coolant question for a tr5
Discussion
Assuming you aren't loosing much fluid I'd start with 50:50 and just top up with water then (gives you a lot of topping-up before the mixture gets to 25:75 let alone dangerously low). Then just change the fluid every 2 years, reverse-flushing the radiator/heater matrix while you are at it.
The radiator should be filled to the brim and the overflow bottle about one third of the way up.
Anti freeze does 3 jobs, it is an anti freeze, a rust inhibitor, and improves heat dissipation. a 50/50 mix is fine in winter or summer.
Water on its own is also fine except that it wont protect against rust!
Just to elaborate on the fill to brim statement. If there is an airgap in the cooling system 2 things happen.
1. When hot, the cooling system will not pressurise properly. It is the additional pressure that changes the boiling point of water and thus provides more efficient cooling. You will note early tr5/6's have 7 psi rad caps. later ones have 15 psi caps.
2. With air in the system cavitation will occur and create air pockets leading to overheating and pointed fingers from passing cars as you wait by the roadside.
Finally it is the job of the overfolw bottle or expansion tank as it should be known to deal with hot expanded water. What few people realise is that a rad cap works in 2 directions, expelling hot water and sucking back water when the engine is cool and because the overflow tube is below the level of the water no air gets sucked back in. It is also meant to allow air to be expelled from the cooling system but on TR's it does not always happen leading to the aforementioned air lock.
Anti freeze does 3 jobs, it is an anti freeze, a rust inhibitor, and improves heat dissipation. a 50/50 mix is fine in winter or summer.
Water on its own is also fine except that it wont protect against rust!
Just to elaborate on the fill to brim statement. If there is an airgap in the cooling system 2 things happen.
1. When hot, the cooling system will not pressurise properly. It is the additional pressure that changes the boiling point of water and thus provides more efficient cooling. You will note early tr5/6's have 7 psi rad caps. later ones have 15 psi caps.
2. With air in the system cavitation will occur and create air pockets leading to overheating and pointed fingers from passing cars as you wait by the roadside.
Finally it is the job of the overfolw bottle or expansion tank as it should be known to deal with hot expanded water. What few people realise is that a rad cap works in 2 directions, expelling hot water and sucking back water when the engine is cool and because the overflow tube is below the level of the water no air gets sucked back in. It is also meant to allow air to be expelled from the cooling system but on TR's it does not always happen leading to the aforementioned air lock.
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