Could use some suggestions on a leak remedy

[ThorneGator]

Merry Christmas everyone,

I have a ongoing leak from the watch glass on my Allisport coolant reservoir (photos attached). This is the second time around dealing with leak. Both times the clear perspex develops small hairline cracks and the coolant seeps around the edges of the perspex and through the bolt holes.
I have pulled it apart numerous times and RTV silicone sealed all around. The perspex just doesn't seem to be up to handling the heat and/or the thermal expansion and contraction.

I now turn it over to you, what should I try next? Different sealant? Tempered glass? etc......

Thanks again,
156466156467

[Bazzle218]

My suggestion is to go to a Perspex distributor and discuss what options they have which may suit your needs. From my understanding not all Perspex is the same. With a bit of luck they may have an off cut. May also be worth advising what coolant your running as it may be the cause of your issue. Worst case perhaps go to Glass .

[alien]

I’ve got one of these waiting to go in when Iveco get the new cap in I want to use.
I note Allisport have mentioned a revised sight glass as part of current offerings, have you been in contact with them?
RTV I expect will not work with 15psi in the cooling system.

[Tombie]

You could go see a glass cutter and get some Borosilicate glass cut to suit.

[ThorneGator]

Thank you all!

I have sent an email to Allisport, and considering the Christmas holiday, figure I will wait a bit to see what they say/recommend.
Short of Allisport having an answer, I will stop by a perspex/ glass place to find out what they recommend.

Cheers,
Taylor

[Discofender]

Just fitted one to my Td5 a couple of months ago no leaks, it appears to have glass not perspex. Keep on to Allisport to send you new glass.https://uploads.tapatalk-cdn.com/20191227/54a255030f4e60da35df3ac303dfcd57.jpg

[ThorneGator]

Thanks DiscoFender, will do. I'm sure their away for the Christmas break, but waiting for them to reply to my original email on this.

Cheers,