Go Back   The 75 and ZT Owners Club Forums > The 75 and ZT Owners Club Forums > Technical Help Forum
Register FAQ Image Gallery Members List Calendar Mark Forums Read
Notices

Reply
 
Thread Tools Display Modes
Old 20th September 2018, 04:05   #1
pieterm
Regular poster
 
Rover 75 Connoisseur SE

Join Date: Mar 2018
Location: Point Cook, Australia
Posts: 83
Thanks: 69
Thanked 8 Times in 6 Posts
Default Heater Matrix - direction please ...

Firstly a BIG thank you to all those members who helped this Rover 'newby'. Following refilling instructions 'to the letter', I no longer lose water but I do still have a small issue with the heater. After flushing out the cooling system, I slowly refilled taking over an hour. The system took almost exactly 7.5 litres of coolant. Disconnecting the heater pipe connection near the battery, I noted blowing one end caused fluid to come out the other. As water seems to flow in and out of the matrix quite freely, I thought all was good. But this is where I need some direction, please. The heater is luke warm. Rear, left and right vents all work OK and the temperature is constant at all outlets ... but it is luke warm and only once the thermostat kicks in. NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD-NAUGHTY WORD- cold until then Although water/coolants move freely through the matrix, and without any apparent restriction, I would have thought the matrix to be OK BUT, I do note the heater pipe that passes near the battery is significantly cooler than the other heater pipe. This has me quite confused as it seems to defy logic. Why would the two pipes vary so much in temperature when water/coolant moves so freely through the matrix? To my expert friends out there, does this still sound like a matrix replacement to you? As usual I bow graciously to the higher powers amongst you
pieterm is offline   Reply With Quote
Old 20th September 2018, 08:33   #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
Default

I'd suggest that the matrix is quite blocked up, in spite of your observations. These are good, but your conclusions are uncertain. The question is coolant flow rate through the complete matrix. Its design has lots of pipes in parallel, left to right, so with a large part of these blocked, there will still be a reduced flow. Certainly enough to pass your 'blow though the pipes' test. This also explains why the outlet hose is significanntly cooler than the inlet. I therefore suggest trying a hosepipe backflush through the matrix to remove any loose detritus. If that doesn't fix it, you may have to replace the matrix. Some people have descaled it using chemicals.



TC

Last edited by T-Cut; 20th September 2018 at 08:36..
T-Cut is offline   Reply With Quote
Old 21st September 2018, 07:54   #3
Chuckles
Gets stuck in
 
NOW a Club Tourer was 1999 - 75 2.0Ltr Connoisseur SE petrol Saloon

Join Date: Jan 2012
Location: Iwerne Minster, Dorset
Posts: 552
Thanks: 63
Thanked 54 Times in 47 Posts
Default

Be very careful with descaling. Use very little as it can and possibly will compromise the metal in the matrix. My old one became a "pepper-pot" after descaling! It would seem scale was in fact helping keeping water in.....

Also be aware that fitting a replacement matrix can be tricky. The joints used are not the best or easiest to master and being very difficult to get to doesn't help. Only use a genuine matrix if possible, some after market ones will not fit without some joggling of the frame.
I did post my experiences some time ago on here if you can find it.
__________________
Chuck
Nth. Dorset. UK
Membership #1896
Don't take life so seriously.... it is not permanent!
Chuckles is offline   Reply With Quote
Old 21st September 2018, 08:16   #4
roverbarmy
This is my second home
 
roverbarmy's Avatar
 
Roverless + 1.7D Sportage

Join Date: Aug 2014
Location: East Norfolk
Posts: 7,026
Thanks: 729
Thanked 2,021 Times in 1,449 Posts
Default

I used to take off the heater matrix pipes in the engine compartment, blow the old coolant out, refill with a flushing agent until the agent comes out of the other pipe and then cork the pipes. Leave to stand overnight if poss, then backflush with a hose. This was not on a 75/ZT but always worked well.
__________________
Oil in my veins!
roverbarmy is offline   Reply With Quote
Old 29th September 2018, 00:10   #5
pieterm
Regular poster
 
Rover 75 Connoisseur SE

Join Date: Mar 2018
Location: Point Cook, Australia
Posts: 83
Thanks: 69
Thanked 8 Times in 6 Posts
Default

Quote:
Originally Posted by T-Cut View Post
I'd suggest that the matrix is quite blocked up, in spite of your observations. These are good, but your conclusions are uncertain. The question is coolant flow rate through the complete matrix. Its design has lots of pipes in parallel, left to right, so with a large part of these blocked, there will still be a reduced flow. Certainly enough to pass your 'blow though the pipes' test. This also explains why the outlet hose is significanntly cooler than the inlet. I therefore suggest trying a hosepipe backflush through the matrix to remove any loose detritus. If that doesn't fix it, you may have to replace the matrix. Some people have descaled it using chemicals.



