Radiator overflow problem

so I've found a problem with my tb.2e that's annoying me. The radiator sends coolant to the overflow bottle as it should but then won't suck it back and it eventually overflows. Any ideas? radiator cap is correct according to manual and Nissan dealer. My only thought is maybe the overflow hose is connected to the wrong side of the overflow cap but I know nobody that has a similar vehicle to check with.
Pete

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Originally Posted by Pete49

so I've found a problem with my tb.2e that's annoying me. The radiator sends coolant to the overflow bottle as it should but then won't suck it back and it eventually overflows. Any ideas? radiator cap is correct according to manual and Nissan dealer. My only thought is maybe the overflow hose is connected to the wrong side of the overflow cap but I know nobody that has a similar vehicle to check with.
Pete

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You may have an air leak in the radiator / overflow / return hose. When the fluid cools and tries to “pull” the water back into the radiator, it will draw air rather than water as the resistance is less.


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Check the radiator and the overflow hose barb for cracks or weeping. Use your nose to track down any smell of coolant. Check the hose and overflow bottle for splits, cracks or pinholes. Make sure the lip of the radiator is smooth and seals properly. Fit some clamps or cable ties to the overflow hose. If it still has a problem, get the radiator and cooling system pressure tested for leaks. Here's hoping it is one of the above.

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Originally Posted by Pete49

snip... My only thought is maybe the overflow hose is connected to the wrong side of the overflow cap but I know nobody that has a similar vehicle to check with.
Pete

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The 'hose should go to the pipe on the overflow cap that has the internal rubber tube on it that is immersed in the coolant.
It should not go to the pipe on the overflow cap that ends at the underside of the cap, that is the pipe that should have the 'waste' hose that disappears down and vents excess coolant onto the ground.

If those are correct then do what the prev posts suggest.
If it is an old Rad Cap it may pay to replace it anyway.

Often the cause is a faulty cap or old perished hoses, if the bottle fills with coolant then it must be OK but the bottle cap barbs are known to crack also

Absolute worst case is you have a cracked head or blown gasket

Thanks guys for the quick answer the resident evil one was on the money :animierte-smilies-f the connection was wrong. I've reversed it so all should be good.
Pete

You might be able to see some white residue where its been leaking.
PITB hope you find it