Le Tonkinois Varnish
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Damaged ports repairs
Occasionally corrosion of a port, usually the exhaust port, becomes severe enough to prevent safe connection of the pipe. We do not have MIG welding facilities or the expertise to use them so considered such repairs were restricted for our users.
Then David Leech sent details of his own repair which required a lathe.
He used Durofix Easyweld and that product allowed us to suggest simpler DIY solutions.
Easyweld allows welding of aluminium and alloys and just needs the material heating to about 400 deg c.
The Easyweld rod then melts in a similar way to soldering or braising, no specialised equipment is needed.
We found an Easyweld demonstration video on Youtube, the results were impressive and opened up two ways of doing a DIY repair. https://www.youtube.com/watch?v=n1njyuPBIH0&t=29s
We were due to try out both methods but Derek died so no practical tests have been completed.
I hope to do them at a later date and am publishing our ideas for users to try.
Repair method 1
Method 1 will be best suited to localised erosion as in the first picture on this page.
Separate the heat exchanger from all other removable parts.
Clean the edges of the repair back to good sound metal.
I would insert a length of steel rod into the port. This serves two purposes.
The port is attached to the metal body which will rapidly transfer heat from the port. The steel should help to retain heat and allow more time for the welding. It acts as a former for the melted Easyweld, hopefully giving a smoother inner surface to the repair.
Once heated and before applying the weld use a stainless steel brush to clean away the surface oxidation.
Easyweld will not adhere to the steel rod and the welding material can bridge the gap in a similar way to that shown in the demonstration video.
Excess material deposited on the outside of the port is a lot harder than the original alloy but can be ground off with a file or angle grinder.
Repair method 2
Easyweld welding rods
Length of steel rod
Stainless steel brush
The steel rod should be a close fit inside the port. This 19 mm rod fits in a D2 port but is slightly too big for this D1LCC.
Method 2 is for more serious corrosion.
I previously had found some alloy tubes on Ebay ready for repairing D2 ports, 24.9 mm OD x 18.9mm ID grade 6082T6 for the replacement and cut one about 30 mm long. It is about a mm thicker than the D2 original and might need some sanding down to fit inside the exhaust pipe.
Separate the heat exchanger from all other removable parts and cut off the damaged port.
Inserting a steel rod as in method 1 additionally holds the replacement tube in position during welding.
Once heated and before applying the weld use a stainless steel brush to clean away the surface oxidation.
Additional notes
There is a risk of severe burns if the metal or blow torch is mishandled during these procedures.
Do not attempt the repair if you are not able to do it safely.
Port corrosion is believed to be mainly due to a galvanic reaction between the alloy port and the stainless steel exhaust pipe.
David heated his D1LCC heat exchanger in an oven to save gas before welding
He found a propane or butane blow torch was ideal for the welding.
He said removing the surface oxidisation was the most difficult part of the repair.
The heat exchanger needs to be hot for the second method, I am not sure if the use of the steel rod would hold enough heat to give a satisfactory repair with more localised heat for the first method.
Easyweld melts at 392 deg C and welds made with the rod are clean and free from slag, with a sound joint which is stronger than the parent metal. Some sites say Technoweld is the same material.
The diameter of ports is not the same for all models, the selected tube matched D2s inside diameter.
The choice of 6082T6 material was simply because it was the only one available on Ebay with the right size.
Specification data shows it was a good choice with high mechanical strength and corrosion resistance.
In theory both these methods should work but any expert will tell you theory and practice do not always agree. I have not tried these methods yet. Please give feedback on them so I can improve the methods.
David Leech repair
Tube for replacement port, 19 mm internal, 25 mm external, 30 mm long
Replacement tube placed alongside a D2 port showing chosen material is thicker.
This repair method requires specialist workshop facilities and may not be suitable for all heater models due to limitations with metal thickness.