Reply To: XJS-C Hood Louvers

David Wardale

For the benefit of anyone out there with a V12 car who is concerned about overheating, I thought I could add a few words about my own experiences.
When I acquired my car, a few years ago, I read everything I could find, trying to learn as much as I could.It became clear that overheating was something best not left alone.Looking at my original heat-ravaged fuel hoses under the bonnet made changing them a first priority. All the fuel hoses were replaced, as was the radiator, thermostats, cooling fan and clutch,and radiator hoses.The engine now ran cool, below the “N” on the gauge. The engine heat that stayed under the bonnet after shut-down concerned me,and I thought long and hard on how to address that. Russ, the original poster, had louvers punched into his bonnet.That means – first, finding someone who can do that kind of work, then removing and stripping the paint on the bonnet, and finally, re-painting everything.

As my paintwork was in good shape, I did not want to do that, and, knew of nobody who had the equipment to punch louvers in sheetmetal.
Here in the USA, Jeeps are very popular- in fact my wife and I both have Cherokees for daily use. There are many sources for aftermarket parts, including bolt-on louvers.
I did some computer searches, and found an outfit called They manufacture many different styles of louvers. I chose the style shown in the photos. They came with holes already drilled around the edges, so they can be bolted, or riveted in place. That was unacceptable to me, so I trimmed each louver, leaving me with a border about one half inch wide all the way around the edges. My plan was to use double-sided automotive tape and GLUE them in place.
Now for the critical part.My car is not meant to be a “Concours” show-winning vehicle. Reliability is much more important- arriving at the destination without concern. Disposing of the damaging heat was more important,too. After deciding where I wanted to locate my vents, and applying several layers of paper masking tape to protect the paint, I measured three times, and cut rectangular holes in the bonnet. After cleaning up the raw edges, paint was applied with a small brush for rust protection. The louvers I selected were unpainted aluminium. I wanted to paint them the same colour as the car.
The next critical part- The louver sections are completely flat. The bonnet is not- it is slightly convex- meaning that the louvers will not sit properly all the way around. The louver sections should be very carefully shaped over a wooden block of some sort until they lie perfectly flat on top of the bonnet. This is important because the louver assembly will try to push itself away from the bonnet when glued down! Small annoying gaps could appear! I applied my 3M double -sided tape to the louvers, and then painted them using heat resistant primer, and heat resistant clear coat , after applying the colour. This ensured that the visible edges of the tape had colour on them, also.
After the louvers were attached to the car, I installed an adjustable thermostat wired to the electric fan that the V12’s have, which means that for a period of your choosing, the fan will run and blow much of the trapped heat out through the vents, away from your vulnerable hoses and wiring! The amount of heat that escapes is surprising! About a month later, I moved my ignition amplifier away from the engine, and installed a ducted cool air supply for it- but that would be a story for another time! I do not know whether some of the parts available here are also available in the UK, but hopefully some inspiration can be put to use…..