HOW TO replace heater core with pix

[foama]

Today I replaced the heater core. Why would somebody do that? If it were leaking or clogged! Clogging happens due to wrong, or mixed or unsuitable coolant or from lime scale from hard tap water (OEM method) instead of demineralized water. The deposits from just one cup of hard water can be enough. A clogged core means not much heat, usually the passenger side is affected first and more heavily than the other side.
Before you go to the trouble of replaceing it, try flushing it with strong lime scale remover first!
There are at least two different makes of aftermarket cores to choose from. I bought mine from Thermotec.

No need to remove glove box, centre console, radio, or centre vents.
On models with autotemperature there might be an actuator or something else to take off for access.


Tools needed: Just basic tools, including pliers, screwdrivers, spanners size 10 and 12, a receptable for collecting coolant, a funnel for filling coolant, a little pocket mirror to aid connecting pipes, a good portable light source, and don't forget a yoga mat to lay on for preventing bruises. It is definitely easier to do the job with the driver seat taken out. It is possible to leave it in place, but that way you will get bruised all over and look like you've been in a brawl. If you do remove the seat, do not forget the electric connector underneath.

Hardware needed: The new heater core, enough new and correct coolant. It is imperative not to mix different coolants, even if both were suitable for the car but from different makers. If it just says "for japanese" or "for Mitsubishi" it is probably the wrong stuff. Beware: The Mirage takes a different coolant than all other Mitsubishi. In Europe Glysantin G30 is good, the same stuff as for non-diesel Toyota. No idea what they sell in the States.


How to do it:

Park the car level, not on a slope. If the core was clogged, the coolant needs replacement! Put a receptable under the left side of the radiator and open the discharge screw. Then do the same under the engine discharge screw. Lift up the little container next to the radiator cap, and empty it out. Put it back. Collect old coolant for proper disposal. Fill radiator to the top with water, and flush it all out by opening both discharge screws. Repeat flushing so it comes out totally clear. Two flushings are enough. Remove the air filter box for access, three bolts size 10. Disconnect the both rubber hoses from the pipes going to the core. A pair of suitable pliers helps.
See picture:




Disconnect the minus pole of the car battery. Spanner size 10 needed.

Push driver seat all the way back. I recommend removing the driver seat for better access. but do not forget the electric connector under the seat. Lay the yoga mat on the floor where the drivers feet would be to protect you from bruises and injuries. Remove the horizontal plastic pieces under the steering wheel, including the piece above the pedals. Small philips screwdriver needed. Looking from the door, you will see the following as in the picture:



The steering ECU with its braket as seen on the top of the picture above is next. Mark the four connectors on the steering ECU so their position is is not confused. Remove the four connectors. Remove the cable clip from the bracket of the ECU. With a size 12 spanner, remove the two bolts holding the braket and set the ECU assembly aside. It looks like this:



Looking from the door with the steering ECU assembly out of the way, you can now see the heater core.




Uncrimp the two pipes from the old heater core. A small flat screw driver is helpful. Remove the pipe-clamps holding the pipes onto the plastic with a philips screw driver, and save them for later. Remove the pipes.
With the pipes out of the way, you can now pull the old core straightly all the way out.

Insert the new core all the way into its place. Install both new pipes and connect them to the core. Take care to do it 100% properly! Connecting pipes to core is the most challenging thing to do. You will be laying on your back, struggling with small parts that may fall into your face, bad view, not enough room to breath, etc. You will remember all the curses you ever heared and seemingly forgot. The pocket mirror is of help to view the rear of those wretched connections.
Reinstall the pipe-holding brackets, and check they are not appying any force to the connections.
Fill new coolant until full. Check thoroughly for leaks before doing anything further!

If no leaks are detected, reinstall the steering-ECU and its four connectors.

Reconnect the battery and start the engine. While it is warming up, keep constantly replenishing the coolant so no air pockets remain in the cooling system. When the top radiator hose becomes hot, its time to put the radiator cap on. Keep the engine in idle with the cap on until the fan comes on. There is now pressure in the cooling system so don't remove the cap. Turn off engine and recheck inside for leaks.

