Engine Cover Purpose

Is any purpose served by the plastic engine cover on my '95 Toyota Avalon’s engine (1MZFE)?

I thought I would have an easier time changing the front (left side) 3 spark plugs the other day. I loosened one of the 5mm allen head screws. When I went to loosen the other one, I noticed that the head had corroded, and my wrench could not get a grip. Realizing that I was screwed, I uttered words not suitable for church.

Fairly easy to remove the screw with my easy-out (screw head was soft, easy to drill). But now I have to replace the bolt, and it has a flange on the bottom that retains it on the cover.

So do I really need this cover?

Sound deadening. Somewhere along the line we lost one on a car we used to have, and engine noise was more obvious in the cabin.



I know people who drive vehicles with it removed.

But what does is, it protects any wiring under it from debris and water. And helps reduce noise from the injectors.


1 Like

Well, then. I’ll have to leave it attached with the two clips underneath, and one screw. It’s all but impossible to replace the other screw, as they’re held in place with some type of flange on the bottom.

Toyota wants upwards of $93 dollars for a new one.
I wont do that, since 1) I believe it can stay on with one screw.
2) I’m cheap.

The engine cover hiding the spark plugs is nothing new. The 1954 Buick my parents owned that I later bought from them had metal covers over each bank of spark plugs. I never did know the reason. When I was in high school, the engine in that Buick was missing badly. I changed the spark plugs, but it didn’t help. My dad made an appointment with the dealer and had me take the car in. My dad was worried that the car might need a valve job. I drove the car into the service area and after it was checked in, I went to sit in the show room. I hadn’t been there 10 minutes when I was called back to the service department. The mechanic had the hood open and the engine running. “Do you see what’s wrong with your car?” he asked. “No”, I replied. He then turned off the light over his service bay and took a screwdriver. He put the tip against the cylinder head and brought the shank up near a spark plug. The spark jumped to the screwdriver shank. The boots on the spark plug wire ends were bad. Had I left the spark plug covers off, the engine would have run fine. The mechanic looked at me and said, “You should have been smart enough to figure this problem out, boy”, and then laughed. He replaced the boots and the parts and labor were $2.45. When I picked my dad up after work with the car running smoothly, he was delighted. When he asked what it cost, I said that if I told you it was fixed for less than $5, could I keep the change? He agreed and gave me $5. I then handed him the bill for $2.45. I had enough money to take Little Iodine to the movie that weekend. That was 1958.


The stud is $1.21, the nut should only be a few dollars.

You could buy a 6 mm cap screw at a hardware store to replace the damaged stud.

1 Like