Is there a sweet scent inside the cabin? Is the carpet damp?

Suspect the heater core.

 

Gonna inspect the carpet tomorrow. Looks like I'll most likely be bypassing my heater core when I replace radiator (also was leaking at a rate of one overflow tank in 8k miles) water pump, thermostat and hoses

 

Out of what rubber plug are you saying you saw the pink coolant leaking? There is a rubber hose that allows the condensation from the A/C evaporator coil to drain out. I've replaced the evaporator core on a Gen 3 Camry, but never on the Gen 9 Corolla and I'm unaware if the heater core and the evaporator core share the same drain hose or if a heater core even has a drain hose or "plug". Here's a photo of the drain hose about which I'm discussing (it's near the exhaust pipe). You can see the A/C condensation dripping out of it:

 

The only internal leak I can think of would be on the passenger front where the HVAC housing water drain tube normally drips onto the pass side of the vehicle. That hose is common to come off inside the vehicle allowing it to leak onto the pass side floor. But yours is leaking internally on the driver side?

 

Thanks for all the replies, concluded it is the heater core. Just bypassed it today and looking for a nice diy for it

 

From what I can see in my online Chilton manual (take Chilton with a grain of salt, btw) it is quite a big job. Not sure why yours was leaking other than lack of proper maintenance of the cooling system. I have over 380K miles on my Corolla and have never replaced anything in the cooling system besides the P-HOAT coolant/antifreeze on a regular basis. No problems.

 

It is a huge job to replace the heater core, the entire dash and steering wheel have to come out. Nightmarish mess. I did see one comment where the DIYer was contemplating cutting the two aluminum pipes so that the heater core would slide out of the plastic box without removing everything, then, he would have attached longer heater hoses to re-make the connection. He never followed up. I would consider that route if faced with heater core replacement. IF you do this please post the job so all can benefit.

 

I did see one comment where the DIYer was contemplating cutting the two aluminum pipes so that the heater core would slide out of the plastic box without removing everything, then, he would have attached longer heater hoses to re-make the connection. He never followed up. I would consider that route if faced with heater core replacement. IF you do this please post the job so all can benefit.

I love it when creative people can come up with innovative ways to make a repair job less laborious. Would like to see a DIY for that alternative technique.

 

Realistically, if you could somehow access behind the shifter without removing the upper section of the dash, it would be heck of easier.

Unfortunately, this isn't the case.

Top dash and lower dash will have to come out. The steering wheel could stay in place. On the driver's side, you just need to remove the cluster and the side vent to access the hardware for the lower part of the dash.

Disconnect the air bag connector and you can leave the passenger air bag in place. Don't forget the A pillar covers for more access.

 

GUYS (and GALS)
found an interesting channel on youtube, I've used his diys before for reference and it seems that this method is a viable option. This video was performed on a camry but looking at the matrix, it looks like the same concept can be applied
Camry heater core DIY
Edit:
(Skip to 3:20)

 

GUYS (and GALS)
found an interesting channel on youtube, I've used his diys before for reference

In a few of this videos he's wearing a toyota tech type shirt and has a video called "visiting my old place of work" which looked like a toyota dealership, and a lot of his videos are on different types of toyotas

I've seen some of his (Fix It Angel) videos. He never speaks or says anything, but might put some info typed out on the screen. There are some who like that he never talks because some of the YouTube mechanics just talk and talk and talk and never get to the point (and perhaps love to hear themselves speak?). On the other hand, the talking often has a lot of good information, so take his videos for what they're worth (which is usually a lot). There's also a repair shop in Taiwan which does videos showing whole jobs without saying a word. Problem is there are little to no explanatory captions like how Fix It Angel does. The videos are still helpful, though. The name of the channel is: mesing2005

Here's the link to the channel: https://www.youtube.com/channel/UC44zMBXJ-dPJc-9VkdAZl6w

 

Great find on that video XtRaSlo! That guy on the video is a genius. I did not know that the aluminum heater pipes were crimped on at the heater core, and that they can be uncrimped like a bottle cap! The key to his repair is the 'hi-temp' silicone gasket sealer.

In case you are wondering about the long term reliability of this type of repair consider the following story: I bought two volvo diesels with 90,000 miles and bad heater hoses. There was a 7/8 stub out on the engine and 5/8 heater stub out at the fire wall, the 'official hose' was belled on one end and needed a 90 degree turn towards the firewall, a truly weirdo hose. It was not availble anywhere except 'The Death Star Volvo Stealership'. Four such 12 inch heater hoses at the stealership cost $134 dollars. I made hose replacements with a 90 degree copper plumbing adapter (its ID necked down a 7/8 truck heater hose to 5/8 car hose). I smeared the metal to rubber connections with blue silicone 'hi-temp' gasket material followed by hose clamping, total cost for all four hoses, ~$20.00. Both cars made it to ~225,000 miles with this repair in place, and both eventually went to junkyard heaven with their heater hoses still functioning.

The uncrimping inside the car looks somewhat difficult. You can also think about just cutting the metal pipes, de-burring, and joining them with a repair sleeve made of a 1-1.5 inch long piece of 5/8 heater hose. Smear all the connections with hi-temp silicone gasket sealer. This type of repair will function just like a 'glued in' PVC pipe coupling. The clamps may not actually be needed, but they represent a cautious 'belt and suspenders' type of approach.

 

Sounds like this should make it to 250k if I'm at 160 now, looks like it just takes some patience and a pick

 

Ouch. Angel's 'uncrimping' method might not work on a Matrix heater core, remember, he was working on a Camry. Unfortunately, a Vibe heater core removal (identical to Matrix and Corolla) video shows that the crimped aluminum pipes are pointing upward, not outwards towards the door. Check at 21'min 34"s. This could be a serious problem for 'uncrimping'. Might cutting and splicing still work?

Here is is the video (Vibe but it should be identical):

Check out the massive disassembly required, he reviews it at 21'00". Not just the steering wheel. The whole steering column had to come out! He was just able to avoid depressurizing the 'freon' in the A/C!!! (but Toyota officially recommends that step!!!).

Good luck. Let us know if there is an alternative to complete Steering & Dash Removal.

 

When I looked down there yesterday I saw two crimped outlets pointed to the door, I'll get some pics when its bright outside

 

Interesting. Good fortune has smiled upon you. That was a 2003 Vibe in the video. Maybe there was a small change in orientation after 2003 or, it was always different in Corolla/Matrix.

One more suggestion, if you buy a coil of generic 5/8" heater hose you could go continously from the engine through the firewall and clamp the end of the hose onto a 1"-2" 'cut-off' stub at the heater core (using sealant). No interruptions or splices are involved. Zip ties could be used to secure the hoses so they do not flop around. No crimping and un-crimping required.

Could it be that simple, when Toyota recommends a complicated disassembly of the interior shown in the Vibe video and the discharging of the AC system?

 

They never want to show the easy way. Use of the official book time for the job and then do some Mickey mouse job to cover. This is why YouTube is a valuable tool for DIY and education.

If they gave away all their secrets, they'd be looking for work like everyone else.

 

In a few of this videos hes wearing a toyota tech type shirt and has a video called "visiting my old place of work" which looked like a toyota dealership, and a lot of his videos are on different types of toyotas
Most likely gonna fart around with it on sunday
Playlist for different DIYs

 

Also, for inquiring minds, my 04 matrix xrs heater core looks like this