TC
Again thanks for your help. There seem to be so many threads on this subject it is not easy to find answers as all seem to differ in some way. So, I pulled out the matrix (much simpler than I had thought) and flushed the matrix. Used hot water flushing in both directions. Lots of brown coloured water came out and, after around a dozen hot-water flushes, had a total of about a tablespoon of grit as well. Also a bit of what looked and felt like cotton wool - not much, not even half a teaspoon. So having achieved that, I still flushed twice with a flushing agent and no more gunk or grit was seem. Followed the instructions on this web site and took almost two hours to SLOWLY refill the system. Horror of horrors - still cold air from the heater. What I did notice was that the two pipes feeding the matrix were far from warm. The bottom pipe was only slightly warmer than the top pipe but both were tepid (to say the least). I was holding the metal pipes attached to the matrix inside the car. Several days have now passed and there is no drop in coolant level and no improvement to a very cold heater (it's still winter here in Australia !). Does this sound like the system still has a major air lock? Or is there something I have missed in all of this. Again, thanks for any help you can give

Last edited by pieterm; 29th September 2018 at 00:13..
pieterm is offline   Reply With Quote
Old 29th September 2018, 07:24   #6
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,271
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by pieterm View Post
Followed the instructions on this web site and took almost two hours to SLOWLY refill the system. Horror of horrors - still cold air from the heater.
Did you follow the MG Rover procedure Pieter which includes raising the expansion tank? Two hours?

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 29th September 2018, 13:39   #7
roverbarmy
This is my second home
 
roverbarmy's Avatar
 
Roverless + 1.7D Sportage

Join Date: Aug 2014
Location: East Norfolk
Posts: 7,026
Thanks: 729
Thanked 2,021 Times in 1,449 Posts
Default

Sometimes, the matrix is blocked in the middle but free at the end where the pipes go in and out. The coolant takes the point of least resistance, ie straight in and out again without circulating through the matrix.
__________________
Oil in my veins!
roverbarmy is offline   Reply With Quote
Old 1st October 2018, 22:53   #8
pieterm
Regular poster
 
Rover 75 Connoisseur SE

Join Date: Mar 2018
Location: Point Cook, Australia
Posts: 83
Thanks: 69
Thanked 8 Times in 6 Posts
Default

Yes, raised the tank. I let the water dribble in ... instructions did say slow I took around two hours in total ... including many cups of tea etc. Still not certain of the issue as if I start the car then turn it off for a while, then restart sometimes I get a different result. That is, sometimes both pipes are cold but sometimes top is cold and bottom hot. I've now invested in a vacuum kit so hopefully that will be the end of airlocks ! I'll keep everyone informed of the result on this thread.
pieterm is offline   Reply With Quote
Old 1st October 2018, 22:55   #9
pieterm
Regular poster
 
Rover 75 Connoisseur SE

Join Date: Mar 2018
Location: Point Cook, Australia
Posts: 83
Thanks: 69
Thanked 8 Times in 6 Posts
Default

That's what I suspected but when I ran the test with boiling water ... that is, took the matrix out and poured boiling water into it .. it was burning hot all over. No cold patches. Have now invested in a vacuum kit and will let everyone know the outcome on this thread
pieterm is offline   Reply With Quote
Old 11th October 2018, 02:14   #10
pieterm
Regular poster
 
Rover 75 Connoisseur SE

Join Date: Mar 2018
Location: Point Cook, Australia
Posts: 83
Thanks: 69
Thanked 8 Times in 6 Posts
Default Result !!!

All I can say is go buy one of these:

https://www.youtube.com/watch?v=IVyikhHE_38

There appear to be heaps on eBay. Of course you will also need a compressor but as these tend to be useful items anyway, it might be worth investing in one. Either that or borrow from a friend.

Now a word of warning ... when you buy this, it comes with no instructions. Well, mine didn't. Just as well I found the youtube video a per above.

You will need to fit one of the included rubber rings. It needs to be connected to the top of the expansion tank - I found the mid sized rubber ring to fit. Don't make the same mistake as me and push the base into the expansion tank ... it only needs to go as far as the ridge in the filler opening.

Also I found the tap on my unit to be the reverse of the video.

BUT IT WORKED !!! Now I should add I did NOT empty the coolant system to start. I simply tried to purge the air out - I was surprised how well it performed. I now note the following ...

Touching the heater pipes where they connect to the matrix seem to be almost the same temperature with the heater off. The top pipe slightly cooler, which is understandable. Turn on the heater fan and the top pipe is even cooler. Again understandable. I am happy with the result though feel some greater benefit will be gained once I actually drain the system and use the vacuum then. The heater is definitely nice and warm on a cold day, but the pipes are not too hot to touch which I would have thought should be the case - especially the bottom pipe. I have noticed the fan rarely kicks in so maybe there is a thermostat problem as well ???

Anyway, am happy for now so thought I would share my experience - just wish I had bought one of these things earlier instead of spending days fluffing about
pieterm is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 13:19.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright © 2006-2023, The Rover 75 & MG ZT Owners Club Ltd