Warning: Bypassing the Heater Matrix - DON'T DO IT!

[Ruan]

I've been reading recently on the forums, there seems to be more and more people doing it, either if you've snapped the heater matrix hose connections, which is stupidly easy to do as they get brittle from the heat from the exhaust manifold, or because the heater matrix has failed.

DON'T DO IT!!!

The cooling system is finely balanced on these engines, it's quite heavily engineered to do it's job. If you shove a bit of pipe between the inlet and the outlet, you'll end up passing the almost the entire cooling system flow through the pipes off the head since this is the easiest route, meaning you lose approximately 2/3rds of your radiator flow to just pumping it through a closed loop where no cooling will take place.

The other way is to block it off - this causes hot spots in the cylinder head, since there's an outlet to the matrix on the back of the head in one corner, this means that the corner doesn't receive much water flow at all, causing it to locally get very hot in that one spot.

Just replace the heater matrix as soon as possible!

The XUD9s are VERY sensitive to heat - it's their one downfall that affects their longevity, if you overheat them, they just destroy themselves very quickly - the gasket goes, you fill the head with air, then you just massively overheat the cylinder head and then warp it to high heaven. If you see the temperature gauge go above around 90*C - lift off and leave it cool down, you WILL eventually pop the head gasket if you keep using the power above there.

Just a quick warning really, unless you like replacing heads/gaskets - keep the matrix in. The cooling systems are much more complicated than they first look!

[Sambarker]

Think after what you told me, I'm going to try and plumb the heater matrix back in. Going to need to ra*e a 205 td for the pipes though

[Dave]

What about fitting a clamped pipe in? something which restricts flow ...

[Ruan]

You could do yeah, but it could be too much one way... It's hardly worth it considering a heater matrix literally takes what, an afternoon..

I've done it and I didn't think it was that bad in all honesty... Considering everyone makes it out to be the worst job on a 306, I didn't think it was at all that bad!

[Dave]

Ah fair, touch wood never had a matrix go so wouldn't know... I'm sure It'll happen sometime ...

[petegledhill]

would upgrading to the xantia rad help at all?

[Xud Missile]

I just had a quick go at seeing the difference in flow between a matrix and open pipes. I have no need for a heater matrix in a car with no windscreen or roof so if I can match the flow of the matrix then maybe I can run without one.

One used but working heater matrix:


One pond pump and containers, a length of pipe the same size as connected to the heater matrix:


I ran with and without the matrix for the same time. 51 seconds seems odd but I didn't have a stopwatch. I used the workshop CD player and used 2 parts of a song as reference points for starting and stopping the pump


End result: the heater matrix has 66% of the flow of an open pipe. This is only from 1 test though, I'll do more to confirm and then try and match the matrix flow by turning a sort of hose joiner with a small internal diameter (which can be drilled out in small increments until it's the same/close enough to the matrix) There may be flaws in this, so please point them out If i do need to run a matrix it's not the end of the world

[cwspellowe]

[Xud Missile]

<3 Bill Nye

[Dave]

Love to see abit of science behind stuff... stick a jubilee clip round the pipe to simulate matrix

[Jonny81191]

Interesting stuff, will watch closely!!

[Ruan]

Absolutely perfect mate, this is just the information we need! If we can definitively say what size is needed then we are in business!

My only concern with this method is that you're only measuring the restriction at one flow rate, it could get exponentially worse as flow increases? I'm not fluid dynamics expert so I've not a fecking clue, but that's my only concern, I don't know if it make enough of a difference... Other way to do it is to get an XUD running with a larger than normal header tank, then pull off the matrix hoses either side and then measure at 3000rpm, that way we know the flow rate is about right for the engine?

Dunno what your thoughts on this are?

[Xud Missile]

That's a good point. The pond pump I was using has a fixed flow rate which I can't alter, unlike an engine at different revs. I also don't know what pressure the water is at in the engine (which will also change with temperature), the pump I'm using is low pressure, high volume. Rigging it up on the engine, like you say, would definitely give the best 'real world' results. Would use a lot of water Outside workshop: pallets, empty IBCs, use of a forklift...

