http://www.cssevents.com/Flathose2.jpg
http://www.cssevents.com/Flathose1.jpg

Pressure hose? normal as I recall. BUT
do you think it's related to heating issues?

I have never in 30 plus years of looking under hoods of dozens of vehicles, tractors, etc. seen a collapes hose like that. You may call it tight system, I call it weak rubber.
Or, this is the first tight system I have ever seen and all other systems I have looked have been loose?
And if it's a week hose, is it possible when it gets up to highway speed it's being sucked in and restrickting the flow? I don't know.

http://wheels.coxohio.com/wl/Content.jsp?page=content/straighttalk/straight052805.htm

I have never in 30 plus years of looking under hoods of dozens of vehicles, tractors, etc. seen a collapes hose like that. You may call it tight system, I call it weak rubber.
Or, this is the first tight system I have ever seen and all other systems I have looked have been loose?
And if it's a week hose, is it possible when it gets up to highway speed it's being sucked in and restrickting the flow? I don't know.

The bottom hose is the suction side of the water pump. When at operating temp, the upper hose would by nature have a considerable amount of pressure in it when the thermostat is open. No doubt the hose is weak though. I can't really see the upper hose collapsing during operation at full temp. But the lower hose is another story. If it is weak,that's where it would/could collapse.

Mike

Mike

You need a new cap on the surge tank. Then your hoses will remain round.

Jim

You need a new cap on the surge tank. Then your hoses will remain round.

Jim
WINNER!

The radiator cap or recovery/surge tank caps act as a two way valve. When the coolant is warming up it expands and puts the cooling system under pressure. When this pressure reaches a predermind amount, usually 11-15ish psi., the cap will vent coolant to the recovery tank to keep the system within this amount. As the coolant cools down, like turning the engine off, it will contract. The other part of the cap should allow the released coolant back into the radiator via suction. Your cap is not allowing this coolant back in and is putting the system under a vaccum, pulling the hoses flat! Make sense?...

WINNER!

The radiator cap or recovery/surge tank caps act as a two way valve. When the coolant is warming up it expands and puts the cooling system under pressure. When this pressure reaches a predermind amount, usually 11-15ish psi., the cap will vent coolant to the recovery tank to keep the system within this amount. As the coolant cools down, like turning the engine off, it will contract. The other part of the cap should allow the released coolant back into the radiator via suction. Your cap is not allowing this coolant back in and is putting the system under a vaccum, pulling the hoses flat! Make sense?...

.:exactly: :exactly: :exactly:

good to know. Can it be a (heating) problem? That's my only question.

If that happened to your top hose, it is also the same at the bottom I think, unless they build the bottom hose intentionally stiffer.

Mines flat in the morning. Checked the bottom and its not.

Is there a new/improved cap part# out there???

.:exactly: :exactly: :exactly:


THAT IS THE PROBLEM! Get a new cap and problem is gone. I played with the valve in the cap a couple times and worked for a day or two, got a new cap and haven't seen the problem for 2 months now.

WINNER!

The radiator cap or recovery/surge tank caps act as a two way valve. When the coolant is warming up it expands and puts the cooling system under pressure. When this pressure reaches a predermind amount, usually 11-15ish psi., the cap will vent coolant to the recovery tank to keep the system within this amount. As the coolant cools down, like turning the engine off, it will contract. The other part of the cap should allow the released coolant back into the radiator via suction. Your cap is not allowing this coolant back in and is putting the system under a vaccum, pulling the hoses flat! Make sense?...

applies to my last quote.........

The QUALITY of the generals parts has not been up to par for some time ,either the sould make the vendors hold to spec or change the spec. with the cost of an engine what it is ,$.25 on a better hose just might make more repeat customers.I'm a 55 year old man and I can remember when " THE GENERAL" was king .they were the best in the world .if they want market share they know what to do ,and the better do it right now or it might be too late . my dad after 45 years of buying GM products bought a ford .his 2003 Cadillac Deville was such a POS he jumped ship and went to the dark side . :rant:

IRA51, go away, ALL manufactures have had ISSUES, PROBLEMS, All i do is fix trucks, for over 30 years, I am 55,a (grey hair) 99.9% of all duramaxes the upper hose is collapsed cold. The surge tank is above the radiator. This is normal

jg, how would the surge tank being above the rad decrease pressure in the rad? If the surge tank is above the rad, the relative pressure should be higher in the surge tank allowing coolant to flow easier from the tank to the rad. I agree with the bad cap diagnosis.

Cooling contraction.. Engine is off right?

I think it's common. I remember this from way back.

Cooling contraction.. Engine is off right?

I think it's common. I remember this from way back.

IRA51, go away, ALL manufactures have had ISSUES, PROBLEMS, All i do is fix trucks, for over 30 years, I am 55,a (grey hair) 99.9% of all duramaxes the upper hose is collapsed cold. The surge tank is above the radiator. This is normal


NO! It is not normal. Faulty radiator/surge cap OR restricted overflow tube. PERIOD.

