Bottom radiator hose

[David M]

Hi,

I've been rebuilding my NP Super Major and today I started it for the first time in around 5 years.
Everything went well but the bottom radiator hose is sucking in when I rev the engine.
I think if I rev it hard enough I could get it to suck in enough to seal itself but I didn't try that.

I've seen hoses with springs inside and this one doesn't have one but it has never been a problem before.

Any ideas what could be causing this?

Thanks,
David.

[Pavel]

I would suggest that your radiator cap could be the problem.
The cap is a two way valve; as the heated water expands it allows excess to evacuate. As the coolant cools it should allow air to be sucked in, otherwise a vacuum is created thus causing hoses to collapse. Better they do than having the radiator implode!
Pavel

[Pavel]

Just an after-thought to my post above.
Unlikely as may be, there is a chance that the overflow hose and/or metal pipe [just below the rad. cap] is completely blocked. This would also cause a vacuum to occur in the system.
In the first instance I would suggest that you run the engine for a while AFTER removing the cap. If the problem disappears, the remedy is simple.
Pavel

[richard the wrecker]

I would be having a look at the inside of the radiator, the most likely cause is that it will be blocked.

[AdrianNPMajor]

Hi David

Do you have a thermostat fitted?

If so, the water pump impeller should be circulating the water in the block, with the radiator not part of the circuit until the thermostat reaches its opening temperature. Once the thermostat does open, the pump will move water to the header tank of the rad where it percolates down to the bottom of the rad and then through the hose in question back in to the block.

If the walls of the bottom hose are being sucked in on start-up, this makes me think there is no stat or it's stuck open, plus the rad is blocked, with the effect that the pump is expelling water from the block through the top hose, but nothing or not enough water is filtering down through the rad to reach the bottom hose, hence the water pump is sucking air instead of water.

I could easily be wrong!

Do you get water coming out of the overflow?

[Kim]

It sounds like flushing out the engine and radiator would be a good idea. Check the thermostat (if there is one) and put some heavy duty cooling system flush and water in the engine and run it for a while as per the instructions, then drain and flush it with clean water. I heard recently of using dishwasher tablets to clean out a system but I haven't tried it yet. Put in a thermostat of known quality, fill with antifreeze an you should be good to go. Small leaks in the system can be treated with BARS LEAKS pellets; the stuff works great!

[David M]

Thanks for all your ideas. I will investigate further at the weekend and let you know what I find.

[super6954]

Hi David
I see in your post that this has been a long term project,I hope you haven't got a mouse nest in the system some where and thats whats plugging it . A friend of mine bought and old international crawler to restore the seat cushion was missing , when he dismantled the motor and cooling system he found it a mouse had hauled the whole thing in the rad and engine block as the thermostat was missing .
I had a customer tractor once that would not turn over a mouse had hauled Canola seed in a hole in the exhaust manifold , then the canola ran down the open valves and filled the cylinders as he kept putting it in. it was totally full on one cylinder. A mouse is an industrius little thing with time
Regards Robert

[Dandy Dave]

Hi David
I see in your post that this has been a long term project,I hope you haven't got a mouse nest in the system some where and thats whats plugging it . A friend of mine bought and old international crawler to restore the seat cushion was missing , when he dismantled the motor and cooling system he found it a mouse had hauled the whole thing in the rad and engine block as the thermostat was missing .
I had a customer tractor once that would not turn over a mouse had hauled Canola seed in a hole in the exhaust manifold , then the canola ran down the open valves and filled the cylinders as he kept putting it in. it was totally full on one cylinder. A mouse is an industrius little thing with time
Regards Robert

Oh Yeah. I revived a 1922 Peerless Automobile a number of years ago. Just outside the door where the car was stored was a grape vine. Little buggers filled the cylinders with open valves with grape seeds. Had a model BM Mack truck also at one time. Engine was stuck. When I pulled the head I found a honey bees nest in one of the cylinders. 10-20 McCormick Deering tractor with a mouse nest in a cylinder. When I used a piece of hard wood and hammer to try and free it up the top of the piston fell out after about 2 gentle wacks. Mouse wiz turned the iron gray and brittle. I've had my share of adventures. Dandy Dave!

[David M]

Finally got a chance to get back to this today...
The thermostat is missing so I have ordered one.
I've also ran a hosepipe through the radiator and the water appears to be flowing through without any problems.
I'll try again once the thermostat arrives and see what happens.

[Pavel]

The lack of a thermostat would not cause the vacuum effect in a hose. In general the heating up of the coolant causes the hoses to balloon slightly as internal pressure increases. There is always the possibility that the hose internal layers are laminating causing a flap to develop which can restrict or stop circulation of the coolant.
Pavel

[David M]

Fitted the new thermostat today and started it up again.
Not sure if its coincidence or not but the pipe is no longer sucking in.
If I get the time I am tempted to remove the thermostat and try it again, just to see if that was the cause but I'll see how it goes.
Thanks for all your input and help.


After a few years its now starting to take shape.

David

[halloween]

Is it just me or does that look to be perched on those wood blocks quite precariously?

Please be careful.

[Kim]

Given the poundage holding those blocks down, I doubt that it's going anywhere! I'm guessing that they are oak or elm or some other dense hardwood. Please take photos from the same vantage point as it goes back together as a " work in progress" series. It is something that seems to be rarely done and will be appreciated as a "remember when" in the future.

[Dandy Dave]

Given the poundage holding those blocks down, I doubt that it's going anywhere! I'm guessing that they are oak or elm or some other dense hardwood. Please take photos from the same vantage point as it goes back together as a " work in progress" series. It is something that seems to be rarely done and will be appreciated as a "remember when" in the future.

Agreed. Lay it on us baby. Dandy Dave!

[David M]

Yeah, they are solid hardwood blocks. Its very stable on them.
I supported it like that to make it easier to paint underneath.
I've got a few photos of the rebuilt up to now so I'll start a new topic and add to it as I go.
David