cooling fan question
Discussion
Just fitted a couple of 10 inch Spal cooling fans to replace my original knackered ones. I have wired one through the original loom which uses a Kenlowe thermoswitch. The second fan I am wiring through a stand alone relay and will be operated by a switch on the dash. The last wire to be connected is the switched positive from the relay to ignition controlled power supply. I have had a good look around but am finding it difficult to find a suitable connection. Do I cut into the ignition switch wiring or is there a less invasive way to provide the required 12v? I specifically wish to keep both fans separate ie not through the same circuit.
Your suggestions would be much appreciated.
Your suggestions would be much appreciated.
Why not wire the relay positive direct to the battery (via an inline fuse) and have the switch fed from the switched ignition-fed supply?
Then the relay will de-energise when you turn off the ignition. You would also be able to add a timer circuit later for a 1-minute or 30 second fan running when the ignition is turned off.
Then the relay will de-energise when you turn off the ignition. You would also be able to add a timer circuit later for a 1-minute or 30 second fan running when the ignition is turned off.
As above
There will very likely be a fuse in the fusebox that has a white wire from the ignition switch connected to one end of it and a green wire connected to the other end of it, the green wire is known as an ignition fused supply and you can connect your cooling fan switch to it
Fuse 17 could be the fuse you need to connect to, it will very likely be fusing brake lights and reverse lights
The problem is that nothing is standard on TVR's
Anyway, you could just as easily connect your fan switch to the green wire at the brake light switch
Soldering into a green wire and heat-shrink sleeving the joint or wrapping it with self amalgamating tape will do the job if you don't have the correct terminals to do it
There will very likely be a fuse in the fusebox that has a white wire from the ignition switch connected to one end of it and a green wire connected to the other end of it, the green wire is known as an ignition fused supply and you can connect your cooling fan switch to it
Fuse 17 could be the fuse you need to connect to, it will very likely be fusing brake lights and reverse lights
The problem is that nothing is standard on TVR's
Anyway, you could just as easily connect your fan switch to the green wire at the brake light switch
Soldering into a green wire and heat-shrink sleeving the joint or wrapping it with self amalgamating tape will do the job if you don't have the correct terminals to do it
adam quantrill said:
Why not wire the relay positive direct to the battery (via an inline fuse) and have the switch fed from the switched ignition-fed supply?
This what I did on my current car as a fan override switch and the fan runs very very slightly faster on this circuit than the standard circuit. On a previous car the fuse holder melted in very hot weather so I like the thought of having a separate circuit as back-up.Thanks for your responses.
I have wired a permanent 12v from the battery through an inline fuse to the relay. its just the where to take the switched 12v. I like the idea of connecting to the green 12v side of the brake lamp switch and will investigate that when I have some time.
One of the old fans had partially seized and I only noticed this when it started making a loud noise. It must have been drawing a huge current because it has melted the fuse in its holder! I have replaced this fuse with an inline fuse bridging the original at the fuse box. This is one of the reasons I wanted to keep the two fans wired separately, the circuit only has to deal with half the current plus of one fan fails I still have the other as a get you home.
I have wired a permanent 12v from the battery through an inline fuse to the relay. its just the where to take the switched 12v. I like the idea of connecting to the green 12v side of the brake lamp switch and will investigate that when I have some time.
One of the old fans had partially seized and I only noticed this when it started making a loud noise. It must have been drawing a huge current because it has melted the fuse in its holder! I have replaced this fuse with an inline fuse bridging the original at the fuse box. This is one of the reasons I wanted to keep the two fans wired separately, the circuit only has to deal with half the current plus of one fan fails I still have the other as a get you home.
Thanks for the advice Penelope. If the brake light fuse blows it will only affect the manually switched fan, the other fan is wired through the thermoswitch so I will still have half cooling.
Anyway I still have air getting in to the system somewhere so more work needed yet. That smug smile will have to wait!
Anyway I still have air getting in to the system somewhere so more work needed yet. That smug smile will have to wait!
Hi adam.
