Spraying water into a hot engine

This will be my first and only somewhat serious post in this thread as I generally just feed trolls a helping of troll food. These types of threads kinda **** me off because there are people who really dont know much about whatever the subject is and this ******** just confuses them more. You have the people who may smell a troll make a less aggressive, measured response just in case it is for real. Then you you have the people who start telling the OP how wrong they are and the **** storm ensues, which is exactly what the troll is looking for. I freely admit I dont know too much about flying/airplanes/engines/avionics etc. Its pretty easy to tell that these are regulars getting their rocks off stirring up people like Tom. Whoever you are, I am sure that you know a helluva lot more than I do, but I can learn and you will always be a dick.
 
I wasn't trolling. This was a serious post. In case the humor impaired don't get it, for the record I am not Ed and not Tom and not Henning and actually nobody else on here. Now just let this thread die a natural death. Stop posting here! Quite simple.
 
Lots of wadded up panties around here. Relax girlies.

Take a deep breath. Exhale. Again.

All better now?

Good.
 
Your responses here kind of remind me of the "navy seal copypasta" you can google. Filters here won't let me paste it.

I know others have said it, but if someone did that to MY airplane I would be upset. I'd want maintenance to check it out. I don't know that it would've caused any issues, but I would be concerned and I would have a right to be since that engine costs over 30k.

The folks on this place can be pretty harsh I've found particularly when people come in to ask a question and then argue with everyone.
 
GLMS_NC said:
Shock cooling? http://www.avweb.com/news/maint/182883-1.html
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And that article is about air cooling, not being hosed down with water, which has around 800 times the density of air and therefore a far greater capacity for extracting heat. The edges of the cooling fins would contract far faster than their conjunctions with the head, placing plenty of tensile stress on them and perhaps being responsible for the "tink" the OP heard. The manufacturers will tell you that cracked fins are cause for taking the cylinder out of service, since the crack can propagate into the head and lead to failure.

See https://en.wikipedia.org/wiki/Heat_capacity

Water has more than four times the heat capacity, per unit mass, than air. Realizing that air's density is so much smaller than water's should tell one that hosing down a hot engine is simply asking for trouble.
 
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"Shock cooling" may have been an incorrect term where simply "thermal shock" should have been used... same thing. I understand some cracked fins may be blendable.
 
I worked for a helicopter operator who had been spraying down hot engines with cans of degreaser before doing 100hr/annuals for as long as he's been in business (20+yrs) never any issues with early failure there. :shrug:
 
jaybee said:
I worked for a helicopter operator who had been spraying down hot engines with cans of degreaser before doing 100hr/annuals for as long as he's been in business (20+yrs) never any issues with early failure there. :shrug:
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Degreaser out of a can has neither the volume of water out of a hose nor the heat capacity of water.

Heat capacity:
Air: 0.0012 J/ml*K
Solvent: 1.6 J/ml*K
Water: 4.2 J/ml*K

And I can't imagine that there's more than a liter of degreaser used. Probably not even close. The hose would be flowing 20 l/min or more.

EDIT: Forgot about the heat of vaporization, which has a huge effect here as well:

Solvent: 250 J/ml
Water: 2200 J/ml
 
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Dan Thomas said:
And that article is about air cooling, not being hosed down with water, which has around 800 times the density of air and therefore a far greater capacity for extracting heat. The edges of the cooling fins would contract far faster than their conjunctions with the head, placing plenty of tensile stress on them and perhaps being responsible for the "tink" the OP heard. The manufacturers will tell you that cracked fins are cause for taking the cylinder out of service, since the crack can propagate into the head and lead to failure.

See https://en.wikipedia.org/wiki/Heat_capacity

Water has more than four times the heat capacity, per unit mass, than air. Realizing that air's density is so much smaller than water's should tell one that hosing down a hot engine is simply asking for trouble.
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I agree with you. Which is why I mentioned the article on shock cooling. I wound never hose down a hot anything I value.
 
Horse said:
of
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Horse said:
What is lost in all of this is that the restart was one of the easiest restarts I've had with an engine only shut down 30 minutes previously.
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Actually, what is lost in all of this is that you did something you didn't have a clue about to a $30,000 engine that wasn't yours. No matter what you "thought", you were out of line and you should show more respect for other people's property. Next time, ask first.
 
mondtster said:
As for the OP and his problem, I seriously doubt any damage was done.
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Seems to me the only stress involved in this incident was due to the CFI's raging diatribe rather than the other way around.

IF the cylinders were toasty hot (i.e. >500F) AND the OP directed a steady stream of cold water at one side of one cylinder then MAYBE there would have been a little mechanical stress involved but even then I doubt there'd be any chance of damage. A back of the napkin estimate of the amount of water encountered per minute when flying at 200 mph through heavy rain comes to around 1-2 gallons per minute for each square foot of exposure. Depending on the hose diameter and length as well as the water pressure at the tap, I'd expect that the hose was delivering 2-3 times that. So yes the amount of heat carried away was likely higher but not so much higher that it would "ruin" a cylinder or two. Probably the biggest effect would be the loss of clearance between piston and cylinder wall and if that was significant the starter would likely have trouble cranking the engine.

For the OP, the next time you want to cool things down in an effort to prevent hot starting issues, soak a rag in cold water and apply it to the, gascolator, fuel pump, and fuel lines assuming you have a fuel injected engine (carbureted engines generally don't have hot start problems). At least that way you won't be as likely to encounter a steaming CFI. The usual source of hot start woes is a hot fuel pump vaporizing the fuel in it leading to near zero fuel pressure out of the pump.
 
I like hosing hot chicks, cold chicks not so much.
 
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