? about the Radiator Coolant Tank Cap
 

I have a 86 GMC V8. Does the cap that goes on the radiator over flow tank need to be vented? I picked a cap up from the wrecking yard today and all he had was a solid cap. It is a screw on tank. Thanks for a reply.

Re: ? about the Radiator Coolant Tank Cap
 

Don't think it matters. A lot of overflow tanks have a built in vent at the top that directs any overflow down the side of the tank. I replaced the lost cap on my 79 Camaro with a metal Wylers bullion cap. Worked for years and a near perfect fit.

Re: ? about the Radiator Coolant Tank Cap
 

Yes, it should be vented.
If not it could vapor lock.