I need to change the thermostat on my Mk1 and I have been quoted £70 just for the labour to change it if I supply the actual thermostat (which is another £15-£20).
I think this is quite high and from what I can see from looking under the bonnet, it just looks a simple job of unbolting a couple of bolts on the thermostat housing, taking the old one out and putting the new one in. Then sealing the housing again with a new gasket (supplied with the thermostat) and using a special silicon sealant
Am I missing something major or is that pretty much all I need to do?
i.e. Do I need to drain the radiator or be careful of any other factors?
1 Like
it is fairy easy to replace but take care the pipes that connect around the housing can be fragile. as your car is old I would be inclined to flush the cooling system and fill with new coolant unless you know it is fresh. it is easy to do.
Also if the nuts have corroded and the studs shear have you the kit to fix it. Yes you need to drain and catch the fluid and if it is less than a few years old replace the fluid.
If not it is better to replace the antifreeze.
Otherwise an easy job once you get the car in the air and supported and get the fluid drained.
1 Like
Thanks for the replies.
I had the cam belt, water pump and thermostat replaced 3 years ago when I had the car restored so there is a fault with the thermostat as my car is overheating and the top radiator hose sucks right up due to the vacuum caused (so the RAC’s call out contractor said when I broke down). The nuts and studs were fine to undo 3 years ago so hopefully they still will be.
I also had a Halfords Major Service 2 years ago and I have checked with them to see if they replaced the water and coolant. They said they did so that should still be OK.
I will probably need to top the water up with antifreeze though as the position of the thermostat is just below the level of the hose so I will lose a bit of water otherwise I will order a new thermostat and hose and get on with it.
With the gasket silicon sealant, would it matter if I put a lot on the gasket (obviously both sides)? or could too much interfere with the opening/closing of the thermostat when the housing is bolted down tight and the sealant is squeezed out?
I have just bought a new thermostat from a certain parts supplier. I went for the actual Mazda one instead of a compatible one even though it was nearly three times the price.
When I asked if they also supplied a gasket sealer they said that the gasket didn’t need it and that it could just be put straight in providing I removed all remnants of the old gasket and cleaned up the surrounding area.
Is that right as I thought I would need to lubricate each side of the gasket?
They are right, just fit it clean and dry. If it’s a Mazda gasket it should have a green ring of “rubber” round the edge of one side, orientate this towards the thermostat.
1 Like
If you have the top hose pressurising you may have a small leak some where. Â It happened to my mk1 not long after I bought her, I was not loosing water but the top pipe swelled up. In the end it was the very small hose on the inlet manifold that we did not find until it let go completely. Â
And jack the front of the car up so the front of the engine is a bit pointy-uppy while you are expelling airlocks etc.
It helps.
About 1 foot should do it.
Â
Â