MG ZS 180 - KV6 Thermostat Replacement Full Guide

The MG ZS 180 uses the Rover KV6 engine, and the thermostats on these are known for two things - they break, and they're awkward to get at! No, making cooling system parts out of plastic then hiding them in the guts of the engine isn't one of my favourite design decisions to encounter.
But I had to replace mine to fix a significant coolant leak, so here's a step-by-step on how you do that. It's a fairly involved job compared to many other cars, but there's nothing too technically difficult, so perfectly possible to fix it yourself.
I also replaced the ignition components (coils and spark plugs) while I was in there, as it's a good time to do it with better access.
Parts for this repair were purchased from www.dmgrs.co.uk
Title music:
"RetroFuture Clean"
Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0
creativecommons...
Background music:
"Wrong"
Dan Henig
KZbin Audio library

[@phoenixmotorsport647]

"access behind the rear bank is a pain" - that has to be the understatement of the Century!!

[@Strike86]

I have no idea why I watched this. I don't even have a ZS. But great video, I enjoyed vicariously tinkering with your car. Thank you.

[@gooburrum]

Great video. I’ve been able to remove the inlet manifold with the fuel rail in place, just disconnected from the fuel line. As long as you are careful, it saves a bit of time too.

[@tawidave7092]

This is why I love inline 6 engines.

[@pedroteixeira4369]

There is something wrong with KZbin. Your channel is way undersubscribed! I have binge watched most of your episodes in the last two days and they are all superb. I really mean it! Good camera angles, good editing, your voice tone is excellent as well as the narrative. The only thing I would try to improve would be the sound. Seems muted. Maybe a better mic will do the trick. Apart from that, there is only one thing that makes my skin itch and that is, dirt and rust! For instance in this episode the engine is all dirty and with some rust spots and I wouldn't be able to work on an engine without leaving it beautiful to the eye. ;). Please keep the episodes coming, the quality is there, it's just a question of time. The more consistent you are putting them out, the more chances KZbin algorithm picks them up. Subbed, cheers and good luck.

[@Life_Of_AL]

It was me who wrote the KV6 Keyhole Method How To on the 75 ZT forum. Mine had snapped off too in the block, I think they all do. At the time I didn’t want to disturb anything else other than the stat itself. This actually isn’t that much more work in all honesty, and as you say you get opportunity to replenish the temp sender and the gaskets. I’ll be doing this full stat service and IMG replacement when I do them on my ZT next

[@Scousewil]

I couldn't seat the curved pipe correctly with keyhole method I tried everything to lever it down and in but nothing worked. I ended up replacing the stat and reusing the old curved pipe but now that's leaking so I'm using this method. Plus I couldn't tighten up the clips on the through pipe as tight as I would have liked - I didn't have the room to get my pliers in. I agree this way I'd not that much more work to get at it. Mine is a ZT too by the way.

[@jezzet-ee2tg]

It's possible to change the stat and pipes by removing the alternator and leaving the inlet stuff in place. Saves a great deal of work.

[@CaulayMaculkin]

A word of caution to those following this guide. I broke 4 out 6 injectors when removing the rails. The tips are stuck in and snap off on removal, despite lots of wriggling and time spent trying to remove them carefully. Genuine new injectors are currently £70 each from Rimmers (and nowhere else seems to have them.)

[@threepotMR2]

When pushing in things like the injectors with the rubber seals on the end, or the thermostat/coolant pipe work with the O rings into the blocks, it a really good idea to have a little tub of silicon grease to lube up the O rings and holes first. Goes a long way for easy installation and reduces the chances of scuffing or pinching the rubber O rings.

[@InitialDave]

I find the aerosol silicone sprays are quite good for that if you put an extension nozzle on them to make it a narrow, accurate spray.

[@MarkieC1990]

Great video mate keep it up! Glad the Daihatsu is still going, made my day when you let me have a sit in it at Doncaster 😅

[@InitialDave]

Thanks! Should be there next year too, might be the Daihatsu I bring, might be something else!

[@mceajc]

Fascinating - and word of the day - recalcitrant!

[@peted7295]

I know it's an old fashioned thing to do but, as smear of grease on paper gaskets really helps to hold them in place during assembly. It's also supposed to help with sealing,

[@rhiantaylor3446]

I once saw a suggestion to use spray glue to apply a thin layer of adhesive to one side of a gasket to secure it temporarily to one of the joining surfaces - same idea but possibly more robust ?

