I went to change the coolant in my truck today. I was surprised, when I drained the coolant from the stopcock on the bottom of my radiator, that only about 5 quarts came out!

I assumed that the rest was in my engine block, but I ran into some problems trying to drain the engine block. First, I was unable to remove the drain plug on the driver’s side of the engine block. It’s seized in there pretty bad. I tried PB Blaster. I tried whacking it with a hammer. No luck.

Second, I was unable to locate a drain plug on the passenger’s side of the engine block. My view is of course partially obstructed by the starter motor. But even still, I looked real hard and couldn’t find anything except the freeze plug.

No matter, I decided to just remove the lower radiator hose and drain the rest of the coolant that way. But when I removed the radiator hose, only about 1 more quart came out!

This truck is supposed to have a 20 quart cooling system, but I was only able to drain 6 quarts. I checked the reservoir before I began and it was right in-between the COLD and HOT lines. Where is the rest of the coolant??

I asked a friend of mine and he said my engine block might have a blockage in it, and the other 14 quarts could be trapped behind it. But that doesn’t make sense to me. If coolant wasn’t circulating in the engine properly then I would have serious engine damage, right?

Should removing the lower radiator hose drain all 20 quarts from my system like I thought? Or do I need to remove those engine block drain plugs to properly drain the system?

What is my next step

 

I feel like there is more to this story. What prompted you to change the fluid?

 

I bought the truck used 1 year ago and I’d never replaced the coolant. Last time I was at the dealership they told me the coolant needed to be changed.

 

Try some heat on that drain plug but I never messed with it. You can be low on coolant and still not overheat but I would check your dipstick and oil cap for coolant to make sure you don’t have a blown head gasket. Make sure you have heat to ensure you have no blockage in the heater core. Other than that I would flush it real good, refill, and monitor. If you had a blocked cooling port it would have overheated at some point. When I have done this job I find most of the old fluid is drained during the flush…not when disconnecting the hoses.

 

If there is good color in the coolant now you can try and fill with fresh water only, then drive it a couple of days and drain again. If it has coolant color (not rust) there was something hiding somewhere...

 

This will get it all out.
Always has for me.
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

 

Use heat. A torch or a good heat gun. It will soften any sealant and expand the metal. It should be a tapered pipe thread, I think.

 

I changed the oil at the same time and I didn’t see any coolant in the oil or any oil in the coolant. So I’m pretty sure the head gasket is fine.

This is exactly what I did. It looks like after this week we’re through with most of the cold weather this year. So I just topped off with 6 quarts of water and I’m going to run it for a few days then drain again and see what comes out.

Obviously, I don’t want to melt the metal or set anything on fire. Is a hair dryer hot enough for this? Do they make 3/8 inch square (female) sockets?

 

If you are careful you won’t. Just make sure any excess grease and dirt is removed and no wiring harnesses are close by. But you will need a Propane torch from Walmart for $15-20 bucks.