Thread: Remove pipes from heater matrix D4

I suspect you have a different problem. It would be a single heater core for both sides and heat would be controlled by blend flaps, one each side.

These days, the heater works all the time and temp control is done by blending cold air with air from the heater. I don’t know how the D2 does temp control but I suspect I’m right.

The answer is yes others have swapped the matrix and reconnected the pipes. Matrix does block up from far end.

Originally Posted by p38arover

I suspect you have a different problem. It would be a single heater core for both sides and heat would be controlled by blend flaps, one each side.

Possibly. A cold passenger side is an indicator for a blocked matrix. In the D3/4 they use a parallel flow core fed from the drivers side. Over time the passenger side of the core acts as a coolant filter and progressively blocks up with grunge leading to "cold wife syndrome". While there is one core for both sides, the air flow is such that there's little crossover between sides and the core is effectively half and half.

To have heat on the passenger side and not drivers side is not characteristic of a blocked core, but as you say blend motors. Not saying the drivers side won't block up first, but given the water flow I'd say it's incredibly unlikely.

Is pre-emptively flushing these cores something anyone has ever done? I figure better chance of cleaning it out whilst there is still some flow in there right?

Is it, 'easy'?

Thanks very much.
I will certainly check for errors indicating the blend door motor(s).

In my original investigation I removed the centre console and centre dash which was easy enough, then seeing that the pipes were crimped on I figured I should go back a step and try a flush before committing to the steering, instrument cluster and dash. Prior to beginning there was very little heat coming out with the heater on full tilt.

A little back story for reference: the car was owned by my Dad who has maintained it well and has put about 350 k on it with lots of trips. Apart from this, a knock in the steering noticable when changing direction at low speed and a bit of front diff noise above 120 km/h I'm feeling pretty lucky (I'll address those next). He has a new vehicle now so I scored this one. His trouble with the heater followed plugging a slow weeping coolant leak with an aluminium silicate leak stopper. The weeping leak was cured and the temperature gauge happily sits in the dead centre of the display.

My flush setup is shown below but before I hooked up the pump I blew on one of the braded hoses till my ears hurt like if you try to blow up one of those long balloons used to make balloon animals. Eventually i heard some gurgling and the fluid in the cup shown below came out. I strained this sediment out - if you guessed that it sparkles in the light, you have guessed right. After no more fluid came out I ran the pump with about 70 deg C hot water circulating around for yonks. During this time I could feel the pipes and core end cap become very hot to touch. I regret not feeling whether or not they were hot to touch with the engine running prior to beginning.

I'm guessing I created a clear path or paths on the passenger side but the driver side paths remain blocked.

I put it all back together and now have warm air on the passenger side and slightly warm on the drivers side. An improvement and a vote in confidence that the issue is more likely to be a blockage than blend door motor.

I looked at crimp tools online for this type of job but access is pretty tight so that might not be an option anyway. Perhaps folding the housing on the new core over the existing pipe flange with a suitable flat punch will do the trick. Has anyone seen a post where someone has had success with this?

Perhaps clamping is another option if the mating parts are compatible as is cutting and joining new and original pipes with heater hose as I have read folk have done. Taking the dash out is still an option too I guess.

Sorry for making you rotate your head or monitor for these:

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Thanks again.

Originally Posted by veebs

Is pre-emptively flushing these cores something anyone has ever done? I figure better chance of cleaning it out whilst there is still some flow in there right?

Is it, 'easy'?

D3 grunge in the coolant bottle

Easy is one of those relative words. Easier than replacing the core anyway.

I found this...

Heater core change with out pulling dash | Lexus IS Forum

Looks 'easy'

Originally Posted by BradC

D3 grunge in the coolant bottle

Easy is one of those relative words. Easier than replacing the core anyway.

That's a nice air/water rig. I'll try that before bending things. Thanks.