Blocking off the heater matrix

Just read the A/C post and it has reminded me that I need to block off my heater matrix, then maybe it’ll mean the fans will blow air at least the same temp as outside (and not the same temp as the engine )…

So do I just bung up the pipes to and from the heater matrix? Or is there a more canny way of doing it? Block it off in the engine bay?

Has anyone done this and does it actually cool the car a little?


There is already a valve for stopping the flow of water to the matrix, its controlled by the hot/cold setting on the heater panel

However the problem is heat soak into the aluminium by the radiator pipes that run down the r/h sill and then across into the cabin, plus the air routing from the 2 pickups at the front use the alu frame to direct the air about and thus heating nice cool outside air to the same temp as the chassis bits.

Ar$e! So is there any way of actually getting ambient temperatured air into the cabin (via the vents, not windows )?

How about if you drained the matrix? Or just ditched it?

I heard that there was always some flow of hot water going through the matrix? Or did I dream it???

If find the top half is OK temp wise with the windows open but regardless my feet still boil and burn after 30 mins And heel / toe in sandals, while possible, isn’t quite a smooth… Especially when the soul get’s caught under the throttle

I guess you could try disconnecting the tube that leads from the heater matrix to the vents and somehow route another one to the front of the car, you wouldn’t have any control over it without flaps etc nor any fan control, just pure (?) air from the outside !!
However the major problem is the heat generated from the oil cooler and rad warming up the alu at your feet, plus the heat retention in it from the sun

Its almost a lose lose situation

You could always try reto-fitting somebody else A/c?!!


A/C… Pah! Plus I don’t think I could be ar$ed to be honest

OK, so could you not run some pipe like so:

There by stopping all the coolant flow to and from the matrix… I understand it’ll still get warm but even if it could knock a few deg’s off

Yep - you could do, i take it you dont need the heater?

I never used it through the whole winter… I’ve only turned the heater on once when I was stuck in traffic for ages to try and drop the temp (didn’t know what temp the fan cut in and scared of a HGF) so nearly died of hypertheremia

Does anyone here need the heater? I guess maybe in bonnie scotland but for us “sarferners” it never gets that cold… Even when it was snowing (and yes I did have to do a 30 miles journey in the snow )

Air con cars have much better ventalation at foot level

But weight more

Well in that case

Strip the whole heater matix out and bung up the heater hoses in the engine compartment.

p.s. When you get to my age, you will need your heater

Hmmm… OK So you don’t need the heater circuit as a engine bypass IYSWIM???

Hmmmm you probably do, the water capacity of the engine alone is very small and will probably heat up too quick, thats why i said earlier it was a lose lose situation

Question, are you actually serious in doing this ?

Yeah, if it’s feasable… The fact it blows pretty bloody hot air, especially if I’ve been “giving it some berries” (even more so trackdays) is just a PITA

I’d rather be cold in the winter and wear more clothes


like you the only time i ever used my heater was to help with engine cooling when stuck in traffic so if you remove all this gubbins you could save some kg’s but you might suffer when trying to get sufficient litres per second thru’ the cooling system when the going gets tuff… that’s just a 2nd thought… 'cause i don’t actually know and my original thought would be that it should be okay because all that should happen is the radiator gets used more frequently and the rad fan will come on more.

What do the jedi from SELOC say?? or what about Dave Andrews?..

In fact Pesky… do the racers have heater matrices ?? i’d have thought not…

It would also be an opportunity for you to move the thermostat to the outlet side of the head.


it IS possible to have cool air coming through the air system.
Searc my posts regarding it, they’re somewhere in this site. But in short, my car was always hot and now I can have cold air (from the outside) at will.
You just have to seal all the hot air entrances, because the cabin is a low pressure zone.

It’s very well explained in my posts, but I’m too tired now to search it.
Off to sh@g the missus instead…


Rox, glad you’re thinking along the same lines and again that was my only concern, to loose heat when stuck in major traffic But then my fan is now set to come on at 95C and off at 92C… Unlike the 105C or whatever it is… But still unsure.

Udlis, I remember reading about your windows half up, half down and what not… I’ll dig it out

Have fun (or should I say had fun unless you’ve been at it for 3 hours nudge nudge wink wink fnar fnar

Maggsy had a leak in his heater matrix so we took it out and connected a bit of hose across the gap, as a makeshift fix, and it worked fine. You could still circulate a bit of water if you needed it, say for demisting, but the bulk was not there…