[hunterstein555]

I noticed that my local do-it-yourself auto wash place allows you to clean engine bays. However, would I have to park my car in the cleaning bay, and let it sit until it cools off? Wouldn't that take an hour+?

 

[swedespeed7]

Not a good idea. Engine bay should be cold. Pressure washer also bad idea. Clean by hand. Here's a great guide:

 

[hunterstein555]

Not a good idea. Engine bay should be cold. Pressure washer also bad idea. Clean by hand. Here's a great guide:

How to SUPER CLEAN your Engine Bay - YouTube

My only problem is there's a fair bit of oil and grease in the engine bay and wouldn't feel the best about letting that run in to my driveway/grass with a hose

I would also be using GUNK engine cleaner and not using high pressure at the car wash, but yea I am worried about putting water on a hot engine block

 

[swedespeed7]

My only problem is there's a fair bit of oil and grease in the engine bay and wouldn't feel the best about letting that run in to my driveway/grass with a hose

Don't use a hose. You need to use a quality degreaser, spray it on the oiled areas, let it soak, scrub with a good brush, rinse, spray more degreaser, soak, then rinse. You really shouldn't be using that much water at all.

 

[toxicavenger]

I have been using a pressure washer for years on all of my cars with never an issue. On older cars I had to cover the carb and distributor. On newer cars I have never had to cover anything.

 

[swedespeed7]

I have been using a pressure washer for years on all of my cars with never an issue. On older cars I had to cover the carb and distributor. On newer cars I have never had to cover anything.

If you're strategic about it, it's fine I guess. Most people would just go to town though. Adds unnecessary risk to an otherwise simple job.

 

[hunterstein555]

I'm less concerned about pressure washing (probably won't use it) rather than my main question about putting any sort of water on a hot (or warm) engine

 

[swedespeed7]

I'm less concerned about pressure washing (probably won't use it) rather than my main question about putting any sort of water on a hot (or warm) engine

Right. Don't do that. Cold engine only. Hot metal does not do well with cold water.

 

[jvanabra]

Yep, cold engine and water, and not much of it.


My approach is to put a big piece of cardboard under the car, liberally hose everything down with Purple Power (I read some comparisons, it's the best bang for the buck), use some Harbor Freight wire brushes all over the place, wash it away with more Purple Power, then a little bit of water to clean up. Cardboard turns into a gross mess, but generally leaves the ground clean and contains the waste. You really need chemicals and elbow grease for this task - a pressure washer won't emulsify the goop well enough to actually get rid of it... it just moves the grease and oil somewhere else.

 

[swedespeed7]

yep, cold engine and water, and not much of it.


My approach is to put a big piece of cardboard under the car, liberally hose everything down with purple power (i read some comparisons, it's the best bang for the buck), use some harbor freight wire brushes all over the place, wash it away with more purple power, then a little bit of water to clean up. Cardboard turns into a gross mess, but generally leaves the ground clean and contains the waste. You really need chemicals and elbow grease for this task - a pressure washer won't emulsify the goop well enough to actually get rid of it... It just moves the grease and oil somewhere else.

+1,000

 

[toxicavenger]

If you're strategic about it, it's fine I guess. Most people would just go to town though. Adds unnecessary risk to an otherwise simple job.

What is the risk? My wagon I have owned for 10 years and I clean the engine about once a month with a power washer. I do not use chemicals on the engine to clean it. I use the actual hot water from the power washer.

The only thing i can see it doing it maybe breaking a hose that is weak. At that point the hose should have already been replaced.

 

[swedespeed7]

What is the risk? My wagon I have owned for 10 years and I clean the engine about once a month with a power washer. I do not use chemicals on the engine to clean it. I use the actual hot water from the power washer.

The only thing i can see it doing it maybe breaking a hose that is weak. At that point the hose should have already been replaced.

Main risk would be water getting into any electrical component, pushing past any weather seals. These cars have enough gremlins on their own. But, definitely impressive that you haven't had any issues powerwashing the engine for so long.

