Water pump? or Lower Radiator Hose?

Yesterday after dropping down Teton Pass I got the Coolant Level Low message on the DIC. hmm... Got home (5 miles later) with no high temperatures, and gave the expansion tank a good long drink - it took almost a half gallon to satisfy the D-Max's thirst. hmmm.
Today, after dropping down Teton Pass I got the same message. Ok, there's a problem. Got home again with no issue other than the message, and peeked under her skirt to see that there was orange cool aide everywhere on the driver's side. Immediately jumped to Water Pump Failure, and began to steel myself for the upcoming 9 hour project.

Tore into the easy stuff this evening (remove the radiator shroud, ECM/TCM, move the A/C compressor, and pull the lower splash shield) and got a close look at the weep hole on the pump. It appears clean. Stuffed a q-tip up the hole, and it came out clean and white, with the exception of a bit of black road grime. Hmmmm. The point at which the lower radiator hose clamps on to the pump inlet is a mess though. What're the odds I just need a new lower radiator hose?

I'm going to source a cooling system pressure tester tomorrow and see what that tells me, but what do y'all think given the above info and this pic that I'll try to upload in a moment?

https://drive.google.com/file/d/1GOl...ew?usp=sharing

There we go.
You can see the weep hole in the center, and I suspect that if it was indeed a bad seal my Q-tip would've come out of the hole with some orange on it. But it didn't.

Doesn't sound too complicated. Weep hole is dry, but lower coolant hose isn't. Go with your second suspicion. If it were leaking from the WP weep hole, it wouldn't not leak (or show signs of it) when you're looking at it. The black "grime" is a good indicator that coolant hasn't passed through there in a while, and that much coolant loss in a day is a lot. Time to replace the pressure cap, as well. You're probably getting out of this one easy. A pressure test is never a bad idea, in any case.

Concur with DMax. Lower Radiator Hose, clamps and Radiator Cap, done!
You are one lucky man!
Dave
PS. Let's not talk about the other nasty things it could be right now. I'd just go for the low hanging fruit and see if that takes care of it.

Any signs of black smudging inside the coolant surge tank?

Pressure testers. Saving shadetree mechanics from shotgunning parts since this morning.
There's a cooling line that runs under the turbo intercooler line on the driver's side that has a fair sized blowout in it. You can see a stream of coolant spewing forth in the pic attached. Now to dig down to it and find the replacement part...

https://drive.google.com/file/d/15_-...ew?usp=sharing

If anyone knows what the part is called, I'm all ears. I'll be searching my alldatadiy account.

A closer look makes me think I just need to replace a short chunk of small diameter heater hose. Crossing my fingers that this'll prove to be a cheap (!!!) repair.

Replaced the 5" piece of 3/8" heater hose that is the flexible part of the coolant return line from the turbocharger, put the cooling system back together, filled it up, and put the pressure tester on it. Pumped it to just under the cap pop pressure of 15#, and it seems like it's holding. Now it's lunchtime.:D

Rapid,
After reading about your experience with the Turbo coolant line hose I'm thinking a preventative maintenance action might be to change them on my 03 LB7 - one near the water pump and one at the turbo. It wouldn't be fun to have one fail when towing my 5th wheel on a hot day. And I might as well replace the other hoses too. Back in the day it was common practice to replace hoses periodically to prevent failures. I was curious why modern hoses seem to last much longer and found the following info in the following Consumer Reports Article.

https://www.consumerreports.org/car-...lts-and-hoses/

“Experts recommend, however, that all hoses be replaced at least every four years or when one fails. Always use replacement hoses designed to fight ECD. Trademarks will vary among hose manufacturers. (Gates uses "ECR" for Electro-Chemical Resistant). Look for a "Type EC" label on the hose or its packaging. That is a Society of Automotive Engineers standard signifying "electrochemical." Most vehicles built after 1993 come with ECD-resistant hoses.”

And here’s another link with more detail on ECD

http://www.highwaystars.net/blog/wha...radation-mean/

Anyone have thoughts on replacing hoses as a preventative maintenance action?

Quote:

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Originally Posted by jbplock

Anyone have thoughts on replacing hoses as a preventative maintenance action?

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Generally, it's heat that contributes most to a coolant hose deteriorating over time. The top radiator hose, for example, usually needs to be replaced about twice as often as the bottom hose. So, the trick is to locate the hoses that see the most heat, and change those more frequently.

Could be that the small coolant hose on the turbo sees more heat.

I know that GM went to using a blue silicone hose for the top heater core hose on the 6.5L diesel. That heater core hose lies close to the turbo exhaust housing and downpipe. Just maybe, there's a blue silicone hose available for that Duramax turbo coolant line...

Full disclosure:
During the head gasket replacement project I did on the truck a few years ago, I twisted the hell out of that turbo coolant return line that I just had to replace. I'm sure the stress that I put on it back then contributed to last week's issue. That said, the rubber was pretty soft when I took it out.