Blown gasket, cracked head or cracked block?

[holderd]

2000 3.0 Flex Fuel
Engine quit on interstate. Found water in oil and water soaked air filter. Did not overheat. Assumed blown head gasket. Removed both heads and had them overhauled. Reinstalled with new head bolts and proper torque to yield. Cranked up, looked good. Ran down the road about a mile and the same thing happened again. Assumed I screwed up a gasket. Removed heads again, reassembled with new gaskets. Cranked engine and ran a moment. Removed drain plug and oil and water came out. Put water hose in radiator and water flowed straight out of the oil drain. Before I remove heads again, is there any way to determine where this coolant leak is? I wonder if the shop missed a crack in one of the heads? I'm a helicopter mechanic, so I'm not completely without a clue, but this has me puzzled. Help appreciated.

 

[adsm08]

The more I think about this the only thing it really can be is a cracked block.

The rings hold air. If it holds air it will hold water, which means the breach is likely below the level of the piston.

Kind of a pointless test but, run the water through it and slowly crank the engine by hand. If the water stops at any point you know that you moved a piston below the level of the crack.

I would have the spark plugs out while doing this though, so that you don't hydro-lock the engine by accident. Also, that way, if water suddenly starts flowing out of a plug hole, you know where the problem is.

 

[RonD]

The way you describe it, it would have to be one heck of a crack, coolant is generally sucked thru a cracked head, or pushed thru depending on where the pressure is.
Just filling the rad and having water come out the oil pan would have to be one heck of a hole.

Engine stopping is not a sign of a blown head gasket or cracked head, overheating due to loss of coolant could be a sign a blown head gasket or cracked head, and then you pull over and stop.

Water in the oil AND air cleaner is an odd one, cracked or blown intake gasket could account for both.
Water would exit blown/cracked intake into cam cavity(under intake) and directly into oil pan, water/steam entering the intake itself would shut down engine pretty quick, and I assume water was hot at that time so after engine shut down steam would have exited intake and into air plenum and condensed on the air cleaner.

Water in oil and air cleaner, I would inspect the intake very closely.

This would also match the filling rad and exiting oil pan description.


I remember some of the Ford 3.0s had RH/LH head gaskets, not sure if that applies to the 2000 models though

 

[holderd]

Thanks for the thoughts guys. Air filter was completely soaked. That is probably what shut down the engine. I started it at home after the first incident and got a lot of steam out of the tailpipe. I will try ADSM08's suggestion to try to find leak location. It ran perfectly smooth yesterday so I think compression is good. I didn't see any issues with intake or gasket, but it was not dye checked or anything, just visual. Head gaskets did not have rt or lt but did have up and front and rear markings. On the original head gasket, I did not see a smoking gun type of failure. Any other suggestions on how I should proceed to find the problem? I don't want to jump back in on the thing before I have a better idea of what's wrong.

 

[RonD]

Air filter only has two sides so either it sucked water in via the fresh air intake or it was soaked by water/steam coming from the engine.

There is usually a vent tube from valve cover(oil filler tube) to air plenum, steam in the oil pan, from a cracked block, could have been pushed up into the valve cover and then into the air plenum stopping the engine and soaking the filter.

 

[holderd]

Air filter only has two sides so either it sucked water in via the fresh air intake or it was soaked by water/steam coming from the engine.

There is usually a vent tube from valve cover(oil filler tube) to air plenum, steam in the oil pan, from a cracked block, could have been pushed up into the valve cover and then into the air plenum stopping the engine and soaking the filter.

It would have to be steam from the engine. But I'm having trouble seeing how it could migrate to the filter with a steady flow of airflow in the opposite direction while the engine was running. Could it be that the filter got wet after shutdown?

I'm still looking for a way to determine the point of failure

 

[RonD]

While engine is running the crankcase has positive air pressure, from blow-by, not much, a few pounds maybe, to prevent pollution this pressure is reduced by pulling the crankcase "air"(oil vapor) into the intake via the PCV valve and Vent to air Plenum.
If there were an internal crack in the block, then the cooling system pressure, 13+psi, would add to that pressure forcing steam out into the PCV valve and vent tube and then into the intake stalling the engine.
That pressure would continue until equalized, soaking the air cleaner after engine shutdown.
Same would happen with intake gasket or crack.


If you pull the intake and then the water pump you have separated cooling system on the two banks of the V6, you can then add water to each bank separately to see if either leaks into the oil pan, seal the water pump holes, that way you can fill it all the way up via the heads, just a rag will do.
A crack behind the water pump could produce the same symptoms.

 

[holderd]

While engine is running the crankcase has positive air pressure, from blow-by, not much, a few pounds maybe, to prevent pollution this pressure is reduced by pulling the crankcase "air"(oil vapor) into the intake via the PCV valve and Vent to air Plenum.
If there were an internal crack in the block, then the cooling system pressure, 13+psi, would add to that pressure forcing steam out into the PCV valve and vent tube and then into the intake stalling the engine.
That pressure would continue until equalized, soaking the air cleaner after engine shutdown.
Same would happen with intake gasket or crack.


If you pull the intake and then the water pump you have separated cooling system on the two banks of the V6, you can then add water to each bank separately to see if either leaks into the oil pan, seal the water pump holes, that way you can fill it all the way up via the heads, just a rag will do.
A crack behind the water pump could produce the same symptoms.

RonD
Good idea! I guess if I had paid attention when the heads were removed, I may have noticed that there was no water in the passages on one bank?