Topic: Cleaning the Engine - hot or cold?

[andy750]

I have to clean the oil leak on my K4 engine, and after a little research have a few questions.
1. It seems that its recommended to clean a COLD engine and not a hot one - anyone know why?
2.  Is there any cleaning difference between GUNK and Simple Green (never used it but Ive used GUNK before).
3. Any other tips for getting rid of the oil residue between the fins?

thanks
Andy

[dusterdude]

the only reason i know of between hot or cold is,the cold water on a hot engine could possibly make the engine cases or something else on the motor crack.

[johnny-from-bel]

the only reason i know of between hot or cold is,the cold water on a hot engine could possibly make the engine cases or something else on the motor crack.

Correct. It is called thermo shock. Use hot water if you decide to clean the engine while warm.

[andy750]

Mmmm but what about when its raining?? Wouldnt cold rain crack hot motors according to this logic? 

Thanks for the replies,
Andy

[paxtonpony]

Rain and standing water tends to have a temperate very close to the air temperature.  Since the metal is already in contact with the air, and therefore that temperature, there is not a large variance.  However, if it's a warm day and you have a very warm or hot engine, there will be a large difference in temperature from very cold hose water.  That's when you have your problems and can develop stress fractures.

Good question though, most people don't know.

[SD750F]

Rain cracking engine, well not really. It has to do with thermal capacity. Water is an excellent retainer of thermo energy (insulator) that is why water will hold heat for a long time, or cold for that mater. Also is has good thermo conductance. Okay so really the volume of the water is direcly propotional to it's capacity. Spraying large volumes of water such out of a hose will wick away much more heat than small individual rain drops. Even if the rain is coming down hard. But if you would drive through a large puddle of water, that would be the same as spaying with a hose. But in that case wouldn't you have "other" problems like hydroplaning???

I tried to make this physics problem straight forward. But I could provide the thermal capacities of water calculations if anyone is interested...

[andy750]

Ok so its beginning to make more sense now -thanks for the very informative replies -SD750F if you were serious about those thermal calculations then yes Id be interested in learning some more. Particulary about how the surface area of the water versus its thermal capacity can lead to such a dramatic result such as cracking the engine....and I realise its about thermal conductivity and metal fatigue. More physics please 

Thanks,
Andy

[kghost]

I like simply green....

Use it undiluted to get the really heavy stuff off...let it sit a bit

Be sure to rinse completely...leaving it on will foster corrosion of aluminium.

[Nate]

I have a Simple Green knockoff sold by Costco, just called all purpose cleaner.  I just tried it on a part the other day and it seems to work even better than simple green, not to mention it's cheaper and is only sold by the gallon.

[mcpuffett]

spray carb cleaner is good for those awkward areas  ,   mick.

[SteveD CB500F]

Gunk is old-fashioned and nasty stuff.

Don't let it drip off your engine onto tarmac as it disolves the binding agent. (don't ask...)

It's also very nasty when washed into the water course.

[Terry in Australia]

I had 4 gallons of stale gas so I mixed it 50/50 with diesel and sprayed some of it on my warm engine, and it cleaned the gunge off really well. I've heard "Simple Green" is very good, but I've never used it. Cheers, Terry.

[andy750]

Thanks all - great info as usual. Much appreciated.

cheers
Andy

[chippyfive50]

I know they use DAWN dish detergent to remove oil from wildlife after a spill...
I have seen it used after a semi oil tanker crash to clean the road..

[kghost]

I use tide laundry detergent to was my floors and even my hands....suppose that would work too in a water mix.

Tide and gas....mmmm might set off the TSA....

[jabbadeznuts]

I spray on the cleaner with the engine hot, hoping that the grime will be a little looser. I then wait for the engine to cool 'till it's warm to the touch. Spray it down and attack with a tooth brush for the hard/extra dirty spots.