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Coolant system leak - what would you do?

What would you Do? 185,000 miles 2003 Z-71 leaking antifreeze - pretty sure it's the radiator

  • Replace just the radiator (yeah, probably not this one)

    Votes: 0 0.0%
  • Replace the radiator and all hoses

    Votes: 1 33.3%
  • Full system refresh - radiator, hoses, water pump and thermostat

    Votes: 2 66.7%
  • Other - please explain

    Votes: 0 0.0%

  • Total voters
    3

frito

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Ok, so Bumblebee has thrown a low coolant level warning a couple times this year. For the time being, since I'm not really going anywhere, I just top off the reservoir. It hasn't been dry, just a bit low. Tonight I think I figured out the source is the radiator. I could smell anti-freeze taking the dogs to the park and when I got home I checked it out while it was running. The brace for the radiator was a bit wet with antifreeze and the hoses seemed dry. Before I popped the hood I was expecting it to be the water pump but that looked dry.

It's a 2003, Z71 with 185,000 miles on it. I bought it with 109,000 six years ago and don't know it's prior service history. I've done no coolant system maintenance since I've owned it. I figure I should at least replace all the hoses, including to the heater core, while I'm doing the job. My question is whether I should proactively replace the water pump and thermostat since I don't know if they are original or replacements. All I know is that they have at least 76,000 miles on.

My tendency is to replace things that make sense "While I'm in there" so I don't have to mess around with it later. So my pool is, what you do?
 
Trying not to think about it. Let's just say an extra $300 over a radiator and coolant lines, while an unpleasant thought, won't kill me - especially if I'm going to end up going in there again within the next year.

So, I guess let's not say unlimited budget, but what makes sense.

To put it in perspective, when I had to replace the vanos and thermostat housing on my Bimmer I went hog wild. I replaced the entire cooling system except the radiator since it had been replaced. I upgraded the water pump "while I was in there" from a $25 OEM with plastic impeller not to it's $50 metal impeller counterpart but to a Stewart high flow lifetime warranty pump for $200. I also did a bunch of other stuff. That all made sense since a bunch of stuff had to come off for some of the repairs - kind of like replacing knock sensors on out our trucks if we have to yank the intake for any reason. Of course, my total cost was still about the same as the dealership cost for far less work.

So, budget aside I want to do what makes the most sense now so I don't have to futz with it in the near future.
 
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If it was me...
The minimum job you have to do it replace radiator...

I would look at any part I have to remove to get the radiator out; and I would probably go back with new.

But anything else I would leave as is, since extra cost and work.
Plus mine is not my daily driver anymore so I could afford to be without it for days..

NOW if you are BORED and have time and money to spend and/or this rig is you daily driver:
Then I would be thinking hard about R&R (Remove & Replace) all the coolant items that could need replacing...

PS check coolant cap too as they do not last forever and one that relieves to low pressure compromises engine cooling big time.
 
Before I did anything, I would toss a radiator pressure tester on the cold engine and pump it up to 15 PSI.

I tend to replace a lot of stuff when I do repairs, especially if the age and condition of parts is unknown.

I have already replaced the water pump, thermostat, all hoses including both heater hoses, surge tank and cap, belts, idler pulleys and tensioners on the 2003 Z-66.

This project started because I had a leak at the water pump and a radiator hose and I wasn't sure of the condition of all of the other parts.

Just a couple of days ago I spotted some coolant on the ground where I park the truck.

I put my pressure tester back on and found the upper radiator hose at the radiator was leaking.

I retightened the hose clamp and the leak stopped.

I'll be looking for a better clamp.

As you recall, my search for and repairing several coolant leaks in the EXT lead me to the crack in the driver's head which has sidelined that truck for the foreseeable future.

After using the pressure tester to find and fix every visible coolant leak, I found I was still losing coolant and it was finally determined that last leak was through the crack in the head.

I certainly hope your experience is much better than mine was on that truck.
 
Thanks guys.

@ygmn It's a hybrid as far as use. It is a daily driver in the winter. And a lot of it's other use is on longer hauls - destination 200+ miles away (camping, moving kids from co-op job and back, etc). Last thing I want is for a ruined vacation or to break down moving a kid. Now that I think of it, my fuel pump blew as I was pulling out from my daughter's apartment when we move her home from (thankfully local) school. Looked like the Beverly Hillbillies on the back of the flatbed. ??

@EXT4ME Your issues on the EXT are what prompted me to ask the question and post the poll. The pressure tester route was crossing my mind as I was driving home but when I popped the hood and found the wet spots it became pretty obvious. The whole time I was driving your nightmare ran through my mind. So while I'm not thrilled about a radiator, It's far better than the alternative. ?
 
