I have a 2001 Silverado 2WD 4.8 liter with 175,000 miles on it. About every 2 months or so, I have to add coolant (low coolant light comes on). Problem is there is absolutely no coolant leaking, no coolant in the oil, and no smoke coming from exhaust pipe while engine is running. Logic would tell you I have a blown head gasket, but why no coolant in the oil? Why no smoke from exhaust pipe? The engine runs great, but I can't figure out where the coolant is going. Any suggestions? Thank you

 

First place to check is the simplest: radiator cap. Just by a new one.

Edit: You could do a pressure test on the cap, but they are super cheap so why bother?

 

I had a similar problem. No leak but losing coolant. It could be a head gasket with a leak and the coolant gets burned out the exhaust pipe with the exhaust. I know its only a stop gap measure but I used some block seal for head gaskets and this stopped it for about a year

 

New here, I add my idea in. May be water pump gasket seeping. I know my 00 5.3 is. Check for staining below the pump on the block.

 

I had the same problem with my 5.3. Couldn't find anything. Turned out to be the water pump to block gasket.

 

I had the same exact problem 99 5.3, so first check water pump. Mine ended up being head gasket and it was doing the same symptom for about 6 months or so and I changed oil on Thanksgiving Day 2 years ago, no water in oil and everything looked good, I went to drive back to school next day (90 miles) and heard an almost valve tick sound and literally 30 seconds after I had an entire marching band under the hood. I limped off an exit and killed motor and after checking oil it was chocolate milk. If you have the means, just change the head gasket because I had the joy of replacing motor after ripping the old one to shreds (wouldn't have been destroyed by the minute it ran knocking it's a** off but lets just say I got a little frustrated and she held together like that for a good little while lmao). This was worst case scenario here but the pain of the head gasket is not nearly as the pain of ripping motor.