Under Hood Heat With Electric fan

I’ve been finishing my 420 project. I was calibrating my oil pressure gauge and noticed the plastic bottles for washer and brakes were getting rather warm as they felt like they were starting to soften. Also my brake and clutch master cylinders were getting so hot I could barely touch them. It explains why my brakes feel slightly softer after driving a bit in the warm weather we’re having as it may also be part of my recent clutch problems as it happen again tonight where it pumps up and holds pressure. Once it cooled down its back to normal.

I have only an electric fan so now have less air movement under the hood unless the electric fan is running. The original clutch fan would move some air all the time.

With that said how about a custom heat shield by the exhaust manifolds?

On my 3.8S I run the engine driven fan and a Hayden electric fan in front of the radiator controlled by a radiator thermostat and wired to run with the ignition off so it cycles on and off during engine shut down heat soak period. In the summer usually about 3 cycles on and off during a 10-12 minute period before going to sleep permanently. To check engine bay temperature you could use an oven cooking thermometer and see what it is. If you feel heat is excessive you could wrap your exhaust manifolds and head pipes with insulation tape that motorcyclists use on their manifolds. Easily available on Ebay and totally reversible. Looks much like seat belt webbing but of a very different material.

I’ve thought about modifying an XJ series 3 heat shield to fit - should be pretty easy. It might help some, but I’d consider upping the air flow if you can set the fan thermostat at a lower temp. Those high temps are bound to eventually take a toll on all your under-bonnet components. Your engine compartment looks great, btw.

A heat shield cannot hurt, and it is very likely to help quite a bit. Those manifolds really really radiate a lot of heat!

You could modify a late XJ6 heat shield to fit in there pretty easily. If you want one, you can have it for the cost of shipping.

Ceramic coating the Manifolds is a good way to reduce the heat from them , some people wrap them !

I have the fan coming on at 185+/-.

Do you have a heat shield for the steering u joints?

You could make something that shields it all from the heat and it will do a lot. Still very hot in the area but better.

Car is stock, no heat shield was used from factory. I’m definitely going to fab something up.
I have some thick material for wrapping mufflers I’ll probably use. I’ll make some stainless steel brackets or clamps to secure it over the exhaust manifolds and one near steering joints.

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I’m asking because for the XJ6 they decided to use a small heat shield for the steering. 4mm asbestos (or whatever it is) with an aluminum backing. Riveted to L brackets that are bolted to the nuts from the downpipes to headers.

The E Types had a large sheet roughly like that and that seems to do well. I’d say pretty much anything that shields the heat is good, even a thin strip of aluminum would go a long way. You can still deal with the hot air if you need to…

A sheet of alloy or stainless that bolts to the head together with the manifolds would look nice.

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I got “heat blanket” type material that is meant for headers. You don’t wrap the manifolds completely, more you fit the sheet to lay over the top and around the sides of the manifold and secure it with steel bands. Easy to take off and made a noticeable difference in heat. I also put reflective heat shielding layers on the firewall so it doesn’t heat soak, and it’s a Mk2 so not sure if it’s the same or not, but cut a 3" x 3" or so hole in the side of the engine bay to give the heat somewhere to go. Another thing that helped a LOT is a small spoiler under the radiator which directs cool air from under the car up into the engine bay.