whats a normal radiator temp?

[DA9B18C]

just wondering,

whats a normal radiator temp?
stock B18c, 30min drive, cool weather, vtec dose minimal.

[fatboyz39]

84-92 degree.

[DA9B18C]

so, if i had a aftermarket temp gauge connected with an adapter to the top radiator hose and it read 50 degrees, is it because the sensor is not screwed in all the way? just half till pretty tight?

what u think

[JohnL]

so, if i had a aftermarket temp gauge connected with an adapter to the top radiator hose and it read 50 degrees, is it because the sensor is not screwed in all the way? just half till pretty tight?

what u think

If it's an electric guage then it's probably earthed through the sender unit. I.e. + power passes from battery to dash guage and then to sender then to earth. The name 'sender' is a bit of a misnomer, it's more like a 'controller' in that it's what controls electric flow through the system. The flow of electicity is 'restricted' by the sender unit depending on water temp (creates a changeable resistance dependant on temp), so less power can pass through the whole system including the guage, which is what the needle reads off as a temperature.

If the earth connection at the sender is not good then there will be an unwanted electrical resistance and this will restrict power flow through the system and the guage will 'assume' the temp is lower. Check that the sender has a good and clean electrical contact with the engine (not the wire, the sender unit body).

The sender's earth connection is probably by way of the attacment bolts or studs, so make sure the threads, under the bolt or nut heads, and any washers are clean. Silicone or similar sealants won't help electrcal conductivity either. Don't forget the adaptor, this must also be properly earthed. If there is any difficulty in earthing the sender through the adaptor, then you could utilise a dedicated earthing wire to the engine.

Metal oxides can affect resistance, so make sure the metal to metal contact is very clean and shiny. If this still doesn't work then check all other connections in the system are clean and properly tight. Of course the sender or guage unit might be faulty.

PS Nearly forgot, all this assumes that the guage is reading low when the engine is actually hotter than the reading, but the guage might be accurate. Make sure that you don't have a faulty thermostat, i.e. stuck open.

[DA9B18C]

hey, thats the shit! thanks johnL

[DA9B18C]

another Q? whats a too hot (worry about) temp?

[JohnL]

another Q? whats a too hot (worry about) temp?

Assuming the guage is reading correctly, I'd expect to see somwhere between about 80°C to 90°C as a normal temp. You might see more than this on a hot day in traffic with the air-con going (or even without it), but it shouldn't be this high when on the move at reasonable speed for a reasonable time (air moving through the rad' due to reasonable speed should be enough to keep the temp at the correct level without the electric fans kicking in, though the air-con may by default turn at least one of the fans on).

Don't panic if the temp does go a bit higher than 100°C, this doesn't necessarily mean it's boiling because the cooling system is pressurised and the pressure raises the boiling point somewhat. However, if it continues rising it will still boil at some point, and this is very bad because you get pockets of gas inside the cooling sytem and the cooling becomes uneven inside the motor, which can lead to a warped head and blown gaskets etc.

If it stabilises a bit above 100° you can probably still drive it safely for some distance (enough to get you home say, depending on just how far that is) if you really have to, but only if the temp stabilises and doesn't keep rising. If the engine is running hotter than it should, keep an ear out for 'pinging'. If you hear any pinging (which will sound like a metallic 'rattling') stop immediately and shut down. Also, of course, if you see any steam stop the engine. If the engine is consistently running hot, or intermittently running hot with no obvious reason for it, you need to take the car off the road and get it fixed!! Never remove the rad' cap from a hot cooling sytem, it can be very painful, scalds hurt! Wait until the pressure drops, you can feel it by squeezing the top rad' hose. Never put cool water in a hot rad', you may wreck the engine because of 'thermal shock'.

Don't ever be tempted to take the thermostat out in an attempt to fix an overheating problem. This won't fix it, at best delaying how long it might take to overheat, but only because it will delay how long it takes to get to operating temp in the first place. Removing the thermostat may actually make the problem worse because it speeds up the rate at which coolant flows through the system, and this can mean that there is insufficient time for coolant to pick up heat (when flowing through the motor), and also too little time to dissipate it when flowing through the radiator. In this case the metal of the engine might get hotter even if the temp guage may read a little lower

[DA9B18C]

champ. thanks again.