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If it were me, I would replace all hoses, thermostat, and radiator. You’ll have it all apart anyway, so might as well install new stuff.
 
Frito, how have you been? I hope 2020 hasn't been too much of a disaster for you.
On these trucks, first place I look is the heater hose connectors that attach the hoses to the heater core.
As you probably already are aware, it's a plastic piece of junk, and a very common failure point.
GM really dropped the ball when they conceived the idea of a quick connect heater hose. Just stupid.
A quick look on RockAuto reveals that GM, Ford, and Chrysler have used this idea since around the 1970s.
Planned obsolescence for a long time, folks.
Anyway, either replace them, or throw them in the trash and connect heater hoses directly to heater core without the worthless plastic bit that could potentially cause someone to lose an engine.
My road side repair is still holding to this day.
No need to spend $25 for a piece of plastic that's worth a nickel.
Take care and long live the Avalanche :cool:

CarMech1969
 
Doing well @CarMech1969 hope you are too. Yeah, Mad Dog 2020 was named that for a reason. ?

I'm definitely doing the heater lines after seeing what you and @EXT4ME went through. Probably every line since they are all at least six years old and probably older. I see fluid on the radiator support and nothing up top. I've concluded it's either the radiator itself or the lower radiator hose where it meets the radiator. I see ample rust at the connections so Im pretty sure it's the radiator. Even if it's just a hose, the way my repairs go is that the radiator will spring a leak if all I do is the hoses.

So, I'm doing radiator and all pipes/hoses. Might as well do the thermostat since it's cheap. I'm pretty sure the main belt tensioner is on its way out so I'll do that to. Just don't know about preemptively doing the water pump and calling it a day.
 
On second thought. (Or 3rd or 4th ?) After reading your OP again, with the unknown service records before you owned it, and the age, for the $$$, I would do up the water pump as well.

Just having that “piece of mind” would be enough of a reason for me. :cheers:
 
I think I'm going to skip the water pump for now. If I did the water pump I of course would want to do the thermostat and housing - no big deal. But I would also want to do the fan clutch. I think I want to go with electric fans so replacing the clutch doesn't make sense at this time. I love how easy my Bimmer with electric fans is to work on, the extra room you get with the electric fans and less amount of drag on the engine. If my Bimmer was on the road (long story) right now, I'd do the switch to electric fans now but I need to make this a one day job to keep it on the road.

I don't which would be less overall hassle - replacing the water pump now and moving the existing fan & clutch to it just to remove it when I do install electric fans or replace the water pump & thermostat when I switch to the electric fan. The former would give me peace of mind - I just don't want to deal with that fan clutch.
 
Electric fans sounds like a good idea
 
Did everything except the electric fan - water pump, radiator, all hoses and pipes including the crossover pipe. I even got a new reservoir figuring the plastic was bound to snap when I remove the hoses. Boy was that ever a mistake. The plastic didn't snap but the bleeping bolt that secures the reservoir did. To top it off, it looks like it's one of those boots that's somehow welded to the body so I'm SOL. Here are a few pictures. Any ideas as to what I can do?

PXL_20201115_222224921.NIGHT.jpg

PXL_20201115_221653920.NIGHT.jpgPXL_20201115_221637490.NIGHT.jpg
I was also going to forgo the blasted quick connects but the hose isn't big enough to fit over retainer sort of thing so I need to get those tomorrow. Oh, and as my projects typically go, I ordered an assortment of hose clamps in multiple sizes. Of course, none are big enough for lower radiator hose so I need to also get those tomorrow.
 
Sucks about the bolt. Is there room to put a nut 1/2 way on the remaining part and then 1/2 on a new bolt section and still have the reservoir attach/sit properly? Or maybe add a full new bolt coming through the fender well?

Just some off-the-cuff ideas without going outside in the rain at night to look at mine and how it is fixated.
 
Sucks about the bolt. Is there room to put a nut 1/2 way on the remaining part and then 1/2 on a new bolt section and still have the reservoir attach/sit properly? Or maybe add a full new bolt coming through the fender well?

Just some off-the-cuff ideas without going outside in the rain at night to look at mine and how it is fixated.
Hmm, maybe I can try a bolt on bolt. Thanks for the idea. (y)
 
What kind of hose clamps are you replacing?

If it is the original spring clamps and they are not rusted, I'll take them off of your hands.

After dealing with a couple of bothersome worm clamps and having a hard time coming up with a clamp I like, I find I actually prefer the OEM spring clamps.

And they seem to be impossible to find in the exact size I need.

I only need a couple for the main radiator hoses.
 
