Weird Rad Hose

[CoachWagner]

I was towing my RV trailer and atv's a couple of weekends ago and it started to heat up real bad going up a long grade. Outside temp was cool and it was evening. I have an 03 dmax and it brought back bad memories of my 95 6.5. Well once I got up the grade it came back down and I thought it was really odd since I have towed this load before with no issue at all.

Next morning I opened the hood to take a peek and noticed the upper rad hose completely collapsed together. The coolant was a little low so I drove to the closest town to see how it would do. I checked the hose again and it returned to normal ( although now it had warmed up) I added some coolant (not much though).

Once I got it home (no overheating on the way home) I changed to thermostats and bled the system. Next morning the hose was collapsed again. It seems to run slightly warmer than usual but I haven't towed with it since.

Is it normal for the hose to collapse like that when cold?

[Mark Rinker]

Add some specs for your '03 in your signature line to help us out. How many miles on it? How hot did it get? Were you using tow/haul the entire pull? Did the fan clutch engage properly during the overheating?

Sounds like the radiator hose collapses when cool. Personally, I have not seen that happening with the two LB7s I have owned. Not sure what this might indicate - a new overflow jug cap might be in order - at least a cheap part to throw at the mystery.

Could your waterpump be on the way out? They don't always leak visibly - but coolant had to go somewhere mine both went at ~150K.

[CoachWagner]

Just under 130,000 km. It got to the point where the engine coolant warning signal came on. I think I will try the new cap as well. No coolant was lost, I just thought I would top it up just in case. It seems to me the level has been the same for a year since I bought it.

[killerbee]

The cap is not working correctly. There is a feature of the cap that is suppose to vent when the system is under suction, as in what happens on cool down, and other times when operating. It results in trapped gas, essentially crippling an essential function of the degas bottle. Autozone sells one that seems to work better.

MORE INFORMATION (http://members.cox.net/beekiller/GMC%20Light%20Duty/The%20Degas%20Demystified.doc)

[Mark Rinker]

Yeah - what he said! :) I guess my 'throw parts at it' strategy would have paid off in this case! (Hey, parts are way cheaper than labor many times these days.)

I need to find where 'my cap' is located, I seem to have trapped gas and am de-gassing alot lately - it has my wife annoyed.

[CoachWagner]

And that is why I LOVE this forum. Thanks Killerbee!

I suspect this problem to have started about 2 to 3 weeks ago. Should I replace the upper rad hose (integrity compromised?) as well or just the cap? I will also follow the advise of topping up the coolant until all "air" seems to have escaped.

[killerbee]

just the cap. But sometimes the hoses become compliant, but a good cap should purge still.

[NutNbutGMC]

just the cap. But sometimes the hoses become compliant, but a good cap should purge still.Is this you SkinnyBlinky?

[Kennedy]

The cap is not working correctly. There is a feature of the cap that is suppose to vent when the system is under suction, as in what happens on cool down, and other times when operating. It results in trapped gas, essentially crippling an essential function of the degas bottle. Autozone sells one that seems to work better.

MORE INFORMATION (http://members.cox.net/beekiller/GMC%20Light%20Duty/The%20Degas%20Demystified.doc)


What happened is the system apparently "burped" and when it cooled the cap did not allow air back into the tank. As soon as the engine warms up the hose will expand and the system will have pressure. That or if you open the cap and let the pressure equalize. Replacement at this point is optional and you will NOT see a significant change in cooling system performance. Use the STOCK GM AC-Delco cap.

This situation has no significant impact on the performance of the cooling system.

[CoachWagner]

Replaced cap and no collapsed hose this morning.

Thanks guys.

[killerbee]

What is a skinny blinky?

[killerbee]

Replaced cap and no collapsed hose this morning.

Thanks guys.

I am interested in knowing if this seems to have an effect on your cooling system performance.

[CoachWagner]

I haven't towed with it yet but casual driving seems to be normal temps just below the 100 degree Celsius mark (not sure what that is on the US trucks but it is the middle hash mark on the gauge) with warm (30 Celsius) outside temps and AC on full.

[Kennedy]

I wouldn't expect any significant change.