Bypassed leaking heater matrix, now the waterpump is leaking

So I've had a leaking heater matrix for a while on my '03 Td5 Defender, 120k, with the usual dripping beneath it and fogging up the windscreen when it was turned on... I bypassed it by connecting the two pipes going to it and joined them with some metal pipe. When I disconnected the hoses to the heater matrix there wasn't any coolant leaking out, so just joined the two with some pipe and voila, leak fixed. Well, two days later and 6 hrs of off-loading in the "hills" here (everywhere else you'd call them mountains!) I've now got the leaking o-rings behind the water pump (coming from that little hole back there). There's no evidence of a head gasket failure (top hose is soft when fully hot, no contamination in the oil/coolant), as I was thinking extra pressure could cause some leaks. Also I opened up the bleed screw on the top coolant pipe while running, no air came out, just coolant.

So I'm thinking it's just dumb luck, that perhaps the heater was releasing a little pressure and now that it's not there anymore the water pump o-rings are worn enough they went too.

I'm waiting on a new heater matrix to arrive in a month or so, and now I guess I'll wait on the water pump as well.

Any ideas or suggestions? Thanks in advance.

I'd say it was just coincidence. Bypassing the heater matrix would not cause any extra pressure in the system.

Thanks for the reply... Good to hear from someone with more experience than I have. Cheers.

So finally got around to changing the water pump with an OEM unit, and thankfully found that it can be done on the td5 without removing the aux belt and turbo. Key is to have a ratcheting 8mm spanner, and to take off the turbo intake hose and centrifugal oil filter. Thanks to those who posted that info. The parts came from FamousFour, who did a great job of sending all of it and doing so quickly, which is quite important when any mistake equals a two week wait here.

My Defender looks like it had only water in the coolant system, as everything was pure orange, hoses were caked with orange rust deposits, water pump was too. I guess here in Nepal they didn't put OAT coolant in, or, well, any coolant, and once it started leaking it was probably just filled up with water. No wonder my heater core and fuel cooler are also leaking (the latter is on the next to do list, since from what I understand it's a fairly easy fix w/ new gaskets).

So, the new dilemma is the heater core. Everyone I talk to says for the '03/3A VIN it only comes as a bloody "unit" that costs upwards of 500 pounds. Going to pull it off soon and take a look but thought I'd ask first...