I was curious if anyone had been in this situation or has any knowledge. 2005 3500 express 6.0 V8 with 90k miles. I noticed the coolant was low and had been leaking a little. The other day, as I pulled into the parking lot, it lost all of its coolant at once. Drain plug, water pump? Any ideas? I'm just trying to get a feel for what it'll cost when I have it towed to the dealer. Thanks in advance!

 

I doubt that you could lose your coolant from the water pump. If the pump is bad it will drip for a while then finally seize. If you blew a hose you should know it. If your head gasket is gone, you will force the coolant out with engine compression.
I would pressure test the system. You can buy a tester, but since you are having it towed, you may as well have them do that.
When you pulled into the lot and it lost its coolant was the engine running or did it happen after you shut it off?

 

Thanks for the response. When I pulled into the parking spot, it was still running. I noticed only because it beeped, check gauge was lit up and I saw the temp was in the red. I shut it off imidiatelt.

It still starts a drives (had to drive it up my steep driveway as the tow truck didn't want to go up there) and has no issues running. Obviously, I don't run it more than a minute or so.

I had noticed it was low on coolant (there were drips where it was parked) and I was actually at the parts store getting some dex cool when this happened. Something completely gave out in the lot and all the coolant was under the van.

 

Well. I guess go for the obvious first. Check all your hoses. They are the weak spot. If one blew, then you would lose it all because after stopping the engine you lose the cooling effect of the coolant being circulated. It would all flow out the hole.
Don't run the van at all without coolant....you don't know how much is in the block, and you will seize it or vastly shorten its life.
Fill up the rad with water...and see if you can find a leak.

 

I filled it up with about 2 gallons of distilled water the other day. Nothing came out even when I started it.

And about running it without coolant, I was told by many this is ok if you just have it on for about a minute, because there's no way it's close to being warm. I'm obviously not using it, but I was planning on driving it onto the back of the tow truck.

 

I had a similar problem in my 1997 1500 5.7 van. The coolant would be there for a while then for no reason seem to just drain away. Traced the problem to weeping core plugs at the rear of the block. The garage refilled the coolant and added some industrial grade rad-weld and it seems to have stopped the leak (running now for 6 months without any further leaks). A cheap solution worth trying before any more expensive rebuild work

 

Buy the looks of the picture its the water pump. And yes a water pump well usually start off with a small drip then give way. Once it cools down it will seal up enough to...maybe hold water. Once it heats back up the bearing will give way and start leaking water again. If it was a hose you would see it spraying all over the place.

 

my water pump started to leak at about 125k miles. i got home after 2 hours on the road parked the van in the driveway. went back out 20 minutes later and noticed a large amount of coolant under the van. i took a look with a flashlight from under and on top and suspected the water pump. i gave the pulley a wiggle and there was a ton of play too. changed it out and ive been good since.