Bypass heater matrix

[RJBingham]

Might have to bypass the heater matrix, is it better/easier to do it from the matrix end of the hoses, or the other end? and what size hose would be best?

Thanks in advance.

[oilyrag]

The ends of the hoses are moulded so not a simple matter of putting a connector in.  It doesn't matter too much which end is bridged but the original upper end, at the bulkhead has an air bleed screw. I'd suggest cutting the hoses a few inches down from that end, adding a suitable diameter connector with juibilee clips. 
When filling it would then be straightforward to raise the joint and slacken one of the clips to allow any trapped air to purge until water flows out.
The pipe diameter is larger than 12mm, so you may need to search for a stepped connector or make one - a straight piece of tube without a lipped end may not hold in when under pressure.

[geoff]

1/2" copper pipe ???

[Kieron G]

I've done this temporarily before on an early van. I just removed pipes at bulk head inside engine bay and joined them together. I think I used 15mm copper pipe like Geoff suggested. Changing the matrix in an M49 is not a very nice job

[RJBingham]

The ends of the hoses are moulded so not a simple matter of putting a connector in.  It doesn't matter too much which end is bridged but the original upper end, at the bulkhead has an air bleed screw. I'd suggest cutting the hoses a few inches down from that end, adding a suitable diameter connector with juibilee clips. 
When filling it would then be straightforward to raise the joint and slacken one of the clips to allow any trapped air to purge until water flows out.
The pipe diameter is larger than 12mm, so you may need to search for a stepped connector or make one - a straight piece of tube without a lipped end may not hold in when under pressure.

Amazing detailed answer, all the information I was after.  Thank you.

[RJBingham]

I've done this temporarily before on an early van. I just removed pipes at bulk head inside engine bay and joined them together. I think I used 15mm copper pipe like Geoff suggested. Changing the matrix in an M49 is not a very nice job

That's interesting, thank you, I'm still at the procrastination stage at the moment.

[oilyrag]

A further couple of thoughts ........assuming that the matrix you have is leaking, have you tried using Radweld ?  It worked well on mine, which weeped a little after I'd flushed the matrix out as the heater had just about given up. I now have a working heater and no leaks. 
If there is a matrix leak you'll smell spicy anti-freeze, possibly have a damp carpet driver's side, and the screen may also fog up when you turn the demistter on. 
Also rather than cutting the pipes you could just make up a couple of clamping plates and 'squash' the pipes near the bulkhead. 
Although the heater matrix is part of the permanent cooling system the system seems to cope OK even when the matrix is blocked - just keep an eye on the water temp. after closing off the pipes - it should warm up more promptly but settle at much the same running Normal that you had before.

[RJBingham]

A further couple of thoughts ........assuming that the matrix you have is leaking, have you tried using Radweld ?  It worked well on mine, which weeped a little after I'd flushed the matrix out as the heater had just about given up. I now have a working heater and no leaks. 
If there is a matrix leak you'll smell spicy anti-freeze, possibly have a damp carpet driver's side, and the screen may also fog up when you turn the demistter on. 
Also rather than cutting the pipes you could just make up a couple of clamping plates and 'squash' the pipes near the bulkhead. 
Although the heater matrix is part of the permanent cooling system the system seems to cope OK even when the matrix is blocked - just keep an eye on the water temp. after closing off the pipes - it should warm up more promptly but settle at much the same running Normal that you had before.

I've gone down the Radweld route today, and so far it seems to be OK, going to flush the system, and keep my fingers crossed, thanks for taking the time to reply.

[IHateMyDadsM59Berlingo]

A further couple of thoughts ........assuming that the matrix you have is leaking, have you tried using Radweld ?  It worked well on mine, which weeped a little after I'd flushed the matrix out as the heater had just about given up. I now have a working heater and no leaks. 
If there is a matrix leak you'll smell spicy anti-freeze, possibly have a damp carpet driver's side, and the screen may also fog up when you turn the demistter on. 
Also rather than cutting the pipes you could just make up a couple of clamping plates and 'squash' the pipes near the bulkhead. 
Although the heater matrix is part of the permanent cooling system the system seems to cope OK even when the matrix is blocked - just keep an eye on the water temp. after closing off the pipes - it should warm up more promptly but settle at much the same running Normal that you had before.

I tried this on my dad's M59 and I think all I did was hammer the nail in the coffin for the matrix it as it exploded filling the cabin with steam and my shoes with hot coolant in the drivers footwell as well as filling the passengers footwell up more ?.

[notsofast]

I bypassed the heater matrix on my M49 a few months after this thread was started. Assuming the configuration is the same on the M59, the important point to note is that the ends of the hoses at the bulkhead end have a moulded connection that can no longer be replaced, so if you want to be able to possibly re-connect the matrix at some point in the future, the hoses should be disconnected at the engine end and a bypass loop put in place there. I kept the heater hoses intact and still connected at the bulkhead - I tied them to one side so they weren't dangling in an unsafe fashion. Probably best to cover the open ends with foil or something similarly non-combustible, to prevent spiders etc. from crawling inside (well this seemed a wise precaution in my case cos the vehicle isn't used often).

Regarding hose size, on my M49 I bought the largest diameter available at my local motor factors, which if memory serves me correctly was 19mm diameter. However this was extremely tight to fit to the 2 outlets on the back of the engine block, and I suspect that 19mm is just a metric conversion from an imperial size and that, it being a continental-made vehicle, probably the original size was 20mm. I did manage to fit the 19mm size though, with a bit of washing-up liquid for lubrication and lots of swearing lol.

Another thing to be aware of is that it isn't easy to route the bypassing loop of hose so that it isn't kinked or rubbing against the bulkhead or dangerously close to the exhaust. I opted to put a sheath of central heating pipe foam insulation around the bypass hose, basically held in place by being wedged between the hose and the bulkhead. This prevents the hose rubbing the bulkhead but also, as it's wedged quite tight against it, keeps the hose above the exhaust. Some wire ties to keep the foam in place would probably be a good idea.

Also remember to inform your insurance company that you have made a change to the engine. In my case I was surprised to find that it didn't affect the policy or the premium, as I hadn't removed or upgraded any part of the engine, instead just a note was made on their records. However not all insurers may be so obliging.