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Where is it leaking coolant?

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2001 Suburban Loosing Coolant

3954 Views 48 Replies 10 Participants Last post by  Magicianelectrician, 
bazar01
Got a message on the DIC "Low Coolant". It has 290k miles. WP replaced around 150k miles. Radiator, hoses and connectors are original. Reservoir level is very low. I saw coolant dripping at the back of the engine oil pan under cover. Probably dripping on the under cover and running down the back.
I'm going to park it for a while until I can find time to investigate as I am going out of town for a few weeks.
Any guesses?
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bazar01
Hey Greg, it's a 2001 burb 2wd with the 5.3L.

I'll pressure test it when I get back in town.
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bazar01
Thank you for the advice.

I know I have a complete set of hoses and plastic fittings I bought a few years back and had planned on replacing the original ones but never got around doing it. I have to find them though and they are in a box some place in the attic. I hope they are not dry rotted. 😒
Won't be able to work on it til next two weeks.
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bazar01
Brenden16 said:
Dealt with a similar issue on my old 06 Z71 before it was totaled. Gonna say it’s your water pump weep hole, all of the coolant would seep down and drip behind the pan. Literally just had this job done 3 months ago (2 weeks before my wreck...) change out the water pump ($110 on Amazon & $200 in labor if you don’t do it yourself) and you should be good.

Hope this helps man!
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Everything helps, thanks.
I'm still out of town and can't get to it until last week of May.
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bazar01
RayVoy said:
Bel, if it's coming down the back of the engine, I'd be suspicious of a leaking freeze plug.
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Thanks Ray
I'll update when I get back in town last week of May.
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bazar01
Finally home yesterday.

Started working on removing the MAF intake tube, upper and lower fan shroud and fan clutch.
Now I can see the wet surfaces. The coolant leak is behind the water pump on the passenger side.
Tomorrow I will remove the old water pump, install new water pump, new hoses and plastic heater Tee connectors.

@Brenden16 guessed it right. It was the water pump but the leak is not on the weep hole due to a bad bearing. The leak is on the passenger side water pump coolant inlet gasket. I think the gasket silicon surface area is so thin and it easily breaks away from the metal support. The water pump bearings were still good and quiet. If only I had known, I would have just bought the gasket set. Oh well, I already have the new water pump so it will go in.

Brenden16 said:
Dealt with a similar issue on my old 06 Z71 before it was totaled. Gonna say it’s your water pump weep hole, all of the coolant would seep down and drip behind the pan. Literally just had this job done 3 months ago (2 weeks before my wreck...) change out the water pump ($110 on Amazon & $200 in labor if you don’t do it yourself) and you should be good.

Hope this helps man!
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bazar01
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Second water pump failed on gasket at only 123k miles. First one leaked at 167k miles.

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Done. No rusted or broken water pump bolts.
New water pump and thermostat, all new hoses and heater plastic fittings and new AC compressor belt.
Added a little more silicon gasket maker around the metal gaskets for better sealing.
Filled it up with 60% Dexcool and 40% distilled water.


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Good for another 100k miles? I will find out if the 5.3L engine and 4L60e holds up.
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bazar01
Yeah still running smooth at 290k miles.
Thanks @Brenden16 .
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bazar01
I have a coolant leak again!
I wonder where?

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bazar01
It's not getting driven much because I got a 3.0L sprinter lately.
I don't see any wet spot in the engine compartment.
It's going to sit a while.
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bazar01
I just looked under. There's a lot of coolant drops in the steering link and on the AC compressor bottom. All hoses are new.
It must be the water pump gaskets again.
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bazar01
May not need a new wp. Just the gaskets. I'll know more later when I start removing fan clutch and shroud.
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bazar01
My new water pump only logged 9k miles so it must be the rusty block surface which I sanded down or a bad gasket.
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bazar01
4
I need to fix this 2001 Suburban for my business.
So I worked on it today, removed the air intake, fan shroud and fan clutch.
The 1 year old new AC Delco water pump is leaking at the front seal.
What a POS. Made in Mexico? Not sure. RockAuto sold it. April 29, 2021.
I have to call and find out if covered by warranty.
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Traces of coolant

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Underside of intake snorkel.


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Underside of water pump casing and fan pulley.
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bazar01
Update:

I filed a warranty claim from RockAuto. But I have to buy a new one and return the old one and file a refund.

AC Delco replacement parts has a 1 year or 12k mile warranty on general items like the water pump.
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bazar01
Thanks Jacob.
No more RA.
Only local auto parts store from now on for easy replacement of defective parts like this.
Can't trust ACDelco brand anymore.
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bazar01
Got the new AC Delco water pump from RA. Had to pay for this then return the defective one for refund.
Hope it lasts longer than 9k miles this time. Currently at 299,700 miles so I shd hit 300k miles soon

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bazar01
Fast forward, Feb 20, 2023.
I found coolant dripping on my driveway. Just a small puddle maybe about 1 inch dia.
Drip is suspended on the front lower cross member below the oil pan on the passenger side. Bought 1 gal dexcool ready to use and used up about half quart. Will observe rate of coolant loss.

I have new hoses and all are dry.
New water pump is dry.
Oh boy, I hope it's not an intake gasket.

Any guesses?
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bazar01
Thank goodness, it was just a loose hose clamp on the plastic coolant expansion tank.
Back to service and racking up more miles.
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bazar01
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Nope, that was not it. It has one more area leaking coolant.
The plastic fitting that goes to the heater core is also leaking.
I just replaced both when I replaced all the hoses.
Well, I guess poor quality coolant fitting from China?

It's parked again for repair.

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