XK120 operating temps
Discussion
Hi,
Does anyone use an XK120 regularly? Upon driving mine (1954 OTS), the temperature gauge stays around 80-83c on the motorway but touches 91-92c in traffic and when you turn it off, heatsoaks to around 95c.
Is this normal? The manual doesn't give an ideal operating temp range. I would rather stay away from auxillary fans etc, but this seems warm to me.
Does anyone use an XK120 regularly? Upon driving mine (1954 OTS), the temperature gauge stays around 80-83c on the motorway but touches 91-92c in traffic and when you turn it off, heatsoaks to around 95c.
Is this normal? The manual doesn't give an ideal operating temp range. I would rather stay away from auxillary fans etc, but this seems warm to me.
The one I don't like is the heat soak when the engine is switched off after running hard. My gauge goes right off the scale, yet doesn't seem the boil. The temperatures around the cylinder bores, especially the rear one can get rather hotter than the gauge suggests.
My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
A friend of mine has an XK120 in which he's fitted a modern electric water pump in place of the original.
As well as allowing the engine to warm up more quickly and absorbing less power, it also continues to run when the engine has stopped thus preventing the "heat soak" effect.
My own XK140 Special has a larger radiator and an electric fan. It never overheats under any circumstances.
The standard XK's don't have a lot of excess cooling capacity and in hot-weather, slow-moving conditions I would imagine they are on the limit.
If I'm not mistaken the standard radiator can be rebuilt with extra capacity (tropical core?) which will also help.
As well as allowing the engine to warm up more quickly and absorbing less power, it also continues to run when the engine has stopped thus preventing the "heat soak" effect.
My own XK140 Special has a larger radiator and an electric fan. It never overheats under any circumstances.
The standard XK's don't have a lot of excess cooling capacity and in hot-weather, slow-moving conditions I would imagine they are on the limit.
If I'm not mistaken the standard radiator can be rebuilt with extra capacity (tropical core?) which will also help.
a8hex said:
The one I don't like is the heat soak when the engine is switched off after running hard. My gauge goes right off the scale, yet doesn't seem the boil. The temperatures around the cylinder bores, especially the rear one can get rather hotter than the gauge suggests.
My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
This is what happened last night. I got the car home after a 25 mile motorway trip and then some slow roads (speed humps) for a couple of miles. Got it back and the temp gauge was at about 92. After 10 minutes it was off the chart, looking just over a 100 but the gauge stops. Since the boiling point with 50% antifreeze and a pressure cap is probably 125c or so, it didnt seem to boil (although the overflow kicked in - I fill the radiator all the time to ensure I am not leaving any elements dry). Living in Dubai, the temperature issue was always going to be my chief concern.My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
Anyone got a link to the auxillary waterpump kit? I think the "heatsoak" element when turning the car off is my chief worry and I want to keep it looking stock.
By the way, thanks for the replies.
427James said:
This is what happened last night. I got the car home after a 25 mile motorway trip and then some slow roads (speed humps) for a couple of miles. Got it back and the temp gauge was at about 92. After 10 minutes it was off the chart, looking just over a 100 but the gauge stops. Since the boiling point with 50% antifreeze and a pressure cap is probably 125c or so, it didnt seem to boil (although the overflow kicked in - I fill the radiator all the time to ensure I am not leaving any elements dry). Living in Dubai, the temperature issue was always going to be my chief concern.
Anyone got a link to the auxillary waterpump kit? I think the "heatsoak" element when turning the car off is my chief worry and I want to keep it looking stock.
By the way, thanks for the replies.
The electric water pump that my friend has fitted is Australian made. It completely replaces the mechanical pump, but I'm almost certain it wasn't a kit and he made it all up himself. I'll find out.Anyone got a link to the auxillary waterpump kit? I think the "heatsoak" element when turning the car off is my chief worry and I want to keep it looking stock.
By the way, thanks for the replies.
I would suggest a re-cored radiator with increased capacity will also solve your problem. I had this on my own modified XK120 and it ran cool at all times, even with an uprated engine. If I recall correctly my water pump was also modified ( Series 3 XJ6 impeller seems to ring a bell) Again I'll try to find out.
a8hex said:
The one I don't like is the heat soak when the engine is switched off after running hard. My gauge goes right off the scale, yet doesn't seem the boil. The temperatures around the cylinder bores, especially the rear one can get rather hotter than the gauge suggests.
My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
Very familiar with this on racing XK engined cars, actually an electric water pump simply circulating the water to minimise the soak after switch off is fine, no real need for the fan. It is worth doing a flow check on the radiator though, if the engine block has ever shed a load of iron flakes having been previously antifreeze deprived, that's where they will be, sitting in the top, blocking the thing!My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
Edited by Flatinfourth on Thursday 12th December 10:16
a8hex said:
The one I don't like is the heat soak when the engine is switched off after running hard. My gauge goes right off the scale, yet doesn't seem the boil. The temperatures around the cylinder bores, especially the rear one can get rather hotter than the gauge suggests.
My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
Very familiar with this on racing XK engined cars, actually an electric water pump simply circulating the water to minimise the soak after switch off is fine, no real need for the fan. It is worth doing a flow check on the radiator though, if the engine block has ever shed a load of iron flakes having been previously antifreeze deprived, that's where they will be, sitting in the top, blocking the thing!My XK150 now only has an electric fan as there's an oil cooler where the normal fan goes. I've thought of putting an auxiliary pump into the cooling system so that it can keep water moving around the engine as long as the fan is running.
But then my 150 isn't very original under the bonnet.
Edited by Flatinfourth on Thursday 12th December 10:23
The one I've looked at is the Davies Craig one from Australia. They have a range of different solutions from purely electric pumps to replace the mechanical one and the one I've considered which is an auxiliary pump you put in parallel with the normal pump.
In my case my electric fan keeps running after the engine is switched off and I'd like to have the water pump running at the same time as the convection currents in the block won't amount to much. Currently I tend to switch off the engine then wait a minute and restart for a few seconds which pumps the cooler water from the rad into the engine, then switch off again.
In my case my electric fan keeps running after the engine is switched off and I'd like to have the water pump running at the same time as the convection currents in the block won't amount to much. Currently I tend to switch off the engine then wait a minute and restart for a few seconds which pumps the cooler water from the rad into the engine, then switch off again.
Flatinfourth said:
Very familiar with this on racing XK engined cars, actually an electric water pump simply circulating the water to minimise the soak after switch off is fine, no real need for the fan. It is worth doing a flow check on the radiator though, if the engine block has ever shed a load of iron flakes having been previously antifreeze deprived, that's where they will be, sitting in the top, blocking the thing!
Very interesting. Will look out for electric waterpumps. Whats the draw on the system like? I am running the original charging system, which is barely adequate.Edited by Flatinfourth on Thursday 12th December 10:23
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