Top radiator hose restriction?

[71RS]

I was revving the engine above 2000rpm when I noticed the top radiator hose would flatten out during acceleration. The higher the rpm the more it would flatten out. No doubt this would restrict coolant flow and wondering what can be done about it? The top hose is new and does not have the inner supporting spring as found on the bottom hose or original. Thought I might be able to use an old inner support spring in the top hose and see if it helps.

Has anyone else had the same issue and have a reccomended fix?

[jross]

thermostat closed

[71RS]

thermostat closed

Thanks, but I dont think it's a closed thermostat which is new and working.

With the engine warmed up, I took the top hose off at the radiator end and water was easily flowing out during idle. I did not try increasing the engine rpm as I was concerned the water from the hose would not keep up.

I'm thinking it might be more of a vacuum situation which is collapsing the rad hose during higher rpm? Perhaps the thermostat is not allowing enough coolant flow? Would a braided hose help?

[blackoutsteve]

Did you check the thermostat in a pot of water on the stove before installation? It's something you should do.
I had a brand new GM 'stat, out of the box and into a new (refit) engine and it just about killed it because it failed to open.

Also, do you have the intake to waterpump bypass hose in place?
(I'm not sure if all SBCs bypass internally, but if there's supposed to be one, I'd fit it. It's a must on BBCs.)

Are you sure the engine was up to temp with the 'stat wide open? There is no reason why a top hose should collapse unless there is a restriction on the engine side, while the pump is pulling on the radiator side.

A spring in the upper hose or using a braided hose is not curing the problem.

One problem might be that you're low on water.. Have you purged all the air out when filling?

[67SS502]

what sort of water pump do u have?

[blackoutsteve]

what sort of water pump do u have?

A working one by the sound of it..:)

[67SS502]

it may be a reverse cycle water pump.......:confused:

[71RS]

Thanks Steve. There's no bypass as I've seen on the BB's. It's a long water pump and my heater hose goes into the pump. I'm not near the car at the moment so not sure if the intake or pump have the extra holes to fit a bypass. I notice the edelbrock intake that I will buy soon does!:D I did not check the thermostat in boiling water but will do that next week. I'll then get it well warmed up and try it again at higher operating temp.

I believe the system is full but now curious what procedure do you use to get all the air out.

Thanks again

[steelin time]

Try the radiator cap. It has two valves, One to hold pressure (the main one) and one to let air in ( the small round disc in the very center underneith ). This second valve rarely gives problems but can definiatly cause the problem your having.

[blackoutsteve]

it may be a reverse cycle water pump.......:confused:
Hmmm, I doubt it, but good point.

[lazy69]

Maybe the pump is a high flow pump with a standard thermostat , that will restrict flow.

[71RS]

Must have still had air in the system. Went for another drive and resevoir was down a bit when I got back. Topped it up and went for another drive. With engine hot or cold now the top radiator hose maintains it shape with increased revs. Steady temps.

Thanks for all the help.