Quite true...new parts are not always good. Think I will order a selection of caps, although they all might be made at the same place.

 

Soooo.....I seemed to have fixed the right radiator hose being sucked-in. For several months I had been letting the engine completely cool-down, see that the hose was sucked-in, removed the cap on the expansion tank, hose pops back out, give it a couple of squeezes, replace cap. As I said I have been doing this for several months.

Two weeks ago I did a bit different....radiator hose was not sucked-in, still warm to the touch, so I gave the hose a good squeeze, with the expansion tank cap on. Let it sit overnight...next day...hose was not sucked-in. Have driven around for the past two weeks and every time I check...the radiator hose is no longer sucked-in.

I must have cleared something...a big IDK here.

 

I spoke (wrote) too soon. Hose is once again collapsed.

 

99% sure I found the issue. I had replaced the hose between the thermostat housing to the coolant reservoir in which I used heater hose and hose clamps, did this several years ago. Anyways found that when the engine is cold, this hose is not tight at either end. I assume that as then engine cooled down, air was sucked-in causing the hose to collapse. I replaced the hose with a smaller ID, much, much tighter fit. So far no collapsed hose after two heat cycles.