 

[toxicavenger]

Main risk would be water getting into any electrical component, pushing past any weather seals. These cars have enough gremlins on their own. But, definitely impressive that you haven't had any issues powerwashing the engine for so long.

My wife's 06' I did the same to it up until I sold it last year and we owned it 9 years. My 99' and 00' got the same treatment. If the weather seals are going to leak I would suspect it would that from even driving in a heavy rain.

Maybe my mileage is different from others but I have never had an issue.

 

[CarpeCyprinidae]

My 900NG had multiple oil leaks. On a weekly basis I power washed the entire engine bay while hot. only part I didnt power wash was the distributor & coil - which instead I would give a light coating of WD40 water dispersant.

Would always start up afterwards and after a few moments of revving, tick over cleanly. I made a point of always running the engine for 30 minutes after a power wash to dry it out properly

I would absolutely not advise using water on a cold engine. For me it has to be hot.

 

[Diggs]

I would absolutely not advise using water on a cold engine. For me it has to be hot.

wow.....

 

[swedespeed7]

Start watching at 4:10 for why you wouldn't want to use a pressure washer.

Start watching at 9:24 for hot/cold engine discussion. Cold/warm engine is fine, hot is not.

 

[Joshinator99]

Wow, so a few thoughts:

1. Temperature: the engine can be slightly warm but I would definitely not let the engine get up to it's normal operating temp (ie HOT). Shooting a hot engine with water will drastically cause metal components to rapidly contract. Wouldn't surprise me if an exhaust manifold cracked if it was hot enough. So my vote would be a cool/lukewarm engine temp.

2. Pressure: most new cars (and even my '11 9-5 Aero) had factory stampings in the fuse box and power distribution box covers that specifically said "no pressure washers". Factory weatherpak connectors are designed to resist water, but they will not stand up to direct, high pressure, water streams. I always use low pressure water (take the end off the hose).

3. Chemicals: aggressive degreasers like Gunk and Purple Power tend to etch the aluminum components and really do a number on your plastics. I'd suggest Griot's Engine Cleaner. But honestly, the key is to *maintain* your clean engine bay! That way you never need heavy degreasers. I only use car wash soap with a soft brush in my engine compartments, followed by Griot's Vinyl & Rubber dressing.

Here are a few of my recent engine bays:
https://photos.app.goo.gl/4qVtX1JJXKJETvn19

I'm far from an expert, so this just my 2 cents of course.

 

[hunterstein555]

My car is pretty old, so now I'm nervous about using my 'aggressive' Gunk engine cleaner after what you say about plastics/aluminum

The car has 195k miles. How nervous should I really be about using it? It would definitely be a one time thing - the engine bay looks like it has never been cleaned, and afterwards I'd maintain it. But for the initial cleaning, should I avoid Gunk?

 

[Joshinator99]

My car is pretty old, so now I'm nervous about using my 'aggressive' Gunk engine cleaner after what you say about plastics/aluminum

The car has 195k miles. How nervous should I really be about using it? It would definitely be a one time thing - the engine bay looks like it has never been cleaned, and afterwards I'd maintain it. But for the initial cleaning, should I avoid Gunk?

Keep it mild, say Simple Green or the like. You might even want to disconnect the battery before hand, then use some rags to wipe down some of the harnesses, etc after you're done rinsing before reconnecting the battery. I think you're wise to be cautious on an older car.

Another option for a very dirty part or two would be to take it off the car for a good scrub down, then dry and reinstall.

 

[hunterstein555]

Keep it mild, say Simple Green or the like. You might even want to disconnect the battery before hand, then use some rags to wipe down some of the harnesses, etc after you're done rinsing before reconnecting the battery. I think you're wise to be cautious on an older car.

Another option for a very dirty part or two would be to take it off the car for a good scrub down, then dry and reinstall.

I actually just took a look at the bottle of the Gunk cleaner and it's the 'Foamy' version. Out of 3 different options 'foamy', 'regular', and 'heavy-duty', it's the weakest of the 3. Now I'm thinking it might be light enough to not have too many issues

It advertises that it's used for 'dirt and road-grime' whereas the other two are for oil buildups, grease deposits, etc