Yeah, try the bolt on bolt method, if not, cut the bolt flush and then drill it out and either tap the hole, or install bolt from underneath.
 
What kind of hose clamps are you replacing?

If it is the original spring clamps and they are not rusted, I'll take them off of your hands.

After dealing with a couple of bothersome worm clamps and having a hard time coming up with a clamp I like, I find I actually prefer the OEM spring clamps.

And they seem to be impossible to find in the exact size I need.

I only need a couple for the main radiator hoses.
It's the spring clamps I'm replacing with worm clamps. The spring clamp snapped in half vs. sliding down the hose. It's toast. What issues have you had with the worm clamps? That's the way I went with all the other hoses. Since I haven't filled the system yet, I still have time to pivot to the spring clamps.

I will say, it's a royal PITA trying to order them online. I went to the Advance Auto website to order the quick connects and the clamps. All they do is list the clamp but the sizes aren't in the specs. Makes it a bit tough to order and get the 20 - 25% online discount.
 
I think you have to go all the way changing everything and ensure you get another 185k miles out of her;)
 
I think you have to go all the way changing everything and ensure you get another 185k miles out of her;)
I'll tell you what. with the fan, shroud and water pump removed it was like working on the cars of yesteryear. I actually climbed in the engine bay to work on a couple things. As I was looking down, noticing the rust, I couldn't help but wish I had more time to replace a bunch of other things while it was easily accessible while I was in there.
 
It's the spring clamps I'm replacing with worm clamps. The spring clamp snapped in half vs. sliding down the hose. It's toast. What issues have you had with the worm clamps? That's the way I went with all the other hoses. Since I haven't filled the system yet, I still have time to pivot to the spring clamps.

I will say, it's a royal PITA trying to order them online. I went to the Advance Auto website to order the quick connects and the clamps. All they do is list the clamp but the sizes aren't in the specs. Makes it a bit tough to order and get the 20 - 25% online discount.

I had to use one worm clamp on the upper radiator hose at the radiator because the previous owner already had one there.

This was the very first coolant leak I found when pressure testing the system right after buying the truck.

His worm clamp allowed a leak and so did every worm clamp I installed afterwards.

All of the other clamps were the OEM spring clamps, as they are on my EXT.

After having difficulty finding a perfect fitting worm clamp, due to length, I installed a couple of different brands that each eventually worked themselves slightly loose over a week or so and developed a tiny coolant leak at that connection.

I figured if I found one that would stay tight and not have to be messed with every few weeks, I would cut off the excess material and make them look better.

Alas, every one of them loosened up and began leaking enough to leave a spot on the driveway.

My search for an OEM style spring clamp, which I have never had fail, has proven to be difficult.

I would love to have a genuine GM part for this.

But I can't seem to locate any online.

Dorman makes some, but none I have bought fit as well as I would like and I am not sure if I trust their grip.

Currently, I have a Dorman spring clamp that is the closest one to fitting, backed up by one of the worm clamps.

So far, no leaks, but it isn't very pretty.

I try to keep the hillbilly looking fixes out of sight when possible.

I would rather have the correct part on there that I know will continue to work properly.

As you know, rust is not an issue where I live.

If someone has a few OEM spring clamps they aren't going to ever use, I would gladly slip a few bucks your way in exchange for them.

As for your heater hoses with the quick disconnects, take your VIN to a local GM parts counter and they will make sure you get the exact one for your truck.

This is not a part to skimp on with aftermarket parts.

I have replaced all four hoses on both of my trucks that way.

I figured if I can get the same 236K+ miles out of the OEM replacement parts that I got out of the originals, I should be good pretty much forever.

Money well spent, in my opinion.
 
That is not good news about the worm clamp. Last thing I want to do is button the thing up just to be forced to drain it and replace them.

I was thinking about this to replace the quick connects but don't want to wait until next weekend for them to arrive.
 
That is not good news about the worm clamp. Last thing I want to do is button the thing up just to be forced to drain it and replace them.

I was thinking about this to replace the quick connects but don't want to wait until next weekend for them to arrive.


As far as the worm clamp thing, I have used them in the past with no issues.

Maybe you will not have any.

In my case this time, the worm clamps I found did not hold as well as I would have liked.

And my local Chevrolet dealership had the heater hoses with the quick disconnects bonded to the hoses in stock.

Walked in with my VIN and walked out with the hoses.
 
I went ahead and opted for overkill and ordered the Dorman aluminium disconnects. Then again, I'm also the guy who opted for the $200 Stewart high flow water pump for my Bimmer vs. just the $50 upgraded pump with metal impeller.

The disconnects should be here before the end of the week.
 
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