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nissan patrol
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Discussion Starter · #1 ·
Hi. Can someone help with issue I am having? I can find reasonable answer to what I have did.
When I bought my car, I noticed that there radiator hose is very hard to bend. Almost impossible. However there was no bubbles under radiator cap and no bubbles in coolant tank. No matter if the engine is hot or not.
Then when I did repairs, oil/fuel filters change. I decided to change radiator cap. Bought new original one. The same situation. Radiator hose is very very hard to bend. Then I took my old cap and cut rubber inside of it. Just a bit.
Now my radiator hose is very easy to bend. Can do it with one finger.
QUESTION: Can I leave this as it is? Why with new radiator cap, radiator hose was very hard to bend?
Is my head blown? If it blown somewhere inside and with lowering preassure I will not harm anything?
If my head was OK, what about cavitation? Should I start worried about cavitation?

Thank you,
Dmitrijs
 

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BORDERTREK 4X4 & FABRICATION
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8,549 Posts
I wouldn't drive it with a cut seal on the radiator cap. Coolant will go through the overflow bottle at low temps. It wont get up to pressure and lowers the boiling point without a proper seal.
 

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The nutty professor
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the radiator hose is suposed to be hard when at operating temp, if it is still hard first thing in the morning then you have a problem
 

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nissan patrol
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Discussion Starter · #5 ·
Coolant is clear, no oil in coolant. No gases under oil cap, no bubbles in radiator or coolant bottle.
I just had very hard hose when driving. In the morning it was very soft. But when engine is hot they were so hard, even more then tennis ball. On my other cars I have, radiator hose are not so hard. I can easily press them.
In radiator cap i just cut some rubber sealing. Not all, but some. So maybe now i have not 0.9 bar, but around 0.5/0.6
Also what is unclear is that why with new radiator cap i had too big preassure?
 

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nissan
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First thing I'd check is the thermostat, if anyone has ever used a stopleak chemical in the old girl it can build up around the opening and reduce the water flow causing back pressure in the top hose
 

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KICKEN BACK IN THE BUSH
nissan gq
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Squeeze the rad hoses when cold,if ya can hear like a crackling sound , there buggered
Excess stuff builds up on inside and goes flacky when ya press them
Go get another new rad cap,hard to determine a problem if things are altered

Excess pressure can be blocked radiator, rather than blown head gasket
Do a search its a regular topic
 

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nissan
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It's ment to pressureise when hot. That's how the boiling point is raised. Put a new cap on it and throw a new temostat at it and just leave it for a bit and see what happens. But if they go soft when cold and only firm when hot I'd say it's working well
 

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It's ment to pressureise when hot. That's how the boiling point is raised. Put a new cap on it and throw a new temostat at it and just leave it for a bit and see what happens. But if they go soft when cold and only firm when hot I'd say it's working well
 

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Also check the cap/outlet on top of the expansion tank, is it in the correct way round? If it isn't it will hold full on pressure.

Take the small hose line off bellow the radiator cap and try blow through to the exp tank, if you can and see bubbles its fine. If you can't swap the ends, little outlet hose becomes inlet to tank ect.
 

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nissan patrol
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Discussion Starter · #11 ·
So far I have changed new thermostat, new coolant, new radiator cap (original), waterpump, visco fan hub, put new radiator (it came from old rig, but it was new about 6 month old), today I replaced radiator hose.
There is no oil under oil cap or oil in coolant bottle. No bubbles in coolant bottle or under radiator cap.
When car is cold, i can squeeze rad hose. When old rad cap or new original rad cap is placed and when engine is hot, I am unable to squeeze rad hose. They harder then tennis ball. When I put my modified rad cap, with slightly cut rubber sealing on it. I can squeeze rad hose. It's almsot like tennis ball or even softer. So my question was should I stay with high preassure in rad hose with new original rad cap or not lowering preassure using modified rad cap?
Why with new and original rad cap I still have the same high preassure? What about cavitation? IF the preassure is to small can cavitation destroy water pump?
 
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