Best way to clean Engine/Engine Bay

[Onsan]

Would not think it’s likely.

Starting a wet engine is not an issue, throwing water on a hot engine is.

A wet engine that has heat applied to it has to first heat and evaporate the water before the metal itself gets much more than 100oC.
Think what happens inside the engine block, there’s cold water running around it the moment you start, the engine doesn’t really got hot until the cooling water is hot.

Pouring water on a hot engine is a different kettle of fish as cooling steel is a lot quicker than heating it. Think the time it takes to heat a piece of steel to red hot and the time it takes to cool it when quenching in water. Add to it that an engine block is not evenly heated, risk increases.


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[nj swb]

Originally Posted by Onsan

Would not think it’s likely.

Starting a wet engine is not an issue, throwing water on a hot engine is.

A wet engine that has heat applied to it has to first heat and evaporate the water before the metal itself gets much more than 100oC.
Think what happens inside the engine block, there’s cold water running around it the moment you start, the engine doesn’t really got hot until the cooling water is hot.

Pouring water on a hot engine is a different kettle of fish as cooling steel is a lot quicker than heating it. Think the time it takes to heat a piece of steel to red hot and the time it takes to cool it when quenching in water. Add to it that an engine block is not evenly heated, risk increases.

Drive through suburbia, pull into the car wash, leave the engine idling for a minute or two while getting ready. How hot do you think the engine is? How hot do you think the exhaust is?

[Onsan]

Engine is hot, don’t apply cold water to it directly.
Exhaust is rolled steel, not cast steel or alloy. Does not behave the same when quenched with water, does not have oil seals and is a hell of a lot cheaper to replace if you do damage it.

That’s my advice, I get that I and others have disagreed with yours, but I’m not here to argue with you, just a different opinion.
My advice is sound and reasoned, take it or not as you or anyone else see’s fit. It’s all good.


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[nj swb]

Originally Posted by Onsan

Engine is hot, don’t apply cold water to it directly.
Exhaust is rolled steel, not cast steel or alloy. Does not behave the same when quenched with water, does not have oil seals and is a hell of a lot cheaper to replace if you do damage it.

That’s my advice, I get that I and others have disagreed with yours, but I’m not here to argue with you, just a different opinion.
My advice is sound and reasoned, take it or not as you or anyone else see’s fit. It’s all good.

It comes down to language. The engine won't be above 100 degrees, I don't consider that to be hot (in the context of this discussion).

Using the spray wand isn't "quenching" anything - in the context of this discussion.

There is more danger utilising Mitsubishi's 700mm wading depth, where the engine is submerged in water rather than sprayed. What are the warnings in the owner's manual regarding this? When was the last time any of us heard of an engine cracking during a river crossing?

To each their own - I agree. But using analogies of quenching red hot steel is neither sound nor reasonable.

[Onsan]

Originally Posted by nj swb

It comes down to language. The engine won't be above 100 degrees, I don't consider that to be hot (in the context of this discussion).

Using the spray wand isn't "quenching" anything - in the context of this discussion.

There is more danger utilising Mitsubishi's 700mm wading depth, where the engine is submerged in water rather than sprayed. What are the warnings in the owner's manual regarding this? When was the last time any of us heard of an engine cracking during a river crossing?

To each their own - I agree. But using analogies of quenching red hot steel is neither sound nor reasonable.

Maybe your interpretation. I said 100oC in the context that wet metal will not get much hotter than 100oC before water has evaporated, it's just thermodynamics, liquid water can't get above 100oC at atmospheric pressure, so if it is present on the metal, the metal temp will not get much hotter than 100oC. My point was to provide reasoning to reassure.

I accept there's quite a few definitions of quenching, "the rapid cooling of heated metal with water" is what I had in mind, relevant to the context of the discussion, I did not think someone would take it as the specific application of heat treatment and submersion in water, my bad.
700mm is wheel height on most, which when a vehicle is driving through water would be not much more than sump height. It would expose diff seals to water ingress and I would guess that and other valid reasons is why MM put a warning in the owners manual stating

NOTE
• Because the inside of the vehicle is flooded
with water when crossing at a place where
the water is more than 50 cm deep, we recommend
you to have your vehicle inspected.
• Frequent crossing of streams can adversely affect
the life span of the vehicle; we recommend
you to take the necessary measures to
prepare, inspect, and repair the vehicle.
...

• After crossing a stream, be sure to have the
following items inspected at a MITSUBISHI
MOTORS Authorized Service Point and take
the necessary measures.
• Check the brake system and, if necessary,
have it serviced.
• Check the engine, transmission, transfer,
and differential oil or grease level and turbidity.
If the oil or grease is milky, it indicates
water contamination. Replace it
with new oil or grease.
• Grease the propeller shaft.
• Check the inside of the vehicle. If ingress
of water is found, dry the carpet etc.
• Inspect the headlamps. If the headlamp
bulb is flooded with water, we recommend
you to have it drained."

Sure, it can go 700mm or deeper even, no one argues that, but just because it can, doesn't mean you should or if you do, that there won't be the chance of an undesirable affect.


I'm erring on the side of caution by suggesting the least chance of a undesirable effect on someone else's pride and joy is to wash it when cool, forgive my wording if that point was lost.

[pajflareo]

Originally Posted by Onsan

Maybe your interpretation. I said 100oC in the context that wet metal will not get much hotter than 100oC before water has evaporated, it's just thermodynamics, liquid water can't get above 100oC at atmospheric pressure, so if it is present on the metal, the metal temp will not get much hotter than 100oC. My point was to provide reasoning to reassure.

I accept there's quite a few definitions of quenching, "the rapid cooling of heated metal with water" is what I had in mind, relevant to the context of the discussion, I did not think someone would take it as the specific application of heat treatment and submersion in water, my bad.
700mm is wheel height on most, which when a vehicle is driving through water would be not much more than sump height. It would expose diff seals to water ingress and I would guess that and other valid reasons is why MM put a warning in the owners manual stating






Sure, it can go 700mm or deeper even, no one argues that, but just because it can, doesn't mean you should or if you do, that there won't be the chance of an undesirable affect.


I'm erring on the side of caution by suggesting the least chance of a undesirable effect on someone else's pride and joy is to wash it when cool, forgive my wording if that point was lost.

IIRC the Toyota 79 series manual states that before a water crossing the car should left to idle for 15 minutes to cool the Turbo down.

[rotare]

As an FYI if you read the instructions on the back of the can or bottle for some of these degreasers, they'll likely suggest the degreaser will work more effectively if applied to a warm engine.

The description of what is a 'warm' engine is obviously open to interpretation....