Looking at that, I would be replacing the whole relay unit - or, if you can't remove the body, replace the shaft and tufnol bushes. I doubt the spring length is critical, although if it is rust pitted like the shaft, I would replace it, as it is likely to break. Seals should be replaced as well.
The bushes should be regarded as a service item whenever the unit is stripped, and I would regard the shaft as unserviceable owing to the pitting.
The whole thing would seem to be a good example as to why you need to check and top up oil in relay units every so often.
John
John
JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol
Bookmarks