Heater Matrix advice (2.5L KV6)

Redmaestro · 29th November 2018, 15:34

Hi all,

I'm thinking about removing the heater matrix to flush it out before the cold weather sets in. I've read up on the forum on how to do it, but I can't see how to break the seal on the pipes to remove it. Is it a push/pull fit or a screw fit? Do I need to replace any o-ring seals?

Thanks in advance

T-Cut · 29th November 2018, 16:39

The metal pipes that are joined in the footwell have flared ends which are butted/nipped together with a circlip/clamp. There's a rubber seal/o-ring between the flares. Generally considered almost impossible for mere mortals to refit successfully. The usual fix is to chop off the flares and join with a short hose and jubilee clips.

EDIT: Why not back-flush it in-situ? The hoses at the firewall can be split there and a hosepipe attached to the outlet side.

TC

Southern Star · 29th November 2018, 18:33

My mechanic flushed out my heater matrix last weekend by disconnecting a pipe union forward and to the right of the engine and blasting it through both ways with a steam cleaner.

Redmaestro · 30th November 2018, 07:01

Quote:

Originally Posted by T-Cut

........ Why not back-flush it in-situ? The hoses at the firewall can be split there and a hosepipe attached to the outlet side.

TC

I'd rather flush it out in situ to be honest. I've recently tried by disconnecting the top & bottom hoses and and running a hosepipe from the top but it ran clear. I'm trying to find a more direct yet easy way to do it. I don't want to be cutting through pipes if I can help it.

The reason I'm doing this is because the heater isn't great and the passenger side is barely warm at the highest setting

SD1too · 30th November 2018, 07:38

Can you get to the heater flow connection (somewhere on the RHS of the engine facing the bulkhead, you will probably have to look from beneath), remove the hose clip and pull it off?

The heater return hose is shown on the diagram as joining with another hose just after it enters the engine bay (at a guess, probably beneath the battery box).

I've never done it myself but this would appear to be the best way of isolating and flushing the heater matrix without disturbing the pipe connections. I'd be interested to know if it's practical.

Simon

T-Cut · 30th November 2018, 10:02

Quote:

Originally Posted by Redmaestro

I'd rather flush it out in situ to be honest. I've recently tried by disconnecting the top & bottom hoses and and running a hosepipe from the top but it ran clear. I'm trying to find a more direct yet easy way to do it. I don't want to be cutting through pipes if I can help it.

Read my post again, last paragraph. The hoses at the firewall have clipped connections which you can release to acess the outlet side of the heater matrix. Put a mains water hose pipe on there and disconnect the other heater hose at the engine end, so the flushings are directed onto the ground.

TC

Steve2016 · 30th November 2018, 12:24

I fitted a new matrix a little while ago and as has been suggested, getting the seals and clips properly installed was very tricky. My matrix has very stubby straight pipes (others have longer curved pipes which lend themselves to the short piece of hose and jubilee clips modification) so I used the original joining method. If you decide to remove the matrix, the following may be of help:

Working in the footwell, the feed pipes push inside the matrix pipes, using O-rings as seals. The O-rings must end up inside the matrix pipes, not pressed against the ends (so they sit between the inside of the matrix pipe and outside of the feed pipe). This was very difficult to achieve, but I did it eventually with the help of some vacuum grease which lubricated the O-rings sufficiently to slip into place. Fitting the retaining clamp was very fiddly and frustrating but I got there in the end.
To flush and drain the matrix before removal, I disconnected the inlet hose at the connection for the FBH (mine has no FBH so was just a plastic joining piece) and the outlet hose between engine and bulkhead. I fitted a short length of 15mm copper pipe into the open end of the outlet hose (behind engine). I then fitted a short garden hose over the copper pipe (this garden hose was just long enough to reach over the engine and down to the floor).
Into the heater inlet hose I pushed a hosepipe and ran tap water through until it ran clear from the short hose. I then extracted the hosepipe, allowing the short hose to act as a siphon and draw out nearly all the water from the heater matrix circuit. On disconnecting the matrix pipes, very little water came out and what there was, was clean so if it did get onto the carpet it was not going to stain it.
Having fitted the new matrix, I used the hosepipe again to fill that circuit and flush out any air pockets before reconnecting the heater hoses.

