Radiator cap overflow bottle

**Spike** · 24-02-2015, 12:10 AM

Can anyone help me with what the HX model had re cap pressure rating and did the HX have an overflow / pressure bottle. I have fitted a new ally radiator and it came with a 1.1 [kPa or Bar?] pressure rated cap. It spews water out when it gets to about 100 deg C. Do I need a higher pressure rated cap or keep the 1.1 and fit the overflow bottle? cheers

**wbute** · 24-02-2015, 07:57 AM

Are you using a thermostat? It shouldn't get to 100 degrees. Not sure on over flow bottle. They may have been optional???

**Sandaro** · 24-02-2015, 08:04 AM

I don't believe a bottle was an option. I think caps in the 15-20psi range for normal use. By the time temp is at 100 you may have already lost a fair bit of water?

**HK1837** · 24-02-2015, 08:25 AM

I've never seen an original bottle on a HX, just an overflow hose.

**gregbark** · 24-02-2015, 08:33 AM

When Rare Spares had the radiator caps remade with the approved GM logo the part number 9928800 referred to a 15lb cap (518.15). The same cap was used on a HZ without overflow and all HQ Heavy duty. The HQ standard used a 13lb cap 9928799 (508.13). Part number 92006790 (534.15) is for HZ with overflow. That cap has a sealing ring for the coolant recovery system. Firstly you need to check that the cap is a coolant recovery type otherwise it will not seal the system. If you look at this web site you may get a better understanding of the difference. http://www.cpcauto.com.au/radiator_caps.aspx. You should ensure the cooling system has been flushed out thoroughly and check under the cap valve for any dirt. A radiator installer such as NATRAD can check the cap operation with a special hand pump, as well as your system. A coolant recovery system is a better option than just venting to the ground.

**Beachy** · 24-02-2015, 04:54 PM

You have a cooling problem not a radiator cap problem it's boiling and letting go like it should

**wbute** · 24-02-2015, 07:26 PM

Originally Posted by Beachy

You have a cooling problem not a radiator cap problem it's boiling and letting go like it should

I agree.

**Frosty** · 24-02-2015, 07:28 PM

Originally Posted by Beachy

You have a cooling problem not a radiator cap problem it's boiling and letting go like it should

Correct. I don't know a lot about it but decided it was cheaper to fix up every cooling part than root the motor. Twin AU thermo fans go well on a Ali radiator, that fixed it ( and thermostat, housing, hoses and pump ) All good now except bigger Altinator for the fans