www.v8forum.co.uk

[bullyboy]

Hi

I have just rebuilt a 4.6 rv8, running on webber 500 carb,sd1 front end, twin 11 inch fans, large radiator.87 degrees stat.
I know air locks are a common problem and have read lots about this.
My system is pressuring on the top hose, when the engine is hot the top hose is solid, when i take of cap on expansion alot of fluid spills out when hot.
After this the pressure has dropped in the top hose but the hose feels like it has no water in.
Could this be a an air lock?
I have no bubbles appearing in my expansion tank.
The stat opens and the radiator gets hot and both fans fire up.
I know this is a common problem but if you have any suggestions i will be most grateful.

Regards

Chris

[DaveEFI]

[mgbloke]

I also have a 4.6 with SD1 cover, 500 webber but single 16" electric fan.
For the system to work properly the take off to the expansion tank should be at the highest point in your cooling system with the expansion tank as high as possible.
To purge the system remove the rad cap (when cold) and with water in the expansion tank, squeeze the top hose as much as possible. this will push any air out into the tank then when you let go water will be drawn back in. Keep doing this until no more air comes out. Do this periodically when cold to see if you have air in the system.
I had a lot of problems with air locks until I raised my expansion tank and re located the take off to the highest point.

Also Keep an eye on the level in the expansion tank( I have a see through one), when hot the level should be about 2 to 3 inches higher than cold. If its more than this then you probably have trapped air in the system.

Hope this helps
Mark