I need to remove the engine cover because I live in rural AZ and am using everything I can to deter packrats (just replaced fuel injector wiring harness). Apparently there is room for a whole family of the critters under this cover. I have to say that none of the answers here has made me feel overly confident doing this, but don’t feel like I have a choice 
Leave it off. It won’t hurt a thing. The plastic engine covers are just “beauty treatments”
You have a choice to move away from an area with such creatures.
make sure it is just cosmetic. On my wife’s Malibu, the top engine cover is part of the air intake system. It has to be there.
As always on this discussion forum, a Make, Model, Model-Year, and engine size (if known) of the afflicted vehicle helps a lot when seeking advice on things just like this!
CSA
1 Like
I am going to go back in history to engine covers. The 1954 Buick my dad owned had the “nail head” V-8 engine and had the spark plugs under metal covers. When I was in high school and driving, the Buick engine was missing and bucking, particularly at speeds under 30 mph in high gear. I replaced the spark plugs, which didn’t help. My dad told me to take it to the Buick dealer. He was afraid it might need a valve job. I took it to the Buick dealer for a diagnosis. I explained to the service writer that I had replaced the spark plugs, but it didn’t help. The car was driven into a service bay and I went into the showroom and sat down. I had been sitting only five minutes when the service writer called me back to the garage area. The mechanic had the car running and said, “Do you see what’s wrong with your car?” “No”, I replied. He then turned off the light above his service bay and put a screwdriver against the head and brought the shaft toward a spark plug. A spark jumped to the screwdriver shaft. The mechanic looked at me and said, “You should have been smart enough to have figured this out”. He then laughed and said, “You took the covers off, replaced the plugs, and then put the covers back on before you started the engine. The spark has been jumping to these metal covers”. The mechanic replaced the rubber boots on the spark plug wires and the car ran perfectly. The total charge was $2.58. My dad was so happy when I picked him up at work that he gave me $5 and let me keep the change.
After 60 years, I still don’t understand why Buick had these covers over the spark plugs. Today, I really don’t see the reason for the engine covers.
It’s a 2010 Toyota Highlander—-is the engine cover cosmetic or crucial?
Cosmetic on our 2013 Highlander V6. I would bet it is cosmetic only on your model also.
I copied this from some website. I suspect the last bullet is the important one:
The plastic covers in an engine compartment serve a few purposes:
- The obvious, cosmetic purpose of maintaing a “clean” appearance
- Protect the motorist from moving parts and dirty surfaces when performing the most basic maintenance items (checking oil). They also hide things that shouldn’t be messed with by untrained people.
- Controlling engine noise, reducing it in both the passenger cabin and the exterior vicinity of the vehicle (still, a cosmetic purpose)
- Controlling airflow over parts of the engine and supporting equipment to maintain proper cooling
- Increases maintenance time so mechanics can charge more
I think you’ve got it backwards . . .
That is quite possible the one that matters to most people . . . the ones that understand very little or nothing about cars
One of my neighbors fell into that category
When he popped his hood to top off the washer fluid level . . . the extent of his car maintenance abilities, by my estimation . . . the only thing he cared about was a tidy appearance. He cleaned that engine cover until it looked immaculate, even if it took 10 minutes
If you do remove the cover, keep it for when you sell the car.
1 Like
In my 2006 Toyota Avalon, the engine cover helps dampen the sound of the engine into the cabin. I also presume it helps protect the engine components from dust and stuff.
1 Like