I live to tell the tale of a heater matrix Dean

I assisted in the replacement of the one in my 2.1TD and was coached by a real vetaran matrix replacer. But yes, they are a nightmare of the highest order and by far the worst job on a Xantia

11 hours of solid work.
The electrovalve is leaking on the hydractive block when in soft mode. The usual problem of the alloy of the valve body corroding. the block itself is Ok so a new valve should crack the problem. The downside is they're eyewateringly expensive new. Luckily I have a good one in my stash but it needs new O rings and they're not available seaparately. I'll be having a chat with martin at Pleiades about suitable O ring material for that.
Cambelt should be good, except for the cost, I've been very kindly loaned the kit of special tools for the job

Access is currently brilliant
Everything else, relatively, is a nice gentle walk in the park...
I've gone past the stage of just fixing the problems on this car, it's now officially a restoration project...