Hi guys...probably being a bit lazy as I'm am sure there is plenty of advise on the site but wondered if any UK guys had purchased a high flow water pump for a standard 1960's untuned 302 Windsor.... My stock set up has a SA baily large capacity rad and twin fans but I'm having "significant" issues stopping her from boiling over.... Trying to look at the best fix out there so am hoping those in the know will be kind enough to give me the benefit of their wisdom.... Right now I am also looking at a larger header tank also as I have been told that can also help.......
Any feedback would be great..........have waited months to get her on the road and to say its frustrating is an understatement...!!!

Hi. Do you have a thermostat fitted . I have removed mine .. I sat in traffic the other day for around 25. Mins and it was fine . The fans came on and kept her cool .

Bill Kearley

I run a standard water pump, small tank, 427 w with 165 deg thermostat, no problems, I have an air bleed at the top of the rad and a second at the outlet on the intake manifold to ensure no airlocks. And now for the silly questions, is the pump turning in the right direction / serpentine / or could you have a marine pump? left and right pumps are common. I came across this once before.

Ron Earp

What Bill said.

Best thing is to run a thermostat and fix the cooling system. Sound like you need a properly sized header tank, high enough to bleed the air out of the engine, you're on the right track. I spent quite a bit of time sorting this on the Lola T70 replica and once I got it sorted it was rock steady at 180F, the thermostat spec, even in race conditions. Proper bleeding and coolant system functioning requires a good header tank with bleeds from the front and rear of the engine.

Mike Pass

Sounds like air lock in the system. Ensure the highest points like top of rad and engine have bleeds. I have air bleed pipes on both sides of the inlet manifold which feed back to the reservoir.
I have a thermostat and it never boils up.
I've a 302 with standard water pump as has already been posted, bleeds of the rear of your inlet manifold and radiator back to the header tank are key. Air gets trapped in both locations unless you do this.
Also bear in mind that the coolant will expand about 1 litre from cold to hot so you need a header tank with capacity to allow this. I'm running Evans waterless coolant now as the corrosion in the system is really bad over the long term with water/antifreeze.

Ian Anderson

Lifetime Supporter
Is it boiling over at rest, or when crawling in traffic? Are your fans blowing against the air flow - front of car through radiator and out or perhaps wred wrong and blowing air forward and eventually stalling the air around the radiator.
Also seen one system where one fan blew forward and the other rearword!
I had overheating issues on my RCR with a 302. It was simply solved by fitting some very powerful fans from Kenlowe in Maidenhead UK. They were very helpful and had done the cooling on original GT40s at nearby Slough in the 60s. They draw a big current (about 45 Amps) on full chat (2 speed but Kenlowe recommend full speed) so make sure your alternator and wiring is up to it. I have a dash switch to a relay and a dash light when they are on. I also have an auto switch in case I forget to switch them on. At constant speed over around 55mph I don’t need the fans. The liquid is a 50/50 water/anti freeze mix.
I hope this helps. Cheers Roger.


Thanks All for taking the time to respond.... I am going to insert a new bleed at the radiator and run it back all the way to a larger expansion tank... I will try that first before swapping the water pump.... Hopefully I can get it sorted in time to enjoy the Summer...
Cheers All

Dave Bilyk

Dave Bilyk
I went through this pain with my 302, the one thing that made the major difference was installing the cylinder head bleeds, in my case everything else, radiator bleed, electric pump, playing with thermostat, was minor.

Terry Oxandale

Skinny Man
+1 on the Airlift system. Have had to open up the cooling system multiple times since this purchase, and it's well worth the money.
One thing I did on my 40 was on the top of the out tank I have a bleed plug.
I remove the plug screw in a bsp barb fitting and attach a piece of clear 1/4" hose.
I bull clip it to the front clip as high as possible (front clip open) it bleeds the air out nicely, that and bleeds in heads and top of rad tank works a treat.
I can bleed it with out tools, very handy if you are on the road.


Howard Jones

You should vent the system from the high points, rear of cylinder heads, top of radiator (both), and the thermostat housing back to the expansion tank. Place the expansion tank as high as possible as well and run the line to it from the lowest pressure point in the system. That would be the cold side return from the radiator and input to the pump. If you have a heater core then you may need to vent it also if it is trapping air.

Both my cars the SLC and the GT40 are done like this, the system will bleed itself. Nothing else needs to be done as the air must return back to the expansion tank and has no other place to accumulate. If you are fighting air in the system then it isn't designed correctly and there is a place where the air is being trapped. A proper self bleed system will correct this and once you have done that you will never have a air in the system problem again.

Then you can control water temp with a thermostat.

Terry Oxandale

Skinny Man
Because of the constraints of the typical CanAm body, I didn't have the luxury of placing the tank at the highest point. I'm close, but it still has some minor amount of air which can only be bled by doing what Jim noted, which was a tube that goes into a small cavity on the ITB manifold . After I shut down the motor and climb out of the car, I hit it with my fingertip to release any air that passed that way, and I'm done. If that is done while the motor is still hot, it releases air pressure if air exists, and this allows the pressure drop to increase as the engine cools down, drawing additional coolant out of the tank. If there is no air is released (just a small amount of coolant), then it's validation I've got a good situation. This used to be an iterative process until I started using the AirLift system. That system seems to get about 95% of the air out of the system that doesn't have bleeds at the tops of bends, so the bleed seems to get the rest out. Even without the bleed, I no longer have air issues in the coolant system, but it just added another easy check for any air that can be let out with a 5-second thought about it.
Shoot me down if you want... I've never had a cooling issue since I fitted a 7 litre header tank, routed the heater outlet on top of the inlet manifold, which is the engines highest point, to the top of the header tank, the header tank bottom outlet to the heater return on the water pump. Any air in the inlet manifold is removed as the water drops through free air in the header tank. The thermostat bypass hose is now re-routed to the heater and back. I have retained the thermostat, but drilled a 3/16" hole in the highest part of the thermostat to ensure that the closed thermostat does not trap air. I can also observe coolant flow by looking inside the header tank. The header tank input is the highest part of the system. Sounds crazy? It works ! Needless to say, radiator and cooling fans in clean working order, plus the static bleeds as well.