After returning from a long trip (350 ish miles), I discovered a puddle of coolant under my car the following morning. I might've lost about a cup of coolant here. The leak appeared to stop and has not lost another drop since the big loss. The next day I inspected the car above and below to find no apparent spots where it could've came from. The radiator was dry on the outside, water pump looked good, all hoses were dry, and heater hose connections were dry. I did notice i have a small oil leak from the valve covers but upon removing it, there was no gunk inside so no indication of coolant seeping in through the head bolt holes. I do have the 862 head castings which are apparently better than others of my year. I started to think the heads were cracked although I never overheated at any point during the trip or afterwards. I did find that the coolant dribbled down the driver side exhaust manifold and got charred below the cat on that side. Kind of at a loss of words here for what it could be since I haven't lost any more coolant. Maybe a bad head gasket? No white smoke when driving that I could tell...
Sudden coolant loss; 2002 Tahoe 5.3L
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SnowDrifter
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Sanity check: Are you sure it was coolant, and from your rig? i.e. not a random water puddle or a leak from another vehicle? Was your level low?
External hoses / passages on this engine are:
- Water pump
- Lower rad hose
- Upper rad hose
- Heater core connectors / reservoir (it's a big T fitting)
- Radiator-to-reservoir air-purge
- front and rear steam pipes (under the intake manifold in the valley)
Other check: Was your vehicle over heating? Also possible the reservoir vented - there's a hose that comes off the top by the cap and tucks between the reservoir and your air filter box. Will only vent if your cooling system is grossly over-full and no room to expand, over-heating, or if your pressure cap is bad. If it spat out schmoo, you'll see coolant residue. Worth a check.
Might want to see if the parts store has a pressure tester. It'll let you pressurize the cooling system and note for any changes on a pressure-gauge. Useful for getting around and seeing where a leak is, if one is present.
External hoses / passages on this engine are:
- Water pump
- Lower rad hose
- Upper rad hose
- Heater core connectors / reservoir (it's a big T fitting)
- Radiator-to-reservoir air-purge
- front and rear steam pipes (under the intake manifold in the valley)
Other check: Was your vehicle over heating? Also possible the reservoir vented - there's a hose that comes off the top by the cap and tucks between the reservoir and your air filter box. Will only vent if your cooling system is grossly over-full and no room to expand, over-heating, or if your pressure cap is bad. If it spat out schmoo, you'll see coolant residue. Worth a check.
Might want to see if the parts store has a pressure tester. It'll let you pressurize the cooling system and note for any changes on a pressure-gauge. Useful for getting around and seeing where a leak is, if one is present.
Thanks for the reply
I am positive it was coolant, the smell gave t away and the reservoir was low. It did not vent either because where the hose comes off and would drain, it was dry. This all happened in my garage. The vehicle never overheated and I always watch the temp, even before this ordeal. I did check the heater core connectors yesterday and they showed no signs of leaking. Steam pipes maybe since the leak went down the driver side exhaust manifold and got charred below the cat on that side. I'll take a look in that area next. Otherwise I think the only thing left to do a pressure check as you suggest.
I am positive it was coolant, the smell gave t away and the reservoir was low. It did not vent either because where the hose comes off and would drain, it was dry. This all happened in my garage. The vehicle never overheated and I always watch the temp, even before this ordeal. I did check the heater core connectors yesterday and they showed no signs of leaking. Steam pipes maybe since the leak went down the driver side exhaust manifold and got charred below the cat on that side. I'll take a look in that area next. Otherwise I think the only thing left to do a pressure check as you suggest.
Erickk120
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Like snow pointed, check the steam pipes whatever their real name is, those connect at the front and rear, kind of hidden by the intake, the orings in there tend to go bad over time, I actually have the same issue atm, but mine is very minimal, to the point I haven't added any coolant to it since I've noticed, it leaks at the rear driver side over a period of times, sometimes worse than others, depends how much or hard I drive. I will take care of mine when I do my manifold and valley gaskets, just waiting on my back ordered knock sensors.
I tried looking behind the intake manifold for the rear ones. Unless I crawl into the engine compartment they are tough to see, I need to find a mirror haha. I replaced the intake manifold gasket a little over two years ago to fix that dreaded and common problem. You must be getting a rough cold start until things seal up with the engine expanding on the intake manifold? Seems like that is most likely it as I have never lost any coolant and this happened only after driving 350+ miles in one day at 70-75 mph for hours on end. Thanks for chiming in
Maybe a cracked overflow tank with an attitude?
I wish it was that simple; the coolant reservoir is drier than the Sahara underneath itself. As of Sunday I haven't leaked anymore coolant
So I found the caps or whatever you want to call them in the rear of the engine and they didn't seem to have any coolant around them upon swiping with my finger. Just some caked on dirt and oil from the slight valve cover leak I have going. There is only a coolant crossover line (steam pipe, etc.) on the front side of the engine and none in the back except some type of cap looking things (what the front side has but without a hose connecting them). The search continues...
Erickk120
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thats weird, unless they changed them sometime between years, mine connects to 2 at the front and 2 at the back of the heads and mine only leak when running duh! Maybe next time you go out let it cool enough and go back recheck, the mistery continues!
Numb skull (me), replaced the water pump and all is well now. Took the car up on the lift in the shop and the underside of the water pump was discolored from coolant leaking out previously. Please learn from the mistakes of my untrained eyes!
