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New radiator into automatic Superb


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When I got the gearbox replaced the guys at the specialist suggested the radiator was getting to an age where it could fail and take the repaired gearbox with it (if I got coolant passing into the transmission fluid).  They also said not to bother fitting a cheapie radiator.  Anyhow, so I'd held out for the last 20K miles and just managed to score a genuine VAG OE radiator off ebay for £70 delivered.  (box is a bit tatty, but the radiator itself looks fine - though the coolant sensor port cover is missing - annoying.  The other covers are all there).

 

So I'm trying to work out if I could give this a go myself or not; having reviewed the ERWIN manual it looks like the sticking point for me will be if I need to top up the transmission fluid afterwards (I have no safe way of getting the car in the air).  The factory procedure says to check the level after fitting the new radiator.  

 

Does anyone know if the radiator will have any significant amount of transmission fluid in it if the car has been resting?  Best to park up or downhill (flat isn't an option unfortunately).  Thanks! :)

 

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I would be astonished if the two systems were in any way connected. It sounds very much like they are trying to just generate more work. You certainly do not have ATF in your radiator.

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Thanks for the reply.  Actually they didn't want to do it for me (said they hate changing radiators).

Superb radiator has 4 pipes - 2 lines of coolant to one side, two lines of transmission fluid to the other.  It acts as a combined transmission fluid / coolant cooler.

There are lots of cases of Merc gearboxes being destroyed because of coolant in the transmission - very common fault.  It kills them pretty good due to hygroscopic nature of the clutch packs in the gearbox.

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There is an ATF cooler in the radiator on auto B5.5 vehicles.

 

The energy wasted by the torque converter has to go somewhere, so your highly taxed fuel is effectively dumped into the radiator as heat. (The Govt. then taxes you a bit more annually for the privilege). 

 

M-B gearboxes were destroyed by Valeo radiators - to my knowledge, VAG radiators don't do this. Nissens (Denmark) make the best replacement radiators I have found to date.

 

rotodiesel.

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Thanks chaps.  Already have the OE radiator now so if anything is going in it will likely be that - or are the Nissens considered an upgrade to OE?  Looks like the OE is made in UK by Calsonic-Kansei.

 

The gearbox guys weren't VW specialists, so sounds like this could have been generic advice based on the high failures of those Valeo parts in MB cars.

 

I understand from the Passat forums that they do tend to rot in the corners at least though?  Or is that mostly from running the wrong coolant?

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I understand from the Passat forums that they do tend to rot in the corners at least though?  Or is that mostly from running the wrong coolant?

That's exactly what happened to mine and the coolant sloshed around in the undertray. It was main dealer serviced, so don't think the coolant was wrong.

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The standard radiators usually fail due to thermal cycling fatiguing the joint between the core and the plastic end tanks. Using the wrong coolant usually rots out the core. Leaks show up at the bottom corners due to the action of gravity. (VAG have yet to master the principles of water and gravity when rainwater leaks are involved).

 

The last Nissens radiator I fitted to a PSA vehicle had expansion "S" bends in the top and bottom metal core retaining strips. Clearly, they know how to design radiators. The core was zinc plated too - a well made and well designed job. I'll fit one when mine fails.

 

rotodiesel.

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A general rule for all parts that may rot from outside - zinc everything, if in doubt zinc again. Just make sure you use high-temp pure zinc spray, at least 500 degC for anything exhaust.

 

To prevent internal corrosion, replace all fluids regularly, but avoid disconnecting hoses, even if it means partial replacement only (then just replace more often). Except auto transmission fluid, everywhere else fluids are easy to replace, parts are not, and your luck when troubleshooting leaks can vary quite a lot.

 

Using these 2 principles served me well with the Superb. My car is 8 years / 130k+ miles old, a lot of high speed miles (and these do tend to leave imprint from high speed debris impact). The radiator looks at front like it was blasted with gravel, but does not leak at all, neither does the airco circuit (which has an additional, refrigerant filled radiator in front of the main one). As a bonus, both looking at and working in the rust-free engine bay is much more bearable than if it was a rustbucket. Not that there is much work to be done there :sun:

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My aircon radiator looks like it has the whole cast (and then some) of Bug's Life in it...!

I suspected my aircon wasn't as cool as it might be - and sure enough I was down by ~200g of refrigerant to 415g (total factory charge 600g).  Which I guess doesn't constitute much of a leak in 9 years.  Much cooler now.  

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Getting OT here, but the 200g may not have necessarily leaked, could have been under-filled at factory. My Superb's airco was consistently weaker than the Mk1 Octavia's (but working fine otherwise) for ~}6 years. After 6 years I finally got the Halfrauds kit for airco top-up, got a separate pressure gauge as well,  and it turned out the pressure was on the low side. A half bottle top-up sorted it out and 2 years later the pressure is the same as right after the top-up. A 2012 Roomster also was underfilled, and this one I checked 3-4 months from new, so looks like it is one area they consistently save on refrigerant at factory.

 

Speaking of airco, air flap motor errors are much more annoying, especially that the flaps work fine, just dust/dirt messes up the exact resting position sensor readout.

I had the "Flap Motor Faulty" errors 3 or 4 times over the years, and a simple recalibration (VCDS "Basic Settings", group 5) cured the problem, with new flap closed values being only 1-2 out from old one (old one 35, new one 37, range is 240+, so the flap is still very much closed when it says it is closed).

I wonder how many people heard the flap clicking/read the code and replaced the motor instead of just running the calibration....

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Cheap £*(£$&!  Sounds about right as in my case it hasn't got any worse in the 3 years I've had it; has always been a bit poor.  Even 600g isn't quite enough as the manual says to put in to the top of the tolerance due to the amount in the fill tubes, which is + a few more grams.  I had one intermittent motor which the calibration fixed, and one (demist / footwell) which it didn't.  Thankfully I didn't follow the "book" on replacing that, which would have seen me need a "helper" and take the dash out... lol.  With my lady hands and a ratcheting 6mm spanner it came out easily enough.

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