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Joined: Dec 29 2016
Posts: 452

I replaced the heater matrix o-rings on the P38 which had just had the new engine fitted to it and I'm still getting a drip at the end of the matrix so I'm assuming I'm going to need to take the dash out and change the whole lot.

I've seen people talking about the Audi heater cores that do away with the o-rings, are they really necessary? Are they more of a hassle to fit?

Would be grateful for any advice that can be given.

Thanks,
David.

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Joined: Dec 30 2015
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Audi heater core will fit if you do a bit of fettling so it slots in. Then you have pipe stubs that you can put hose directly onto. I can't see anything wrong with the O rings myself, they last about 15-20 years before going brittle and starting to leak.

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Joined: Aug 05 2019
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Audi core fitted here, as noted fettling required but not much. Nissens 70230.

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Joined: Aug 07 2019
Posts: 220

i replaced my o rings about 2 years or so ago , no leaks . i think when people do this they over tighten the screw that holds the o rings in and either crack the housing or damage the o rings , the system needs to be able to move with thermal expansion. that's my 2 cents worth

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I did mine 10 years ago when I first got the car, still no leaks.....

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Joined: Aug 19 2019
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I put the Audi heater in mine a couple of years ago. Not really any more difficult than installing an original would have been. The little bit of filing required didn't take long. After all is said and done, I'm not sure there's really any advantage to the Audi matrix, other than cheaper to buy in my end of the world.

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Joined: Dec 03 2019
Posts: 47

I set out to do the o-rings and discovered that the matrix itself was leaking, I ended up with a bluebox replacement which didn't look great quality but seems to have worked, having said that it was the early part of this year and the RR has since been SORN'ed and done no miles so it hasn't really been tested. I only really examined (became aware of) the Audi style solution after the event but I think if I was doing it again I would go that route, mechanically more satisfactory in my mind, especially for a long term prospect.

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Joined: Jan 05 2016
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I put the Audi one in mine some time ago. A few years ago now, I swapped it back for an original P38 item.

Where the connections are upside down, there is the potential for it to trap air in the top part, and I had relatively poor heat output at times, and gurgling.

This wasn't helped by the presumed cracked cylinder #6, but either way - to be honest, I'm fine with orings. It also helps I have removed and blocked off the ducts that fed the rear centre vents as they're asthmatic at best, and I have other plans for the area. So getting to the orings on mine is very simple as and when they need changing in the future.

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Joined: Dec 29 2016
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To get the screw out of ours i had to lean against the screw driver with quite a lot of force as it was incredibly tight so I’ve got a feeling it might have cracked when I did that.

I think I’m going to change it for an original type matrix. Just need to find one now as I’m not paying the 400 odd quid that Rimmers want for a genuine one.

David.

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Joined: Aug 07 2019
Posts: 220

when it came to removing the screw that holds the o rings i drilled the head off it , took about 2 minutes . the screw will not undo as it had rusted from the back . with the dash out i removed the pipe work and removed the screw from the other side , easy. you dont have to remove the dash the pipes come out easily anyway

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A dob of grinding paste on the screwdriver tip helps as it stops it from riding out and chewing up the head.

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Joined: Aug 19 2019
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The price was the main reason I went with the Audi core. From memory it was around CAD$85 from Rock Auto.

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Joined: Dec 30 2015
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Audi in mine - works a treat :)

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Joined: Feb 25 2020
Posts: 255

If you go Audi, I believe the model was the one for the 100/A6 up to 1997, which is originally made by Hella. Very expensive nowadays as a "Genuine" German part, last year got a batch of those I remember retail was like 105 euro apiece.
If you go Nissens (far lesser quality, but do their job ok) you got two models, 70220 and 70230, being the difference the outlet diameter of the pipes 16mm or 19mm.
Don't go cheaper/more Chinese than Nissens, you might regret it (as see if often as I deal with such Audis)
When I made mine I've decided against it, as I've found a NOS Valeo at a similar price ...

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Joined: Dec 29 2016
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I can’t seem to find a genuine Valeo one without spending over 400 quid which I’m not prepared to do.

Looking on the net I cannot find a Nissens one with the right part number for the P38.

Britpart and Bearmach seem to be the easiest ones to get hold of but I’m not sure I trust them enough.

David.

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Joined: Aug 05 2019
Posts: 159

Plenty on eBay, all located in the UK.

Have a look at item number 303196250927 or 292543581735

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Nothing comes up searching eBay for those numbers. Thought it might be because I'm using eBay.co.uk but tried .com and got the same. Full link might be good.

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Joined: Feb 25 2020
Posts: 255

Sorry dhallworth, in my case I was just lucky! Indeed the OE Valeo is very expensive, if you were to find it at all!
I do not remember Nissens has a part no. for the RRP38 specifically, but I can tell you the Audi cores for the Typ 100/C4 are numbers 70220 - example:
https://www.amazon.co.uk/Nissens-70220-Exchanger-interior-heating/dp/B00CKPXOK6

and 70230 - being the only difference between the two the diameter of the outlet pipes
https://www.autodily-cardo.cz/-25/vymenik-tepla-nissens-70230/

These are aftermarket replacements to the original Hella core, whose original part number 443 819 030 and is now nearly non-available, and remaining stock quite pricey.

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Joined: Aug 05 2019
Posts: 159

Here

And here

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Joined: Dec 29 2016
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I couldn’t find any reference to a Nissens heater matrix anywhere. In the end I ordered a Bearmach one direct from Bearmach. They offer a 3 year warranty on it for just over 60 quid including delivery so fingers crossed it’s decent!

David.