Is washing your engine at the car wash a good idea X Preventive Maintenance (PM) as in the old days (related to oil leaks)? jow

Not a good idea to use high pressure or wash it while it's hot.

I regularly rinse mine on shower setting with simple green. Avoid the fuse box and master cylinder.

/thread

Powerwashing from a few feet out may be ok. Just make sure your engine is ON when your doing it.
Snes

Can you explain that for me. I've heard it before but never got the reason why

I actually heard this is the worst thing to do. This is because the cold water hitting a hot engine can cause some serious damage, such as cracking it. I could be wrong.

Yeah, I've always heard that it needs to be cold, or you can crack the manifold or other parts. I've simply used a "light" wash from the hose with some simple green or another easy cleaner and steer clear of the fuse box or other important electronic components.

But there are electrical components everywhere! Is there some way to "waterproof" the connections and fuse box?

Best thing to do is to AVOID power washing the motor at a car wash. Why? The engine is hot. Cold water and an engine cranking along at around 180-200 degrees is NOT a good idea. Notice with most degreasers, it says to spray on COLD engine, wait 5-10 minutes, then spray.

Clockwork: 100% correct on spraying engine down with "shower" setting. Remember guys, there are all kinds of electronics plugs on the engine, air intake, master cylinder, etc. Do you really want to high pressure wash them down and risk damage? Go ahead at your own risk. Chances are nothing will happen, but you do open the door for BS to occur.

When I used to detail cars (my entrepreneurial endeavors when I was young), we never would touch the engine until it was cold.

I wouldn't recommend a pressure washer. As ClockWork said, a simple soaking with Simple Green and a spray with a regular garden hose can go a long way.

Service guy at the dealership told me to do it while its on because if you happen to get some water where it's not supposed to be, you may not be able to restart it if it's already off. I never had any issues either with the engine on or off in my years of spraying. I just used common sense not to blast it too close so I don't cut into anything with that pinpoint waterstream.

The powerwashes I have used have always had hot water coming out of them. I imagine in theory cold water and a hot engine could equal a crack, but I would think you would have to have ice cold water and an almost submersible amount of it.

Personally, I have never had any negative experiences with powerwashing my engine.

You will not crack your block with cold car wash water since it would have to be real cold and alot of it would have to hit the engine at once. The pressure wash around here is heated in the winter so the remote chance of an engine block cracking became even more remote.

I do occasionally wash my engine at the car wash after muddy off roading and I simply let the engine cool a few minutes and then I spray everything down with some Gunk Engine Brite and use the light pressure being careful to avoid direct spray on electrical components and maybe a little harder pressure on the lower parts of the engine but still use the hard pressure sparingly.

I've been washing engines the same way for 20 years and never had a problem.
I hate working on a dirty motor and a dirty motor runs hotter than it should.

From my 45 years of rebuilding/wrenching/ power-washing I have never had crack or serious problem washing it hot, running or not. My nerves are not what they use to be and I always felt it was a slight risk.

1. Washing hot not running would cause condensation in the distributor and not start until you dried the inside. I doubt you would have that problem today with the electronics and no distributor.

2. I always stayed away from the alternator/electronics, exhaust manifold, worked at a dist except oily areas.

3. I have the Simple Green Etc and that will be my choice but always wondered what did the Dealers do.

jow

Spraying water on electrical connections with it running is not good at all!

Spray the bay down with Simple Green.
Brush with soft brush if needed.
Rinse off with garden hose or nozzle.
This is the most important part-
Use compressed air to blast your engine and electrical connections until they are dry. You can also use a good leaf blower. You do not want water to sit in your electrical connections. It can lead to problems.

I agree spray cold water on a hot engine drops the temperature too quickly and may cause cracking, etc.

What I do is spray simple green on the engine while it is still warm, not super hot though. The reason for this: spray a few mist of simple green is no way going to drop that quick to cause any damage. When the engine is warm, oil and gunk are more fluid and can be cleaned a lot easier.

So, the bottom line, warm engine and mist with Simple Green. It's that simple. lol

Hey guys,

This is turning into a "no clear winner" thread. BUT, I will throw this out:

When I used to clean my wheels with Simple Green on my Grand Cherokee, the clear coat would start to peel and separate after a few months. The stuff also dried the crap out of my hands. Powerful stuff. So, if you are going to apply simple green to the engine bay, apply Amour All on the plastic/rubber stuff in the engine bay. I no longer use Simple Green. I do the following:

1) Cover up the Battery and fuse box (anything with wires/plugs exposed)
2) Degreaser, "shower" setting on the garden hose on cold engine
3) Apply cleaner wax to the painted areas of the engine bay
4) Armor All all black plastics/hoses.

My engine bay is in showroom condition BTW.