where is the drain plug on the radiator for a 1998 5.7L Silverado? I am changing the coolant, looking for leaks, and replacing any 'bad' parts. I ham losing coolant and need to find the problem area...

I just ordered my Haynes, but I would like to get this done asap...
Also, do I have to use Dex-cool coolant? or is that GM's way to making more money?
thanks.

 

I was told if you dont it gets all rusty and foamy.

 

the drain plug is on the bottom of the radiator on the drivers side. it is a black plastic wingnut. I have a 1995 and i dont use Dex-cool. I never have in the 150,000 miles ive put on it personaly and i have no problems

 

also look in your oil make sure it doesnt look discolered. to make sure you dont have a broken head or head gasket. Also another common thing is intake, and thermostat housing gaskets.

 

I added more coolant this morning to the overflow before leaving my parents house and after a few hours of the truck cooling down, the overflow tank had the same amount in it and before, that was after a 300 mile trip. so, it looks like it was just REALLY low? I will keep an eye on it, I didn't see any leaks, I will try the old 'cardboard under a hot engine' trick tomorrow o see if it's dripping anywhere.

If it's not leaking, I will just flush it, and then refill with Dexcool. I use dexcool in my bike and it has kept the previous owner's poor maintenance problems of rust at bay, so I will try it with the truck.

Is the best way to flush the coolant system to drain the radiator, refill with water, run, then drain, and refill with water, then repeat until coolant is clear, add the flush additive and refill with water and run for ten minutes, then drain? how do I get rid of the remaining water to add 50/50 dexcool? thanks.

 

I think your right, but just read the Dex cool bottle. The dealer & an independant mechanic told me that if you mix dex cool with water or other brands it can cause problems. I ran low in my 03 silverado and added water and it got pretty nasty looking. I ended up flushing the whole thing out & and that stuff is expensive.

Just my $.02

 

my 350 engine was losing coolant, later determined it was going into intake manifold and being burned. So you never see a leak on to the ground.

when my water pump when out they replaced coolant with sometype (yellow color coolant) that could be mixed with either orange or green coolants. It has worked fine.

my friend mixed green (old style coolant with the orange coolant by mistake), he had to have the whole coolant system flushed out as it turned to mud.

know what you are doing before you just change coolant types. there could be problems later.

 

I believe I found the culprit. The steel line running from the top drivers side of the radiator is leaking. I believe it is leaking either through the threads of the 'bolt' or at the seams of the plastic tank near the location the bolt protrudes from. Any suggestions on how to fix? I hope to have time this afternoon to disassemble to look at it further...

 

quick thing on dexicoo... do not ever mix with any other coolant. you get some bad results and you dont want that in the water jackets or anywhere near your motor. adding water to the system if its pre-mixed dexicoo is not bad. but then again read the bottle. i cant remember right now. this peanut butter jelly is takin my mind but for the 98... my coolant drain plug was on the bottom part of radiator and its colored green. and its plastic so be a wee careful in turning it. and to properly flush get some of that flush additive from advance or autozone. and you drain the radiator, keep that drain open, start the truck, get a hose and let it run in the radiator. and wait till all the coolant is gone from the plug. then plug the radiator, add that additive, then add water to radiator, start truck and keep adding till full then run for a few then drain and add your fresh dexicoo or choice of coolant ant add to specified amount then run it get the burps out then bubba your on your way. easy right.

 

check the large nut holding the oil and tranny cooler line connectors if you have them on your radiator, I thought I had a leak (well I did have one but..) the nut that holds the cooler inside the end cap was just loose.

Beware if you take it in for servicing some screwy-lube places will do you a favor of adding coolant but adding green to pink or orange Dexi-cool will make a nice cottage cheese mix in your cooling system.
If you have funky stuff floating in your radiator, that's what it is....