Topic: Top radiator hose sucking its self in under throttle (Read 5180 times)

IrishCJ6 · « **on:** September 17, 2011, 08:21:02 PM »

Ok so I got the V8 going yesterday and I have just noticed that when cold the top radiator hose sucks itself together when I give it some quick throttle, as soon as I release it the hose returns to normal, if I slowly apply throttle it doesn't seem to do it?

Anyone have any idea why this is doing this, I thought it may be a air lock somewhere?

Nosebolt · « **Reply #1 on:** September 17, 2011, 09:24:02 PM »

old hose or thermostat

IrishCJ6 · « **Reply #2 on:** September 17, 2011, 09:33:12 PM »

Its a brand new hose, so you think its the thermostate?? Would make sense, I'll order one and install it.

Bubba · « **Reply #3 on:** September 17, 2011, 10:08:55 PM »

dont see how you could get wrong but water pump is rotating the right way

Lornaben · « **Reply #4 on:** September 17, 2011, 10:29:39 PM »

My bro in law had the same problem with his CJ7 when he fitted silicone hoses, he ended up fitting a coil/spring inside the pipe to stop it.

IrishCJ6 · « **Reply #5 on:** September 17, 2011, 11:05:30 PM »

Quote from: V8 Bubba on September 17, 2011, 10:08:55 PM

dont see how you could get wrong but water pump is rotating the right way

Have no idea how I could have the thing spinning backwards but here is a pic of my setup

Some one on another site thought it could be from the thermostate being closed and creating a negitive pressure through the system

Panic mechanic! · « **Reply #6 on:** September 17, 2011, 11:17:24 PM »

I do beleive you may be turning water pump in wrong direction

I know the routing is different with a serpentine belt

IrishCJ6 · « **Reply #7 on:** September 17, 2011, 11:28:34 PM »

I can not figure how you could get the water pump to spin backwards, the crank it the determining rotation, therefore anything connected to it will spin in the same direction, the alternator/powersteering pump are just follwoers/idlers?

This is a picture of another V8 setup, mine is exactly the same except my alternator is where the compressor is

Nosebolt · « **Reply #8 on:** September 17, 2011, 11:29:19 PM »

for the water pump to run backwards with that set up the engine would have to be running backwards too, or someone has built the pump with the wrong impeller.

silly question but you have got the hose from the pump to the bottom of the rad and the hose from the block to the top?

IrishCJ6 · « **Reply #9 on:** September 17, 2011, 11:35:20 PM »

Quote from: Nosebolt on September 17, 2011, 11:29:19 PM

for the water pump to run backwards with that set up the engine would have to be running backwards too, or someone has built the pump with the wrong impeller.

silly question but you have got the hose from the pump to the bottom of the rad and the hose from the block to the top?

Yes thats the way the hoses are, hard to do anything else when they are factory hoses, I'm almost tempted to remove the thermostate and see if it still does it?

IrishCJ6 · « **Reply #10 on:** September 17, 2011, 11:36:54 PM »

even stupider question, is it possible to have the motor spinning backwards??? I can't think of how but is it possible? How can I check which way the engine should spin.

Lornaben · « **Reply #11 on:** September 17, 2011, 11:38:10 PM »

Quote from: IrishCJ6 on September 17, 2011, 11:36:54 PM

even stupider question, is it possible to have the motor spinning backwards??? I can't think of how but is it possible? How can I check which way the engine should spin.

Impossible without major valve timing changes and ignition mods

Nosebolt · « **Reply #12 on:** September 17, 2011, 11:41:10 PM »

assuming its not a defective hose (and a new hose can still be defective) then the problem is the pump pumping faster than the flow, so the thermostat would be the obvious place to start, if that doesn't fix it then sorry but I recon your looking at a blocked waterway in the block, good nows is you say it stops when warm which does suggest the thermostat

Panic mechanic! · « **Reply #13 on:** September 17, 2011, 11:46:23 PM »

the water pump can run either way.

Nosebolt · « **Reply #14 on:** September 17, 2011, 11:48:45 PM »

only if the belt is crossed between the pump and crank pulleys, not the way he has the belt fitted

Panic mechanic! · « **Reply #15 on:** September 17, 2011, 11:56:43 PM »

on the serpetine belt system the fan belt leaves the right side of the lower pulley but goes on to the water pump on the left side crossing over between the two pulleys. Its normal for the lower rad hose to collapse if you do not have the support spring inside it as the pump can pull more water from the rad than it can flow so maye one of the other other issues is does the rad flow at a high enough rate?

Lornaben · « **Reply #16 on:** September 17, 2011, 11:59:35 PM »

Quote from: Panic mechanic! on September 17, 2011, 11:46:23 PM

the water pump can run either way.

The pump is centrifugal so it dont matter which way it spins. Correct hose connection will make a difference though ...

Dave69 · « **Reply #17 on:** September 18, 2011, 10:45:36 AM »

you shouldn't be able to mistake top and bottom hoses as they are made to go to specific places on the engine so any cross over would require specific piping to suit. Easiest way to find out what is going on is to remove the only known obstruction which is the thermostat and then see if the top hose collapses. If it doesn't then you know the problem. you could then put a spring in the top hose but then these do start to rust after time, an alternative is an old mastic tube cut to suit length with a portion removed to allow the tube to be inserted into the pipe to keep it from compressing under load.

if the pipe compresses without the stat fitted then some thinking about the problem might be in order

Dutch · « **Reply #18 on:** September 18, 2011, 10:57:56 AM »

Other alternative and this will not collapse + you can see the flow :

[attachment=1]

Description: Extremely flexible and transparent, non toxic and reinforced with a steel wire spiral Applications: Suitable hose for vacuum pumps, agricultural machines, irrigation plants, boat construction, chemical plants, plastics manufacturing machinery, sludge tankers. Suitable for being in contact with foodstuff that requires simulating liquid type A-B-C in accordance with 90/128 CEE.

