Heater Matrix Clogged.......maybe / maybe not.

[Paulie]

Hey guys,

Sorry to bother you again.  Having got my Supra from the restorer, I have some minor niggles.  One I believe may be a heater matrix that's clogged.  I also am unsure what I'm looking at.

I've read the excellent post by Scooter on flushing the heater matrix and I'm about to give it a go (probably this weekend), when I thought I'd find out where the inlet / outlet pipes to the matrix live under the bonnet.

So a quick look when the car was up to temperature illustrated one pipe was very hot, and another cold at the points where they hit the firewall.  Things then became a tad confusing, for a little way along the cold pipe, where it seems to connect to a piece of metal pipe, the hose became hot.  The metal pipe seems to connect both in  and out hoses into the heater matrix.  When I say connect, there's a piece of metal between them, I'm not sure if it's a hollow pipe or not.  Either way, to the left of this metal pipe, the out hose seems to get much warmer.

I've attached a pic of what I mean and I hope it makes some sort of sense.

Can anyone tell me if this bit of pipework is normal?  And, does it sound like a clogged heater matrix that might respond well to a reverse flush with a hose?  As an aside, the passenger footwell is dry and clean, and the little rod thing is attached to the plastic lever in the passenger footwell and moves admirably when the temperature knob is turned (I do try to read up on the forums before I ask what might be daft questions.....honest).

 

Thanks everyone for being so supportive.  With any luck this thing will behave itself before long.

 

Best wishes,

 

 

Paul

 

 

[rider]

I had a blocked heater matrix in one of my old cars and it turned out that everything from the control valve (tap) had turned to a green jelly that would not dissolve in anything. There was only one solution to that, a new matrix, tap and pipes. The Supra though does seem to have air lock issues with the matrix and this thread may help you out.

 

https://www.mkivsupra.net/topic/128626-heater-matrix-same-old-same-old/

Edited August 31, 2021 by rider (see edit history)

[Paulie]

Thanks Rider,

Much appreciated as always. 

Wow, reading that thread is quite an eye-opener and has served to make me wonder how on earth to get rid of the airlock, it seems pretty complicated.  As luck would have it, I reverse into my driveway which is up a hill (I live in Wales).  So my heater matrix is currently the highest point of the cooling system....which could well fall in line with an airlock scenario..  I'm wondering what the bleed valve is that was fitted to the 200sx as mentioned in one of the comments.  Or, if some sort of pipe as is fitted to the Peugeot (also mentioned) would do the trick.  Given that this issue is so very common, it looks ripe for a mod of some sort.  

 

 

[m12aak]

That pipework looks fine to me, same as mine. I believe the connection between the two sides is hollow and that's why it's hot after there as it's just bypassing the matrix. I can't remember which side is in/out 100% but I think it's the other way round? 

When I did my water pump on the NA I thought my matrix re-clogged itself as it was cold, but I only had a massive air lock in there, as it fixed itself a few days after while I was parked nose down on a steep street (logically this doesn't make sense but it happened!) I now realise that when I re-bled the system after doing the water pump, I didn't have the heater on .

When I initially flushed it a year earlier, loads of brown clay like sediment came out that the speedflush mentioned in Scooter's thread shifted. I suspect there's just a big airlock in there, but attempting a low pressure flush on each side wouldn't be a bad idea. I've got one of the lisle funnels that attach to the radiator and raise the highest point in the system. It's great and has always worked well for me, as it managed to bleed the matrix out after the initial flush, so that might be worth purchasing. 

[Scooter]

Well it's worth a go IMO at the flushing. You've identified the hoses, so half way there. The cold pipe ends over the spark plug well so definitely extend/redirect this somewhere else. I'd personally favour extending into a container so you can observe the grit etc that might come out.

Start gently with hose pressure and any chemical cleaners, the holts ones shouldn't cause damage, but I would only put it in the short run to the matrix direct that way you can do it multiple times as you'll need only a small amount of the holts mixed with near boiling water.

Check the insides of the top coolant pipe to the radiator, sometimes there is rust residue on the inside and IMO it's that that can easily block the very fine heater matrix core. if it's bad then you may want to consider a Holts flush on the whole coolant system, in that instance I would cap off the matrix and link the two metal pipes to avoid debris going to the matrix.  

It'll be hard to get it back you near new but you should get an improvement and I think genuine cores are discontinued and some owner who fitted reproductions claim the heat isn't as good? I was a wuss with the chemicals and pressure but wanted to be patient and not perforate it. If you wanted to get aggressive then I'd advise researching perhaps even testing chemicals on some aluminium etc before using.

Chris Wilson had a a good thread too, I think he ran a hose through them for hours...........

[Paulie]

2 hours ago, m12aak said:

That pipework looks fine to me, same as mine. I believe the connection between the two sides is hollow and that's why it's hot after there as it's just bypassing the matrix. I can't remember which side is in/out 100% but I think it's the other way round? 

