions to get it out of the firewall. Be patient with it as I found my leak was in the two pipes that go through the firewall.

As they say in most manuals "reassembly is the opposite procedure". Of course make sure you follow the MR2 procedure with the hoses for bleeding the air out of the system.

It is a PITA, but it can be done.

11-20-2009, 07:44 AM	#7 (permalink)
mrtwo1991 No Skills Join Date: Oct 2008 Posts: 34 Thanks: 0 Thanked 1 Time in 1 Post iTrader Rating: (0/0% )	I just replaced my heater core last year. My leak showed up on the passenger side. The coolant will first drip into the A/C coil plastic box(located behind the glove compartment) and then onto the carpet. I was able to get a factory heater core from Toyota (since I could not find anyone who made an aftermarket unit). Cost was approx $250. The original unit looked to be made of brass. Depending on your leak, a radiator shop MIGHT be able to repair it. It took me approx 20 hrs to replace the unit. I could not find any writeups on doing this. If I had to do it again I think it would take 12 hours. I found it easiest to also remove both of the seats to get access room. Start by taking out the glove box, center console, radio. I also had to remove the air bag ECU located under the radio (be CAREFUL and follow instructions in the service manual for doing this). The AC coil box comes out as a unit (you will first need to evacuate the refridgerant and then disconnect the fittings located in the front trunk). Then remove all of the defroster ducting on the passenger side. Then start disassembling the heater core box from the bottom. Once you remove the bottom part of the heater core box then the heater can be removed with the top part of the heater core box. Dissassemble the plastic heater core box to finally get to the heater core. When you're removing the top part of the heater core box from the dash it takes several contortions to get it out of the firewall. Be patient with it as I found my leak was in the two pipes that go through the firewall. As they say in most manuals "reassembly is the opposite procedure". Of course make sure you follow the MR2 procedure with the hoses for bleeding the air out of the system. It is a PITA, but it can be done.