Engine Bay Cleaning. Hot or Cold?

After reading countless posts on how to clean my engine bay, I'm still at odds on whether to run my engine while cleaning it, have it semi warm, or completley cold. I would have thought introducing the pretty hot block to semi cold water wouldn't be too good for the engine, but idk. so..poll?

 

Unfortunately I don't have "the" answer, but I play it safe. I think the average car wash water temperature is not cold enough to crack an engine block, but hot metal can be cracked from cold.

Also to add, engines these days are better equipped to handle one extreme to the next, not like yester-year. You are probably safe after a brief cool down, but again, I will play safe and not chance it (hence I have a dirty engine).

 

I Def agree. To be on the safe side I would let the engine bay cool down and then just use hot water.

 

Engine cool. Do not do it on a hot engine as you can crack hot metal. Start the engine once you're done to dry it.

 

Engine cool you have to remember we are still dealing with aluminum heads and a cast block! Doing while hot is an possible way of warping or cracking the heads.

 

COLD!!!!

 

Cold engine. you could crack your manifold if you spray cold water on a hot engine.

 

Dolphins.

 

thanks. was leaning towards cold but this re-assured me.

 

I have used hot and cold method. The engine cleaner I bought said run the truck for 15 min at idle and then apply, rinse thoroughly, then crank and idle for 15 minutes so its dry. Worked great made my engine in my 97 dak look allot better. But on the tacoma I used cold, with a product called simple green and hosed it down. Got most of the mud but still dirty. I don't have a pressure washer so I guess I am sol.

 

Cold!

 

I think it doesn't really matter, its like driving your car in a mean rain or going through a DEEP puddle your engine gets it all the time especially if its lifted. IMO

 

Cold engine. Don't use a degreaser like Gunk, just use SHOUT. Yes, I mean the same shit that you use on stains for your clothes before you wash them. Spray the engine bay with SHOUT, let it stand for 5 minutes, then hose off, start engine and let run for 15 minutes. It works great and supposed to be easier on your rubber components than using GUNK degreaser.

 

A question for you...

When you drive through a water crossing, or a deep puddle on the highway, water enteres your engine bay. It's more volume than a pressure washer and hose. What do you think is happening to the engine?
Rust is happening, that and a possibility of killing your alternator or getting water in your electrical connections. You would need to apply very cold water to a hot manifold to get it to crack. The engine block is not a problem since it's extreme heat is carried through the exhaust.
Wash it as you please. Add dielectric grease to all your electrical connections as a precaution.

 

X2 on the degreasers i always use simple green and my pressure sprayer just watch the electronics.

 

Simple green works well, but etches aluminum.

 

I beg to differ never had it etch aluminum once always used it on all of my motocross bikes as well with full aluminum frames. Now if you use a product like mean green or purple power that stuff will stain aluminum.

 

Used it on my pontoon boat. Your aluminum must have been coated/protected. It etched the hell out of mine.
The simple green bottle used to say "not recommended for use on aluminum." Not anymore...

 

One my spray bottle an gallon refills it say the following (* Note: Do not use on instrument panels, unfinished wood, leather, suede, opals or pearls.). Dont know what simple green you are using. I have been using SG for atleast 16 years with out a hitch. Might be because you are using it on a boat which sees alot of different elements such as various waters and acid rain due to outside exposer. Might have various effects if you also have hard water as well when washing, like I said I am not trying to sell anyone on the product but I have well water and never had any issues with SG.

 

I wash my engine compartment before washing my truck, my truck is an 05' and the enginge compartment looks like brand new. This is what I use on my dirtbike and engine compartment, mix 3 parts water to 1 part wash. this stuff is amazing. Bought from Honda dirtbike / motorcycle dealeship.