HOW TO: Heater Matrix Repair

BL330

Member
Messages
1,121
Well done Cliff for joining the club who have accomplished this task.
When I did mine years ago I also replaced my fan which had an intermittent fault.
I vividly recall the plastic tubing to send air between the fan and the heater box had impossible to reach screws against the firewall.

95442

All back together
95443
 
Last edited:

Cliff

Member
Messages
174
The culprit,
was only loosing 1-2mm in the header tank each time driving the car, when pressure testing the system didn’t loose anything at 10psi but at 15psi cap pressure 1 bar was loosing .25 of a lb over 2-3 min. Seal on one matrix tank leaking.
@BL330
Cross fingers nothing goes wrong with the fan now. Ha
 

Attachments

  • 5E2104A7-DB88-4FDF-8E8D-CB7BF91FDBD5.jpeg
    5E2104A7-DB88-4FDF-8E8D-CB7BF91FDBD5.jpeg
    135.2 KB · Views: 36

digitaladam

New Member
Messages
24
My 4200 had coolant on the floor when I bought it recently, so I did the bypass. I'm about to go through a year of "how often do I really need heat, anyways?" before deciding if it's worth replacing. I store the car for the winters, so we'll see...
Would rather avoid this job OR wait until something else needs a dash-out replacement as well.
 

Cliff

Member
Messages
174
My 4200 had coolant on the floor when I bought it recently, so I did the bypass. I'm about to go through a year of "how often do I really need heat, anyways?" before deciding if it's worth replacing. I store the car for the winters, so we'll see...
Would rather avoid this job OR wait until something else needs a dash-out replacement as well.
The explanation on here is excellent and like a lot of jobs it looks a lot worse than it is, I have spent a couple of days doing it taking my time, I think the worst thing you could do is rush this job as you don’t want to mis something and find you need to strip it again to put it right. There were half a dozen screws missing in my dash so the job has been done before but not finished well, ( I have a chunk of OCD ) get a piece of cardboard and put the bolts in sequence into it then as you put it back together just start at the bottom of the cardboard and work up. I put them on a table in lines and position but band everybody from the garage incase the nocked it. Ha
 

Eightpot

Junior Member
Messages
35
Replaced the matrix on mine a couple of weeks ago following this really excellent how to and input from other forum members. Thought I had all the required tools on hand but got caught out with the passenger air bag torque screws. I have a large set of them but all mine are the usual 6 spline whereas these were 5 spline torques which were not available locally. I know another member who recently changed their matrix and theirs were 6 spline so not sure mine was a one off but thought I'd give the heads up to others about to tackle this fix. MY 2004.
 

Attachments

  • IMG_20211211_124053.jpg
    IMG_20211211_124053.jpg
    83.8 KB · Views: 33

Cliff

Member
Messages
174
Replaced the matrix on mine a couple of weeks ago following this really excellent how to and input from other forum members. Thought I had all the required tools on hand but got caught out with the passenger air bag torque screws. I have a large set of them but all mine are the usual 6 spline whereas these were 5 spline torques which were not available locally. I know another member who recently changed their matrix and theirs were 6 spline so not sure mine was a one off but thought I'd give the heads up to others about to tackle this fix. MY 2004.
I didn’t disconnect mine there I disconnected it at the loom connection the one in yellow
 

Attachments

  • 109E5CA9-99A0-448B-893C-20F4BCAC05D3.png
    109E5CA9-99A0-448B-893C-20F4BCAC05D3.png
    3.7 MB · Views: 32

Eightpot

Junior Member
Messages
35
I'd have done the same but for some reason the connector was cable tied behind the glove box so couldn't be undone without the dash removed.:(
 

BL330

Member
Messages
1,121
Some 5 spline torx also have a pin in the centre. Again for security, such as ones used to to hold the airbag to the steering wheel.
I had to go to a motor industry trade supply store to get mine. Not always available at regular auto stores the public use.
 

Eightpot

Junior Member
Messages
35
Some 5 spline torx also have a pin in the centre. Again for security, such as ones used to to hold the airbag to the steering wheel.
I had to go to a motor industry trade supply store to get mine. Not always available at regular auto stores the public use.
Funny thing is my steering wheel air bag does require a hole in the centre but is a 6 spine. The only 5 spline I had was the passenger air bag. No doubt Maserati used what they had at the time
 

philgarner

Member
Messages
226
What else is on the list 'while you're in there'? I'm in the final stages of this and just about to pull the heater box out. In my past I've had a few old cars with noisy blower motors and it was major surgery to get to them. I'm looking at mine now on the GS and thinking it would be a shame to have that start to whine in 6 months!
 

BL330

Member
Messages
1,121
What else is on the list 'while you're in there'? I'm in the final stages of this and just about to pull the heater box out. In my past I've had a few old cars with noisy blower motors and it was major surgery to get to them. I'm looking at mine now on the GS and thinking it would be a shame to have that start to whine in 6 months!
Depending what year your GS is.
If 2004 or 2005 and you have the rear parking sensors, it is worth moving the beeper from the passenger footwell to somewhere easier to hear.
I put mine in the centre console underneath the cigarette lighter. This not issue for later cars as they moved the beeper to under the rear parcel shelf.
 

RichTaps

Member
Messages
199
What else is on the list 'while you're in there'? I'm in the final stages of this and just about to pull the heater box out. In my past I've had a few old cars with noisy blower motors and it was major surgery to get to them. I'm looking at mine now on the GS and thinking it would be a shame to have that start to whine in 6 months!

I'm removing the CD changer and replacing it with one of these whilst I have access to the bits behind the radio;

https://www.ebay.co.uk/itm/125109730101?_trkparms=amclksrc=ITM&aid=111001&algo=REC.SEED&ao=1&asc=20160908105057&meid=5f8971a998fd4cf4a55d4f86da870b09&pid=100675&rk=1&rkt=15&sd=125109730101&itm=125109730101&pmt=1&noa=1&pg=2380057&brand=Unbranded&_trksid=p2380057.c100675.m4236&_trkparms=pageci:68472530-801e-11ec-9d78-461841c0e680|parentrq:a00f46c317e0a77d84e01014fffcfd28|iid:1

It says "Porsche Becker" on the description, but the connections look identical to me.
 

philgarner

Member
Messages
226
I've never found a problem with the parking sensor beeps so will leave that. I've been tackling horrible sticky covering on the steering wheel cowl, grease and tar remover plus a razor blade is as good as I've found so far!
 

mjheathcote

Centenary Club
Messages
9,033
Is it at all possible to restart the car before putting it all back together? Normally it is a good idea to do a few heat cycles and retighten hose clamps after a change.
Also to check for any leaks too before putting it all back together.
 

Cliff

Member
Messages
174
Is it at all possible to restart the car before putting it all back together? Normally it is a good idea to do a few heat cycles and retighten hose clamps after a change.
Also to check for any leaks too before putting it all back together.
I pressure tested the cooling system to 1 bar before putting it back together