heater matrix flushing feedback

Ok, given the recent threads on the lack of availability of new heater matrices I wanted to post up my experience of flushing my "not quite working at optimum" heater.

Firstly I should say I have a perfectly good very clean low mileage Supra with a piping hot heater to compare my other slightly more worse for wear one.

Symptoms of the problem were the usual poor heat output, particularly at idle, but it was reasonable at cruising rev's. A cold/luke warm return/out pipe from matrix, the return pipe is the nearest (to the front of the car) one of the two that go across the rear of the cam cover. The 'in' pipe comes straight from the rear of the cylinder head as will always be VERY hot.

So I initially thought it may be a air lock and so I fitted a bleed valve into the rubber return section (as this is the highest point in the cooling system) After later work I'm inclined to believe this isn't necessary but it is handy now it's there.

This didn't have any effect on the heat and so I moved to flushing. My first attempt was a simple back flush with plain cold water via a hose pipe. The clips (right at the back of the engine directly of the intake cam cover) can be a pain to fully compress, I found a pair of mole grips with wide enough clamping area to get all three prongs in were best, as they held them tight so you could ease them back along the pipe work before releasing. Prior to this I removed the plastic spark plug cover and placed towels underneath the pipes to minimise water getting into the head channel. I should say at this point I hadn't prepared that well, so only had a small section of old NA coolant pipework to extend the 'In' connection down past the ABS/charcoal canister area. The garden hose I held to the matrix 'out' pipe, and gave it a reverse flush. At first I got zero flow, I increased the pressure of the hose a bit (I had a twist nozzle that meant I could give it a blast and back off cycling) and gradually got some flow out (ideally you'd collect in a bucket and then you can see how much grit etc you are getting out but again I wasn't prepared then and so just ran it to the floor).

This improved things slightly but the return hose was still barely warm and the matrix was still definitely restrictive.

But as I'd seen an improvement I got prepared for a more focussed attempt to clear the matrix.

I bought 3/4" garden hose from Toolstation (it was what I could get at short notice, 19mm internal bore is ideal and also clear tube might help waste less coolant on refilling)

Holts speed flush 250ml from Halfords it had good reviews but I was sceptical (also bought the Holts 2 step rad flush but didn't need to use it)

Some jubilee clips

The hose was 30M! so allowed me to cut 3 sections, 2 for to and from the matrix pipes so I could have the exit one in a bucket and the hose feed away from the engine bay also, and one for the initial input of the flushing fluid (shorter and attached to a funnel that I hung from the bonnet latch)

So I attached the funnel one to the matrix out and one to the matrix in leading to my empty bucket. I then poured in cold water to the funnel to flush out the red coolant in the matrix ie until the water into the bucket ran clear, this might take some squeezing, the hose I had was easy to squeeze shut with finger pressure, and can then be folded on itself towards the matrix to force it through it (and not backup the funnel!) NB also check the hose isn't kinked (it's a soft hose which has it's advantages and disadvantages!)

Once that was done I got half the bottle of the Holts speedflush (this was all I ended up needing) and added it to very hot water (not far off boiling but be careful the hose gets very soft then) and then poured this down the pipe with the goal to get the matrix full of the solution so I did it until warm water came out into the bucket.

Then I left this for a time (may be an hour), then disconnected the funnel hose and attached the 3rd longer hose. The 3/4" hose conveniently slipped over my regular 1/2" garden hose nozzle and I flushed this through, my large bucket was over flowing for 5-10 mins or so after filling (you should see particles of crud in the bottom of the bucket afterwards)

I then reconnected the funnel hose, and poured down new coolant again until it ran out into the bucket (this is where a clear hose would be better)

I was busy that day and so only had the time to reconnect all the hoses and briefly start her up and bleed via the new vavle in the top hose.

The next time I took it out I was REALLY surprised at the difference it had made, it is now piping hot, too hot to endure at the full setting like my other one, I wish I had done an output temp reading before and after to record the difference.

I really didn't expect this result and can only think the Holts speedflush fluid with hot water has really helped (it says it's non acidic and metal and rubber pipework safe) hence me writing this up with specifics for others.

