Battery Box sealing strip

Mar 8, 2021
Visit site
Hi I have removed a damaged battery box from my Lunar and replaced with a new one. I have some sealing strip which has proved troublesome to apply. I am confused as to how it should be applied. Initially I had applied to the box but can’t get the straight mastic strip to go around the corners of the box, I tried cutting into strips and over laying the corners but then the box wouldn’t fit flush to the van as the mastic is too thick. I must be a bit dim as can’t really see how it is applied without gaps in the sealing strip - any advice greatly appreciated
Oct 8, 2006
Visit site
Why not use not setting sealant as used around most other places where water ingress is not a good idea? Readily available at less than £4 a tube <BUT> you will need a larger gun frame as the tube is longer than normal domestic sealant equivalents.


Mar 14, 2005
Visit site
Strip mastic was never intended to be used around corners, and actually it is the most difficult stuff to use as it gets caught by the screws and winds itself round them and leaves gaps which you cannot see, unless you pre drill the mastic , which is tedious to do.

A non setting mastic is only used on items which may need removal from time to time, a battery box is not one of those things.

The best solution is a gunned mastic such as Soudall Fixall which, after preparing the box and van by removing all the old mastic and cleaning with White Spirit followed by a wipe over with Methylated Spirit, is applied in a good bead around the edge of the box where it will sit against the van wall and enough that when screwed back in place wil squeeze out along the outer edge of the box which you then tool off to give a smooth finish.

Temperature is important when using any mastic and you need a minimum of 10 degrees , preferably warmer.
  • Like
Reactions: Dustydog
Jan 19, 2002
Visit site
My recollection of the mastic strip is that you fitted straight strips that just butted up to each other at the corners. Then the corners are carefully trimmed with a spatula like tool once the box is fitted. Follow Damian's advise though for a long lasting solution. As with a lot of jobs preparation is key as new mastic of any sort should not be applied over any traces of old. I assume that once fitted the smooth Soudall tends to stay clean where the original mastic always seemed to attract the muck!


Latest posts