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I have a 2001 Chevy Z71 Suburban with a 5.3L engine and I have been experiencing coolant loss for about year now. i changed ou the water pmp gaskets a couple of times after a GM mechanic advised me it was avery common issue for them to leak, that worked for a while and recently finally was able to see a leak at the water pump weep hole. The water pump was replaced about 2 months ago and I still have a considerable loss of coolant (DEXCOOL) and I have to add some every 3 to 4 days. I just had a shop replace the oil pressure switch which began to leak motor oil severly and he did a pressure check of the cooling system and the pressure held for two hours with no leak or indication of any leak. he told me that the oil looked fine and no coolant seems to be getting burned through the exhaust either. If anyone has experienced the same and found a fix, let me know details.

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That is really puzzling. I'd say check all hoses really closely, but if there was a leaking hose, it wouldn't have held pressure. Maybe try putting some dye in the coolant so you can see if there's an external leak? :jester:

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I'm kinda going through the same problem with my 2001 4.3. I've looked everywhere and can not see a leak, but I have to add some coolant every week. Every once and a while I can smell it when I get out of the truck.

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I've had the same issue with my 2004 Sierra 5.3 V8. The shop I took it to pressurized the system, added dye, couldn't find a leak. Problem persisted, I returned to the shop and they flushed the dex-cool and added regular green coolant. This slowed the leak, but, still adding coolant. I smell burning coolant occasionally and have seen the exhaust puff a significant amount of white smoke recently when following my wife.... My last truck was a Ford with a similiar issue...it was the head gasket. The whole thing sounds like it may get expensive! Any suggestions?

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It is probably going into your oil. I had this problem with my 2000 5.3. At first I replaced the head gaskets and it was nasty under the valve covers. After replacing the head gaskets I went to change the oil. When I pulled the drain plug, nothing came out at first. I ran a screwdriver in the hole a bit and some chunky-gunky stuff came out then the oil. Well, I didn't want all of that in the engine and was worried that with that much mess in the oil pan the engine may be hurt or will be soon. I put in a salvage yard engine and when I pulled the oil pan off of my old engine, there was about an inch or so of sludge in the bottom with just a little clearance for the pick-up.

My truck had been using coolant slowly starting at about 85000 miles but then started getting worse at 110,000. That was when I decided to replace the head gaskets. The gaskets didn't fix it either. I think there's a crack in one of the head but haven't had it checked out yet. Anyhow, when you mix coolant and synthetic oil, it makes a real mess! Keep an eye on it! Good luck.

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If that much coolant is getting into the oil it should be quite evident. Do an oil change and check the oil. When the truck is hot can you smell burning coolant? As the coolant may be leaking out onto something hot and evaporating. The intake manifold gasket may also be leaking. I would suggest putting in some dye to see if that will show up the leak.

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I've never used dye. Where do you get it and how much do you put in? Will it harm anything leaving it in the coolant?

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Any parts store should carry it. You'll need a black light too. Also available, sometimes for a free loaner, at the parts store.

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:jester: The package I got came with the black light and the tinted glasses. The dye won't harm anything. Just follow the instructions on the package.

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Hello,

 

I had the same problem with my 04 Gm Crew cab. I also changed the waterpump, but that did fix it. Turns out the CasTech Heads (They have a 706 cast on the lower right below the valve cover I believe) are prone to crack. Mine was cracked in the well where the center head bolt goes. It was leaking into the oil, but you could not tell due to the dex-cool. It doesnt look like regular antifreeze and oil mixed. When I removed the valve covers there was a bunch of butterscotch coloured gunk. That was the dex-cool and oil mixing and turning to jelly. If you do pull the valve covers off, look for the gunk and look in the wells where the head bolts are for a washed out or clean area. If you find one that may be your problem. When enough dex-cool gets in the oil you can get noisy lifters on startup due to thinning of the oil and smoking on cold starts due to a the gunk blocking your pcv system. I hope this is not your problem, just letting you know what I found. Cheers

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Hmm.. Losing coolant = head gasket about to come off ?

 

Do you see lots of thick white smoke coming out your exhaust in cool(er) weather ?

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There's a TSB for that Castech problem. Also, GM stuff is notorious for intake manifold gaskets going south.

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