I mentioned in a prior post that I would be repairing some cracked copper elbows in the engine preheat loop in my Aqua Hot. The elbows that are used in construction of the Aqua Hot have a very sharp bend and crack at the bend. I lost about a gallon of engine coolant on the road without knowing it and a second gallon during the repair draining down the loop during the repair. For owners of Aqua Hots this is an area to inspect whenever you open up the Aqua Hot or if you notice a loss of engine coolant.
So why does it fail...My guess is that while we drive down the road there are vibrations and oscillations transmitted to this unit (like watching a side mirror vibrate) which eventually fatigue the fitting. My fail was at 12 years and 58k miles for reference.
I spoke with Roger Berke about this repair and he has done a number of them replacing the elbows with new copper. I was concerned that I could not get the pipe and fittings to be dry and clean enough of antifreeze to assure good solder joints. The other issue is you could end up having copper elbows crack again over time so I went the route of silicone elbows that hopefully allow some flex and dampen and absorb some vibration. Roger has coolant hose 5/8th ID elbows and constant tension clamps that would work well and he is a great source for parts.
The actual repair and photos if you ever need it....
!. Pinch off the two coolant hoses with hose pliers or long tip vice grips and release pressure loosening the coolant cap at the expansion tank. If you are replacing the fitting on the pump side (left) you will need to loosen the burner clamp fittings and move the burner to the right out of the working area.
2. Apollo tools makes a circular 1/2 inch pipe cutter that just fits and allows you to cut these hoses with the tight clearances involved which I picked up at Ace hardware.
3. Have a drain pan under the unit. For a left side repair loosen the union between the pump and the elbow, remove the pipe and union by unscrewing the fitting on the pump.
4. Solder a piece of 1/2 inch copper pipe to a female 1/2NPT copper fitting, place it and cut the copper pipe at an appropriate point to be able to work on a hose type elbow. Then screw the fitting and pipe on the pump using Teflon tape or/and Rectorseal. The cuts in the copper pipes have to be back far enough from the elbow points to work the hoses on, see photos.
5. Cut the 5/8 hose elbows to length to allow about 1 inch of hose end over copper. Place a constant tension clamp on the copper pipes beyond where the hose will be fitted, work the hoses on, move the clamps into the overlap section and tighten to the proper torque. The type I used were a number 10 Breeze (O'Reilly's sells these as Master Pro) constant torque which has a range of 50 to 150 inch lbs depending on contraction vs expansion. I used 100 inch lbs and found no leaks heating or when cooled. If doing the right side you will just need to cut the pipe at an appropriate point above and below the elbow. Both elbows on my unit were leaking so I did both sides.
6. Refill expansion tank with antifreeze, run engine up to temp, inspect elbows for leaks, once engine cools recheck antifreeze level.
Parts Ref. These or call Roger Berke.
Hose elbows: http://www.amazon.com/dp/B004OZ8LX0/ref=sr_ph?ie=UTF8&qid=1415544852&sr=1&keywords=hps+5%2F8+silicone+elbows
Constant Tension Clamps: http://www.oreillyauto.com/site/c/detail/MHC0/MP47010/N0189.oap?ck=Search_hose+clamps_N0189_-1_-1&keyword=hose+clamps&pt=N0189&ppt=C0075
I hope that you do not have this issue, but if you do, this is a cure that should never leak at the same point again. It is a repair that is what I would call moderate difficulty but I do not think this method is as bad as trying to sweat in new copper parts given all the antifreeze that is involved. Hope this helps.
Later Ed
