I have a Retroblock D808s that has liquid coupled lenses and there are leaks around the seal between the CRT and cooling chamber which I am going to fix, in the process I am going to be removing the expansion hoses on the back of the cooling chamber and I have some questions.

Are the plastic expansion hoses (that it currently has) better than rubber hoses?
I saw a picture of a brand new CRT that had a rubber hose that was apparently attached for shipping the CRT from the factory with the cooling chamber installed.

The idea I had was to replace the plastic hoses with rubber to allow more expansion and better protect the CRT from excessive pressure as the glycol heats up and to make the hose length longer to allow even more expansion of the hose and better cooling from more surface area.
Can I use the 10mm inner diameter radiator hose that I can buy from my local auto parts store?
Engine coolant uses a small amount of ethylene glycol so there should not be a chemical reaction problem so no deterioration of the hose.
The extra cost of the rubber hose is not an issue, with the effort I will be going to for repairs and how long I plan to use this projector (tubes have no burns at all) I would like to make as many improvements as possible while I have it in pieces.

As for securing the hose to the cooling chamber, a service tech at Barco said to replace the clips that are currently around the plastic hoses with the hose clamps used in a cars cooling system (the type that you tighten with a screwdriver) as they will prevent any glycol leaks from between the hoses and cooling chamber connections.
Is there any issue with the magnetic field from the deflection yoke, should I look for non-magnetic hose clamps like stainless steel?
I have read that it is best to keep ordinary steel and other metals that may become magnetic away from the CRT's and ideally away from the whole projector.

I seriousy doubt you would notice anything detrimental to picture quality depending on which clamps you choose.
I use regular hose clamps like the ones you describe.

I believe all of my Retros (Graphics non S) has a black hose that is about 30cm long.
My tubes are P16LNP's.

Haven't heard of any need for replacing these with better ones and I've hade retros with 60k hours on them without leaks.

Make sure the "hoses" aren't made of latex (ie. dialysis/"slingshot" tubing).

Cheers for the replies.

I was worried about having to degausse (sp?) it occasionally because of the hose clamps being steel, I may still try and get stainless steel hose clamps just in case.

The tubes are PT18-244, how do these rate on the scale of best to worst CRT's?

I was thinking of using a meter or more of the rubber hose so if I take it that the 30cm used on your Retroblock's is the minimum required I should be fine with 3 times that amount.
There should be plenty of room inside the CRT bay in the base of the Retroblock to accommodate the extra hose, I will even rig up some support clips to keep the coils of hose separated and away from the deflection yoke and other bits attached to the neck of the CRT's.

I was even considering adding a 120mm fan to the back to move more air around the CRT's but where to connect it would be a problem, there is a space in the video tray that is supposed to have an 80mm fan (there is 1 fan on 1 side but an empty space on the other) and I was thinking maybe I could find where that fan was meant to be connected and use that to supply power to the 120mm fan, making sure it is correctly rated.
I guess it is meant to keep another input card cool (probably a line doubler) but there isn't one installed there so no fan is installed on that side of the video tray.

The hose I was thinking of is the black rubber hose that is probably made of the same rubber as car tyres, I will definitely avoid latex and other organic rubbers.

BTW, although it has D808S on the sticker on the back it also has another sticker saying Graphics stuck to it, so I guess it has been upgraded from a Data version to a Graphics version at some point before I got it.