day by day the gauge has been coming up
... so do you think you may still have an airlock which is slowly curing itself?
Or a stat which is slowly staying closed longer and longer?

Most interesting.
If you do get to the bottom of this please let us know.

If it were me I think I'd try loosening the cap on the expansion tank, or even removing it completely to see if I could shift the air right out while taking it for a short run round what I call my "test" circuit. While obvs keeping a very close eye on the temp and stopping from time to time to open the bonnet and check things are still OK.

But that is me and I am not offering it as good advice.
 
Well the temp gauge gets up there but still takes longer than it used to so there maybe is a bit of a ‘stat issue but it all seems a bit too coincidental to me how it was fine and with really good heaters and went straight up to temp and the the gauge never moved, then the matrix went so I bypassed it and it was all still fine, then I piped in the new matrix and this starts, it seems to have enough water and day by day the gauge has been coming up which I find odd in itself. Yes all controls are set up properly thanks, only the drivers side was taken apart but was put back together as should be and the passenger side that wasn’t touched is running the same temp as the drivers side. I think it’s the right matrix and fits nice just has slightly different cores

Cheers

Towsey
It all points to the matrix don’t u think, I understand stand the diesel engine is a cooler running than say the petrol engine, so with your coolant and thermostat change the engine temperature is now normal and as Tdis are.
If not, then although the matrix is a size that there’s now not enough cores.
Your issues reminds me of my RR which had a pathetic heat out from the heater in winter the main dealer checked it out supposedly and said it was so i had to live with for 10 years, the D1 is a lot better, i turn the output temp down after a mile or two in mid winter.

If you have a gurgling sound from the matrix, that is one sign of air in the matrix, lack of sufficient heat output is another, the matrix doesn’t have the means to bleed that air out, so drain and refill the system slowly, so the coolant rises slowly pushing air out, its a bit involved with the tdi I understand... the placing the vehicle higher up at the front when filling has also been mentioned in the past, which would bring trapped air into the top of the rad.
Any air will then travel to the reservoir which fitted has a valve to self vent, unlike the days past when the engine had to brought up to temp with reservoir cap off after replacing coolant.
 
It all points to the matrix don’t u think, I understand stand the diesel engine is a cooler running than say the petrol engine, so with your coolant and thermostat change the engine temperature is now normal and as Tdis are.
If not, then although the matrix is a size that there’s now not enough cores.
Your issues reminds me of my RR which had a pathetic heat out from the heater in winter the main dealer checked it out supposedly and said it was so i had to live with for 10 years, the D1 is a lot better, i turn the output temp down after a mile or two in mid winter.

If you have a gurgling sound from the matrix, that is one sign of air in the matrix, lack of sufficient heat output is another, the matrix doesn’t have the means to bleed that air out, so drain and refill the system slowly, so the coolant rises slowly pushing air out, its a bit involved with the tdi I understand... the placing the vehicle higher up at the front when filling has also been mentioned in the past, which would bring trapped air into the top of the rad.
Any air will then travel to the reservoir which fitted has a valve to self vent, unlike the days past when the engine had to brought up to temp with reservoir cap off after replacing coolant.
My 300 tdi never ran that cool, and it heated up enough to keep the cab warm just like you said. If his heater matrix is that efficient, or should we say inefficient in this case, then maybe he should think about fitting a higher value stat, if one is available, or simply a rad muff.
Once knew of a case where a Triumph Herald based kit car started heating the passenger compartment ridiculously well, in fact it was cooking the inmates.
Turned out the rad was partially blocked due to the car not having done a long run for years and all the muck from the coolant ways had moved into the rad. So a reverse flush sorted it out. But the moral of the story was that the heater matrix can do a lot of cooling and the car was running just fine, not even overheating according to the gauge!
 
My 300 tdi never ran that cool, and it heated up enough to keep the cab warm just like you said. If his heater matrix is that efficient, or should we say inefficient in this case, then maybe he should think about fitting a higher value stat, if one is available, or simply a rad muff.
Once knew of a case where a Triumph Herald based kit car started heating the passenger compartment ridiculously well, in fact it was cooking the inmates.
Turned out the rad was partially blocked due to the car not having done a long run for years and all the muck from the coolant ways had moved into the rad. So a reverse flush sorted it out. But the moral of the story was that the heater matrix can do a lot of cooling and the car was running just fine, not even overheating according to the gauge!

