Water pouring from under head block?

I have a 1999 GMC Jimmy SLT 4wd. The heater core seemed to go out as well as a leaking water pump a few months ago so I fixed the water pump and bypassed the heater core. The recent freeze hit and I thought I put antifreeze in the car but forgot people talked me out of adding the antifreeze until after I replace the heater core. Well the cold hit things froze and I tried to go to work and the car seemed to run rough and I thought it was in my head but I did let the car warm up some.

I got about 3 miles away and the car stalled out and would not restart but would try to start. I had the car towed back to the house and when the weather was warm enough. When I looked at the engine when it stalled out it did have frozen water in the radiator but no water at all after the weather warmed up. I put the water hose in the radiator and turned on the water and notices the water leaks out just as fast as I put it in from the bottom of the engine. I took the air breather off and watched it but the water seems to be coming from under the drivers side head block but im not 100% sure. Checked the oil and water was in the oil.

Reading and watching some videos leads me to believe I might be lucky and have a worn intake gasket but those videos show a clear leak from the top of the engine. It might be possible its leaking from the back of the engine running down and around and just falling from near the front bottom of the engine not to sure to many things in the way.

I cannot find a video of water leaking from a head block or much talk about water leaking from the heads. I know the Vortec 4.3 has a water channel but leaking this much water threw a head and under?

Any advise will help me figure this out.

Did you put water instead of coolant in the system? If so, your engine is kaput.
Without coolant, the heat produced through constant internal combustion would destroy the engine very quickly. Water alone is not entirely adequate to keep the system cool, for the high temperatures inside the motor would eventually boil it off.

I hope not. Before the water pump change with antifreeze it was running a bit hot on the temp meter and since it never passed halfway mark. Im thinking a bad intake gasket and blown freeze plug just not sure.

I have 2 suggestions. Never take any automotive advice from the person who told you not to use antifreeze/coolant, and start looking for a used engine, if you want to keep the truck. If there is water in the oil it is more than just a “feeeze plug”.


@PvtPublic is right on both counts. This happens every winter to boaters who don’t properly winterize their motors. You have a cracked block from the water freezing. If the rest of the truck is in very good condition, a used motor is the only economically sound way to go, or possible a rebuilt (much more expensive, though).

Nah the Jimmy was free. Person before me seemed to park it in water he seemed to go boating a lot. Every break line is near rusted threw rust on main frame motor mounts on both sides shot. Steering rods and ends rusted, All break calipers rusted have to be replaced.

I still have hope for the engine but the transfer case is in the way and it’s raining.

In addition, water won’t provide sufficient lubrication to the water pump. Or anticorrosion protection to the inside of the cooling system.

I hate to sound like a sourpuss . . .

It sounds like it’s not worth repairing this vehicle

Considering it was free, count yourself lucky


Rain cleared up for me to take another look. Leak is upper transfer case right above the oil cooler lines if not the lines themselfs.

Have to wait for better weather and pull the case off for a better look.

I think if the OP reads what they wrote pouring money on this thing might not be worthwhile.

1 Like

Just like the ending of even a bad show im on a crusade to figure out the problem. Dosent cost anything to take it apart. I know the water leak, and its pure water, is within 6 inches of the oil cooler lines with water falling off only the right line not the left.

I dont know if a freeze plug is in that area or the line itself. Does water even go threw those 2 lines?

No . . . at least it’s not supposed to

On the left side are the engine oil cooler lines

On the right side are the transmission cooler lines

Yeah I remember getting a call from my BIL in Kansas asking me to go to where he had his Ford parked in Minnesota to drain the water out. The temp was going to get below freezing and all he had in it was water. Whatever, start your disassembly to determine the cause and then get ready to either make an easy repair or shut your tool box and call the salvage yard to come get it. It’s always nice to know what it was for sure. It would be nice if it was just a freeze plug though.

LOL… I prefer the term “engine autopsy” myself.

I found pictures of freeze plug locations and its in the exact area of the leak. $2 for the plug but dosent explain the water in the oil.

So after I verify that plug I will remove the heads and intake and inspect the gaskets for any luck fixing the water in the oil problem. And if it looks to bad ill will scrap the body and sell any usable parts via ebay one by one like an organ donor.

I remember years ago, a colleague of mine bought a used car from a “questionable” individual. He was so happy about the car

Some time later, when it was well below freezing, his car wouldn’t start.

The radiator . . . and presumably the block and every single hose . . . was full of ice, because the entire cooling system had been pure water

The rest of us had a good laugh :laughing:

It’s entirely possible the source of the coolant/oil mix is the oil cooler only, and the coolant leaking out of the engine is just blown freeze plugs. Given all you say, your engine may indeed be kaput, but don’t discount the lesser-damage idea entirely.

Freeze plugs are not there to protect the block from being damaged when water freezes. When blocks and heads are cast there must be a link in the mold’s exterior and interior including the water jacket and so there are holes in the castings for the connection to plug and a core plug is used. If water does freeze in the block it often pushes one or more of the plugs out but often cracks the block anyway.

They are called “core plugs” in the profession and “freeze plugs” by the junk yard.

The engine was run without any type of fluid in the cooling system until the engine quit, sounds like a lot of damage was done.

I saw a Dodge 318 V-8 that was driven with a seized water pump until it died and one of the pistons had the valves frozen in the top. The piston had become semi liquid from heat and somehow tangled with the valves. The head was hammered and pried loose from the block and nothing of any significance was salvaged from the pile of scrap metal. The owner had sent the car to the shop complaining of a no crank problem.