Loosing coolant leak?

Tiny
SIRCODY
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 108,000 MILES
I am loosing coolant from my system. I have no idea where this is going. I changed the spark plugs for the first time, with no apparent issue to the plugs. There doesn't appear to be water in the oil for I have changed that recently. There are no apparent leaks onto the ground. I have put more than a gallon into the system since Late November. Could there be a leak in the heater coil that is loosing water while driving and running the heater, but not leaking onto the ground while sitting, not running?
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Wednesday, January 7th, 2009 AT 10:09 AM

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Tiny
BRIAN 1
  • MEMBER
Pressure test only way to find a leak.these vehicles have cylinder head porosity cracks that are hard to see.the coolant has to go somewhere,if it's internal it might be a leak that is very small and hard to see.here is some info:Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

This guide will help us find it

https://www.2carpros.com/articles/car-is-leaking-coolant

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

Important: If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss. If the cylinder head(s) is a Castech casting (1), inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time (2).

Important: If No evidence of coolant loss is found on inspection of Castech casting cylinder head(s), follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

The crack location can be found in any of the five cylinder head(s) oil drains. This can be seen as a clean or shiny area, on an otherwise stained surface (1). Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. If inspection reveals evidence of coolant witness marks (1), replace the entire cylinder head(s) assembly.
I've replaced alot of heads for this problem,pressure test it and check for leaks,it's gonna be internal or external.post back with any other questions.
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Wednesday, January 7th, 2009 AT 10:23 AM
Tiny
KIML2009
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 85,000 MILES
I have been loosing coolant since oct 08 had it pressure ck nothing, changed the intake gasket inside was oil/coolant, then changed the oil which was congealed and some milky to it, gm/chevy wont admit to using faulty heads, and my extended warranty wont cover because its not caused by mechanical problems? How many trucks have u had with this problem? I have a copy of the tbs that chevy sent their service dept. I need facts to support my case to the attorney generals office to force gm to pay to for the repairs please help im a single mom who still owes $ on this truck
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
BRIAN 1
  • MEMBER
I've replaced some cylinder heads on these trucks, there castech heads, those are the ones that leak. There is a bulletin for this, but it states only a small amount of vehicles are affected. You can call the office at GM and tell them they might help you out. Post back with any other questions.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
SCREECH
  • MEMBER
Common issue w/ chevy's. Had to replace intake manifold gasket on my '97 at about 80K but haven't had another problem in last 100k miles. You can get a lot of water in the case so make sure the oil stays clean and get milky again. (You might have to change it more than once). Warranty likely won't cover because it's a gasket (a lot of good that does you!). But you might be able to talk to the warrenty guy or gal at the chevy dealership and see if they'll cover you on a good faith basis. I got them to pay for a brand new tranny at 70K (well out of warranty) but not much they can give you if you did the work yourself.
Hopefully you won't have any more problems.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
CUDA74
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 90,000 MILES
I have coolant dripping from tailpipe, loss is about 1 quart/200 miles. No coolant in oil. No loss around hoses, radiator, water pump or heater core.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
DENNYP
  • EXPERT
That sounds odd. Have it checked for exhaust gasses in the cooling system. It could be a blown head gasket. If it was dripping out of the tailpipe, I would expect a much greater amount of coolant to be lost in 200 miles. I would check the water pump gasket very carefully. What you're seeing from the tailpipe could just be condensation.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
RANDY SHARP
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 4.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 110,000 MILES
I have been losing coolant, every couple of days I am having to add coolant. It is not leaking any coolant at all, I have pressure tested it, I have also did the test for the combustion gases in the coolant you know the one with the column and you add the liquid to the line and squeeze that also passed, it has a new water pump thermostat, and I also know this year falls into the years were a company was making the heads that they could crack around the head bolts under the valve cover. So does anyone have a theory for this problem, what would be the next step and also it has a new cap also.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
Consider adding a small bottle of dark purple dye to the coolant, then search a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. Check inside the tail pipe and around the intake manifold. Auto parts stores will have the dye, and those that rent or borrow tools should have the black light.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
RANDY SHARP
  • MEMBER
So just add the dye without pressure testing it? How much dye should I add?

And thanks by the way.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
You're losing coolant now without performing a pressure test, (although the loss may be only occurring when pressure builds up in the system). The loss will continue just as before, only now there will be dye in the coolant. The goal is to maintain the same conditions as when the problem occurs.

The bottles of dye aren't very big to start with, but I usually used only half of one bottle. That's enough for it to show up easily with the black light.