Took her to a car meeting on Sunday which is about 30 miles each way. All was going really well, temp holding at an indicated 90 degrees going up to about 110 in stationary traffic which is ok. Suddenly noticed gauge climbing up and not coming down, I think it got to 130 on the gauge. I pulled in to a garden centre and waited for it to cool and all was fine after. It could be the gauge although there are traces of dried coolant at the back of the vee where the heater pipes exit. I think there may be a leak from the plenum heater or somewhere around there that is allowing air in.
Took her to a car meeting on Sunday which is about 30 miles each way. All was going really well, temp holding at an indicated 90 degrees going up to about 110 in stationary traffic which is ok. Suddenly noticed gauge climbing up and not coming down, I think it got to 130 on the gauge. I pulled in to a garden centre and waited for it to cool and all was fine after. It could be the gauge although there are traces of dried coolant at the back of the vee where the heater pipes exit. I think there may be a leak from the plenum heater or somewhere around there that is allowing air in.
wedgewood said:
110 in stationary traffic which is ok. Suddenly noticed gauge climbing up and not coming down.
I had a similar issue in mine after the radiator had been refurbished by a garage. I put it down to air locks in the heater matrix etc so when I replace the coolant I put the car on a slope and fill from both the swan neck and the expansion tank. Start and move the car the other way around and keep topping it up at the expansion tank. I did have to replace all the hoses a few years ago for silicon ones as a few leaks started developing.Thanks for the responses. Im away for a few days but when I get back ill get a head gasket check done and I think I will still get the cooling system checked to find out where it is escaping from. If I have to have the heads off I can do any cooling system repairs at the same time.
Sorry Adam I always thought that whilst an engine was cooling it could draw air in through a leaking pipe etc. I stand corrected and I appreciate the advice.
Sorry Adam I always thought that whilst an engine was cooling it could draw air in through a leaking pipe etc. I stand corrected and I appreciate the advice.
wedgewood said:
Thanks for the responses. Im away for a few days but when I get back ill get a head gasket check done and I think I will still get the cooling system checked to find out where it is escaping from. If I have to have the heads off I can do any cooling system repairs at the same time.
Sorry Adam I always thought that whilst an engine was cooling it could draw air in through a leaking pipe etc. I stand corrected and I appreciate the advice.
Sorry Adam I always thought that whilst an engine was cooling it could draw air in through a leaking pipe etc. I stand corrected and I appreciate the advice.
I always thought and still think the same. Certainly after a very hot run my overflow bottle does fill up, and as the engine cools the liquid is drawn back into the expansion tank. On a few occasions in the past, with insufficient water in the overflow bottle or pipe is too high above liquid level, air has been drawn back into the expansion vessel. Surely if there's a minor leak in the system then hot liquid will be expelled and when the system cools air may well be drawn back in? Only if the leak is above the water line. Don't forget that the pressure cap is designed for coolant and then air to be sucked back in, it will enter here first.
Another good test is to go for a run, then leave the car 30 mins or so, and squeeze the top hose. While the hose is hot down to warm (40C) it should be significantly pressurised. After a couple of hours it might start to get slack.
Also as part of the test above, when you shut off the engine, immediately after listen for any hissing.
To test for head gasket leaks I now use the "lime water" test, as I have an old house and always have a sack of lime hanging around....
Another good test is to go for a run, then leave the car 30 mins or so, and squeeze the top hose. While the hose is hot down to warm (40C) it should be significantly pressurised. After a couple of hours it might start to get slack.
Also as part of the test above, when you shut off the engine, immediately after listen for any hissing.
To test for head gasket leaks I now use the "lime water" test, as I have an old house and always have a sack of lime hanging around....
Ive just been out to the garage, Im now back on talking terms with the car after a few days sulking. I have tightened some hoses where there was evidence of leaking (Just had the rad repaired and I didn't tighten the hoses sufficiently). I have put a jubilee clip on the catch tank from the expansion bottle which was the reason that the coolant wasn't returning to the expansion tank upon cooling and I have one third filled the catch tank so that the pipe is submerged in coolant.
One thing to note was that even though the car hasn't been started for several days, when I removed the expansion tank cap it burped and gurgled for about twenty seconds like it had just downed a can of Fanta in one gulp!
One thing to note was that even though the car hasn't been started for several days, when I removed the expansion tank cap it burped and gurgled for about twenty seconds like it had just downed a can of Fanta in one gulp!
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