[@peted7295]

@@rhiantaylor3446 Not so sure glue is a good idea, what happens when it comes time to remove said gasket? I wouldn't want to be the poor guy that gotta try and scrape that off.

[@StegoMan]

I did it with grease few fays ago

[@ROTSTarge]

Great Father, all that work just to replace the thermostat? Someone forgot about maintanence when designing that engine o.o also inb4 all the old rose tinters in the comments with how plastic parts is the work of the devil and back in their day their cars were made out of proper steel and ran to the ripe old age of maybe 80 thousand miles.

[@peteraudley4671]

A very good and instructive video but still beyond me . I can only do jobs that involve a hammer and chisel and a stick of dynamite 😨

[@sqike001ton]

No I'm guess I g they did think about matainance there thoughts were its a pain people will not change it it will fail dealer mechanics get more work for the emergency repair to make the dealer mechanics happy

[@Life_Of_AL]

Most of the KV6 thermostats have more than outlived what was deemed as the life of the car, say 10yrs or 100,000 miles

[@johnj3577]

Good grief, remember old BL engines where the thermostat was on top of the motor looking right at you when you opened the bonnet? 3 bolts and it was out.

[@Life_Of_AL]

PS; I was most impressed by dropping ‘recalcitrant’ into a KZbin video 👏😃

[@julianvendre3418]

What a great video, well explained, thank you!!

[@TheUltimateToad]

Large V6 engine - check Engine bay for a standard 4 inline - check Absolutely no collaboration from the maintenance team when designing the engine - check

[@Dochty]

Great job, just like a professional. Thanks !

[@scaleartsg]

love videos like these! keep them coming!

[@TheJRL99]

Is the Daihatsu still doing well?

[@InitialDave]

Yep, still seems happy enough!

[@DarrenBoss1984]

Love the videos keep them coming!

[@InitialDave]

Thanks! Like the username, too!

[@adrianlane207]

Awesomely detailed procedure. It makes internal combustion engines look insane, when you compare them to an EV's synchronous motor, which for the V6's performance level, would be the size of a saucepan, and have one moving part plus bearings. I'm looking forward to the next installment of the 180's revitalisation. 🙂

[@ianhill20101]

The fuel system is simple compared to a battery managment circuit swings and round abouts, ive got 3 broken ev less than 100k miles and one working diesel with 135k so u do the math

[@peteraudley4671]

It's almost worth doing the head gasket or rebuilding the engine while you're there . I got lost after lifting the bonnet !😨

[@wayneaylott6703]

Hi Dave thanks for putting up these videos I've watched them all. Well I mean I had to as I am buying this exact car on the 22/2/20. Lol

[@rogerfenton5210]

You did not mention the 2 rubber mount's at the rear of the manifold

[@Taydrum]

The radiator cap should've popped before the tube burst. So either the tube was really weak and worn, or the radiator cap isn't popping when it should. My money is on the tube being old and weak, but it wouldn't hurt to check or inspect the rad cap too

[@InitialDave]

The 180 has a higher pressure cap than the 4 cylinder cars, which may not help matters, but yes, I replaced it with a new one doing this. I think it was just old, heat cycled plastic finally giving up the ghost.

[@Taydrum]

@@InitialDave figures all the plastic parts tend to give our after a short time

[@guygadbois1068]

There is a 'keyhole' method to do this without removing all that except the throttle body and the air filter box.

[@InitialDave]

Yes, though with the curved pipe having snapped off at the bottom into the block, I wanted to be able to see what I was doing to get the remains of it out, and also replace the lower intake manifold gaskets

[@Scousewil]

@@InitialDave I couldn't seat the new curved pipe properly with keyhole method it needs downward pressure from above - this video has really helped with my ZT so thanks!

[@ranjvilkz8178]

Nice work How to fit a gearbox on a mg zs 180.

[@CarlCostelloPlays]

👍🙂

[@jimdailey1985]

What a pain. Better you than me.

[@Pasha_Shkaf]

Eyy I missed u

[@mickyanderson3639]

Did you notice the casting marks "COSCAST.".

[@gumpy4960]

Thank bmw for replacing a metal thermostat with the crappy plastic one