Simrad IS20 Wind Vane ... top bearing seizure : possible to replace?

[TradewindSailor]

I have a Simrad IS20 Windvane : part no 27118082. The top bearing (wind direction) is partially seized : generally stiff ... no significant hard spots.

I've managed to free it off a little with penetrating oil and a lot of manipulation, but alas it is still too stiff. Has anyone any idea how I might replace the top bearing? It seems to be pressed into an aluminium casting with the circuit board stuck into the other side of the casting. I suspect the circuit board can be removed, and perhaps the bearing pushed out?

I'll take some photos tomorrow

Failing a repair, are there any good NMEA 2000 units out there at a reasonable price ..... 500 odd quid is hardly reasonable for just the masthead unit

 

[TradewindSailor]

With no advice I decided to investigate a possible repair.

I discovered that the top part of the body is a one piece aluminium casting. The top bearing sits in the top of the casting and does not extend into the cavity holding the electronic circuit boards. This means that any water or oil put on the bearing will no work its way into the cavity and damage the circuitry ..... and no need to replace any seals. Also here is no need to split the main case.

However, the bearing can't be easily removed, and considering that it has a stainless steel case in an aluminium casing, it is probably corroded in anyway. Rather than damage the casting by trying to pull the bearing out with the shaft, I decided to try further manipulation of the shaft .... I put machine oil on the bearing, attached my drill chuck directly to the shaft (only about 2mm in diameter) and rotated it with the drill .... probably about 200 -500 rpm. When the casting got warm I let it cool down. After a few minutes the shaft rotated freely properly .... i.e. the bearing rotated.

I made sure there was plenty of oil below the bearing.

Hopefully this will work for a good while more. In the mean time I will try and source a new top casing ..... or perhaps info on how to remove the bearing.

I suspect that I could attach a small chuck directly to the shaft and give it a few sharp taps with a hammer while supporting the casting to remove the bearing .... but this risks damaging the casting, the shaft, and bearing ..... not something I need to try yet.

At least I still have a working wind vane and the 500 quid is still in the bank

I hope that this will give forumites some encouragement to investigate similar repairs .... if encouragement is needed!

 

[roger94503]

repair to partially seized IS20 masthead unit

Hi Tradewindsailor

did your IS20 masthead unit repair last long?

I have a similar problem with mine - it under reads because although it does spin - it does not spin freely enough

Trying to decide whether worth trying what you did and going through the hassle of putting it back up the mast or whether to replace it with a new unit

Geoff

With no advice I decided to investigate a possible repair.

I discovered that the top part of the body is a one piece aluminium casting. The top bearing sits in the top of the casting and does not extend into the cavity holding the electronic circuit boards. This means that any water or oil put on the bearing will no work its way into the cavity and damage the circuitry ..... and no need to replace any seals. Also here is no need to split the main case.

However, the bearing can't be easily removed, and considering that it has a stainless steel case in an aluminium casing, it is probably corroded in anyway. Rather than damage the casting by trying to pull the bearing out with the shaft, I decided to try further manipulation of the shaft .... I put machine oil on the bearing, attached my drill chuck directly to the shaft (only about 2mm in diameter) and rotated it with the drill .... probably about 200 -500 rpm. When the casting got warm I let it cool down. After a few minutes the shaft rotated freely properly .... i.e. the bearing rotated.

I made sure there was plenty of oil below the bearing.

Hopefully this will work for a good while more. In the mean time I will try and source a new top casing ..... or perhaps info on how to remove the bearing.

I suspect that I could attach a small chuck directly to the shaft and give it a few sharp taps with a hammer while supporting the casting to remove the bearing .... but this risks damaging the casting, the shaft, and bearing ..... not something I need to try yet.

At least I still have a working wind vane and the 500 quid is still in the bank

I hope that this will give forumites some encouragement to investigate similar repairs .... if encouragement is needed!