Engine Bay Cleaning

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Would appreciate advice on best methods to clean the engine bay. I wouldn't say mine is awful but it could certainly use some attention. It strikes me turning the hose on and blasting everything is less than ideal for a series of electrical reasons, but using a smaller brush on every inch also seems like less efficient. Probably some balance in the middle but would love to hear how everyone approaches keeping their engine bay looking just as good as the rest of the car!
 
Yes, I also would be interested in hearing how others handle this. I've seen videos of people that spray down the entire engine bay with a protectant such as Aerospace 303, let it set for some time, and then hose off all the excess.

But my Outback Owner's Manual specifically advises to not wash the engine compartment. I have always followed that advice. But just recently cleaned all plastic surfaces, such as the air cleaner box, fuse box, intake manifold, strut tower caps, etc., with Aerospace 303. It does look much better, but it still doesn't look like what I have seen from engine bays that have been detailed professionally.

On other cars, I've washed engine bays at the car wash before, but have always been careful to avoid the alternator. I'm just not convinced that this is the best practice.
 
I remove the engine covers then cover the alternator, fuse box, throttle body electrical stuff and anything else that looks expensive or not well sealed with grocery store bags, saranwrap and rubber bands. Then spray the dirty areas with degreaser, and the painted areas with car wash soap in a spray bottle, and scrub with an old sock. Rinse with the hose, then I blast it with compressed air or put the hose from the vacuum cleaner on the exhaust side and use the crevice tool, to get rid of large amounts of water. Then remove the plastic bags and start immediately. Drive with ac on until totally dry, usually some highway, followed by some idling and more highway.

I've had issues with water getting in spark plug holes on a couple of cars that don't have the bolt down cops, but blasting out the hole with air solves this, and always drive until totally dry.
 
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I was told by an auto detailer that cleaning an engine was something you should never do. He did it for a living but thought it lead to corrosion and other problems. It sure would be nice to have a clean engine but I just live with the dirt. I live in the rust belt, maybe it's a different story in other environments.
 
I washed my engine a couple times with no problems.

What I do is:
1) Cover the Alternator and Fuse Box with tin foil.
2) Spray engine with Simply Green and scrub with stiff brush
3) Rinse with Garden Hose being careful of electronics
4) Repeat 2) & 3)
4) Let air dry and start engine
5) Spray engine compartment with an Acrylic Sealant
 
Originally Posted By: WobblyElvis
I was told by an auto detailer that cleaning an engine was something you should never do. He did it for a living but thought it lead to corrosion and other problems. It sure would be nice to have a clean engine but I just live with the dirt. I live in the rust belt, maybe it's a different story in other environments.


Is it true that excess dirt on an engine results in an engine retaining heat that it would normally dispel as radiant heat, thus resulting in an engine running hotter? And if this has any basis in fact, how dirty would an engine have to be to make any significant difference?

So if a guy drove a lot of miles on dirt roads, would it be worth the risk to clean off an engine on a regular basis?
 
Originally Posted By: BHopkins

Is it true that excess dirt on an engine results in an engine retaining heat that it would normally dispel as radiant heat, thus resulting in an engine running hotter? And if this has any basis in fact, how dirty would an engine have to be to make any significant difference?

So if a guy drove a lot of miles on dirt roads, would it be worth the risk to clean off an engine on a regular basis?


I would imagine that the cooling system does most of the cooling so a dirty engine wouldn't make much difference. Look at high end luxury cars that have the engine bay covered with plastic covers, a cover under the hood and a closed hood. As long as the radiator is clean the car should stay cool.
 
Originally Posted By: BHopkins
Originally Posted By: WobblyElvis
I was told by an auto detailer that cleaning an engine was something you should never do. He did it for a living but thought it lead to corrosion and other problems. It sure would be nice to have a clean engine but I just live with the dirt. I live in the rust belt, maybe it's a different story in other environments.


Is it true that excess dirt on an engine results in an engine retaining heat that it would normally dispel as radiant heat, thus resulting in an engine running hotter? And if this has any basis in fact, how dirty would an engine have to be to make any significant difference?

So if a guy drove a lot of miles on dirt roads, would it be worth the risk to clean off an engine on a regular basis?


Good point, who knows...
I have read that of all the heat generated in an engine approximately 1/3 goes out the exhaust pipe, 1/3 leaves via the radiator and 1/3 is radiated by the drive train. That being said, I've driven through the mountains of Georgia at 99F fully loaded with a dirty engine and an old radiator without any problems. If the cooling system is good, I can't see a problem.
 
The main thing is to not use a jet spray nozzle. A "fan spray" is more than adequate to wet the engine down, and then you use some soapy solution with a SOFT brush to scrub away any grease, then rinse with the fan spray.

Once that is done, use an electric leaf blower or shop vac (on blow, not suck) to dry off the engine bay, paying attention to any spot where water can "pool" near electronics.

No need to dress the engine bay with anything unless you're prepping for a car show. Any chemical you leave on the surfaces will just attract dust quicker than if it were dry.
 
i have washed many cars engine bays with my pressure washer and a all purpose cleaner like purple power. spray it down with degresser. wait a few minutes and then blast it with my pw.

recently i have started foaming the engine with my foam gun. never had an issue with cleaning the bay
 
too many electronics in modern engine bays to spray a pressure washer all over the place.

I use a can of wd40 (big blast), and some microfiber towels and it cleans everything up.
 
I lightly hose my engines and engine bays down down with most vehicle washes. I'll slosh some of the soapy water from the car washing bucket on dirty spots, give what ever areas I can a wipe with a rag and rinse. I never do it on a hot engine and I don't concentrate water spray on the electrical components.

I've been doing this for over 30yrs and I've never had a problem associated with doing it that I found.

My engine bays look new. Hopefully subsequent owners appreciate it.
 
I've always heard that the best & only way to clean an engine bay is with steam, but very few places do it or have the equipment for it.
 
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^ Yes, that's the one I linked on the previous page. And yes your engine bay does need a clean. At least the oil cap is clean.
smile.gif


 
Anyone ever use the Gunk Foam Engine Cleaner? I heard about this process (foam) a while back and seems straight forward. Cover your engine in it and lightly rinse with water.
 
Originally Posted By: NewEnglander
Anyone ever use the Gunk Foam Engine Cleaner? I heard about this process (foam) a while back and seems straight forward. Cover your engine in it and lightly rinse with water.


I've used it over the years, it works well for dirty, leaky engines. I found the Simple Green purple colored formula to work very well too, it doesn't smell as bad as the gunk, and is safer for aluminum than regular Simple Green.
 
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