Rad hoses pressure - soft to touch

[phaetn]

Should the hoses to and from the rad be hard with fluid at all times?

The reason I ask is that I just had my rad's core replaced, as well as the system flushed. (I was taken to the cleaner's because I was in a jam but I'll leave that story for another day).

The car definitely runs cooler at speed, but I saw the temp precipitously climb on Sunday. I wondered about a stuck needle (it's been acting up a bit), but tapping it didn't help. It took a real while for the fan to kick in and then it didn't bring down the temp as quickly as I would have liked. Something definitely wasn't right. As far as I understand it, the temp gauge sensor is in the top of the block while the sensor to turn the fan on and off is in the bottom corner of the rad. Both top and bottom hoses were hot, indicating fluid was definitely travelling through the system.

Temp and fan operation was a lot better yesterday and today, but it's been cooler weather. I suspect maybe air in the system, because the heater core is bypassed so there's a tube running over the cam cover and it's likely the high point in the system -- certainly even with (maybe higher?) than the rad cap. The rad shop might not have taken this into account and therefore not raised the front of the car when filling with fluid.

Before, my rad hoses would always be quite firm, even if the car was cool from having sat overnight. Just tested them now and they're much softer to squeeze. Is that normal? Is that because fluid just goes to the overflow reservoir? I'm not sure because my old rad was so badly plugged there may gave been a falsely high pressure before.... Or is it a possible indicator of air trapped somewhere? As I say, both top and bottom hoses get hot so I know fluid is circulating.

Since it's been fine the past couple of days, is it possible the air worked its way out through the system?

Thanks and cheers,
phaetn

[So Cal Mark]

when there isn't any pressure you'll be able to squeeze the hoses. When the system is pressurized the hoses will be hard. If the system never gets pressurized then you most likely have a leak somewhere or a cap that doesn't hold pressure. Each lb of pressure raises the boiling point 3 degrees, so having the system pressurized is important

[AriK]

Phaetn,
Hoses are soft when car is cool. Compressing them does not create bubbles through the overflow reservoir. The heater hose definetely is higher than the rad cap so if you do not have a flushing T, install one and let the car idle a couple of fan cycles with a funnel half filled with coolant into the T. Make sure theres a tight seal between the funnel and the T's rubber seal you can watch for bubbles while you stand from a distance and have a coffee.

[phaetn]

Thanks for the quick reply, Mark.

Indeed they had seemed hard when the car was running (a good sign!) but I was surprised at how soft when cool. Maybe it was different with the old rad (overly high pressure because of being plugged) or maybe I have always tried them when hot before.

Thanks for the reassurance!

Cheers,
phaetn

[GeorgeT]

How old is the radiator cap? A bad cap will not let the system pressurize and cool properly.

[phaetn]

Thanks AriK (sorry, I didn't see your post yet when replying yesterday) and GeorgeT.

I have a Coolant System Air-Bleed T that I bought from A/R at the same time as my Timing Belt kit with water pump. I'll see if I can get it installed when I get the other work done, but I may run out of room under the hood as the heater is bypassed.

I'll see if it can work...

The hoses are definitely under pressure when the system is hot, which is good news.

Cheers and thanks again,
phaetn