Thats how I survived the winters in my RR days.. fit a rad blind, mine was a diy just piece of cardboard covered with tin foil covering half of the rad, it lasted the month or so that snow and ice was about. Landy mags (LRO) has adverts for manufactured blinds back then.:)
 
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Well I fitted the new stat and found the one I removed to be a 78 degree so 10 degrees cooler than standard so fitted the new 88 and It has made a bit of difference to the heaters but they are still not to the temp they were, and the gauge still runs exactly where it was so...cooler stat was still capable of giving excellent heat and standard 88 degree stat hasnt made a difference to either the blowers or the gauge.

If I drain the system again I don’t think il empty the matrix anyway because the pipes rise up from the matrix to the bulkhead so short of using an airline some will remain. I could of re-piped the matrix incorrectly as I didn’t pay attention and just put the pipes on and fired her up, they are on the right way round but maybe I should of fitted the lower one first or payed attention to a sequence to get the air out.

It has been run with the cap off but I haven’t been near the steep bank yet that I want to try parking on to see if any air moves, if there is any.

Don’t get me wrong the heaters aren’t useless and do produce heat just not the amount they did. I usually remove the fan in winter anyway but to be honest I was really happy before that no matter wot the temp stayed the same, fan on or off, summer, winter, pulling up long hills etc the gauge just stayed in the same place

Cheers

Towsey
 
As u stated in an earlier post the two matrix ports flow and return are side by side, my disco appears the same when view from the engine bay but once fitted in the heater box does one end up higher that the other.

I’m asking as the early the early RR the flow was at the bottom port and the return port was higher up therefore the flow appears to be upwards, different from what was expected, as in at the top out at the bottom, just like the engine radiator.
 
Thats how I survived the winters in my RR days.. fit a rad blind, mine was a diy just piece of cardboard covered with tin foil covering half of the rad, it lasted the month or so that snow and ice was about. Landy mags (LRO) has adverts for manufactured blinds back then.:)
exactly like the one I made for my cortina Mk 1. It hung on a string from the rad filler. Told a mate of mine about it, he had a Capri and was also suffering. told him how to make it. He complained to me that his car had boiled over. I went over with him again how he had made it. He forgot to make sure it only covered half the rad!
 
Yes one is above the other but can’t remember which is which, but...
After looking at different matrixes I THINK that my original had about 22 cores and this one has about 14, so that’s about 1/3 less cores so it’s hardly going to run more heat is it!

Towsey
 
Yes one is above the other but can’t remember which is which, but...
After looking at different matrixes I THINK that my original had about 22 cores and this one has about 14, so that’s about 1/3 less cores so it’s hardly going to run more heat is it!

Towsey
Exactly, with domestic central heating as an example, a small radiator in a large room but the room is still cool what do we do, install a larger capacity rad, nothing else changes... assuming the boiler has the capacity that is. :)

So what are u going to do now? replace the matrix or put up wit what you have. :(
How long did it take u the first time around,may be quicker the second time do u think. ??
 
Yep, our hallway is a prime example of that!

I think il leave it over winter and see how it copes, I spend quite a bit of time up on the moors and wolds in the middle of winter so we shall see, hopefully although I notice the difference by touch it will still keep it warm enough but if not then out it comes, but I would imagine the one I’ve used is one of the most common ones used as replacements if not the most common

It didn’t take long really just undoing bits and bobs but what slowed me down a bit was deciding where to cut the pipes as they look an absolute nightmare to change as the screws are put in from new from the other side

Well this is my effort at attaching a link to a thread I’ve written a bit of a how to but as you can see I’m poo at this stuff so this is all I can offer sorry vvvvv

Disco 1 Definitive way to remove heater matrix on discovery 1 ..300tdi
 
whoops, and that didn't work!
Bad luck!
Uploading stuff is never as obvious as you think it is going to be!
don't let that stop you trying!:):):)
 
Thanks, hope it helps people as it seems to concern many

I would do it the same way again if needs be

Towsey
 

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