Like I said earlier, Put on a new one, solved. Spend the $11.00 and see...:grd:

NO! It is not normal. Faulty radiator/surge cap OR restricted overflow tube. PERIOD.

Like I said earlier, Put on a new one, solved. Spend the $11.00 and see...:grd:

Your right! The coolant can not siphon back to the rad. (when cool) if there's a vacuum above it. The cap would have to vent.

Mike

If that happened to your top hose, it is also the same at the bottom I think, unless they build the bottom hose intentionally stiffer.

the bottom hose *normaly* has a wire coil in it to prevent it from colapsing from the water pump suction durring normal operation

IRA51, go away, ALL manufactures have had ISSUES, PROBLEMS, All i do is fix trucks, for over 30 years, I am 55,a (grey hair) 99.9% of all duramaxes the upper hose is collapsed cold. The surge tank is above the radiator. This is normal

JGREENLESS ,6 OUT OF THE LAST 10 UPPER HOSES (on Dmaxs)I HAVE SEEN THIS MONTH ARE NOT FLAT IN THE MORNING COLD . AND I AND MANY MORE WILL GO AWAY IF THE GENERAL WON'T IMPROVE QUALITY AND STOP CUTTING CORNERS. WOULD YOU STAY WITH A WIFE THAT CHEATS ON YOU ?THEY CAN DO BETTER AND WE AS CUSTOMERS DESERVE BETTER .

Get that rad cap replaced. You will end up with air pockets in your cooling system. cant automatically refill itself from tank. flat hose is vacuum. Air pocket cause bad things

It is a by-product of the truck getting too hot. We covered this in detail last year in the over heating thread, I was able to duplicate it on my truck. It is the leftover remains of the coolant moving into the surge tank when the truck gets hot and then when the system later relaxes and coolant returns to the system the hose itself does not have "spring" enough to raise enough vacuum to overcome the check in the surge cap so it stays flat. You lose the volume of the hose to the surge tank.

Even a properly functioning cap will allow this to happen, it is the getting hot part causing coolant to move into the surge tank in the first place that is the root cause.

One problem, when you take it to the dealer who is the "blocker" for GM , anything you take it in for is "NORMAL" Friday, even though my tranny, and water went to RED, Service Manager comes back with all system normal, or they could not duplicate problem by taking it on a 4 mile test ride. Even though all the problems are at highway speeds under load, and or climbing hills.
Of course this is from the same dealer who when I took it in for a LOB, which means Lube, and every zerk is bone dry with road grime on it, proof it wasn't touched, or with 2 extra quarts of oil in it, an inch and a half over the full mark.
Guess who's problem this is, when the linkage goes bad from no grease after the warranty is up, or too much oil which may cause leaks as the extra oil is forced past seals and gaskets. That's right MY problem.
Good point, I think the rubber is deteriorating due to it being subjected to HIGH temps, which weaken the rubber, but then I'm not a scientist or rubber expert.

I think the rubber is deteriorating due to it being subjected to HIGH temps, which weaken the rubber, but then I'm not a scientist or rubber expert.

You may want to slow down. Is it safe to say then, that there are children in your future?

One problem, when you take it to the dealer who is the "blocker" for GM , anything you take it in for is "NORMAL" Friday, even though my tranny, and water went to RED, Service Manager comes back with all system normal, or they could not duplicate problem by taking it on a 4 mile test ride. Even though all the problems are at highway speeds under load, and or climbing hills.
Of course this is from the same dealer who when I took it in for a LOB, which means Lube, and every zerk is bone dry with road grime on it, proof it wasn't touched, or with 2 extra quarts of oil in it, an inch and a half over the full mark.
Guess who's problem this is, when the linkage goes bad from no grease after the warranty is up, or too much oil which may cause leaks as the extra oil is forced past seals and gaskets. That's right MY problem.
Good point, I think the rubber is deteriorating due to it being subjected to HIGH temps, which weaken the rubber, but then I'm not a scientist or rubber expert.

Nah, not the rubber deteriorating, although that is a good idea as well. The hose simply is just nice and pliable and its walls don't have the strength to pull more vacuum than the surge cap requires.

Here is the link where we went over the flat hose thing:

http://www.dieselplace.com/forum/showthread.php?t=14625&page=19

.

It is a by-product of the truck getting too hot. We covered this in detail last year in the over heating thread, I was able to duplicate it on my truck. It is the leftover remains of the coolant moving into the surge tank when the truck gets hot and then when the system later relaxes and coolant returns to the system the hose itself does not have "spring" enough to raise enough vacuum to overcome the check in the surge cap so it stays flat. You lose the volume of the hose to the surge tank.

Even a properly functioning cap will allow this to happen, it is the getting hot part causing coolant to move into the surge tank in the first place that is the root cause.

In other words... move on... non issue.

Exactly. It doesn't look good, but its a non issue. Its an indication that your truck is moving maybe more coolant to the surge tank than you might like, indicates its getting hotter than you might like, but otherwise......non issue.

The link I posted will show you and explain what causes it, and how to duplicate it on your own truck as I did.

.