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Discussion Starter #1
I'll be doing the o rings on the heater matrix in the next few days... quick show of hands from those who have done it (and not sprung a leak since !!) - did you just dip the o rings in coolant as per rave, or was anyone tempted to use rtv/ silicone/ something else as well?
 

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Roman-- I simply bought Viton O rings and used an O ring lubricant I have been using for years. No leaks from the O rings the last three months. Of course, I have other coolant leaks just to keep me on my toes.
 

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never ever use silicone sealant with O rings, in the past I have doused in coolant or used a bit of vaseline, just enough to make them slide with out pinching. wd40 can be another option if nothing else is available.
 

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Don't bother just replacing the o-rings. You will just have the issue again.

The problem is the design and having one single screw to hold the matrix to the metal tubes that run through the firewall. Both the matrix and tubes in the firewall are rigid with no flexibility allowed. At the auction between them the single screw just does not have enough force to hold them together with all the vibrations of a car.

Best to replace it with the Audi matrix or cut the tubes after the junction with the matrix and run heater hose through the firewall. This way there is some give and flex at the junction.

Either way is better than just replacing the o-rings.

And yes I replaced only the o-rings the first time around only to do the entire Audi matrix a year later.
 

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If you are using genuine O rings then they should last as long as the originals. The single screw is quite sufficient as it isn't intended to hold the tubes rigid. If you look at the design, the screw holds the plate but that plate has lugs around the outer edge so the tubes aren't held rigid but rely on the flexibility of the O rings to seal and also to allow movement. They only leak when the O rings lose their flexibility and go hard.

If you follow the instructions (https://www.rangerovers.net/repairdetails/heateroring.html) and use a long (300mm or longer) PZ2 screwdriver it is usually a straightforward job. I've done them 7 times now (on 7 different cars) and only once have I had to drill the head off the screw. A dob of coarse grinding paste on the end of the screwdriver will make it grip the screw better and you may also find trying to tighten it first will crack it free. If the screw head is damaged or if you do have to drill it, an M5 Allen bolt is a far better option should it ever need to come out again (in another 18 years or so).
 

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I did it, normal O-rings, put some grease on your fingers, roll the O-rings in your fingers so the surface has a bit of grease on it, and put them in.

Cut a hole in the center console behind the covers, the job is than done in about 7 hours, in a very easy pace.. Take your time, don't hurry, don't get stressed, it's not too hard..
 

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Don't bother just replacing the o-rings. You will just have the issue again.

The problem is the design and having one single screw to hold the matrix to the metal tubes that run through the firewall. Both the matrix and tubes in the firewall are rigid with no flexibility allowed. At the auction between them the single screw just does not have enough force to hold them together with all the vibrations of a car.

Best to replace it with the Audi matrix or cut the tubes after the junction with the matrix and run heater hose through the firewall. This way there is some give and flex at the junction.

Either way is better than just replacing the o-rings.

And yes I replaced only the o-rings the first time around only to do the entire Audi matrix a year later.
Uhm, the tubes through the fire wall are not rigid at all! If that's the case you have an other problem..
 

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I did it, normal O-rings, put some grease on your fingers, roll the O-rings in your fingers so the surface has a bit of grease on it, and put them in.

Cut a hole in the center console behind the covers, the job is than done in about 7 hours, in a very easy pace.. Take your time, don't hurry, don't get stressed, it's not too hard..
on left hand drive, use two sets of needle nose vise grips, gently pinch heater hoses above right side valve cover, undo heater hoses. with compressed air blow into heater core to remove coolant. inside, remove glove box, center console side covers, radio and hevac control. using a 18 to 24 inch long phillips screw driver, guide with one hand and drive with other, undo screw, separate pipes replace O rings.
reverse procedure.
tops with out experience 3 hrs, with experience 45 minutes max. 7 hrs is almost dealer time and removing dash.
don't need to cut or modify anything at all. I'm sure right hand drive may be easier and possible faster as glove box is opposite.
 

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Discussion Starter #9
Thanks everyone, I'm building the longest PH2 screwdriver I can find !!
 

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NOT PH2, PZ2, it's Pozidrive not Philips. A PH2 will round it out the first time you apply any grunt to it.
 

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Discussion Starter #11
Roger that
 

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Last time I had a leak from the heater core area, turned out that the problem was not orings but the heater core itself. Make sure you test out the system while you have access to the heater core, so that you don't have to disassemble everything again.
 

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Discussion Starter #13
At the moment I've bypassed the core (joined the hoses under the bonnet) and I was going to fill the core with water first, but I haven't worked out how to pressurise it yet, maybe I'll just bridge both Ali tubes with a bike inner tube plus scraper valve. I observed the drips coming from the lower seal tho, so fingers crossed it's not the core, I assume then the leak obviously comes from the housing?
 

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Discussion Starter #14
Schrader valve. Predictive text drives me mad
 

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I did my o-rings I guess about 7 years ago. The car is now 19 years old, so the orignal seals lasted around 12 years from new. I replaced them with OEM and also fitted a stainless steel allen bolt. The job took about 3 hours including drilling a hole to get better access. Next time round I reckon I could do it in under one hour. Never had a leak since.
Not keen on the audi heater core mod. Hoses perish just the same as o-rings and having hoses and hose clips behind the dash is not a good idea.
 

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I replaced the ones in my 2000 last summer using Viton O rings and no lubricant. They were leaking and I needed to get the heater working for winter. Had a bypass hose in place over the summer. I could not get the original screw out and had to cut a hole in the side of the plastic center consul underneath the side cover in order to drill off head with a 12 inch drill bit. After I got the assembly out I had to put it in my vice and use a Vise Grip to turn out the remainder of the screw as it was so rusted in place. The old O rings were brittle as chalk, probably 18 years old. I used fresh water to test and had a leak. Discovered I had not lined up the pipes correctly before tightening the socket head screw that I used. Realigned so that the pipes went in straight and have not had a leak since then. I have a heater core from a parts car and it seems well made to me so I would not be inclined to replace it offhand as I don't think it is that easy to get out.
 

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Discussion Starter #17
RHD. Turns out the last guy in had put silicone sealant around the rings, other than that the rings were OK, so I guess the silicone seal ruptured when I did the head gasket/ replaced the hoses. I didn't have to cut any ducting, but did forcibly move some, after removing the instrument panel with the speedo. I also gave myself a couple of nice holes to put my tools through. Filled with water to test. Tnx all for your advice
 

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I've found that when they only have a slight leak, the rings are usually still in one piece just squashed into a square section and fairly hard. When the leak is worse, then they are so hard they are in pieces.
 

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LHD, Mine was spewing coolant all over, carpet soaked, foam core soaked. O-rings were original and completely disintegrated.

That was over 3 years ago...and now with many, many rough off road miles later she’s still 100% leak free.

With the help of a 3 foot long screwdriver and the radio removed for access. It only took about an hour start to finish..oh yeah and I used the coolant dripping out of the heatercore as lube..
 

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I'll be doing the o rings on the heater matrix in the next few days... quick show of hands from those who have done it (and not sprung a leak since !!) - did you just dip the o rings in coolant as per rave, or was anyone tempted to use rtv/ silicone/ something else as well?
Hi Rob, used coolant, since it is a slippery mess after they leak anyway. worked fine, no leaks for the last 2 years now.
Somebody put a really handy video on youtube with pointers on how to get access, including the circular hole and a very long plus driver. worked like a charm..
 
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