pwood999

pwood999

Well-Known Member
Full Member
After sorting my heater flap gear problems the other day, this morning the new o-rings arrived, so sunny Tuesday seems a good time to fit them & rebuild the dash.

  • Cleaned up the pipes, and the o-ring seats in the heater core.
  • Refitted heater, and then lubricated & installed new o-rings, using new Allen Bolt instead of the old screw.
  • Connected some spare hose to pipes in engine bay and filled heater with water.
  • Left it for approx 30mins, and no signs of any leaks . . . .
  • Re-installed dash . . . . . . what a mistake.
Once it was all in place, I fired up the engine and all seemed ok . . . . until it warmed up a bit, and then 5mins after starting the engine, I was getting drips from the new o-rings. :mad:

Removed HEVAC, Radio & bent vent pipe to gain access to the both. Several hex extensions & quality allen bit, but it already seems quite tight - don't want to shear it.

So now I'm in the middle of removing the dash again for proper access, and considering several options:
  1. Plan-A is to try using proper sealer on the o-rings. Household radiators never leak when I use Fernox Sealant on the joints. http://www.screwfix.com/p/fernox-ls-x-leak-sealer-50ml/23614
  2. Plan-B is to go the Audi Heather Core route . . . . . . anyone had any issues with airlocks in the heater due to the pipes being at the bottom, or is the cooling system pressure enough to clear the air ?

Pete
 
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no idea when i did mine i was lucky and it sealed first time and i didnt remove the dash either. you mite have nicked one of the O rings on instalation
as for the fernox sealer that wont help a domestic radiator has an olive in a fitting and is a very tight compression done up with heavy duty wrenches/ spanners

check the O rings and may be try a nut and bolt mod to secure it
good luck
 
The pipes have a square cutout that must be indexed into a boss in the matrix. You need to twist to locate then push fully home or the O'rings will not seal under pressure.
 
yes did that, and checked twice . . . both pipes felt like they were seated properly before I tightened the bolt. Had loads of access with dash out. . .

Dash 1/3 unscrewed this evening and will be fully out again tomorrow, so I will extract the heater & pipes, and then do close inspection on bench.

While it's out I will try low pressure leak check on bench as well. I have a nice valve & piston ring leak tester with regulator, so I can use that so it won't blow the matrix.

Pete
 
pwood999 said:
yes did that, and checked twice . . . both pipes felt like they were seated properly before I tightened the bolt. Had loads of access with dash out. . .

Dash 1/3 unscrewed this evening and will be fully out again tomorrow, so I will extract the heater & pipes, and then do close inspection on bench.

While it's out I will try low pressure leak check on bench as well. I have a nice valve & piston ring leak tester with regulator, so I can use that so it won't blow the matrix.

Pete
Click to expand...


Matrix should be good to + 22psi but best not to go over 15 psi.
 
There should be no need to use any sealant, a smear of silicon grease helps though. I'm sure the pipes were not seated properly.
 
Us plumbers use a product called Fernox LSX ,it greases the O rings then sets but remains flexible,its fabulous on difficult O rings and high pressures. You can get it in Plumb centre or any good plumbing stockist. It can be pressurised immediately or if you have concerns let it set overnight.
 
Busterthebulldog said:
Us plumbers use a product called Fernox LSX ,it greases the O rings then sets but remains flexible,its fabulous on difficult O rings and high pressures. You can get it in Plumb centre or any good plumbing stockist. It can be pressurised immediately or if you have concerns let it set overnight.
Click to expand...
Great until the next time you have to get them apart.
 
Datatek said:
Great until the next time you have to get them apart.
Click to expand...

It can be removed without too much effort..although ime once used job done. It was merely a suggestion ,I too only ever used grease on O rings but this product is far superior. I use it on all high pressure boilers with O rings and its the only thing that stopped my pressure washer leak as new O rings only lasted briefly before popping out.
 
So yesterday afternoon I laid out the heater matrix & pipes on bench. Cleaned the joints again, and lubricated the o-rings & fitted it all together. Blocked one pipe, and blew into the other, but no matter how many times I re-seal the joints there's a small leak even at lung pressure. Din't try Fernox cos I couldn't be bother to drive to Screwfix !!

So decided to order the Audi A6 Matrix. Ebay sellers all seem to be about £25 so tried Eurocarparts . . . £10.26 and ready for collection this morning !!

Got some 16mm hose plus 16-22mm hose adapters from local MDC and fitted it this afternoon, and no more leaks.

Pic 1 = Audi Matrix fitted to heater box.
Pic 2 = New hoses fitted
Pic 3 = Hoses still accessible beneath air duct.
Pic 4 = Hose Adapters in engine bay.

Pete
 

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So does the heater water temp sensor still fit on the pipe, didnt see it in the pics.
 
Yes it does fit. The 16mm ID hoses are almost the same OD as the metal pipes. The only potential problem is a slightly slower reaction to water temp, but once the car is warm that shouldn't be an issue (hopefully). If it does become a problem in the winter, I can easily insert a short length of 16mm (more likely 15mm) copper tube for the sensor.

This time I connected the HEVAC & Instrument pack, and then ran the engine with the dash still out. Much easier to check for leaks this way !

BTW, after all the work freeing the distribution gears, I found an intermittent issue with the HEVAC drive. Nanocom kept reporting Motor Open Circuit, and calibration failed. Powering the motors direct from 12V feed they work fine. . . . so HEVAC diag time again. I happened to have another HEVAC with duff display, so connected it up. Calibration works ok with this one, and everything works except display. Already tried to fix this so it's only useful as an ECU test.

Later indoors I got the PCB out, but couldn't find any obvious dry joints, so I re-soldered ALL the connections, chips, transistors related to C261 which feeds the motors. Will see if this sorts it out tomorrow morning.

Pete

Pete
 
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pwood999 said:
Yes it does fit. The 16mm ID hoses are almost the same OD as the metal pipes. The only potential problem is a slightly slower reaction to water temp, but once the car is warm that shouldn't be an issue (hopefully).

If it does become a problem in the winter, I can easily insert a short length of 16mm (more likely 15mm) copper tube for the sensor.

Pete
Click to expand...

Ok, it was just a thought as Littlewill has done the matrix mod on his and I never gave the sensor a thought when I had the nanocom plugged in checking out his hevac, just blend motors.
 
Aslo wondering whether I can fit the working I/O board from AWR102550 together with the working Display from AWR5051. The I/O boards look identical including resistor values, etc. Only difference I can find is the PCB version.
 
Went the "bastardising" route, for two reasons. 1) to avoid having future o-ring issues, and 2) because is was significantly cheaper. Hose adapters are in the engine bay, for easy access and so that, if the joints leak it doesn't get inside the car.

Finally tracked down the Distribution motor problem. It's not the ECU, but the crappy 16pin connector on the end of the motor cables. Feeding the motors works fine, but the connection to the ECU is intermittent.

Anybody got a set of Motors with good working connector going cheep ? I don't care if the servos are broken.

Thanks,
Pete
 
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