When I did my water pump on the NA I thought my matrix re-clogged itself as it was cold, but I only had a massive air lock in there, as it fixed itself a few days after while I was parked nose down on a steep street (logically this doesn't make sense but it happened!) I now realise that when I re-bled the system after doing the water pump, I didn't have the heater on .

When I initially flushed it a year earlier, loads of brown clay like sediment came out that the speedflush mentioned in Scooter's thread shifted. I suspect there's just a big airlock in there, but attempting a low pressure flush on each side wouldn't be a bad idea. I've got one of the lisle funnels that attach to the radiator and raise the highest point in the system. It's great and has always worked well for me, as it managed to bleed the matrix out after the initial flush, so that might be worth purchasing. 

Thank you, I was wondering why there was a connector between the in / out pipes.  I'd have thought it would go straight through.  Oh, I shall have to re-check that I have the in / out the right way around.  I suppose, the worst case, I could just run a hose through it both ways.

Oh dear, that's the sort of thing that would happen to me.  I'd do that very same thing when re-bleeding after swapping the water pump.  It is amazing that the airlock fixed itself after parking nose down on a steep hill.  

I've just added the funnel to my cart on Amazon, that looks like a pretty good bit of kit, thanks for recommending it.

 

Paul.

[Paulie]

2 hours ago, Scooter said:

Well it's worth a go IMO at the flushing. You've identified the hoses, so half way there. The cold pipe ends over the spark plug well so definitely extend/redirect this somewhere else. I'd personally favour extending into a container so you can observe the grit etc that might come out.

Start gently with hose pressure and any chemical cleaners, the holts ones shouldn't cause damage, but I would only put it in the short run to the matrix direct that way you can do it multiple times as you'll need only a small amount of the holts mixed with near boiling water.

Check the insides of the top coolant pipe to the radiator, sometimes there is rust residue on the inside and IMO it's that that can easily block the very fine heater matrix core. if it's bad then you may want to consider a Holts flush on the whole coolant system, in that instance I would cap off the matrix and link the two metal pipes to avoid debris going to the matrix.  

It'll be hard to get it back you near new but you should get an improvement and I think genuine cores are discontinued and some owner who fitted reproductions claim the heat isn't as good? I was a wuss with the chemicals and pressure but wanted to be patient and not perforate it. If you wanted to get aggressive then I'd advise researching perhaps even testing chemicals on some aluminium etc before using.

Chris Wilson had a a good thread too, I think he ran a hose through them for hours...........

Thanks Scooter, do you think I have the right hoses identified (in / out correctly labelled)?  I don't suppose it matters, I could just do it both ways I suppose.

Oh for sure, I have some old hose up in the shed that I'll butcher, it'll be long enough to get to a bucket.  I actually think I have a large clear storage container (about 60L I think), that should give me a decent view of any schmutz that comes out of the matrix.

Good call with the Holts, I've always been a bit nervous about such products but I think I'll give it a go.  Oh yes, I'll check for rust in the coolant pipe, good idea.

I think I too would rather be cautious.  Knowing my luck I'd hook it up to a pressure washer and end up flooding the cockpit.  I'll take it easy and see what happens.  Now that's interesting, I'll search out Chris' thread, thanks for the recommendation.

Paul

[m12aak]

9 minutes ago, Paulie said:

Thank you, I was wondering why there was a connector between the in / out pipes.  I'd have thought it would go straight through.  Oh, I shall have to re-check that I have the in / out the right way around.  I suppose, the worst case, I could just run a hose through it both ways.

Oh dear, that's the sort of thing that would happen to me.  I'd do that very same thing when re-bleeding after swapping the water pump.  It is amazing that the airlock fixed itself after parking nose down on a steep hill.  

I've just added the funnel to my cart on Amazon, that looks like a pretty good bit of kit, thanks for recommending it.

 

Paul.

No worries, you're right, ignore me! Don't know why I didn't just search for a coolant flow diagram in the first place:

[Paulie]

4 minutes ago, m12aak said:

No worries, you're right, ignore me! Don't know why I didn't just search for a coolant flow diagram in the first place:

Superb diagram, is this from a service manual?  I may need have to get one from somewhere, I can see it being very handy.

Cheers,

 

Paul

[m12aak]

10 minutes ago, Paulie said:

Superb diagram, is this from a service manual?  I may need have to get one from somewhere, I can see it being very handy.

Cheers,

 

Paul

Yeah I just googled '2jz-ge coolant flow diagram' and it was on a post from this forum. I've got some manuals saved but the ones I have are split into different systems (e.g. coolant, engine mechanical etc.), unlike this one which appears to be an extract from larger, thicker manual. I believe none of my manuals have this diagram for some reason.