Heating issues

January 25, 2026, 11:48:51 AM

Hi all, I’ve recently got my baby back on the road but struggle to drive in this weather because I keep fogging up because the heater doesn’t work

It’s a relatively new heater core 3-4years old and maybe 3000 miles so I doubt that’s the issue, no leaks and no air bubbles in the coolant.

I’ve shown here in red and blue what’s pipes are hot and cold, the bypass valves are the cutoff for where the heat stop, could this be the issue and I need to go back to straight pipes or new bypass valves

https://www.flickr.com/photos/204163945@N06/55059836466/in/dateposted-public/

Also car tax photo:
https://www.flickr.com/photos/204163945@N06/55060190840/in/dateposted-public/

Thanks in advance!

Re: Heating issues

Reply #1 – Today at 06:50:39 AM

Yeah, those bypass valves will be the problem.
They were only installed as a recall because the original mk2 matrix couldn't cope with high pressure and would fail.
So they were designed to bypass in the event of an over pressurisation.
Though nowadays the fail and bypass for normal operation.
If you've had a new matrix, it will be the newer design (rolled out in 1992) and you'll be safe to either bypass with a piece of metal pipe or if you're feeling like it, you can buy the rubber pipes that run straight from the matrix to the head/crossover pipe and do away with the valves that way.