Hello everebody,can someone help me with my problem please? My Rx-7 fd runs perfectly fine, but after everytime I take it for a drive and let it cool down I always find the main radiator hose pipe(the one from thermostat housing to the left side of the radiator sucked in and as soon as I open the cap it goes back to normal. I changed the hose pipe to a silicone one which is harder to be sucked in and also the cap on the housing bit with no difference. Any ideas please?
thanks

 

Yes, replacing the hose wouldn't help as it's a vacuum/pressure related issue. What's the age/status of your pressure cap? If it's old or you are not sure, just get a new OEM pressure cap. Also it could be useful if you mention any cooling related mods you might have.

 

Sounds like an overflow problem where it can't suck back in from the overflow as it cools down and therefore ends up collapsing.

Did you change the cap? Or do a new line from the overflow to the cap?

 

Definitely sounds like the inner seal on a cap isn't lifting or overflow hose is crushed or blocked.

 

Thanks for your replies, I did change the cap on the thermostat housing to an HKS cap but did not change the one on the air seperator tank as it looks quite new and original. The coolant is new 50:50 pre mixed.Radiator is still original straight mounted and single turbo conversion.

 

you also need to make sure that the hose to the overflow isn't clogged, they do that

 

Thanks for the useful tips on your replies. It resulted that the air separator tank cap valve was not opening due to age most probably as it was still original. Replaced it and no issues.