1995 5.7 head / head gasket issue.

[youtubemechwitsense]

I had a faulty radiator and my wife ran the truck really hot. This caused a blown head gasket. I replaced the radiator but not the head gasket as I did not know I had a blown head gasket at first. Bought a new all aluminum radiator which started leaking down both sides getting progressively worse
( I'm guessing because of too much combustion pressure in cooling system); this in turn blew the head gasket again. ( I'm theorizing this sequence of events) My truck started slowly blowing white smoke out of the tailpipe but never had the yellow milkshake under oil cap either time; yet it all of a sudden has the milkshake today after I put Blue Devil in the cooling system. Now I know it has nothing to do with the Blue Devil. My question : Does it mean anything that it all of a sudden has milkshake even though the truck hasn't been driven only idled for 5 minutes or so from time to time and also is there any way to tell if it's the head or block being cracked without disassembly and a machine shop. Thanks in advance.

 

[movietvet]

Welcome to your first post on the forum.

You did NOT blow a head gasket "again". Only way to do that is to fix it after the first time. You did not say you did that. Have the radiator tested for problems. Typically head gaskets go because of another problem, like overheating from too low on coolant because of a leak "somewhere". Doubt that you cracked a block. Adding a "miracle cure" will clog passages, like the radiator and heater core and at the thermostat.

 

[Road Trip]

I had a faulty radiator and my wife ran the truck really hot. This caused a blown head gasket. I replaced the radiator but not the head gasket as I did not know I had a blown head gasket at first. Bought a new all aluminum radiator which started leaking down both sides getting progressively worse
( I'm guessing because of too much combustion pressure in cooling system); this in turn blew the head gasket again. ( I'm theorizing this sequence of events) My truck started slowly blowing white smoke out of the tailpipe but never had the yellow milkshake under oil cap either time; yet it all of a sudden has the milkshake today after I put Blue Devil in the cooling system. Now I know it has nothing to do with the Blue Devil. My question : Does it mean anything that it all of a sudden has milkshake even though the truck hasn't been driven only idled for 5 minutes or so from time to time and also is there any way to tell if it's the head or block being cracked without disassembly and a machine shop. Thanks in advance.

Greetings youtubemechwitsense,

When an engine is run really hot, the resulting parts expansion with nowhere to go will
cause the cylinder head to weaken, warp, and force movement between head & block, creating
places for air and/or coolant to leak where there wasn't any place to travel before.

Here's a photo of a small block cylinder head where the head gasket failed between the 2 center cylinders.
I've marked up this photo to show you the 3 primary failure paths:

* Cylinder compression pressure forcing itself into the water jacket via a failing head gasket.
* Engine coolant escaping passage, and forcing itself into the lifter valley creating the oil/coolant milkshake.
* Excess heat creates crack in exhaust port on unpressurized side of exhaust valve, allowing coolant to escape into hot exhaust = white steam.

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I would avoid running the engine any more, for repeated thermal cycles will only turn a seep/weep into a leak,
and you may end up with a hydrostatic lock, bending a connecting rod & further wounding the engine.

Note: The majority of the time the cylinder head sustains the damage, while the block is OK -- but if some long
ago mechanic used an impact gun to reinstall the cylinder head instead of a torque wrench, it's possible that the
block is also cracked in the head bolt threads, and the block is also bad.

At this point all I have is theories & conjecture. The only way to really know what you have to work with is to
take it apart and give it a good visual inspection, followed by magnafluxing, pressure testing, etc.

Wish I had better news to share. Hope the above helps to explain why an overheated engine has at least 3
different ways to express a failing head gasket.

Best of luck with your situation.

 

[Schurkey]

Leakdown testing of the cylinders, looking for bubbles in the radiator. (And also for leakage past the valves, and assessing leakage past the rings. If the engine is shot, or the valve leak, you'd want to address that before you cram another head gasket in place.)

Pressure testing of the cooling system, looking for coolant in the cylinders when spark plugs are removed and engine cranked, and also for coolant in the oil by letting the water settle-out of the oil and then pull the drain plug on the pan.

And after that...disassemble for cleaning and inspection.

When my '88 popped the gasket between #3 and #5, the blowtorch effect gouged the block and the head. The block might be salvageable with remachining the deck. The head is toast.

You must be registered for see images attach

You must be registered for see images attach

In my case, it was pure compression/combustion leakage, no coolant in the oil, no bubbles in the radiator.

 

[Sean Buick 76]

Step 1 replace head gaskets in both heads. Step 2 report back

 

[Erik the Awful]

While you have the heads off, check them very carefully for cracks between the valves and the spark plug. Clean the heads off carefully and use a magnifying glass.