The people at the parts store will ask what you're using this for so they give you the right product. The dyes are different depending on the fluid it's going into.
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Tuesday, July 7th, 2020 AT 1:24 PM (Merged)
Tiny
CADDYDADDY93
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 66,000 MILES
I have a slow coolant leak. Truck loses about a quart of coolant a week. I can not find any evidence of a leak anywhere, and there is no coolant in the oil. Has anyone had this problem and how was it corrected.
Thanks
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
QUAGMIRE86
  • MEMBER
Well, it could be as harmless as a coolant leak in the small coolant lines that go in and out of your TBI unit. If it is leaking and draining on the top of your motor, it will just evaporate. Also, don't forget to check your transmission fluid for "Milkiness" incase the transmission cooling lines are evacuating coolant from the radiator. One other place, check the coolant lines that enter the firewall that supply your heater core. If you have a 2003, there should be a access panel under the dash on the passenger side. You have to remove the kick panel (three 9/32 hex hed screws). There is a small "L" shaped access panel that holds the "Cabin air filters". Remove that, pull the filters out and see if the heater core is not leaking fluid (may be absorded into the filter material).
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
BRIAN 1
  • MEMBER


https://www.2carpros.com/forum/automotive_pictures/147643_head_3.jpg

Subject:
Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found

Models:
2004-2006 Buick Rainier
2001-2006 Cadillac Escalade Models
2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models
2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models
2001-2004 Oldsmobile Bravada
2005-2006 Saab 9-7X

with 4.8L or 5.3L VORTEC(R) GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z - RPOs LR4, LM7, LH6, L33, L59)

Supercede:

This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

Refer to the illustrations on how to identify Castech casting and/or the very specific areas of the cylinder head(s) for a coolant leak from porosity.

Cylinder head(s) location of the Castech manufacturing casting logo (1).

Close up view of the cylinder head(s) showing the Castech manufacturing casting logo (1).

If the cylinder head(s) is a Castech casting (1), inspect the area around the five oil drain holes for witness marks indicating coolant seepage over time (2).

If No evidence of coolant loss is found on inspection of Castech casting cylinder head(s), follow normal diagnostic procedures in SI to determine the cause of the coolant loss.

The crack location can be found in any of the five cylinder head(s) oil drains. This can be seen as a clean or shiny area, on an otherwise stained surface (1). Pressurizing the cooling system at this time may reveal coolant, air, or a combination, weeping in the described area. If inspection reveals evidence of coolant witness marks (1), replace the entire cylinder head(s) assembly.
follow this info,very common.
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
SPIDER711
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 40,000 MILES
My truck has been loosing coolant since I purchased it. I took it to the dealer while still under warranty and they couldn't find a leak. I can smell anti-freeze occasionally but can not find a leak anywhere. Do you know where my coolant could be going?
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
MHPAUTOS
  • EXPERT
Hi there,

Your dealer can't be trying to hard. Have the cooling system pressure tested hot, if there is any external leak this will show it up, leave it on pressure for 1/4 Hr and run under test conditions to check water pup seals. Check Radiator cap seal and hold & release pressure. There are tests that can determine minor exhaust leaks into the cooling system (head problem) I think it may be a case of not wanting to see a leak so they don't have to fix anything under warranty. Tell them to do there job and try harder.

Mark (mhpautos)
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
JBELLARD03
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • AUTOMATIC
  • 160,000 MILES
All of the coolant leaked out. Cannot find source of the leak. Also while driving down the highway at about 70-75mph it felt like it was "slipping" or lopping and it began slowing down while I had my foot pushing down the accelerator.
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Refill the coolant and then pressurize the system when the engine is cold. You will need a pressure tester for a cooling system. Most parts stores will lend you one. Basically, it is a small pump with a gauge on it to identify the pressure you are putting on the system. It attaches to where the radiator cap is located. DO NOT exceed the pressure listed on the radiator cap when checking it.

As far as the engine, was it overheating when it ran the way you described? Did the check engine light come on?
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
BIG G369
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 56,500 MILES
After driving anti-freeze odor present. No leaks, all fluids are good, performance good.
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
MHPAUTOS
  • EXPERT
Hi there,

It would pay to have the cooling system pressure tested, you may have a small leak that is not that evident, this test will help locate it, start here.

Mark (mhpautos)
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Tuesday, July 7th, 2020 AT 1:26 PM (Merged)
Tiny
JEFFSEITZ
  • MEMBER
  • 2002 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 165,000 MILES
Had starter go out in December, had car towed, before it was tolled, the guy said he would tap on starter, he used a pipe and 3 # hammer and was hitting very hard at night when it was dark, two weeks later my coolant light came on, my thought was he maybe missed the starter and was hitting my block, I was inside the truck, used about 2 and half gallons in around 800 to 1200 miles, took it to two places and it held pressure, but the first time engine was hot and second time let sit for 2 hours, still held presure, put uv leak detection in coolant, still nothing, I think it only leaks when cold. Checked for ul solution in oil, when I removed oil cap, I see nothing in the oil. Any ideas Jeff PS temp is good and see no smoke in tail pipe
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Tuesday, July 7th, 2020 AT 1:30 PM (Merged)

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