Hi Joe,
I can?t speak for the performance of my cooling system prior to the rebuild, as the car was definitely not running prior to my starting. However, I had heard a few things about the Series 3 cooling system being a little doubtful, so I decided to uprate. I will describe my upgrades below:
Before even starting, I bought an alloy radiator, not a difficult decision as no radiator came with the car and the price of my alloy item was around the cost of a new copper radiator plus surcharge. I added an alloy radiator cowl fitted with two modern fans, this came from V12s in USA:
http://www.v12s.com/
This was great, except for the ridiculous amount of duty charged by UK customs - over 33%; this was when VAT was only 17.5%!! Cheeky sods, but I had no choice and it was still cheaper than a secondhand set of fans and mountings, also missing from my car when bought.
An immense amount of silt and corrosion was discovered inside the engine ? I hope this isn?t the case with anyone elses? unit; the corrosion was so bad that one of the heads actually refused to come off all the way, despite correct tools and experience of a respected Jaguar V12 engine rebuilder. Sadly, I had to scrap the unit and use a later one from an XJS, although most of the engine internals are from my original E-type motor. This new unit was sent for chemical cleaning and came back like new, internally and externally.
The advice to change coolant is good, but I suggest that you start by ensuring the system is full, then drain it, then capture and measure the coolant you release. You should get 20.5 Litres, significantly less than this is unfortunately bad news and may indicate silt, but at least you will know. A small amount less is not such a problem and you may be able to clean the system by back flushing with a hose pipe ? I suggest you do each component separately to prevent the chance of clogging any part of the system with debris from another. It may be a time to replace some of the many hoses too. You might consider using a flushing agent prior to this, but if you are nervous about this, perhaps do the measurements first and if the system seems clear then a simple fresh water back flush should be sufficient, flush until the water comes out clear ? I think this will take some time with such a large system and a lot of water of course. You can always refill the system, add flushing agent and run according to the instructions of the agent, then cool the engine and flush as described.
My next modification was to replace the Otter switch with a modern item. The parts required came from Coolcat, it required a new ?T? Piece, replacing the original piece where the otter switch is located. The new unit allows you to choose your own temperature setting, as several temperature switches are available. I chose the setting of 75⁰, which seems low, but the sensor is actually measuring the temperature of the fluid exiting the radiator after cooling, other values are available in approximately 5⁰ steps, speak to Mike at Coolcat for advice. The switch design is common to that fitted to several German cars, so fairly readily available.
Of course, I replaced the thermostats and also the header tank. I had to fit a steel unit as I could not find a replacement Alloy version, I actually missed one on Ebay, but never found another.
Wiring the new fans seemed to prove the original design of relay was not up to the job, although that may be unfair since I used a repro item, although bought from one of the more reputable specialists. In the end, I designed my own wiring system loom, using a separate modern relay (40 amps) for each fan, this can be found here:
http://dl.dropbox.com/u/8496016/S3%20Fan_Relays.pps
The wiring is new, and as mentioned elsewhere, make sure it is up to the job and use a fuse, I chose a modern 30 amp blade fuse which has proved up to the job so far. I also used a new sensor on the temperature gauge transmitter.
Also make sure all the cowls are present and directing the air over the radiator, not allowing it to escape around it.
So, the results? Well I have driven around in heavy traffic, including lots of traffic lights and queuing, in temperatures over 30⁰ centigrade and the temperature never reached halfway on the gauge.
Obviously I have quite a few upgrades and a system which is as near new as possible, but it shows what is achievable. I don?t use water wetter, because my system doesn?t need it, but I have heard good things about it, but I guess my experience proves it isn?t required in a good system.
Previously in UK, I always flushed systems out well with fresh water as described above and it is amazing how long it takes for radiators and engine blocks to run clean. Using a quality antifreeze/corrosion inhibitor is a must; for when temperatures dip below freezing and I can travel to the nearby mountains at any time of year with confidence.
Some photos of the system and modifications:
New Radiator and V12s Fans:
Coolcat switch housing installed (I just edited this post to add the V12s Site, they now offer something similar which can be bought complete with the fans, but although I am very happy with the fans and shroud, I have no experience of their switch, so can't comment, I suggest you talk both to them and to Mike at Coolcat as suggested earlier):
One of the two relays installed (it is virtually hidden by the cowl when fitted):
Finally, the old engine, showing the silt build up inside the water jacket - this silt was pretty hard too:
Hope this helps,
Regards,
Simon.
