[nUcLeArEnVoY]

Had a very intermittent coolant leak (like, would occur literally months apart) that dripped behind the passenger tire under the fender only after I would turn the car off. Had the same leak last year that spurred a heater core R&R along with all heater hoses and clamps.

Same leak happened again a couple weeks ago, and my heart sunk wondering if my new heater core failed. Would've been super pissed, since the inlet line is double restricted to prevent water slugging, and I splurged and got the higher quality copper/brass unit. Thankfully, I was able to trace the leak to the inlet heater hose connection. When I did the R&R, I used one of the repro Wittek tower clamps - don't use these, at least for the 5/8" heater hose connection. The radius of the tower end of the clamp is too bulky compared to the actual strap, and so the strap ovals out the house and doesn't seal well. It even slightly caved in the copper tube where the tower part sat (luckily the fitting bead was still round). In hindsight, the same leak from last year might've just been the heater hose the whole time, since it was the original hose, and not the heater core.

And so I tried out, as recommended on this forum, a Gates PowerGrip heatshrink clamp (specifically the 32925# one), and admittedly smeared a thin glaze of Waterpump and Thermostat Housing RTV on the fitting to aid in the seal as well as provide lubrication to put the new hose on. Was able to position the PowerGrip clamp perfectly per the instructions, used my heat gun, and it resulted in a great seal which after two tests of running the system up to temp under pressure and then shutting the car down, didn't leak a drop and is bone dry. So far I'm a believer in these PowerGrip clamps.

Could've probably gotten a proper seal using an old-fashioned worm gear clamp like what the factory used (which I recently found out is how W72 cars actually came from the factory: the engine side of the heater hoses used the Wittek clamps, while the heater core connections actually used worm gear clamps) as well, but I wanted to try out these PowerGrip clamps since they are variable tension in response to thermal expansion/contraction, and I don't plan on removing this hose any time soon since it's a bear to get to in that I have to remove the inner fender liner.

So to nutshell, don't use Wittek tower clamps for the 5/8" heater hose connection, at the very least not flimsy repro ones, and the PowerGrip clamps really are amazing!