Upper radiator hose

scskydivin

SCCoA Member
Why does my upper radiator hose get sucked flat?

Doesn't happen in the winter, but when the temp starts to climb like yesterday when it was 100 outside, the water temp is running about 200 degrees. Pop the hood, and my upper hose is flat. After the motor cools down a bit, lets say a couple hours, I'll take the radiator cap off, and will hear a release of air, the hose will fill out some. I'll top off the water/antifreeze level of the radiator itself. (the coolant tank behind the battery is worthless) and the hose is fine until 20 miles later, flat again. It's been doing this for a few years. And I'm figuring this has a little bit to do with my high temp driving. Especially on the freeway. New Gates hoses do not fix the issue. Neither did a new cap.

What's going on?
 
You have air in the cooling system - the coolant needs to be added to the Vent Cap plug - which is the highest point on the engine.

You need to maintain a 50/50 Distilled water / Coolant mix to maintain the proper coolant ratio.

The pressure cap ( 18 pounds ? ) allows the water to raise its boiling point. For every pound of pressure, you raise the boiling point 3 degrees. Effectively bringing your boiling point from 212 up to about 266 degrees.

... So when you are releasing the pressure ( undoing the cap ) .. you are instantly turning pressurized water into boiling water. DO NOT RELEASE THE CAP WHILE THE COOLING SYSTEM IS HOT.

When your system pressurizes, the Coolant overflows into the tank behind the battery ( yes worthless indeed ) .. after the system de-pressurizes, if there is still air inside of your system, it will create a vacuum pressure which will suck the water out of your Overflow tank and back into the radiator - this is why your Radiator hose is getting sucked flat.


- Dan
 
Went thru the same thing...the hose to the overflow tank is plugged...most likely at the tank. You'll need to pull the tank and wash it out, but don't be surprised if it happens again...something in the coolant isn't right. Keep an eye on it.
 
My coolant tank remains full all the time. I just drained the radiator completly, and the coolant tank was still full. It'll be full even if the radiator is empty. The cap I have is rated at 16lbs. I have a coolant leak on the lower radiator hose at the water pump. Have two ordered from o'rielly's. And two thermostat bypass hoses. Noone in town has them in stock anymore. It's a 2 day wait to get them in. At least I can still get Gates.

As far as air in the system, How do I get it out?:confused: Does it have to be flushed at a service shop? I thought you just left the cap off & it just bubbled it's way up while the engine was running. Okay, you can stop laughing now, :rolleyes: ha ha. My dad showed me that a long time ago and I'll admit, His way wasn't always the best. But it worked at time.
 
Went thru the same thing...the hose to the overflow tank is plugged...most likely at the tank. You'll need to pull the tank and wash it out, but don't be surprised if it happens again...something in the coolant isn't right. Keep an eye on it.

Thanks, I'll take the small hose off at the coolant tank & check for a plug/obstruction.
 
As far as air in the system, How do I get it out?:confused: Does it have to be flushed at a service shop? I thought you just left the cap off & it just bubbled it's way up while the engine was running. Okay, you can stop laughing now, :rolleyes: ha ha. My dad showed me that a long time ago and I'll admit, His way wasn't always the best. But it worked at time.

On the top of the thermostat housing is a riser tube with a vent plug (might have a white plastic ring around it) after you get the system as full as you can, run the engine. Crack the vent open to bleed the trapped air, when coolant comes out close vent. It might help to do this several times to ensure that the system is as air free as you can get it.
If you have leaks: some leak coolant under pressure (when hot), and some leak air when under vacuum (during cool down). Then keeping the system at the correct levels and clean will not happen without lots of attention.
Distilled water is the best type of water readily available to mix with anti-freeze. D.I. (De-Ionozed) is better, but not readily available. or practicle in most cases. If you can find a place to mount a grounded zinc element inside the cooling system (they're sacraficial) it will help keep the electrolitic corrosion to a minimum.
MikeH
 
My coolant tank remains full all the time. I just drained the radiator completly, and the coolant tank was still full. It'll be full even if the radiator is empty.

Yet more evidence that the hose to/at the tank is plugged. Clean that out and the upper hose won't collapse the next time the engine cools down (over nite, usually).
 
Excellent advice from you both, and very thorough. Thank you. My radiator hoses will be in on tuesday. I'll get em on & bleed the system of air that night. The coolant tank will be depending on time as I can get off work quite late.

I'll be riding the motorcycle to work untill it's fixed. The wife's not thrilled about that 'cause we split takin the kids to/from school all week. And I can't strap the younguns to the bike!


I will post up & let ya'll know how it all worked out.
 
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You should be able to do all that's necessary with clearing the blockage in the overflow tank in less than 1/2 hour at the most (preferably when the engine isn't hot).

The coolant tank itself is held in by two short bolts. Unlatch the airbox lid, loosen the large clamp on the intake tube at the throttle body and lay those out of the way.

Remove the small hose from the radiator neck and then lift the tank out, being careful to note how the hose is routed when installed.

Muck out the tank....the hose at the tank has a permanent clamp - you have to destroy it to remove it...don't bother. Just flush the tank and clear the tube with compressed air if you have it. If not, run a straightened coat hanger down the but and into the tank until you clear the junk out. Remove the radiator cap and inspect the overflow nipple to be sure it is clear as well.

Drop the tank back in - there is a small post on the bottom that should locate into it's hole easily. Route the hose the same way it was before you started.

Bolt down the tank, connect the hose to the radiator neck, replace the intake tube and airbox and add coolant to the tank...maybe midway between cold/hot.

Monitor the level over a few cool down cycles.
 
You should be able to do all that's necessary with clearing the blockage in the overflow tank in less than 1/2 hour at the most (preferably when the engine isn't hot).

The coolant tank itself is held in by two short bolts. Unlatch the airbox lid, loosen the large clamp on the intake tube at the throttle body and lay those out of the way.

Remove the small hose from the radiator neck and then lift the tank out, being careful to note how the hose is routed when installed.

Muck out the tank....the hose at the tank has a permanent clamp - you have to destroy it to remove it...don't bother. Just flush the tank and clear the tube with compressed air if you have it. If not, run a straightened coat hanger down the but and into the tank until you clear the junk out. Remove the radiator cap and inspect the overflow nipple to be sure it is clear as well.

Drop the tank back in - there is a small post on the bottom that should locate into it's hole easily. Route the hose the same way it was before you started.

Bolt down the tank, connect the hose to the radiator neck, replace the intake tube and airbox and add coolant to the tank...maybe midway between cold/hot.

Monitor the level over a few cool down cycles.

His is a '94...no need to deal with the intake as the overflow tank is on the other side
 
I had this exact same problem, and it was remedied by replacing the radiator cap. The old one would shoot coolant out into the overflow if you squeezed the upper hose. The new one does not do it.

Just my .02
 
Yeah, mine's a 94. Great instructions for anyone that has an earlier model with the same problem. I did replace the cap on the radiator, didn't do anything except make the radiator look a little better! I'm confident there's a blockage. And shall be pulling the coolant tank one night this week.
 
I pulled the coolant tank yesterday. It had this thick, light colored gel like muck in the bottom inch & a half of the tank. It was also in the first half inch of the small drain hose.

I flushed it all out with the garden hose. I should be good to go!
 
Oh, one more thing...

When I put the new upper radiator hose on, the top plastic tank broke at the hose inlet! So now I've got a Griffin. And will be putting it in this weekend.
 
Thats the best way to get better parts "Whoops, Honey I broke 'fill in the blank' and I need to get a new one. I might as well get the good one while I'm at it.
 
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