The upper radiator hose is collapsing as the car cools

Tiny
DAVIDKRISS
  • MEMBER
  • 1999 SATURN SL2
  • 1.9L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
I’ve replaced the radiator cap with the exact factory replacement, completed a coolant flush and there doesn’t appear to be any blockages, replaced the overflow hose, done a block test that came back negative… I’m at a loss. What could be causing the collapse?
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Wednesday, July 6th, 2022 AT 1:17 PM

21 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

When the engine cools, the radiator cap is what allows excess coolant from the overflow reservoir to return to the radiator. If the cap is new, check the heater return/vent hose to the reservoir to see if something is blocking it or if it is pinched closed. See pic below It's the top hose. That is where I would think there could be a restriction, but again, the cap is what should allow the negative pressure to be released.

Just for curiosity, have you tried a third cap?

Let me know.

Joe
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Wednesday, July 6th, 2022 AT 9:53 PM
Tiny
DAVIDKRISS
  • MEMBER
Hi Joe,

Thank you so much for your response. I m on cap #3. The second one I got was only rated at 16 PSI and the required PSI for this Saturn is 18 the radiator hose collapsed with both of those new caps.

I replaced the top hose you called out in the diagram, and it didn t remedy the radiator hose collapse issue.

Also, the hose collapses with the radiator cap off, or so was told by the initial mechanic I took it to before trying to work out the issue myself. He performed that diagnostic test, not me personally.

I m still at a loss and don t want to start throwing money at new parts randomly. Thank you again for any insights you can offer.
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Thursday, July 7th, 2022 AT 1:56 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If it collapsed with the cap off, there had to be a blockage in the radiator. I never heard of this type of issue.

With the engine cold, remove the radiator cap. Start the engine and allow it to reach operating temperature (with the cap off). Turn it off and see if the hose still collapses.

Let me know.

Joe
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Thursday, July 7th, 2022 AT 3:11 PM
Tiny
DAVIDKRISS
  • MEMBER
Hi Joe,

It looks like the upper radiator hose is not collapsing upon cooling down with the radiator cap off. Is it possible that we ve gone through several new caps that are all defective? That strains the odds a bit doesn t it? Or no?
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Friday, July 8th, 2022 AT 1:48 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

I had a feeling it wouldn't collapse with the cap off. I'm not sure what the person was talking about.

And yes, the idea that you went through three caps, and they all do the same thing, it does strain the odds.

What is the lowest pressure cap you can get?

Joe
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Friday, July 8th, 2022 AT 7:59 PM
Tiny
DAVIDKRISS
  • MEMBER
Joe, the hose returns to normal shape when loosening the radiator cap upon cooling down, and you can hear a rush of air. I think somehow, I ve gotten a couple bad aftermarket caps.

It looks like I can get a 13psi, but I m concerned about overheating as the car runs a little hot as it is. I ve tried both 16 and 18 PSI, but they were AC Delco aftermarket. I m going to get an OEM cap and see if that works. The original was an 18 PSI.

My buddy repeated the test with the cap off last night and the coolant overflow bubbled over badly when he stepped away for a few minutes is there any chance air was introduced into the cooling system? I hope that didn t cause another headache.

Thanks again for all your insights.
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Saturday, July 9th, 2022 AT 12:37 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

No, you didn't hurt anything. Can you record the bubbling you see and upload it for me to take a look at? I'm questioning if you have an issue with a faulty head gasket.

Take a look through this link. In one section it talks about bubbling in the coolant because compressed air enters it via a faulty head gasket. Let me know if that appears the same as what you are seeing.

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know. Also, if the OEM cap makes no difference, let me know that as well.

Take care,

Joe
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Saturday, July 9th, 2022 AT 10:31 PM
Tiny
DAVIDKRISS
  • MEMBER
Will do, Joe. Just to clarify, the fluid wasn t bubbling, it straight up boiled over due to running the car too long without the cap to perform that radiator hose test you recommended. We did a block test for exhaust in the radiator fluid and that was clean, though we haven t conducted all the tests the link you provided outlines to detect a bad head gasket. Will keep you posted as we go through the steps. Really appreciate all your input.
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Sunday, July 10th, 2022 AT 2:41 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

You are very welcome. I look forward to hearing what you find.

Take care,

Joe
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Sunday, July 10th, 2022 AT 7:34 PM
Tiny
DAVIDKRISS
  • MEMBER
Joe, the OEM cap made no difference. I ve gone through 3 GM AC Delco caps and one of another brands. The upper radiator hose continues to collapse upon cool down and when I remove the cap, the hose relaxes and takes its original shape. The hose is the original hose, and the car has around 120,000 miles on it.

Your messages and what I ve read along with this test points to the cap, but all of these caps can t be bad. I m still at a complete loss and I m not sure what to do next. And as I mentioned, the block test for exhaust gasses in the fluid was negative.
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Thursday, July 14th, 2022 AT 1:40 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Something has to be preventing the air from entering the system or the hose is too soft, which doesn't make sense.

