More Eber Hydronics 10 problems

[Ian_Edwards]

I'm still trying to get my old Hydronics 10 working, making progress I think.
On starting up using a 701 controller I get error 71, over temperature sensor open circuit.
Using a multimeter, I can confirm that's the is correct.
Purchase a new over temperature sensor on ebay and that checks out at arount 10k ohms at room temperture, decreasing as the temperature increase.
Time to take the old one out.
It is corroded in:
.

the new one one looks like this:


The temperature sensor is located between the combustion chamber and the outer casing, in the water cavity.
It looks like had a dual function, sensing the temperature and a safety relief valve.
The old one is corroded in, or perhaps the O ring is sticking or both, the unit is at least 15 years old, and I don't think that this part has seen the light of day since it was manufactured.
I've tried various penitrating oils and a butane gas torch to heat it up, I was careful with the gas torch, I didn't want to damage the casting, but it got way to hot the touch and the remains of the penitrating oils boiled off.
It's still stuck solid.
I've used a variety of tools to gab the hex crimp on the top of the sensor to try and rock and twist the sensor out. But I need to be careful it is only a aluminium crimp and I don't want to break it off.
Any ideas on how to free it up?
I have Muriatic Acid and Rydlyme at home, would either of these be effective, without destroying the aluminium casting?

 

[savageseadog]

Don't use the hydrochloric acid (muriatic). The sulphamic acid (Rydlyme) will be ok. I suggest you use a hit water solution and fill the water chamber and wait a while.

 

[Boater Sam]

Compressed air?

 

[Ian_Edwards]

Don't use the hydrochloric acid (muriatic). The sulphamic acid (Rydlyme) will be ok. I suggest you use a hit water solution and fill the water chamber and wait a while.

Thanks, I'll remove the pump, bung-up one of the water holes and fill with a hot rydlyme solution, and leave it over night.
I hope that works.

The alternative is to disassemble the heater, take out the combustion chamber and tap it through with a socket or bit of pipe, but that is a lot of work and with a heater as old as this, may open up a new can of worms, and probably a set of very expensive gaskets.

 

[starfire]

I'd be tempted to put an old screwdriver in the gap & try hammering it in. It might break the corrosion.
Failing that, break off the crimp, drill it so you can get a long selftapper in there (or tap it & use a machine screw) & use that to lever it out

 

[Ian_Edwards]

I've tried the screwdriver and hammer, but that started to dent the aluminium case, and I didn't want to make the extraction process worse, by making the sensor casing oval.
I don't know what's inside the sensor, other than a thermistor (probably), no idea what the packing material is, other than it would have to withstand 110+deg C.
I also don't want to damage the sides of the hole in the casting. It has to take and seal on an O ring and be able to allow the Oring to slide without damage.

 

[savageseadog]

I've had success with siezed nuts and bolts by using an automatic centre punch, a decent one made by Eclipse. It's possible to adjust the impact and it's also possible to align the impact with the required turning direction. I have an induction heater as well but you're too far away.

 

[Ian_Edwards]

Update, and success of sorts.
I tried Rydlyme, 24hrs, lots of bubbles started hot and then I re-heated withe butane torch, no success, still solid.
Tried heat again, and the inevitable happened, I snapped the crimp and broke the cable .... retired for the night.
Drilled it out, first with a 2mm drill and tried a self-tapping crew, which just pulled out some sort of epoxy filling.
Tried a 5mm drill, carefully, using a fernier caliper to ensure I didn't drill too deep and damage the combustion chamber. Reversed the drill so that the shank fitted tightly into the hole, rocked the drill, still solid.
Used a 10mm drill, the OD of the sensor is 10.8mm and drilled down to the o ring.



Tried the self-tapper again in the epoxy filler, it pulled out.
Used the 5mm drill to drill within 1mm of the end of the sensor, reversed the drill, this time there was movement.




Tried several methods of pulling the remains of the sensor out of the hole, and ended up using an old rig saw blade, which slid in and then by angling it, so that the teeth gripped the side of the hole, I was able to ease the remains out.

Now I have to think of a way of cleaning up the hole so that an O ring seal will work.



You can see a ring of crystalized "something" at the base of the and the high level of corrosion.
The best way to clean it up is probably to ream it out, but I have no access to machine tools like that.
Any ideas?
The OD of the new sensor is 10.8mm.