29th November 2018, 15:34	#1
Redmaestro Avid contributor Join Date: Mar 2014 Posts: 106 Thanks: 11 Thanked 4 Times in 4 Posts	Heater Matrix advice (2.5L KV6) Hi all, I'm thinking about removing the heater matrix to flush it out before the cold weather sets in. I've read up on the forum on how to do it, but I can't see how to break the seal on the pipes to remove it. Is it a push/pull fit or a screw fit? Do I need to replace any o-ring seals? Thanks in advance

29th November 2018, 16:39	#2
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,751 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	The metal pipes that are joined in the footwell have flared ends which are butted/nipped together with a circlip/clamp. There's a rubber seal/o-ring between the flares. Generally considered almost impossible for mere mortals to refit successfully. The usual fix is to chop off the flares and join with a short hose and jubilee clips. EDIT: Why not back-flush it in-situ? The hoses at the firewall can be split there and a hosepipe attached to the outlet side. TC Last edited by T-Cut; 29th November 2018 at 22:03..

30th November 2018, 07:38	#5
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,338 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Can you get to the heater flow connection (somewhere on the RHS of the engine facing the bulkhead, you will probably have to look from beneath), remove the hose clip and pull it off? The heater return hose is shown on the diagram as joining with another hose just after it enters the engine bay (at a guess, probably beneath the battery box). I've never done it myself but this would appear to be the best way of isolating and flushing the heater matrix without disturbing the pipe connections. I'd be interested to know if it's practical. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

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29th November 2018, 18:33	#3
Southern Star Loves to post Rover 75 CTDi Contemporary SE Join Date: Jul 2013 Location: Stretton-under-Fosse, Warwickshire. Posts: 358 Thanks: 54 Thanked 134 Times in 83 Posts	My mechanic flushed out my heater matrix last weekend by disconnecting a pipe union forward and to the right of the engine and blasting it through both ways with a steam cleaner.

30th November 2018, 12:24	#7
Steve2016 Regular poster Rover 75 Tourer Join Date: Jan 2016 Location: Nuneaton Posts: 66 Thanks: 14 Thanked 9 Times in 5 Posts	I fitted a new matrix a little while ago and as has been suggested, getting the seals and clips properly installed was very tricky. My matrix has very stubby straight pipes (others have longer curved pipes which lend themselves to the short piece of hose and jubilee clips modification) so I used the original joining method. If you decide to remove the matrix, the following may be of help: Working in the footwell, the feed pipes push inside the matrix pipes, using O-rings as seals. The O-rings must end up inside the matrix pipes, not pressed against the ends (so they sit between the inside of the matrix pipe and outside of the feed pipe). This was very difficult to achieve, but I did it eventually with the help of some vacuum grease which lubricated the O-rings sufficiently to slip into place. Fitting the retaining clamp was very fiddly and frustrating but I got there in the end. To flush and drain the matrix before removal, I disconnected the inlet hose at the connection for the FBH (mine has no FBH so was just a plastic joining piece) and the outlet hose between engine and bulkhead. I fitted a short length of 15mm copper pipe into the open end of the outlet hose (behind engine). I then fitted a short garden hose over the copper pipe (this garden hose was just long enough to reach over the engine and down to the floor). Into the heater inlet hose I pushed a hosepipe and ran tap water through until it ran clear from the short hose. I then extracted the hosepipe, allowing the short hose to act as a siphon and draw out nearly all the water from the heater matrix circuit. On disconnecting the matrix pipes, very little water came out and what there was, was clean so if it did get onto the carpet it was not going to stain it. Having fitted the new matrix, I used the hosepipe again to fill that circuit and flush out any air pockets before reconnecting the heater hoses.