They make radiator hoses that have a large spring the length of the hose in them to prevent collapse. However, that was always for the bottom hose. I attached a pic below so you know what I'm talking about.

I don't know if you can get one like that for your vehicle, but I believe they make anti-collapse spring.

I am going to talk with the site owner and get his input.

Let me know if you can get one of these hoses.

Joe
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Thursday, July 14th, 2022 AT 7:19 PM
Tiny
DAVIDKRISS
  • MEMBER
The hose is pretty soft in general. Sort of spongy but not from deterioration. I m reluctant to put something on there that isn t factory to artificially keep it from collapsing. I don t know how hard or inflexible that upper hose was from the factory, but maybe I should check one out and compare.

Thanks for checking with the site owner. Will be curious about his thoughts and recommendations.
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Thursday, July 14th, 2022 AT 11:49 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I spoke with him. Like me, he can't think of anything other than the cap or maybe there is something plugged in the radiator.

Do me a favor, check a new one and compare the two and let me know your thoughts. Also, let me know if there are any other issues with the vehicle other than the hose.

Take care,

Joe
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Friday, July 15th, 2022 AT 9:22 PM
Tiny
DAVIDKRISS
  • MEMBER
I m going to check that out asap. I am also planning on replacing the valve cover gaskets as there is a bit of oil in the tubes and some smoke upon start up sometimes, so I think they re worn out. Sound reasons?
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Saturday, July 16th, 2022 AT 3:10 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

That sounds correct. They do start leaking. Let me know what you find and if I can help.

Take care,

Joe
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Saturday, July 16th, 2022 AT 5:06 PM
Tiny
DAVIDKRISS
  • MEMBER
Joe, the update is that the car runs much better after new plugs, wires, and valve cover gaskets. The molded vacuum tube that runs over the valve cover snapped as I was removing it, heat has made it brittle, so I repaired that with a piece of brass tubing and covered it in shrink tube. Since replacing the upper radiator hose, it has not collapsed upon cool down so I m wondering if it was a combination of a completely worn-out original hose (which had become spongy) and a possible air leak. I drove it extensively yesterday and put it through its paces and the only odd thing is that when I parked it, the idle wouldn t come down from 2k. I turned the motor off and restarted it and it idled normally so I m wondering if there is a small leak in on of the emissions vacuum hoses. It did not happen today, but I ll keep testing. Overall, I think we may have patched up the rough spots in this car for now if these repairs hold over the next week of testing, I ll take care of some of the lesser issues, air conditioning, and cosmetics.

Thanks for your help and suggestions along the way.
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Saturday, July 30th, 2022 AT 1:07 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Thank you for the update. I suspect the hose was worn out and allowing it to collapse. Now, you indicated the high rpm after the repairs. Did you have the battery disconnected when you worked on the vehicle? If you did and this was your first drive with it since reconnecting the battery, the computer may be going through a relearn. See if it starts acting normally after you put a few miles on it.

Again, thanks for the update. I'm glad it's running better.

Let me know if the idle issue stops.

Take care,

Joe
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Saturday, July 30th, 2022 AT 8:26 PM
Tiny
DAVIDKRISS
  • MEMBER
Hi Joe,

The engine idle seems to be normal now. Another issue has cropped up since doing the radiator flush, changing out the thermostat, and putting some fuel injector cleaner in one tank of gas. There is a white smoke that comes out of the exhaust - rather heavy at times, and not at all other times. It s intermittent, so I m wondering if it could be a bad ECTS. The car isn t overheating, the coolant level isn t dropping, nor is it creamy from oil contamination, and the oil isn t contaminated either. The upper radiator hose hasn t collapsed since it s replacement either. The white exhaust doesn t smell sweet like coolant, and the engine runs great since I replaced the plugs, wires, and valve cover gasket.

Any idea what would cause this intermittent white smoke? It smells bland - like regular exhaust, but maybe a little harder. Not sure if that makes sense. The main thing is it doesn t smell like coolant or oil. I appreciate your thoughts.
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Friday, August 5th, 2022 AT 10:47 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The only other thing than coolant would be condensation. Does it happen when the vehicle is first started? I'm not sure where you are located, but we have had so much humidity here that I see it from my truck when I first start it.

Let me know.

Joe
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Friday, August 5th, 2022 AT 5:55 PM
Tiny
DAVIDKRISS
  • MEMBER
Los Angeles it s been humid, but I think the volume of it intermittently is more than condensation. It s irregular, sometimes none, sometimes a lot. It absolutely does not smell like coolant or oil. Any chance it s the fuel injector cleaner I put in the gas from the last full tank? Thank you again so much for your insights.
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Friday, August 5th, 2022 AT 6:36 PM

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