[Jake949]

dont cooling systems usually run at about 1 bar pressure?

[306Puggy]

I understand that bypassing the heater matrix would cause the water to take the easiest path through the bypass pipes instead of through the cylinder head channels, but what I don't understand is why I didn't end up blowing my gasket when I did it. I drove it hard during the time but it still didn't overheat. Not that the tempature gauge would pick up over heating anyway, since the sensor is situated in the radiator, not in the engine.

[Xud Missile]

I looked at that PDF in a sticky in the XUD section the other day and noticed the coolant flow rate was 92l/min @ 2500rpm. My pond pump is 100l/min so it's close. I did another test today.

First I did 3 runs with the matrix, and 3 without

Results were consistent

Then I tried using an XUD exhaust manifold spacer/stud thingy (8mm hole, I didn't measure the open pipes but I'm guessing they're 18mm ish?)

The result of this was a higher flow than with a matrix. So I welded on a chunk of steel and drilled it @ 6mm

I welded a lip around the other end too to stop it popping off. Bunged it in and tried again

6mm flow was too low, I went up in .5mm increments


7.5mm (says 7.5m on the pic, ignore :p ) was cock on so I'll run with that in place and see how it goes.

[Jonny81191]

Great! And you've used parts easily found in any XUD owner's garage

[Ruan]

Awesome, perfect for all xud owners this!

All xud owners that like being cold anyway!

[SuperGalen]

You could do yeah, but it could be too much one way... It's hardly worth it considering a heater matrix literally takes what, an afternoon..

I've done it and I didn't think it was that bad in all honesty... Considering everyone makes it out to be the worst job on a 306, I didn't think it was at all that bad!



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www.fifacoinsbox.com

[Piggy]

rebuilding a beam is worst job on a 306....

I'll happily do a matrix over that!

[Alex]

Has anyone figured out an easy way to change a heater matrix yet?

[Mattcheese31]

Has anyone figured out an easy way to change a heater matrix yet?

what you getting stuck on mate? . . . . . it's just time consuming really, i did mine a few weeks back . .

[Alex]

Wasn't stuck, I understand it's a dash out job, just not looking forward to it.

[Mattcheese31]

Wasn't stuck, I understand it's a dash out job, just not looking forward to it.

Just be methodical, there's a decent guide on the gti6 forum that helped me
If you scroll down to the bottom of this page my thread about pissing steam is there, link to guide is in there too.

[nominous]

How do you control heat on a 306 ?
This thread would suggest that water is always flowing through the matrix no matter what?
But if you turn the knob to cold, doesn't that operate a valve in a 306 to shut off flow to the matrix and leave it with static water sitting in it ?

Or does the cool knob just control vents and there is a constant water flow through the matrix no matter what ?

[welshpug]

knobs move flaps, matrix is a full flow thing.

not a wanky valve like a renault or a ford.

[205steve]

hi all, im fitting a xud into my track car and i dont have a heater matrix can i replace it with a drilled bung? if so what was the final hole size please? was it 7.5mm
thanks steve

[205steve]

hi all, im fitting a xud into my track car and i dont have a heater matrix can i replace it with a drilled bung? if so what was the final hole size please? was it 7.5mm
thanks steve

not sure if anybody has seen this yet?
i am very interested as my car doesnt have a heater matrix so would be looking for a solution quite soon, thanks steve

[toseland]

cold XUD owners? haha

the heater on my vitara is about as effective as lighting a tealight on the passanger seat in winter..

will be interestingt o pull the dash apart and see how the heater matrix differs in mine

[Sambarker]

cold XUD owners? haha

the heater on my vitara is about as effective as lighting a tealight on the passanger seat in winter..

will be interestingt o pull the dash apart and see how the heater matrix differs in mine

It's the small radiator which becomes an issue on the Vitara as soon as you start tuning. Your heaters will be constantly on hot!