I would say that at some point this car has been run on less than optimal coolant, as the matrix pipes had a internal coating of rust residue, not horrendous but the matrix is an ideal trap for these particles and there is no escape for them from the system (check your overflow/expansion tank for residue too, if there is some in there odds on there is some in your matrix too). If your main coolant pipes show any signs of residue internally then I think an occasion flush would be advisable even if it's currently showing zero signs of heating issues, as it's obviously far easier to flush a barely/lightly clogged matrix than one a more clogged one.

If you have no signs of residue and the coolant system seems in great shape then just keep on top of those coolant changes and perhaps make an extra effort to get to the annoyingly positioned block drain bolt (that we often don't bother with!)

PS if anyone local wants any hose I've a 'slight' excess that needs to go!

Will provide pics if anyone semi clueless wants to give it a go

Thats a really good write up.

I need to flush mine out, i barely get any hot air atall

Brilliant Scooter, you're a proper asset to the club, thanks for taking the time to write it up bud

Cheers guys, I tried to get across that it's easy to try flushing when you have the right bits and take a bit of care, I may have been lucky it wasn't very badly blocked or it may have been that the Holts is really good, but I can say it's worth a go. Even if you got no flow, I'd try putting some neat Holts down both pipes, leave and try again a few times, little to lose.

As a last resort you could add the whole bottle to the system in general (the way it's designed to work) and see if the combination of sustain operating temperature and flow/pressure/turbulence to the matrix entrance does the trick, you just need to be ready for a full drain, rinse and new coolant refill in that case.

I did this with mine a few years ago and it worked perfectly for a week or so. After a long run down to Cornwall and back it decided to empty the entire contents of the matrix into the drivers foot well! Had to replace the matrix in the end.

Well fingers crossed here! I'll try and keep popping back to the thread to update on what happens.

Slugger what did you use to flush yours just water or anything potentially corrosive?

I see there were three years of it's not really working.....

http://www.mkivsupra.net/vbb/showthread.php?205097-Heater-issues&highlight=matrix

to the eventual flushing.....

http://www.mkivsupra.net/vbb/showthread.php?280001-Bloody-heater!&highlight=matrix

which may have had a bearing on the failure? ie if you'd have flushed in 2009 might it have lasted longer than 2012? pure speculation but perhaps?

Anyway I accept there is a risk of perforation in some cases, may be it's a job for March/April time when if the worst happens you can bypass it for a short time before actually fixing it. It would be interesting to see a failed one as aren't they aluminium and so can't rust per se but obviously fail some how?

I use some fairy liquid in my flushes too. The foam really gets all the bits out. Someone used radseal in mine before I got the car so I've got to do these flushes every 6 months. I normally do 30 mins reverse and 30 mins forward. I then use a drill pump to pump in distilled water and then use the same process to pump in antifreeze before connecting the hoses back up.

I have done afew heater matrix flushes at work recently.

(Mazda CX5s seem to have abit of an issue with them clogging up)

Mazda recommend using 30ml of citric acid in a large bucket of warm water which we flush through using a swimming pool pump lol (the type of pump for emptying a pool)

Hook it up so its on a constant cycle whereby the outlet of the heater matrix is draining back into the bucket with the pump.

We leave it for an hour then empty it and do it again.

The citric acid is possibly less aggressive than holts so it might be better for the longevity of the heater matrix... or it might not be strong enough to shift 20 years of crud. Suppose it could go either way.

Probably tempting fate but as I was here searching for the holts stuff I used I thought I'd post saying all is good. Think I will give it another pre winter flush soon.

Good result, your matrix is doing well, mine let go a long time ago

I have a good used one in the parts bin and can see why they perforate, they are quite small delicate looking things and looking into the innards the coolant pathways are tiny really so no wonder they get clogged.

This on my long list of to do things, and once again Scooter turns up. You really are incredibly useful, even for a seakhawks fan..

Thanks....I think

Should have put up a few pics, I think being patient and going easy with any products (ie don't rush in with drain cleaner etc) and doing it a few times helps to avoid leaking. My affected ones heater is still less potent than the other but has not been an issue this winter so far. I will I think have another go and try and document it fully with pics.

Well tbh I think mine might be fubarred but I'm gonna have a pop at at first. Worth it even just to unclip a few tubes and have a look round. I have learnt more in last month just by being patient and taking stuff apart, reading articles, watching you tube and putting some work in.

