Well, this fellow is partly correct, but he misses the point that even a well maintained car can produce a vacuum at the water pump inlet at high RPM (of course, as he notes, a failing radiator cap will make this happen more easily). He is definitely wrong, however, when he states that once the car leaves the factory there is no further need of the spring (or whatever he wants to call the coil of wire inside the hose). This is easily proven by removing it and trying a high speed blast down the freeway - most cars will have a problem with the lower hose collapsing, especially when the hose is a few years old and getting a little soft. On Packards, the problem was resolved by using a length of solid tubing, with rubber hose only used to connect at both ends to the radiator lower outlet and the water pump inlet. Dick Benjamin ----- Original Message ----- From: "DR CHALLENGER" <drchallenger@xxxxxxxxxxx> To: <mailing-list@xxxxxxxxxxxxxxxx> Sent: Wednesday, June 16, 2004 11:42 AM Subject: Re: IML: '68 running warm <--my '67, too! > here is an article on springs in hoses. > > http://automotivemileposts.com/autobrevity/moldedhosecoil.html > > > >From: "Dick Benjamin" <dickb@xxxxxxxxx> > >. > > > >Another cause of high speed overheating is the lack of an anti-collapse > >spring in the lower radiator hose. The average gas station mechanic > >doesn't know much about physics, and discards that spring when replacing > >the > >lower hose. It is important - the water pump inlet side can actually go > >way > >below atmospheric at high RPM. > > > >So squeeze your hose to see if you can feel its ribs. If you can't - > >you've > >found your problem. > > > > > >