Question about cleaning engine bay

**mrq0604** · 04-20-2019, 01:29 PM

I soaked a rag with degreaser and wiped the various parts of engine bay as long as my hands could reach them.

I did not rinse the engine bay with water. I just let the degreaser dry.

I was wondering whether this could damage plastic parts in the engine bay

Thanks in advance

**SWETM** · 04-21-2019, 06:10 AM

Depending on the degreaser yes it can damage the plastic and also other material in the engine compartment too. At least try to mop up the most of it and maybe use a waterless wash or rinseless wash to get it neutralised. Plastics has oils in them and most degreasers is to desolve oils. So the plastic will be drying out more and more over time if repeated this way of cleaning. Maybe 1 to a couple of times it can be fine with it but it's a risk of when it's actually done damage. The plastics become brittle the more oils that desolves in it. I'm always carefull to have chemicals drying on a vehical if it's not says it's good to be doing that. Smaller amount can often be evaporated off but if it's still wet for a long time it keeps working with what it's made for as desolve oils mostly with a degreaser in this case. Something like an IPA sprayed on the paint and while you wipe it off you see it evaporate and that's fine. But say you have used masking tape and it gets soaked with IPA. This if leaved on too long can make the clearcoat so soft it wrinkle when takeing off the masking tape. It's an extreme scenario but also something to have in mind to.

**Thomkirby** · 04-21-2019, 10:21 AM

Originally Posted by SWETM

Depending on the degreaser yes it can damage the plastic and also other material in the engine compartment too. At least try to mop up the most of it and maybe use a waterless wash or rinseless wash to get it neutralised. Plastics has oils in them and most degreasers is to desolve oils. So the plastic will be drying out more and more over time if repeated this way of cleaning. Maybe 1 to a couple of times it can be fine with it but it's a risk of when it's actually done damage. The plastics become brittle the more oils that desolves in it. I'm always carefull to have chemicals drying on a vehical if it's not says it's good to be doing that. Smaller amount can often be evaporated off but if it's still wet for a long time it keeps working with what it's made for as desolve oils mostly with a degreaser in this case. Something like an IPA sprayed on the paint and while you wipe it off you see it evaporate and that's fine. But say you have used masking tape and it gets soaked with IPA. This if leaved on too long can make the clearcoat so soft it wrinkle when takeing off the masking tape. It's an extreme scenario but also something to have in mind to.

I agree with SWETM, you must rinse off that degreaser product. Read the manufacturer's recommendations, most recommend to flush the product off.

You did not say what year is your car but most modern engine compartments can take a light spray of water and keep on running strong. Think of all that rain you drive through does the same thing.
AG sells several great products to help protect and keep that plastic and rubber looking great. And suggest you try a wheel brush in that engine bay next time to protect the hands from the degreaser and any cuts. Read some of Mike Phillips articles on engine bay cleaning, and he knows the process very well.

I attended the Boot Camp at AG and ours looked like this:

Question about cleaning engine bay-img_0008-jpg

**TTQ B4U** · 04-21-2019, 01:16 PM

I use a spray bottle of water to rinse off areas that I work on under the hood. Most engines are pretty shielded from water from below but I've been around long enough to know that I'm not risking a garden hose or pressure washer under the hood of a vehicle that's not mine. Never had an issue with my method and it doesn't take much longer at all.

**Calendyr** · 04-21-2019, 04:15 PM

A little off subject here but I tried using the foam cannon to coat the engine in degreaser foam and it worked amazingly well! Thank you Mike Philipps for showing that in one of your videos. You used a foam gun but the foam cannon works just as well. Also I purchased a 40 degree tip for my pressure washer with a larger hole (from 2.0 mm to 3.0 mm) and I can rinse the engine off safelly with the pressure washer now. Super happy!

Now in response to the OP, don't let degreasers dry in the engine bay. Grab a garden hose, put it on a low pressure setting like Garden or fan and spray the engine off.

**Oz_TCH** · 04-21-2019, 04:41 PM

**mrq0604** · 04-21-2019, 06:07 PM

OP here

My car is a 2011 BMW (original owner). And this is the first time I used degreaser to clean engine bay. I just didn't want to spray the engine bay with water, so I just wiped it with a rag soaked with degreaser.

I used a degreaser from a company called Simoniz. It wasn't diluted at all.

I do not drive this car often. Less than 3000 miles per year. I've probably driven the car fewer than 5 times since cleaning the engine bay. But I noticed some white spots in plastic parts. When wiped, it went away. Is this bad?

Can I just wipe the engine bay with rag soaked with water? Or should I just apply 303 Aerospace Protectant?

**SWETM** · 04-22-2019, 04:35 AM

Originally Posted by mrq0604

OP here

My car is a 2011 BMW (original owner). And this is the first time I used degreaser to clean engine bay. I just didn't want to spray the engine bay with water, so I just wiped it with a rag soaked with degreaser.

I used a degreaser from a company called Simoniz. It wasn't diluted at all.

I do not drive this car often. Less than 3000 miles per year. I've probably driven the car fewer than 5 times since cleaning the engine bay. But I noticed some white spots in plastic parts. When wiped, it went away. Is this bad?

Can I just wipe the engine bay with rag soaked with water? Or should I just apply 303 Aerospace Protectant?

Proberly it's residue from the degreaser the white stuff. Yes wipe it off with water and then apply 303. If it's clean enough that is. Otherwise try to get a waterless wash or rinseless wash to clean it a little more thoroughly if you are hesitate to use running water. And then apply the 303.

**mrq0604** · 04-22-2019, 03:18 PM

Originally Posted by SWETM

Proberly it's residue from the degreaser the white stuff. Yes wipe it off with water and then apply 303. If it's clean enough that is. Otherwise try to get a waterless wash or rinseless wash to clean it a little more thoroughly if you are hesitate to use running water. And then apply the 303.

Thank you. Will also clean wire wrappings (rubber?) as well