Dear mmal231294,

May this find you well. I've done heater hoses on two 940s. I did not need to use RTV or any other sealant.

If one or both of the copper nipples - to which the heater hoses are attached - have been scored longitudinally (from the open end towards the fire wall), then some sealant may be needed. The reason: coolant, under pressure, will be forced along the gouge, and drip out at the edge of the hose. The hose cannot be compressed enough, to seal a gouge, such as that made by the blade of a knife, used with excessive force, to cut the hose, in order to remove it.

Even then, only a small amount of sealant should be used. I'd guess it will make hose removal much harder.

Here's a method to remove the hoses, that minimizes risk of (further) damage to the copper nipples.

Using a utility knife, cut through the hose about 4" away from the clamp. Then, make a 1"-long longitudinal cut, from the open end of the hose, towards the firewall. This means cut the hose along its length.

Use your fingers, to spread the cut end of the hose. Then, starting at the point where the 1" cut ends, use the knife to score the hose, towards the firewall. Go only 1/2" and do not try to cut all the way through. Keeping the hose end spread, use light pressure on the knife, to deepen the 1/2"-long cut.

As you do this, you'll eventually see the end of the copper nipple for that hose. Score the hose, lightly, from the edge just in front of the copper nipple, towards the fire wall. As you LIGHTLY re-score that area, keep the open end of the hose spread, with your fingers.

Once you've scored deeply enough, the remaining hose material will separate and you can peel it from the hose stub. If there is RTV on the copper, do not scrape it with the knife blade or any steel tool!! Let some oil sit on the RTV, to soften it. It should then come off with brisk rubbing with fingers.

This method avoids the risk having the blade cut into the copper nipple. Indeed, if you score lightly, the blade will never touch the copper.

This method requires some patience, but reduces the risk of damage to the copper nipple, and so a leak caused by damage to the copper nipple.

Hope this helps.

Yours, faithfully,

Spook