I want to have it ready before Drew Brees lifts that super bowl trophy

Good info there scooter think I need to do this on my silver supra

This is something I need to do to mine, I'll give it a go this weekend I think

Brilliant write-up, thanks. Heater works amazingly now, initially, it was barely warm, even after a long drive.

My coolant system was very dirty so I ended up doing about 6 flushes (3 with speed flush) and it got to a point where it was the same colour for the last two, so I then just filled up with Toyota Red. I used deionised water for the flushes which I got from Amazon (£1.50 for 5l!) which is the cheapest I've found it personally. (https://www.amazon.co.uk/Carplan-Diw005-De-Ionised-Water-5Ltr/dp/B000C74XPE/ref=sr_1_7?crid=3IZ5H1ZTVSQ5X&keywords=distilled+water&qid=1581752169&sprefix=distille%2Caps%2C159&sr=8-7)

Also, for you guys that are NA, I managed to get away with not needing the 3/4 hose, by taking off the metal pipe closest to the firewall (that connects both lines) and then just stuck some 1/2 (thin wall) garden hose in there and used jubilee's to hold them in. (see photo)

Thanks again, hopefully this has saved my Heater Matrix!

Bit of a thread revival, my matrix became basically useless over the past few months unless the car was fully warm (even then it was producing a measly amount of heat), so I carried out another flush as above.

This time I decided to replace the return hose from the matrix as recommended by Keron as it was holding some of the sediment that would've found its way back to the matrix eventually. 

This was the result after reverse flushing from the hosepipe the matrix the first time, I can't believe how much rubbish there still is in the system! It was completely clear when I last did a flush only a few thousand miles ago.

For the second round I used a 12v fuel transfer pump from Amazon and some near boiling water with the Holts Speedflush, which seemed to work very well. I just left it for 10/15 mins and it seemed to clear nearly all of the sediment. I was afraid it would have too high a flow and not be good for the matrix, but it was surprisingly weak, which was reassuring.

After a final hosepipe flush and refill using Toyota pre-mixed red, the heater is now almost as good as the other Supra ; still it will mean I won't need to completely deice the windscreen myself every morning!

I suspect I will need to do another flush as there's bound to be more rubbish in the system (the original radiator must still be acting as a trap for it), which I will wait to do when I fit the TT radiator from the other Supra, as that'll be getting a Koyorad when I replace the A/C Compressor, Condenser and Dryer on both cars. 

I still have no definitive answer as to how it got so full of sh*te, everything on the car cooling wise was OEM when I got it and the original rad seems to be totally fine, so I've just chalked it up to the coolant probably never being changed before me!

I understand this isn't particularly interesting, but if you do take one thing from this, PLEASE CHANGE YOUR COOLANT REGULARLY!!!!!!!!!!!! lol
 

Thank you for the updates! This is really good info, especially with photos too. Great tip with the 12v pump too, making it a closed loop flush

I'd guess the inside of the original rad will be de grading and be part of the problem 

2 hours ago, stevie_b said:

Thank you for the updates! This is really good info, especially with photos too. Great tip with the 12v pump too, making it a closed loop flush

Wouldnt this mean you are just pumping back through the dirty stuff though?

3 hours ago, Ric said:

Wouldnt this mean you are just pumping back through the dirty stuff though?

It does, but you can use deionised water and change it regularly, and use a fine filter to prevent pumping chunks of it through the system. Flushing with a garden hose means there'll be tap water in the system, which would be a pain to get out. Problematic if you're in a hard water area (like me).

5 hours ago, Ric said:

Wouldnt this mean you are just pumping back through the dirty stuff though?

I lifted the transfer pump off the bottom of the bucket so it wasn't sucking in the sediment, but yeah it was pumping through the dirty water with the speedflush in. The water did get progressively darker/muddier so I think it was working.

2 hours ago, stevie_b said:

It does, but you can use deionised water and change it regularly, and use a fine filter to prevent pumping chunks of it through the system. Flushing with a garden hose means there'll be tap water in the system, which would be a pain to get out. Problematic if you're in a hard water area (like me).

The water from the hosepipe wasn't really an issue as I just lifted the feed hose above the matrix and used gravity to remove it until the outlet was pure coolant. Also ~500ml of hosepipe water in a system full of good coolant probably won't be an issue, if you couldn't get it out.