The V8 Owners Forum -

Hoping there's a cooling meister here.

V8 Healeys have a poxy small engine bay and no space for a big radiator and we all have cooling problems but there are guys in Texas who have less hassle than I do.

If I run the fan all the time and can keep the car moving then we're OK but traffic lights and stop-go traffic sees the temp start to climb. I'm running a 12" pusher fan and might be able to squeeze in two 10" slimline pullers. That might give me just enough cooling as the rad can't be increased in size but it's supposed to be good for 400bhp.

My biggest problem is dumping water. I've got a header tank fed off the water neck extension with a return to the bottom hose which seems to work until the temperature reaches 90 and then the coolant starts being fed out of the header tank.

Anybody want to comment on the setup. Is the header tank setup
wrong???? H E L P

Its hard to tell...but height could be your problem.


The system needs an air space to allow for expansion when it gets hot. So this air space needs to be higher than the level of water in the system.

When roasting hot, that vessel that looks like a header tank, should NOT be full. Leave it about 1/4 full, then it should never be able to expand so much, that it blows the cap.

Looking at the pic..its probably dumping water from the header tank, out that small pipe to the cap beside the air filter.


All air vents for the cooling system, should dump from the highest point where any air pockets could develop...and into your expansion chamber, at the top.

ie. from top of radiator header tank
ie from the pressurised side of the stat housing on top of manifold ( not where you have it )

And IMO, your expansion chamber needs to be higher.

I allways seal the rad to the bodywork so no air can get round it, and all incoming air is forced thru the rad, Ive sealed it with self adhesive foam strips to close the small gaps, the fan should also be as tight as practical to the rad so, again, all blown air goes thru the rad

Excellent info guys. I will act on them ASAP.

Cheers,

Ian

The fill cap on top of the thermostat housing should have a flat cap on it, not the valved type, just an observation

ian.stewart wrote:I allways seal the rad to the bodywork so no air can get round it, and all incoming air is forced thru the rad, Ive sealed it with self adhesive foam strips to close the small gaps, the fan should also be as tight as practical to the rad so, again, all blown air goes thru the rad

And if the fan isnt tight to the core. Duct the fan so as much of its air, goes through as much of the core of the rad as possible.
As per many OE radiator cowlings

Pullers are more efficient than pushers too.

So you want the fan to draw air through as much of the core as possible. Although once above 20mph or so, the fans arent doing anything.

JSF55 wrote:The fill cap on top of the thermostat housing should have a flat cap on it, not the valved type, just an observation

If it had a sealed cap, then that could sort the problem of water oveflowing from the expansion tank.
Although it would need to be sealed at the uppermost level, not the internal bit where it currently seals.

My gut feel is your header / expansion tank is not big enough for the amount of fluid in your system. On the GT40 the header mus be about 3 litres and when cold has about 1 litre of air in the top and when ot is red hot to the top so presumably then full (air squeezed to nothing)

If your pressure cap has 2 rubber seals (on on the spring and the other to sel the cap) put the otlet frm your header into a no pressure container - fluid will move out the pressurised system when hot and draw back in once cooling down again

And on the fans a single 12 inch will move about 800 cfm (not really enough (IMO)) so by going to 1 11 inchers you will increase airflow to about 2 * 700cfm = 1400 cfm which will be a lot better. (all fans are rated differently so check what cfm yours does)

And lastly can the air get out of your engine bay reasonably easily or is it too sealed and becoming a "high" pressure area at low speeds?

And lastly the one nobody admits to is the fan moving the air from the front of the car to the back as opposed to trying o blow it out the front - 30mph will basically nutralise any flow!

Ian

Plan is now to install new bigger header tank on firewall at back of engine bay which is as high as I can possibly get. I will also fit twin 10 inch fans.

Watch this space for further questions