G/box: 850 Auto: How To Fit a Volvo x70 Transmission Cooler

[CNGBiFuel]

No risk of coolant contamination? I think you'll find there is. The extra cooler goes in series with the standard cooler (in addition, not instead of). An air cooler rad will never be as good as the water cooled one but has to be a good aux.

I would do a coolant flush if that is your worry. Stop it rotting in the first place, thus distilled water or 100% AF.

[CNGBiFuel]

Came to do mine and you are correct, I found the hoses are all different sizes. If you have the 'right' kit not an issue. But... it so happens the Volvo quick-release fitting is actually secured by a 3/8" BSP pipe threead to the standard in-radiator cooler so you can remove that, and replace with a 3/8" BSP barbed hose-tail for £2-3 at you local hydraulics / hose supplier [or £5 on Ebay]. That way you can get any old transmission cooler and plumb it using any combination of hosing you can cobble-up. I actually put a Transmission Thermostat in there too [Derale 25719 1/2" NPT Fluid Control Thermostat]. Nailed it to the underside of the battery tray. That way the stock cooler does its job of warming-up the fluid quickly without the aux cooler in circuit to delay this or over-cool, and when to temperature it is kept at a steady 85-90 degrees by the Derale dropping in your Aux cooler. Much like the coolant does in the main cooling system by its thermostat. I 've always had a 3/8" Magnefine filter in there. Shown in pic before I installed the stat. Amazing things that really work. (I think earlier cars like 850s take a 1/2" Magnefine). To fit the Magnefine get yourself a second bottom hose from the breakers, [a crows-foot spanner is best for gettign these off] and cobble this in too. I shall post better pics as soon as I can.
http://derale.com/products/fluid-coo...ol-thermostats