Heater matrix

Am I right in thinking I need to get the gas out of my aircon to change the heater matrix?

After I thought all my overheating problems were solved and I have had everything but the heater matrix changed......coolant smell in the car, steamed windows and a wet passenger footwell.

bugger.

So, new matrix is on the cards.

If I need to get the gas out of the system how do I do it?

Job looks time consuming but not hard so I will do it myself.

also, anyone tried these....

http://www.demisterman.co.uk/Toyota/Toyota%20Supra%20Mk4%201993-98%20heater%20matrix.php

The matrix's are not expensive its labour involved. Gutted for you mate. If I can help just call.

Cheers dave. Reading Jezz's guide it doesn't seem like a hard job, just a long job. Couple of days I would guess if I take it easy.

Its the aircon part I don't get. The gas doesn't run through it does it? so why do I need to de-gas the aircon?

Nope heater matrix is only for hot air I believe. As its part of the engine cooling system. air con is completely separate.

Bit of advice. If you do it yourself get some food bags and label each part you take apart and keep it in a bag, also label all wiring as you remove and I mean all, It will make life alot easier.

Thats what I thought, which is why it is confusing me that the guide says you need to get the gas out the aircon to change the heater matrix.

Anyone know why? Is it just to make it easy to get to something else?

Bit of advice. If you do it yourself get some food bags and label each part you take apart and keep it in a bag, also label all wiring as you remove and I mean all, It will make life alot easier.

Yeah I will be doing that. good idea

As I said if you want some help just shout.

There are a few more bolts than the guide suggests! I am in the middle of doing this now! It's straightforward but just time consuming!

Take it easy and do it over a couple of days and you won't want to set everything on fire hehe!

The gas needs to be removed as you need to pull out the heater box to remove the matrix.

The aircon is part of the heater box, hence the gas removal.

ok, matrix on order and a job planed for the bank holiday.

In the meantime I have been reading a million threads on bypassing or blocking the matrix to see if it solves overheating issues. I see bypassing it and allowing faster water flow can actually cause a blown head gasket, so bypassing with restriction (i.e. blocking of the pipes to the matrix) is the best option as this allows the block to cool down as it should.

I am sure there must be a 'how to' post on this somewhere but I can't find it. Can someone help me out? either by telling me which pipes to block - with a picture or a link to the post that I can't find please

So far the rad has been replaced 3 years ago, water pump been replaced a few days ago, thermostat done couple of weeks ago along with the rad cap and rad pipes. Viscous coupling being replaced today and now the heater matrix next weekend. Is there anything else that can cause over heating or am I going to be safe now??

Compression test says the block is fine and sniff test says no coolant in engine and no oil in coolant. Coolant in the footwell and steamy windows say the matrix has gone pop but my heaters are still very hot.

anyone know where it is?

Where what is??

Attached are some photos from when I did my matrix on my Soarer.

Basically the same bits with a few changes here and there.

In the second photo you can just see two copper coloured humps. That is the top of the matrix.

You have to take the gas out of the air con because you have to disconnect all the pipes running to the heater box (the big grey box holding the matrix) and then semi remove the box until the matirx can be pull out upward away from the windscreen.

Toyota wanted just under £250 for a new matrix for mine so I took it to a recon place just up the A10 from me into Herford, called Hertford Rads. Charged me £40 to recon my old one and a find job he did too! Pressure tested it in front of me as well to find the problem and then prove he had fixed it.

Here is a snap of a Demisterman unit next to an OEM.

It doesn't get as hot, but fits and works fine.

The matrix can be changed without loosing the gas from aircon.

Just be patient, and brave.

it looks an ok job, just a bit messy as there are cables all over the place and takes time I guess.

I have ordered the demister one. Do you need to change any hoses at the same time or are the old ones generally ok?

There was nothing wrong with mine, and only replaced it as a 'might as well do it whilst in there' option, whilst changing the dash loom.

My hoses were fine, but good idea to replace the 2 clips under bonnet with stainless jubilees, they are a b****** to work with.

The dash wiring loom usually comes out with the dash shell.. and really isn't too bad a job.

don't suppose you know what size I would need?

I can't remember the size, but you can see and measure the heater pipes at the back of the head easy enough.

You can see the 2 spring clips, but they are difficult to get at to remove and replace.

You need to remove these 2 clips and hoses, and the 2 X 10mm bolts to ease the heater assembly away from the fire wall to replace the matrix.

Brilliant, my car alarm has been going off all afternoon and after inspection guess what I found......the car alarm brain is fitted in the passenger footwell and is soaked.

ECU is fine though, just my alarm.

there you go mate http://www.mkivsupra.net/vbb/showthread.php?t=127044

btw demistermans matrix are better than MR Ts

i found the fiddlest job was reconnecting the two hoses that go through the bulkhead

Before tearing your dash out, just just check that it is not coming from the air con drip pipe that goes through the bulkhead just above the ECU.

just above the ecu is dry, mor over to the right is soaked, its deffinatly the matrix. thats my bank holiday planned.

how long does it actually take, taking it easy that is.