We use this in the yard and have always got spare bits kicking around. If interested tell me what size/length
and I can send you some.

Warthog · « **Reply #19 on:** September 18, 2011, 12:14:15 PM »

I'd say its the radiator cap.

The cap allows coolant to pass out into the overflow when the coolant expands due to heat. It also is supposed to allow it to siphon back in as it cools and creates a vacuum. If the cap will not let the fluid back in then the vacuum is causing the hose to get sucked flat.

Hope that helps?

IrishCJ6 · « **Reply #20 on:** September 18, 2011, 06:24:21 PM »

Here's what one of the american boys said

OK, what's causing the issue,
When you have an old water pump, or when you have a replacment with poorly designed impeller in the pump,
When you hit the throttle, you CAVITATE the water.
The impeller actually rips holes in the water before it can get moving.

When you create those holes (some call them 'Bubbles', but 'Bubbles' are POSITIVE pressure,
These are NEGATIVE pressure holes in the water.

Since there are 'Holes' in the water, that's all that can be forced into the block...

When these holes in the water collapse, they cause a vacuum in the block, and you get your top radiator hose sucked shut...

------------------------------

Now, when you rev up SLOWLY the water can move fast enough to fill the block and circulate without ripping it apart, and you don't get the hoses sucked shut.

(Cost me $5,000 in the early 80's to machine apart blocks and put in lexan windows to watch and understand this, so pay attention unless you have a large milling machine, a 25 horse power electric motor, strobe lights to stop the action, ect. to do your own testing!)

A PROPERLY designed impeller and water pump housing will NOT rip holes in the water...
So you either have a CRAPPY water pump, or your water pump is on it's last legs.

The upper hose is SHOT, when they get spongy, they are SHOT, CHANGE THEM!

There are also metal & plastic springs that go into the hoses to keep the problem you describe from happening...
LOWER HOSES SHOULD ALWAYS HAVE A SPRING!

When a lower hose sucks shut, it dries out the pump for water flow (meaning the water can get into the block faster than the radiator can supply it via the hose).

This is VERY BAD for the pump and usually means you have a radiator plugged up and it can't supply enough water fast enough for the pump.
High vacuum on the inlet side of the pump will cause REAL PROBLEMS for the pump so don't let it happen,
Have your radiator cleaned out, use a spring in the lower hose, and change hoses about every two years.

----------------------------------------

As for the 'Air' in the system questions,

Any Air in the system is gone the first time the vehile reaches full temprature and the radiator cap 'Burps'.
Doesn't matter if there is a 'Puke Tank' or not, it will vent the air in the system as 'Steam' when it reaches operating temp/pressure listed on the cap.

If you have a 'Puke Tank' hooked up properly, and you have the correct radiator cap for a Puke Tank, the expelled air will blow bubbles in the tank, along with any coolant that gets puked out.

With the proper radiator cap (Two Way Valve) as the radiator/engine cools down, the coolant will be sucked back into the cooling system instead of lost.

Air in the system CAN NOT EXIST at around 15 PSI (operating temp/pressure),
Since outside pressure is around 14.7 at sea level or less, anything above the rating of the cap the system will 'Burp' any air right away.
No air means it can't be an 'Air' differental causing the issue.

It's the 'Voids' in the water that get into the block causing the vacuum at the top hose.
As the voids close up, they draw water back into where they were, and the HYDRAULIC PRESSURE of that water closing the voids is what is collapsing the hose.

Air pressure COULD NOT collapse the hose since there is no AIR PRESSURE in the system.

Again, VOIDS are not AIR, they are not BUBBLES, they are VOIDS where there is a 'Rip' in the coolant.
Coolant is 'Heavier' than water, so it's slower to close the voids, and when it finally does, it will create quite a big of NEGATIVE hydraulic pressure above the coolant pump, and it will do it at the speed of sound when the voids collapse...
It take a while for the pump to catch up, but eventually it will...

Remember, your coolant pump is NOT a pressure pump, creates VERY LITTLE pressure.
It's a VOLUME pump, it's designed to circulate the coolant, not create pressure...

Again, that's a hydraulic thing that people don't get unless they are educated in hydraulic movment and see it themselves...

bigjeepzj · « **Reply #21 on:** September 18, 2011, 07:53:09 PM »

that make sense
thats a good find

dieselj20 · « **Reply #22 on:** September 18, 2011, 08:09:07 PM »

impellers on serpentine belts turn the opposite way and are the opposite hand

Dave69 · « **Reply #23 on:** September 19, 2011, 06:48:41 PM »

in other words the system cannot supply the water to meet the demand of the pump

Author Topic: Top radiator hose sucking its self in under throttle (Read 5180 times)

Nosebolt

Panic mechanic!

Nosebolt

Nosebolt

Panic mechanic!

Nosebolt

Panic mechanic!

dieselj20