If there are no leaks, let the car cool off. The other parts taken off can now be put back in place.
When the car has cooled for at least half an hour, remove the radiator cap to recheck coolant level and refill the external coolant canister. Observe the fill level marks on the canister.

Expect the job to take about half a day.
Good luck! Of course, all at you very own risk.

[Christopher_B]

Hey Foama.
About how long did this take start to finish?
What was the reason you replaced?
In the states we have different colors of "Asian coolant" but they are actually all the same technology. They are a P-HOAT (phosphate hybrid organic acid technology) coolant in either blue, green or red/pink. If a customer called looking for a Mirage coolant I would have sold them the blue version based upon my initial findings. I usually sell G30 coolant for European vehicles. However, the owner's manual states "similar high quality ethylene glycol based non-silicate, non-amine, non-nitrate and non-borate coolant with long life hybrid organic acid technology"
. It seems the Asian and the G30 coolant both meet all of those requirements. The Asian coolant has phosphates however. This is where the HOAT comes in. Like this coolant -->:

Your G30 specs are here:

GLYSANTIN® G30® is an engine coolant concentrate based on
ethylene glycol that needs to be diluted with water before use.
GLYSANTIN® G30® contains a corrosion inhibitor package based on
organic acid salts (OAT coolant). GLYSANTIN® G30® is free of
nitrites, amines, phosphates, silicates and borates.

I could not say with any certainty that the OAT would not work as well as a HOAT (as specified in my manual) Yes I am aware the manufacture GLYSANTIN does recommend it. And the fact that it is free of everything the owner's manual says it needs to be free of makes me think it will work fine.
Out of curiosity, does your owner's manual also call for HOAT coolant?

[Wallythacker]

How much was the replacement core? What was the cost of the other core? the one you wished you got?

[foama]

Hey Foama.
About how long did this take start to finish?
What was the reason you replaced?
In the states we have different colors of "Asian coolant" but they are actually all the same technology. They are a P-HOAT (phosphate hybrid organic acid technology) coolant in either blue, green or red/pink. If a customer called looking for a Mirage coolant I would have sold them the blue version based upon my initial findings. I usually sell G30 coolant for European vehicles. However, the owner's manual states "similar high quality ethylene glycol based non-silicate, non-amine, non-nitrate and non-borate coolant with long life hybrid organic acid technology"
. It seems the Asian and the G30 coolant both meet all of those requirements. The Asian coolant has phosphates however. This is where the HOAT comes in.
Your G30 specs are here:

GLYSANTIN® G30® is an engine coolant concentrate based on
ethylene glycol that needs to be diluted with water before use.
GLYSANTIN® G30® contains a corrosion inhibitor package based on
organic acid salts (OAT coolant). GLYSANTIN® G30® is free of
nitrites, amines, phosphates, silicates and borates.

I could not say with any certainty that the OAT would not work as well as a HOAT (as specified in my manual) Yes I am aware the manufacture GLYSANTIN does recommend it. And the fact that it is free of everything the owner's manual says it needs to be free of makes me think it will work fine.
Out of curiosity, does your owner's manual also call for HOAT coolant?

Plenty of questions.

The reason for doing this job was to replace the clogged heater core. For examination, the old core was flexed open on both sides. The openings for coolant are tiny, very small indeed, maybe twice the thickness of a piece of letter paper. On the cooler side, these openings were partly clogged with lime scale (mineral deposits) which restricted coolant flow. The total amount of all the scale was such that it may have originated from only one pint of hard water. I originally assumed this core had silicate gel problems, but that was obviously not the case.


Coolant The Factory Service Manual (FSM) which every technically interested owner should have, says the same as the owners manual and the same as your quote. Coolant colours just as the coolant formulation itself is not standardized, and any maker can do what they want, and they do just what they want!

Since some of these cars have or had silicate gel related problems with OEM coolant (see several threads), I contacted the world's largest chemical factory which also is the world's largest coolant maker. Anybody can ask their coolant experts (Gysantin brand) detailed technical questions by phone or mail and expect a qualified answer. The engineer recommended I use G30 (OAT) which is also good for all recent GM "Dexcool" and all non-diesel Toyota, or otherwise to be absolutely safe, resort to the more expensive G64.
Volvo typically takes G64, it being a PSi-OAT formula = Phosphated OAT = a special HOAT variety free of silicate. Other HOAT contain silicate! I think this may be exactly what the FSM calls for. I was told to thoroughly flush out every trace of old coolant, to stick to the recommended concentration (50% volume), and to use only demineralized water for dilution. He emphasized not to use tap water.

