: Flattened radiator hose



Kauai 1
01-25-07, 08:48 PM
After my '04 N* sits overnight, and is cold, the lower radiator hose is flat. In other words, as the coolant temperature lowers, a vacuum develops in the cooling system, and the hose is "sucked" flat. If the pressure cap is loosened, air is sucked in and the hose regains its shape. (The cap itself does not allow air to be sucked in.) Or, if you warm up the engine, pressure builds and the hose "shapes up".
I am told by the dealer that this is normal. However, it seems to me that the hose will break down faster with daily flexing/reshaping.
Any comments; eWill3rd, is this really "normal"?!
Thanks.

c5 rv
01-25-07, 08:57 PM
I wonder how many of us went out to the garage and looked? Both my hoses are normal. Then again, I've been driving my AWD truck and my SRX has been parked since Sunday.

donjumpsuit
01-26-07, 02:25 PM
I doubt this is correct.

If I can give a scientific explaination, your ratio of coolant to water is wrong, having more water in your Radiator, causes the liquid to turn into a gas, expanding in the system, when your system cools, the steam returns to water, reducing the pressure in the system. I would try adding straight coolant all the way up to the fill line. get the orange stuff

john d
01-26-07, 05:10 PM
Many radiator hoses have a widely wound metal coil (like a streched slinky) in the lower hose to prevent it from collapsing during cool down. Seems the upper hose is often made with stiffer walls than the lower or also has an internal spring.
I'd suspect the pressure cap is not allowing the coolant displaced to the reservoir during warm up to be syphoned back during cool down.

Kauai 1
01-26-07, 07:58 PM
Thanks for your replies.
The coolant has had no water added since I took delivery of the vehicle, new. It is still the orange Dex-Cool color. It is filled to the proper mark when cold. I will check the percentage concentration.
I looked at an '05 V-8 when it was cold, and the bottom hose was also flat.
I have now spoken to 2 dealers who both say this is normal. I was told that the pressure cap does not allow displaced air and/or fluid to syphoned back during cool-down.
If other SRX owners would check their cold engines, with flashlights, for the flattened hose syndrome, I would greatly appreciate it.
And, if eWill3rd reads this......please check cold N*'s at your dealership.
Thanks for all of your assistance!!!

wifescaddy
01-27-07, 08:10 AM
My v-6 does it also,ive had my car completely apart new radiator etc...,thought maybe it was air in the system also.It took me 3-4 driving cycles each time coming back loosening the cap and watching the level in the overflow go down,add seommore drive it again ,each time i came back the lower hose was flat,take cap back off went back to normal.After the 4th time it stopped doing it and level is fine now.Hasnt collapsed since but also havent had it out for long drive yet either.

ewill3rd
01-27-07, 09:20 AM
The vent is stuck in the radiator cap.
It maintains system pressure when the engine runs and the coolant expands to help control the boiling point, but as the coolant cools off at night and the fluid contracts the cap should allow atmospheric air to enter the cooling system to prevent this condition.
The radiator/coolant tank cap needs to be replaced.

It doesn't really hurt the hoses, but it is not helping anything.
If they won't do it under warranty just go buy one.
The service manual test for the cap only tests for it's ability to hold positive pressure, not negative pressure.
They must not understand the cap's job.

Kauai 1
01-27-07, 01:42 PM
Thanks, ewill3rd. What you report is what I thought, and discussed with two dealers' service departments. I am finding more and more that the dealers do not understand these cars, and that I have to bring in TSB's, etc., and "educate" them. Takes numerous trips to solve minor problems. And, an owner is not allowed to talk with the GM tech support guys to explain more complex issues. Not good for the owner, and not good for Cadillac!
I will purchase a new cap on my own, then give the dealers H...!
Thank again to all who answered.

ewill3rd
01-27-07, 09:58 PM
Just for informational purposes, they did used to put springs in the radiator hoses, but from my understanding it was on the suction side of the water pump. Their function was to keep the hose from sucking shut, particularly under high rpm from the water pump moving such a large volume of coolant.

I rarely see these springs in use anymore, at least not on modern cars.

I am confident that your cap is either bad or clogged.
I am not really fond of the design of the caps they use on these reservoirs these days. They are hard to get on and off really.

