Some background:

• Radiator blew up 2 months ago
• Multiple hoses have exploded on me within the last few weeks
• Heater core was making weird waterfall noises so I am bypassing until I have a chance to look at it
• No leaks, radiator is full. (I check it every morning before I leave for work.)
• Bled the lines by leaving rad cap off and letting it bubble and squeezing upper radiator hose.

I replaced my radiator, ECT sensor, thermostat, and rad cap.

WITH the OEM thermostat, it will overheat within 10 minutes of idling. I always get uncomfortable when I see the tack that high, so I just shut it off.
WITHOUT the OEM thermostat, it will stay cool and never reach normal operating temp. But the truck runs great and doesn't overheat.

I currently have the thermostat out, and have been driving this way for 2 months. Just a few days ago I bypassed the heater core because I believe it has a leak. Just today when I popped the hood, I noticed my upper radiator hose looked HUGE. There is obviously a lot of air built up in the system.

NOTE: Overflow tank is almost empty when it reaches operating temp.

Has anybody else been through this and have a solution? Thanks.

 

Do you know if the radiator cap is good? Is it getting stuck closed? I see you replaced the radiator cap, but you cannot completely rule it out.

Does the coolant in the overflow reservoir overflow?

Does your exhaust have any unusual "white smoke" (coolant entering the combustion chamber) or a sweet smell? It is okay to see steam after startup and a few minutes after on cold mornings, but more than that could indicate a problem.

It does sound like air (or gases) are being introduced into the cooling system when it shouldn't be.

With the radiator cap off, start the engine and look to see if bubbles are coming from the radiator filler neck. You will want to do this with the engine cold, of course. Don't take the radiator cap off when the engine is warm.

If there bubbles, you may have combustion gases entering the cooling system.

To definitively check for combustion gases in the cooling system, you will need a combustion leak tester for the radiator.

If it comes to checking for combustion gases, here is a short video:

 

Replace thermostat. Looks like the one thats in there is stuck closed. Without a t-stat, engine takes much longe to reach op temp. That will increase engine wear and fuel consumption.

If coolant level drops, check for leaks at cap (if poor quality or not at recommended psi rating), hoses, and head gasket as suggested. Water pump also can leak when they fail.

 

I'm willing to put money on head gasket

Compression test it

 

Ok. I'm just going to replace the head gasket as soon as I have the money. Thanks for the help.

 

Its suggested to test for a reason...to help you save money.

Can rent a compression tester for free from auto parts stores. Even a vacuum pump and gauge can help narrow down on possible suspects.

Buying HG usually involves buying a bunch other gaskets and that expense adds up. So while saving up, test and you'll be glad you did.

 

It takes almost no work to do a block test that checks for combustion gasses in the cooling system. Go that route first. Don't just throw a gasket at it hoping it'll fix a problem that hasn't yet been diagnosed.

 

Yes, do some testing before taking a guess on the problem.

Also, even if there are combustion gases in the cooling system, it may not necessarily be the head gasket. It could be a cracked head or block, although it is less likely, it is still possible.