[stochastic]

I recently took my i30 on a camping trip where it faces 200km of gravel roads in the rain.  Now my engine has spatters of mud all over (even on the underside of the bonnet).  I'm taking it to the dealership to get a it looked at as it now shakes when in reverse, but I think I should clean the engine first.  Is it safe to just spray it down with a hose?  How would you clean the engine?

[eye30]

  Is it safe to just spray it down with a hose?  How would you clean the engine?

I, personally, wouldn't hose down with water.

It would be best if you take it to be steam cleaned?

[Dazzler]

I have cleaned engine bays with a hose many times but I am careful how I do it not spaying any electrical parts like alternator, etc too aggressively 

[Surferdude]

A Gerni high pressure cleaner gives you better control IMO. But like Dazz I have no problem cleaning with a hose.

[kabukiman]

Never ever hose your engine down.

People say it's alright, I see little workshops do it sometimes and detailers at some car yards will do it.

But it can cause serious problems.  Many of the electrical connections in the engine bay and the computer itself are not completely waterproof, if at all.  High pressure hoses etc especially might cut through road grime on metal parts but they wreak absolute hell on smaller connectors and wires.  A mate of mine hosed his engine down, including the computer and fuse box and several connections were wet when I saw it, and he wondered why it wasnt starting properly and revving by itself

It can litterally kill a car.

I'd get some brake cleaner or wd40 with a damp cloth and get in there and wipe everything down yourself.  Mind some of the plastic and rubber parts as wd40 can harm certain types I think

Maybe work top down, damp cloth, cleaner when necessary and then jack the car up and clean it from underneath (use stands when you get under it or you may slightly die a little)

[Phil №❶]

Sound advice IMO, water travels up electric cables by capillary action like mercury in a thermometer. The copper oxidizes and becomes brittle, you know what happens next 

[Surferdude]

I understand what you guys are saying. However, every car I've ever had gets pretty wet around the engine bay when I driving in heavy rain.
So how is that different?

[Phil №❶]

Are you talking rally or conventional 

[Surferdude]

Are you talking rally or conventional 

Any car if the rain is heavy enough. Try it and lift the bonnet after a decent run. Spray goes everywhere. I appreciate it's not a direct pressure against vulnerable parts but it happnes a lot more than an occasional engine wash which might be necessary only once or twice in the life of a car.
IIRc the original query concerned a one off type clean after running on muddy roads.

[Phil №❶]

We mustn't get rain like you do up north. Even freeway driving shows residue in the bonnet channels. Engine heat does a good job at keeping the electrics dry. Connectors like horns are not well protected and sometimes do fail, as you mentioned, any water that does enter is not under high pressure and I think that point is significant. 

[2i30s]

a lot of cars come with factory fitted bonnet scoops,there engine bays must get covered in water. 

[rustynutz]

I've washed down the engine & bay of pretty much all the cars I've owned over the years, usually after spraying with engine degreaser and had no issues.
About the only car I haven't is my i30, and that has probably more to do with not living on dirt roads these days than anything else.

[kabukiman]

The spray fron under the car and through the grill is minimal when compared to a concentrated blast from a hose.  There is quite a bit more volume of water from hosing an engine down than driving through the rain

Driving through the rain can kill a car too.  Watch those deeper puddles!

If you must wash an engine with a hose, perhaps try and water proof the connections and electrical stuff yourself, temporarily, and use a low pressure

Also wait until the engine is cold, don't run a hose on a hot engine 

[bryanj86]

I have and will continue to hose down my car engines every so often. Dont stand there soaking it with 10 minutes of water. But I will give it a lite hose down to get the dust off... Never had any issue with my Magna, Rav4,Xtrail and now my i30

[Phil №❶]

But subsequent owners probably have   

[bryanj86]

I know most panel beaters will hose off the engine once work has been done. I think as long as you dont hose at electrical equipment you're fine.

[i30niko]

I have and will continue to hose down my car engines every so often. Dont stand there soaking it with 10 minutes of water. But I will give it a lite hose down to get the dust off... Never had any issue with my Magna, Rav4,Xtrail and now my i30

With the ever increasing electical components in a modern vehicle I would be hesitant to wash down an engine. Maybe 40 years ago it would be a different story, but there are cables and electrical components wherever you look now. Just the thought of it scares me

[Dazzler]

Don't think I better hose the motor in my new car ...

[komaterpillar]

I have washed down hundreds (probably approaching thousands) of electronic engines, with both a hose and pressure cleaner, both petrol and diesel, and am yet to have a drama. I will continue to do so aswell. If the engine harness is in bad enough state to allow the ingress of moisture to affect operation or damage/corode wiring, than it will be in need of repair/replacement anyway. Almost all engine harnesses for the last 10 or so years have utilized "deutsch" style plugs wich are a waterproof plug anyway.

[Shambles]

I once had my XJ6 (3.6L) engine bay jetted by a mobile valeter. He insisted on keeping the engine running whilst he was doing it, despite my reminding him that petrol doesn't grow on trees. I seem to remember his response was along the lines of "too many complaints from owners unable to start their cars after he'd visited".

So, a no-no from me.

[rustynutz]

It would be a no no from me too if I owned a Jag.....


Otherwise it's a yes from me......

[Doggie 1]

Don't think I better hose the motor in my new car ...

That's a pretty pink. 

[Dazzler]

That's a pretty pink. 

Yeah    Actually this one is a bit nicer under the bonnet than the previous one