DMAX upper radiator hose collapsed

[mdrag]

I opened the hood before starting the truck today. The truck had not been started Monday through Friday, and was parked in the shop. Local temps have not been below 40 degrees at night.

The DMAX's upper radiator hose was significantly collapsed side to side. The coolant level in the overflow tank was showing a normal level. Squeezing the hose caused a slight clicking sound - probably the thermostat. I took the cap off the overflow tank - seemed like a slight vacuum, and the upper rad hose partially re-expanded, but not all the way. I did not have the digital camera at the time...

I've never added any coolant, and the oil level is normal. Fuel about 1/4 tank in the 56 gal Transfer Flow tank.

When I started the truck, it ran like crap - idle all over the place, and much louder - sounded like the pilot injection was off. The DMAX idle did not stabilize after about 30 - 45 seconds, so I shut it down and restarted - normal this time.

Last year I posted a similar occurrence with the upper hose collapsing (the truck ran normally). IIRC, it was about this time of the year with the weather getting colder. No real suggestions or similar events noted in the replies to that post. I tried a search but could not find that post.

This is only the second time that I have noticed this - but I normally don't open the hood before starting. I wanted to check the GREEN eyes on the batteries to see if there was any noticeable change with the StreamLight charger (trickle mode ~ 100ma) running for 5 days without a start -> both batteries had a large, bright GREEN eye.

Any ideas?

[SoMnDMAX]

Mittie, I wouldn't be too concerned about the hose collapsing. As a safegaurd, you could replace the pressure cap, since it doesn't seem to be venting the system properly from time to time. I've seen collapsed hoses on everything from my trucks to my snowmobile, and have never had any issues with it.

As for the rough running, who knows.. Maybe a bit of air in the system? The temp swings that caused the hose to collapse could have allowed some air into the fuel system (thru a line, the filter, etc..)... Just a guess.

[chevmeister]

Mdrag
Isnt the overflow tank supposed to be vented. Vacuum?? maybe your vent tube is clogged?

[FirstDiesel]

The cap on the DMax tank is not vented. It is not an overflow tank in the old style. It is pressurized like the radiator itself and there is no real overflow.

[mdrag]

Thanks for the replies, doesn't sound like anything to worry about.

mdrag

[HawgGuy]

FWIW - I noticed the same thing on my truck two weeks ago and chalked it up to the weather turnin' cold in west texas.
-bob

[SoMnDMAX]

First Diesel, the pressure tank cap is designed to vent when the pressure is right. It's supposed to let air in if necessary, and it'll release excessive pressure when necessary, just like a normal radiator cap.

[Wally]

I've had two trucks do this. One was a blazer with a 6.2 and it was caused by a leaking head that resealed when the block got cold. Changed caps, checked overflow hoses and it continued to do it until one morning I had a hydrolocked motor from coolant. Changed both head gaskets and it went away.
The second was my 93 with a 6.5 and it was caused by a plugged overflow line to the expansion tank. This one also had a passenger side head that would bubble coolant out the side when the block was hot. Unplugging the overflow line stopped it and I did tell the person that bought it about the leaking head.

[mdrag]

Wally,

In your trucks that did this, was it an every day occurance? Were you adding coolant? I've not had to add any coolant yet.

mdrag

[mackin]

mdrag

I have mentioned my upper hose also collapses ......As I type I haven't driven mine in two days I checked the erl this mourning, yes it's collapsed.....I have never added or lost a drop of coolant....If you ask me it's outside temp related..If you were to poll a crowd numbers would show it's a normal thing i would believe as I've seen gasser do the same thing,tiss the reason the started putting wire in them,for stability.....No??? Since you are the gadget man,this company sells a do it your self kit...
=>http://www.eastwoodcompany.com/ To check for Gases in coolant if your concerned.....It is item number 46134 I have their catalog type it in search ..... They sell quite alot of good stuff......To finding coolant and oil leaks to buffing aluminum wheels, to much to mention......Check it out if your not familiar with the company.....Let me know how you make out......

MAC

On edit; Great prices the above mentioned is under 50 bucks........
Everyone should check it out from grease zerk covers to testing equipment......A whole smorgish board ......

[ 11-03-2002: Message edited by: mackin ]</p>

[Turbo Al]

Well you got me curious, trucks been sitting 2 days, below freezing both days, opened hood and hose is fine BUT it's "Made in Brazil" hummm. I does make a clicking sound when squeezed.
Turbo Al

[Kennedy]

Just like a fuel cap, the radiator (surge tank in this case) cap is designed to maintain a limited amount of pressure OR vacuum in the system.

[Wally]

Mdrag, I did have to add coolant but very little and it was dependant on how much they were driven. The 6.2 needed coolant about once a month until it failed completly. (driven daily). The 6.5 needed about a quart added about every six months,(driven weekends only). If I ran the 6.5 hard as in towing or hauling the water tank it would need a quart of coolant about every thousand miles. On both vehicles the collapsing hose got much worse when the weather was cool.
How sucked in is it? Do the opposite sides touch each other? Both of the vehicles mentioned previously would pull the hose completely shut. Open the rad cap and it would re-expand.
I definately think you should check for combustion gasses in the coolant. I've never seen either one of my Dmaxes do this.

[BigO]

A collapsed hose can show a sign of a faulty cooling system if it occurs when your motor is running. Be sure to check it after the engine has warmed up to proper temps and with motor running. If your hose is collapsed then you have a problem somewhere.

If it really bothers you, you could insert a radiator hose spring in it and that would eliminate your situation.