Got under the car today to look at a few things and noticed that the heat exchangers (1600 motor by the way) have a fair amount of movement. I'm talking movement of the outer shell part, however the exhaust pipe that runs through the middle is rigid and secure so all movement is in the shell rather than the pipe. It is the same on both sides. They aren't rusted on the outside so not sure if this is a normal state for these parts. They cause a bit of noise understandably as they vibrate and move against the tinware on the bottom of the motor.

Logic tells me they shouldn't move that much. Is this a problem? Is it fixable or is it time to look at replacements? If replacement is the only option, is there another way to give some heating if I go with the j-pipes ie electric heating?

ideally they should be tight and sealed

As long as the main pipe is solid I would be happy

You will loose some heat - but that is about all

There are 2 sorts - the early cast aluminium J tube and the later straight steel j tube
the early is probably better

I spent time and found some good ones and got them ceramic coated
They are the later style - but solid and snug fitting

If you want heat - heater boxes is the bst way to go

Take your time and find some good ones and get them coated

last for ever then

I have seen them welded up.
Seemed to work.
You can also buy new ones, but they are pricey.
It'll cost the best part of $500 plus shipping for a pair.

I've found that most are leaky around the exhaust pipes.. but there isn't any actual pressure there when the heaters are on so they still work..

the tinware is just crimped around the solid inner part...
at least on the early [heavy] types.

Biggest problem usually is when the exhaust pipe wears out or rusts out and leaks into the heater box..
Saying that, I haven't actually seen it happen..
I saw repair pipes for heater boxes on some overseas website
so the exhaust pipes must rust out in some countries..

LEE

Welding repair is possible and necessary, if they get too loose, they will vibrate and wear holes right through them.

It's the vibration that is a concern for me. Not sure if there is an easy way to check if there are holes between the inner pipe and the outside - any tips? You can't always smell the CO gas or the exhaust so may not notice and they don't really come apart to check them. I've priced new ones at around $160 each side but if it can be avoided I'd rather not replace them obviously. Losing a bit of heat on a very basic system like a kombi won't concern me much, I went through last winter with no heater on my last car and drove a lot further with that.

I'm sure the outer covers are actually removable.
The seams can be prised apart and the heat exchangers checked.
They are reassembled by fitting back together and peening the seams back over.
Sounds like a huge PITA!
I believe the outer covers used to be a service item but have been unavailiable for many years.

The actual exhaust pipes are very thick and the covers just sheet metal, so usually there is no problem with exhaust leaks inside the heater boxes. And yes, the covers can be removed but a fiddly job to do nicely. I do this when fitting heaters to a stainless J-pipe set-up.