The valve cover is one of the critical components of your engine. Without this part, there wouldn’t be a way to get motor oil contained within the unit to deliver lubrication.
Most valve covers are made from aluminum or steel. These metals deliver strength and durability without the same cracking risks as plastic designs, but that doesn’t mean they’re an impenetrable product.
Steel and aluminum can crack or warp when exposed to high temperatures or extreme conditions, leading to a potentially catastrophic situation.
That’s why knowing the information about your vehicle’s valve cover is helpful, especially when you’ve got more than 60,000 miles on the car, truck, van, or SUV.
Valve Cover – Aluminum vs. Steel
Aluminum and steel valve covers both work adequately for your needs. Although debates exist about which is better to stop leaks, most problems occur because of an improper installation. Both metals can fail when you over-tighten the bolts and put them back on without straightening the flange.
You can find the valve cover on the top of the cylinder head. It’s sometimes referred to as a “rocker,” and it’s one of the engine’s most critical components.
Although some valve covers are made from plastic, most of them are either steel or aluminum. The component gets bolted to the top of the cylinder head.
There’s a gap between the valve cover and the cylinder head. That’s where the valve cover gasket seals up everything to create the performance you want for the vehicle. The oil stays inside the engine with this setup, contributing to the overall health of the mechanism.
That’s why having a loose or a cracked valve cover is bad news for your engine.
Why Is It a Bad Thing to Have a Cracked Valve Cover?
Even if your valve cover gasket is in good shape, you can still have engine problems if the valve cover cracks. This issue happens with plastic ones more often than aluminum or steel, but it is still a problem impacting any design.
When the valve cover cracks or becomes loose, oil forces its way through the gap. You’ll end up with an entire compartment under the hood coated in the stuff, and you might even see smoking or drips while parked.
Three primary causes of cracking or looseness occur when examining a valve cover that fails.
- Poor Craftsmanship. The plastic or metal components might have a fault in the material from the manufacturing and processing work done at the factory. These issues typically show in the first 15,000 miles, although failures have come close to the end of a driver’s warranty coverage.
- Extreme Wear and Tear. When there isn’t enough oil in your engine, it eventually self- destructs because it cannot function as intended. The excess friction causes pistons to stick and other parts to wear down, eventually causing something to break.
- Overheating Problems. Oil lubricates your engine parts while working with the coolant to keep everything from overheating. When you don’t have enough flowing underneath the valve cover, the temperatures will get too hot. Even if the gasket is the only thing that is leaking, you can still develop this symptom.
When purchasing a used vehicle, it isn’t always easy to spot a fine crack in the valve cover. That’s why it helps to have a trusted mechanic review the make and model you want to buy before completing the paperwork.
You’ll reduce the risk of purchasing something that might need a repair soon.
What Are the Symptoms of a Cracked Valve Cover?
The symptoms of a cracked valve cover, whether made from plastic, aluminum, or steel, are all the same.
You can experience these issues if the valve cover is intact and the gasket is your problem.
Most people experience an engine that starts running rough. You’ll notice a perceptible change to the rhythm from what you’re used to hearing and feeling from behind the wheel.
If the crack or gap is extensive enough, you’ll have less engine power when stomping on the accelerator. There is a definite lag between the command and when you begin to travel faster.
There is almost always the smell of burning oil in the cabin when you have a loose or cracked valve cover.
When you open the hood, you’ll typically find dirt and debris covering the valve cover because of the oil that sits on the surface. You might experience an entire compartment filled with the stuff, which will get all over your clothes if you lean in to inspect things.
The symptoms of a cracked or loose valve cover aren’t always immediately apparent. Some vehicles don’t display anything while you’re on the road. You might notice some oil spots on the garage floor or in your parking space and nothing else.
If you’re unsure about the status of your valve cover and have these symptoms, it’s a good idea to have your vehicle inspected by a professional.
The cost is quite reasonable for this part. When shopping online, you can find products that range from under $40, like the MYSMOT engine valve cover kit, to ones priced around $700 for BMW vehicles.
My Experience with a Valve Cover Replacement
When I was in high school, I saved up my money to get the best car I could afford at the time. It was a 1979 Mercury Capri.
The Capri from that era looked like the Ford Mustang. My car had a sporty look to it that made you feel like you were going fast, although there was no oomph in the engine for going up the hills near my home.
I drove that car for about six months before I realized that the reason why I had zero acceleration going up hills or for a quick pass was that I had a cracked valve cover.
It was Veteran’s Day. I was on my way into school for a concert when my Capri decided that it was done. The valve cover cracked with a massive popping sound, smoke rose from under the hood, and the timing belt snapped.
My stepfather told me that since it was my car, I needed to learn how to fix it. The Capri had a strange set up in the front, requiring me to take out the radiator to reach the valve cover connections. I got really good at taking it out and putting it back together.
It was before e-commerce was a big thing, so I ordered my valve cover replacement direct from the dealership. The part took two weeks to arrive.
Once it came, I excitedly pulled off the old valve cover, scraped away the gasket, and put on the new one. Then I clamped down the new part, reviewed that the timing belt was positioned correctly, put in that radiator, and fired up the car. I was ready to do some cruising!
Except that oil immediately came through the gasket. I had to shut everything down, get the car cleaned up, and get the spills managed from underneath the vehicle.
Figuring that I’d done something wrong, I pulled off the valve cover. I took out the oil-soaked gasket, replaced it with a new one using the part number from the manual, and tried it again.
I got the same result. In fact, it was a little worse because I ended up having some of the oil get into the coolant, so I had to flush that entire system.
I pulled the parts, replaced the gasket, and tried with my stepfather’s direct supervision a third time. I still got the same result.
That’s when I learned that you need to compare the part number to the make and model of your vehicle. It turned out that my dealership had the same part number assigned to the Ford Mustang engine and the Mercury Capri engine. I was getting the correct valve cover, but not the right gasket.
Once I figured out that problem (and now on my fifth valve cover gasket), I gave everything one last cleaning.
I double-checked my hose clamps, made sure each bolt was tight, and hoped nothing would leak once I got the vehicle started. When the engine turned over and buzzed as it had before, I knew I was in business.
I could even start passing people on the hills!
That car got me through the last two years of high school and the first three years of college. In retrospect, I shouldn’t have put a bunch of gold thumbtacks into the interior’s ceiling because an accident would have been devastating, but it looked great with the red interior!
Those leather seats were always comfortable, and my friends and I learned to love mixtapes because the radio was shot.
It was still a fantastic car, even with the repair troubles I had with it.
If you experience changes in how your vehicle drives, especially from a power perspective, I encourage you to inspect the valve cover thoroughly. Even a tiny crack can have devastating consequences.
