When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My 2000 5.3 Silverado is puking coolant and sometimes over heating. I parked it for six months or so after my wife got a new car and I started driving her old one. Then I drove it locally and it got hot. Ended up having to put a ton more coolant/water in it. It's always used a little - like for a decade - so I didnt think much of it. Until I drove it again and it got hot. Put more coolant in it. Drove it again and it got hot, put more coolant in it with a healthy amount of WTF going on in my head. The last time I put coolant in it looked like it was leaking half of what I was putting in out half as fast as I could fill it. It was running BTW. Thought maybe I was just spilling it cuz for the life of me I couldn't tell WHERE it was leaking from, just somewhere inside the wheel well.
So after I filled it up I drove it up on ramps and let it sit for a few days so everything was bone dry in an attempt to find a possible leak. I took the passenger wheel well cover out. I started the truck and after a couple of minutes I started noticing specks of liquid on the ground and could smell anti freeze. Still, even looking through the wheel well I couldn't see where it was coming from. It looked like it was coming from under the expansion tank so I pulled the entire air cleaner assembly out to get a better look at what was going on.
That's when I discovered this little fng thing.......
I'm referring to the black hose going running down to the metal clip. Once the truck got up to temp it did not overheat but was PUKING coolant out of this thing. Which is why I couldn't tell where the leak was coming from without taking the air box out, as that hose is not visible excelt at the cap.
So what is going on? Am I correct in thinking that this is an emergency puke line? Like in case temp and or pressure get too high? If so why in the world would they design it to just pour out into the engine compartment, down the wheel well and then right in front of your tire? Is there a valve in there? Do I need to replace the tank? I'm getting so frustrated with this thing.
It's an overflow line, doing exactly what it's designed to do. That's not the problem, my truck has it too. You need to figure out why your coolant is overflowing all the time, which is usually from air in the system. It could be caused by any number of things; a leaking/collapsing hose, bad head gasket, etc. My radiator had a hairline crack in the driver side tank that would only seep coolant when it got hot. These trucks don't have a radiator cap, so it's not that.
I quit working on it Saturday night and let it sit until yesterday afternoon so everything could dry out. I started it up and let it run, and monitored temps with the Torque app. Not a drop of coolant leaked anywhere. Not 1, single drop. I let it run for half an hour. It pretty much stayed between 194 and 197. It crept up to 202 with the AC on for a few minutes but went right back down when I held it at 1,500 rpm for 30 seconds. This thing appears to be working perfectly and again, not 1 drop. I am baffled. The coolant in the overflow tank rose a 1/4 inch as the truck warmed up.
I put ls1 F-body electric fans in it several years ago. I noticed that I had one of them wired backwards so that that fan was running backwards. I must have done this when I had all sorts of stuff apart up front last fall while installing a giant, fan cooled trans cooler. Probably didn't notice because of the cool fall and winter temps, and then I parked the thing. But that doesnt explain why my coolant was low for no reason or why it kept being low. What am I missing?
Gonna try a new thermostat later on today. I'd say I changed it like 4 or so years ago.
Drove it around the neighborhood last night for literally a couple of minutes. Crept up to 210 immediatly. I'm so done with this thing. I've been driving and working on it for years. Didn't used to mind when things went wrong, but I'm seriously starting to. I have ZERO fng interest in working on an old (non classic) vehicle at this point in my life. I parked it for the six months becasue we got my wife a new car and we didn't trade the old one in becasue the dealer wanted to give us way too little. So I spent half a year driving a newer Cadillac. I think it ruined me. Got into an accident a few weeks ago and now the car is gone.
Once you drive a Cadillac, its very hard to go back to a Cheby. Keep your chin up lad, morale is important as time goes on the burdens pile up so stand up straight and march on
Went to auto parts store yesterday and bought a thermostat, Got the old one off, new one wouldn't fit. WTF....back to store and got a different one. Put it on and it leaked. WTF..... took the gasket off and put the factory one on and it didn't leak. Success. Filled expansion tank up and started it. It was at 230 within minutes. OMG.... So this is what I was seeing after shutting the truck off. I have a temperature gun....
Boiling fluid in expansion tank.
Upper rad hose 155
Lower rad hose 110.
Over flow tank 180
Heater hose 135 and 105
No heat was coming out of the vents when it was running, just normal air.
I let it cool down and added more water to the tank. Started it up and the same thing happened. The air being blown by the fans isn't warm/hot like usual so it seems like the radiator isn't doing anything. Is is still empty? Clogged? Bad thermostat?
I bought another thermostat from a different store last night. Going to see if that's the problem. Also going to see how much coolant comes out of the lower hose when I take it off. I'm suspicious that I have a ton of air in the system and the coolant isnt even reaching the stat. Maker any sense? The amount of coolant that came out of the block and lower hose seems like a lot more than I put in, which is basically half of a expansion tank full.
Changed Thermostat today. Again. Took off upper hose from water pump. Pumped water into heater core (I have a flush thing in onee of the lines that you can attach a hose to to flush the system) until it started coming out of the water pump. Stuck hose in upper rad hose and somewhat pressurized the system with said hose, kept this going until air bubbles stopped coming out of the water pump. Filled upper hose with water and qucikly put it back on water pump.
I basically tried to force water through as much of the system as I could with a hose. Fired it up and with a minute or two could feel heat coming from the heater vents. Gooood. Temp finally stabalized around 200. I took it for a drive and it seems OK.
Weird thing that makes me nervous - the water level in the tank never dropped when the thermostat opened. Maybe I just did a good job of getting water everywhere. It did drop a couple of inches after driving which I think is good, that's what normally happens.
Got an o2 CEL code. F this thing. Think I'm gonna park it and go buy a new Jeep.
08-26-2018, 11:51 AM
Expansion tank confusion, I feel so lost.... 
I'm so done with this thing. I've been driving and working on it for years. Didn't used to mind when things went wrong, but I'm seriously starting to. I have ZERO fng interest in working on an old (non classic) vehicle at this point in my life. I parked it for the six months becasue we got my wife a new car and we didn't trade the old one in becasue the dealer wanted to give us way too little. So I spent half a year driving a newer Cadillac. I think it ruined me. Got into an accident a few weeks ago and now the car is gone. 