In the USA, I would mail Valvoline (Zerex) asking them which products are suitable.
I have been using G30 for many years, ever since noticing the heater core becoming clogged using OEM coolant. The heater core problem has remained unchanged with G30 ever since. I recommend checking coolant PH value every year or so, and changing it immediately if PH changes the slightest. Value should be at approximately PH8.5 and any change means unwanted chemical reactions taking place. A good set of PH indicator paper costs less than a Dollar.



The time it took was about four hours in total. I took my time to do it right, and in hindsight probably could have done it in less than half the time.
This is not a job you want to do in a hurry! In particular, connecting the pipes to the core may require endless patience. If you try to rush it, you can not succeed.



The new core was branded Thermotec, type D65003TT.
The Thermotec core starts around €50.- (US $50.-)
A different and well reputed brand is Nissens.
The Nissens core type 707183 costs around €123.- (US$123.-)

Examples:
https://www.ebay.de/itm/154624120570...Bk9SR6az7LOWYQ

https://www.ebay.de/itm/325006564325...Bk9SR6iz7LOWYQ

[Wallythacker]

Another thought came to me. If you can't use tap water how are you supposed to flush the damn system? Only hose I have emits municipal water, which to be fair, where I live has virtually no trace of sediment or byproducts. It might have some to do with capturing fast flowing water from the Niagara River before it has a chance to slow down and gunk up.

[Top_Fuel]

If you can't use tap water how are you supposed to flush the damn system?

I flush my cooling system over the span of a few days using 5 1-gallon jugs of distilled water as follows...

1. Open the radiator petcock and drain the radiator (collect old coolant for recycling)
2. Refill radiator with distilled water
3. Start engine and let it run with radiator cap off for a few minutes to bleed any air pockets
4. Install radiator cap and drive the car for at least 15 minutes
5. Let engine cool off until it's safe to remove radiator cap
6. Drain the radiator (It's mostly water at this point...I just spill it on my driveway and let it evaporate. That may be a death penalty crime in some countries.)
7. Do you have at least 1 gallon of distilled water left?
   
   YES: Go back to Step 2.
   
   NO:
   Refill radiator with enough new coolant to make it a 50/50 mix (I think I use 3/4 of a gallon for a 5-speed). Top it off with distilled water. Run engine for a few minutes with radiator cap off to bleed any air pockets.

[Mark]

Another thought came to me. If you can't use tap water how are you supposed to flush the damn system? Only hose I have emits municipal water, which to be fair, where I live has virtually no trace of sediment or byproducts. It might have some to do with capturing fast flowing water from the Niagara River before it has a chance to slow down and gunk up.

A gallon of distilled water cost $1.22 at my local Walmart. A couple gallons would probably do the job?

I can't tell you what a liter costs in Canada, but it's cheap stuff here.

[foama]

The problem with tap water is scale. If you look into an old cut open core, you can see how tiny those slits are, and what a minute amount of deposit is enough to clog them.

If you flush the system, you open the tap on the bottom of the radiator, and also the opening on the engine block. Virtually nothing more than a few drops will remain after flushing, and all will be drained out. Therefore I wouldn't worry about flushing it with tap water.
Important is that hard water (tap water) does not remain in the engine so the calcium and other minerals do not mess up the core.

Here in Germany tap water has no chlorine and is of table water quality. Sometimes it has mineral water quality, meaning it contains minerals like calcium and magnesium as well as others in moderate concentrations.

[Wallythacker]

Thanks gang. I have so much on my plate I don't have a clue if I'll get around to a heater core on my 2014. Annoying as I have 100% decided to sell my 2017. I'll keep my Vue until I find a decent Mazda 2 5MT or a Fit as a secondary vehicle.

Probably going to sell my Burgman also. Have not ridden it since 2018. Wow. I put it away carefully, going to gas and start it this weekend. It's insured so I'll probably go for a spin.