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Model specific boards => Golf mk7 => Topic started by: Bluest on 27 September 2026, 09:37
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Had a slow steady coolant leak and on further inspection could see a nasty crusty mess on plastic housing behind the water pump. I think it's official name is the coolant rotary valve housing, but people sometimes call it the thermostat housing or water pump housing.
So I took a deep breath and got stuck in on the drive. It's perfectly DIYable if you've got a bit of time and patience, but there's a few things it would have been handy to know, so I thought I'd put them here in case they help someone else.
Apparently it's possible to do this job without removing the intake manifold, but access looked extremely tight so I decided to get it out of the way.
The Haynes workshop manual is pretty good for walking you through removing the manifold, but doesn't fully cover replacing the pump and housing. However, the INA pump kit I used came with a QR code link to some excellent instructions on their website. There are also good YouTube videos from Humble Mechanic and FCP Euro that are worth a watch before you start. For the manifold in particular, just take your time and be really methodical.
Be cautious with any US based advice relating to the inlet manifold. The US spec cars seem to have a lot less going on in and around the manifold than European cars. They don't have the secondary port injectors and associated pipework for example.
There are a lot of wiring connectors to be disconnected, but they are all different so it would be nigh on impossible to reconnect them incorrectly.
There's a few hand tools that'll make this job a lot easier. A long T30 torx bit (150mm+) for the manifold bolts. Tool for releasing spring band clamps on pipes and hoses and a small torque wrench (9nm) if you're fussy about the bolts on the pump housing and the manifold.
I used an INA pump kit. No complaints. Even though the OE pump is made by INA, the aftermarket one doesn't look exactly the same for some reason, but seems of equal quality. The only other part you need for this job is a replacementment inlet manifold gasket.
If you are changing the drive belt for the pump, the official procedure is to loosen/remove the drive pulley on the balance shaft. It's held on by a single use reverse thread bolt, a replacement bolt comes with the pump. I found access to said bolt almost impossible. There is not enough room to get any kind of common spanner or socket in and no chance of getting my torque wrench in to tighten afterwards. I was still keen to replace the belt. The way I did it was to remove the water pump first, then have by apprentice (Wife) turn the engine over by hand at the crank pully, while I fed the belt off the pulley. It tight, but it does work and the new belt can go back the same way.
After fitting the new pump and housing, I decided to pressures test the coolant system before going any further and putting the manifold back. Id read of a few people who had problems with leaks after doing this job and had to dismantle it all again, which would not be amusing. I got a cheap pressure tester off Amazon. I had no leaks, but worth it for piece of mind.
When it came to refilling the coolant, I used a vacuum filller (again, a cheap one off Amazon). I don't know if that is strictly necessary, but worked for me, although my little compressor struggled to draw sufficient vacuum. I replaced about 5l of coolant in total and thats after removing all the coolant pipes at the front of the engine on top of the pump.
I used OBDEleven to do an adaptation on the new rotary valve. This may not be essential, but as I had the tool I did it.
Whilst the manifold was off I cleaned the little metal flaps that go in the intake ports in the cylinder head as they had a bit of carbon build up. I also swilled the manifold out with white spirit which brought quite a loyal of black sludge out. The backs of the valves didn't look too bad, so I left those.
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Thanks for sharing your experience. After 9 years / 52000 miles I've been lucky so far with no sign of a leak but if/when it does happen I'll be doing the job myself and will be removing the inlet manifold to clean it and inspect the inlet valves.