Good luck.

robhersch
01-28-07, 01:46 PM
I have no way to test my radiator caps, but after reading this thread I checked both my 2005 SRX N*V8 (all original) and my 1999 DeVille Concours (all original except for replacing the orange coolent and thermostat ~ 3 yrs ago); I find no flattening of any coolent hoses.

King3244
01-30-07, 02:31 PM
The spring, if present, is put in at the factory for one reason and one reason only and that is because they suck the air out allowing for a faster fill on the production line.

Hydraulics 101......you cannot suck a liquid.......you must push it!

As to the water pump creating a vacuum.......wont happen as it is not a positive displacement pump and is therefore unable to create a vacuum no matter how fast you spin it.

I go with the faulty rad cap.

n7don_srx
01-31-07, 08:00 AM
I am not really fond of the design of the caps they use on these reservoirs these days. They are hard to get on and off really.

I coated the cap threads on my '03 Envoy with teflon pipe thread sealer. It had become harder than h... to get off. Drastically reduced the effort to get the cap off and it's worked for over a year. This is the stuff you brush on but teflon tape will also work per a friend who used on his TB.

Kauai 1
02-03-07, 12:24 PM
I purchased a new pressure cap ($12.49 + tax) at the local Cad dealership, put it on the surge tank, and............NO MORE FLATTENED HOSE! I checked it the past five mornings, including leaving the car outside in the cold, and it is perfect.
I suggest that anyone with the "flat radiator hose syndrome" replace theirs. It should be a warranty item, but if the dealer considers the problem "normal," it would be a fight. I wonder if GM knows that the caps are lousy?
Thanks again to ewill3rd and others who responded.

ewill3rd
02-03-07, 02:58 PM
Kauai, thanks for posting that you got it fixed.
I don't know if I would say they are "lousy" but I am definitely not in love with them.
The real problem in installing and removing the cap is the O ring that goes down inside the neck of the jug. It makes it hard to get the threads started on the upper part of the cap and it makes it hard to turn when removing the cap.

The problem with them not replacing the cap for you is the fault of the techs. They really don't train us on radiator caps and you sort of have to know how they work to know when they are broken. Most guys are too lazy to even care about how they work.

At any rate, I am glad it is fixed. The cooling system will work more effectively with a properly functioning cap.

john d
02-08-07, 11:48 PM
Kauai, thanks for posting that you got it fixed.
I don't know if I would say they are "lousy" but I am definitely not in love with them.
The real problem in installing and removing the cap is the O ring that goes down inside the neck of the jug. It makes it hard to get the threads started on the upper part of the cap and it makes it hard to turn when removing the cap.

The problem with them not replacing the cap for you is the fault of the techs. They really don't train us on radiator caps and you sort of have to know how they work to know when they are broken. Most guys are too lazy to even care about how they work.

At any rate, I am glad it is fixed. The cooling system will work more effectively with a properly functioning cap.
ewill3rd - what is the cause of this failure and is there a way to fix the cap when there is this problem?

ewill3rd
02-09-07, 09:05 PM
John,

If you mean the problem that causes the hoses to collapse, it is just a problem with the vent that allows the system to maintain pressure when the engine is running and allow air to re-enter the system when the system begins to build negative pressure due to the contraction of the fluid as it cools. The only real fix is to replace the cap.
They usually don't cost enough to warrant trying to repair them and they are not really made to come apart anyway.
It is quicker, easier, and not really too expensive just to replace the cap.

john d
02-14-07, 02:30 PM
Kauai 1 - Thanks for bringing this issue to our forum. It seems that over time as the hose gets brittle that the constant flexing would cause a rupture sooner than later.
I thnk i found a fix using a paper clip.
In the underside center of the cap you can see a shiny disc smaller than a dime. It's the one-way diaphram valve that is held closed against it's seat when the system is pressurized. It's designed to open under suction of depressurization as the cooling system loses it's heat and allow air that was displaced during warm-up to back into the cooling system. If it doesn't "breathe" then then the hoses under negitive pressure collaspe as ewill3rd has described.
Taking the unbent paper clip I wedged the clip between the edge of the diaphram and the plastic wall of caps valve seat and lifted the diaphram with a upward pulling motion. There was a "breaking" of the seal sound like when a medicine bottle cap is first removed.
Result: no more collasped hose on cool down!
I'd guess we need to check for a sticky release diaphram ever so often as it shouldn't have stuck in the first place.
Probably another design or sticky coolant issue.