Mechanics

WHAT DEFECTIVE SEALS OR GASKETS COULD CAUSE STEAM?

2000 Cadillac Catera • 90,000 miles

Super-heated water entering via normal channels,

Questioner is a retired car-salesman who turned plenty of wrenches over the years. His car has dual overhead cams. It is a cast iron block with aluminum/alloy heads. I was relatively problem-free since bought with 7,000 miles [lil’ old lady lease-return]. It just turned 90,000 miles. Dealer says they replaced the timing belt and tensioner around 20k; also repairing an oil cooler leak under the intake plenum [car developed a minor leak worsening and later found to be heater control].

Driving at highway speed on a very hot Dallas day [over 100 degrees] engine stopped without notice or any notice by the driver. (It appears that the radiator sprung a leak and emptied coolant sufficient to overheat the engine).

When the engine shut-down the driver attempted to restart it, while coasting in neutral on the highway. The starter motor turned but the engine would not restart.

After coasting to a stop, the engine compartment was smoking. The driver [hoping to cool it to avoid melting rubber seals] added regular tap water to the reservoir, which produced a significant amount of steam and whistling noise when entering the engine.

After the engine cooled, driver tried to start the car - finding the starter motor turned very fast, apparently not engaging the flywheel [or suggesting a broken timing belt.]

Driver had the car towed home. The next day he added water to the reservoir which infiltrated the crankcase [suggesting busted gaskets somewhere]. He then left the car in that same state, in his garage [for few months while driving another car].

Upon recent disassemble and inspection of the timing belt, it is found in good condition i.E, it is not broken or frayed [the teeth are NOT spun down or missing at the crank balance pulley gear/sprocket]. Also, prior to releasing belt tension, it was near impossible to manually/hand-turn the crank (after draining the crankcase). However,
On removal of the intake manifold, rust on the underside of the intake valves on both sides of the engine is apparent. Obviously, water or steam entered those areas.

From these facts, it appears the car reached a sufficient temperature to cause the ECM to shut down operation [however, the starter motor turned (as if unimpeded by resistance suggesting the solenoid was not engaging the flywheel [by fail safe engineering].

His objective is to avoid time and costs of taking apart and reassembling anything needlessly or braking anything in the process.
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Dallasdoer
November 15, 2011.




When the cold tap water was introduced to the motor, it most likely caused more internal damage by cracking either the block or a head.

You should have air checked the cylinders prior to dis assembling the motor to see which cylinders are involved.

The motor, at least the heads need to be removed and inspected by a machine shop for warpage, craks, if they are ok, most likely the block is bad.

From leaving it set for months, I am also concerned with the main and rod bearings being subjected to coolant which will destroy the babbit material.

It sounds like you will most likely be replacing the motor.

Roy
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ASEMaster6371
Nov 15, 2011.
You need to remove the spark plugs. If the crank is turning. The starter is good. Watch for coolant coming out the spark holes. When you turn it over. With coolant in the oil. Youll need pull the heads. Buy rebuilt heads and a head gasket set.

Cadieman
Nov 15, 2011.
Thanks for the comments guys but neither answered the question directly like whether the the starter solenoid is overridden by the ECM when the engine is hot and what gaskets other than heads can cause the mix of water and oil?
As for air checking the cylindeers, I did not want to risk turning the engine before checking to see if the timing belt was spun or broken [resulting in bent valves that I conclude are not now bent]. I have not torn down the engine, just pulled the timing belt to inspect it. I was hoping that maybe a seal around the cooler I mentioned had busted or some other gaskets since, once I begin to pull head bolts, I will have to buy new bolts and gaskets for sure. I am trying to fix the least harmful failure first since this is my time and money.
Save for suggesting a cracked [iron] block or warped aluminum head [which I accept as a more likelypossibility], isn't more likely that a gasket blows before metal fails or warps?
There was no coolant in the engine, only water at the bottom of the pan [i.E, oil floats] so; I am not worried about bearings, which were probably sitting above the water. This car has an oversized pan so I am not too worried about bearings which last I looked were made of metal. If it is only a little surface rust that will soon be chemically removed once refilled with detergent oil and maybe an additive or two. [I once replaced main and rod bearings, on another older caddy and found the journals amazingly resistant].
Any other answers or comments to my questions are appreciated.

Tiny
Dallasdoer
Nov 15, 2011.
Anytime you have water in the pan it is more likely that a cylinder wall has cracked, not a head gasket. The oly other thingmay be an intake gsket has leaked into the centerof the engine going to the oil pan. The starter does go through teh ecm and it wold revent the starter from operating due to not sending a signal to the relay. Anytime that there is coolant entered into the bearing area it tends to etch the bearings due to the silicone in the coolant. This will cause premature bearing failure. How long? Who knows. But they will fail.

Hmac300
Nov 15, 2011.
When I think of cracked blocks, I think of frozen water with nowhere to go but out. How often do cast iron blocks crack under the conditions described? Every time they fire, the explosion in each cylinder has got to be producing force greater [per sq. Inch] than the force of steam which can and does blow seals and gaskets. These cars had a problem with the oil heater/coolers, located in top center under the intake manifold. I understand and would expect the aluminum fins to be thin and if any one of those are cracked, wouldn't water enter the oil supply right then and there? Obviously, it is less trouble to check it first. If any other gaskets or seals come to mind for a guy experienced with these cars in particular, they are appreciated.

Tiny
Dallasdoer
Nov 16, 2011.
I'm glad you are such a great analyzerif you thinkit's what you say it is replace it.

Hmac300
Nov 16, 2011.
All time and money saving ideas are welcome but, obviously, mechanics get paid for what they do; not for what they do not need to do. The reason I posed the question here is because, though I like to fix things, I do not like to work or spend money I do not need to. I do not have particular knowledge and experience on this car. I was hoping a certified and experienced caddy tech or owner with particular knowledge would answer so I could avoid extra work and expense. In the land of the blind, the one-eyed man is king. Sadly, its like asking for directions. Sometimes people are so happy to know more than the asker that they lose track of the specifics of the question. I will check out the oil cooler first before tearing everthing up or replacing an engine [as if a minor operation or expense].

Tiny
Dallasdoer
Nov 16, 2011.
Rust on the underside of the valves was more than likely the result of water vapor(steam) being cooked out of the hot oil. The ecm strategy would not allow starter function without going through the solenoid, there would be no reason for it, it just would not engage the starter at all. Yes the engine oil cooler could have leaked, but water would not 'infiltrate' the crankcase. Infiltrate sounds like a pretty low resistance leak, that would suggest block or head damage. Remove the spark plugs, and manually roll the engine over. If it still does not turn, the water in the bearing surfaces could have caused corrosion, there could be scored/seized cylinder wall/piston, wouldn't know until torn down. As far as why it turned over fast, that would suggest maybe no compression, possibly rinsed cylinder walls, valves seized in guides, any possibility. The simple fact is that this engine went through a catastrophic thermal event, and the repair will exceed the value of the vehicle. It is not necessarily steam pressure the causes gaskets to fail, it is dissimilar metals with different expansion and contraction rates. That is why we have evolved to using aluminum block/head configurations.

Factoryjack
Nov 16, 2011.

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