A piece of maintenance that people might not know about is called a valve adjustment. It entails changing the gaps of your valve assemblies within your engine. It sounds like a daunting task, but it’s surprisingly easy if you have a good mechanical background.
The average valve adjustment will cost you around $50 to do on your own, less than $300 for a mechanic to do, or less than $600 for a dealership shop to do. If you have a manual transmission, adjusting your valves is very easy and you should try it on your own (if you’re comfortable turning wrenches).
In this guide, I’ll talk about valve adjustments. I’ll explain what it is, why it’s important, how much it costs to get one done, and even how to do it on your own.
What Is a Valve Adjustment?
A valve adjustment is when you adjust the valves of your engine — but, what are the valves and what are you adjusting? The valves in question are an assembly made up of the lifter, pushrod, and rocker arm.
When you take this valve assembly, give it a combination of fuel and air, compress it, then ignite it, you get power. That’s how your engine works and creates energy in the first place.
Without this process, your engine will be completely silent, and you’ll have a really expensive Flintstone car.
The adjustment process involves changing the height of the valve assembly. This assembly needs to be positioned very accurately, and that will give you the most out of every rotation. If the valves get too far out of position, they can start knocking into nearby components and cause extensive damage.
Why You Need a Valve Adjustment
Every cycle in your engine results in a ton of force. Your valves are attached and assembled pretty rigidly, but these forces add up over time.
After driving long enough, your valves will start to creep out of position thanks to the cyclic loading of force on them. That results in valves that now need to be adjusted.
They could be too close or too far, and either scenario is bad for you.
Problems with Ignored Valve Adjustments
If you never get a valve adjustment, you can run into some issues. Depending on the location and how out of position the assembly is, you could experience:
- Burning oil
- A rough idle
- Loud clanging from the front of your car
- Rhythmic clinking while driving or idling
When you hear a noise, that’s a sign that the valve assembly is running into something else. With rough idles and burning oil, it’s a sign that the sequence is slightly off when it comes to timing, so the valves could be either too close or too far.
If you ignore these problems for long enough, you could seize your engine or consistently lose power to the engine while driving. It’s a very quick and easy piece of maintenance that can save you a ton of money in the future.
How Much Does the Average Valve Adjustment Cost?
The cost of your valve adjustment will depend on your vehicle, how much they need to be adjusted, and where you live.
In general, a shop should be able to do a valve adjustment for less than $300. If you go to a dealership, you should roughly double that figure.
The repair technically can be done by yourself, and doing that will cost less than $50.
For more complicated engines in areas that are more expensive to live in, all of these estimated prices will go up.
Should You DIY The Valve Adjustment?
In an effort to save a few hundred dollars, should you try to DIY the valve adjustment? On paper, the process is very easy. It entails using some feeler gauges and a new gasket.
However, the process also takes a lot of mechanical prowess and background knowledge. If you’re not very comfortable taking things apart and putting them back together, you should avoid this piece of maintenance.
After all, it’s not very expensive for a mechanic to do the job for you.
If you’re determined and comfortable with your mechanical skills, then I’d say that you should go for it.
The only problem is that you can make the problem worse by setting the wrong valve distance. It’s easy to mess up the adjustment, especially if it’s your first time.
How Often You Should Get a Valve Inspection
Your owner’s manual will tell you exactly when to inspect your valves, but I typically do it every 40,000-60,000 miles.
If you take your car to a shop for this inspection, they’ll be able to set it for you in the same sitting (as long as you give them permission).
Step-By-Step Guide to Adjust Your Own Valves
Let’s say you hear a knocking noise in the front of your engine and your car is idling roughly. You want to try adjusting the gap on the valves on your own.
Here’s the quick step-by-step guide to doing exactly that (video guide to follow along):
Step #1: Park on Flat Ground and Get Your Tools
Before getting started, you need to make sure your vehicle is on flat ground. In later steps, you might be moving your car by hand, and this is very dangerous if the ground isn’t flat.
Also, take a moment to gather a flathead screwdriver, feeler gauges that have the thickness found out in step #2, and a set of socket wrenches. That’s all you’ll need for this process.
Step #2: Remove the Valve Cover
On the top of your engine block, there’s a big metal piece that hoses and lines running on the top. This is your valve cover. Start by removing all the fasteners, and getting the wires and hoses out of the way.
The valve cover likely has the cap to check your oil level, so look for that cap if you need help spotting it.
Since it’s in a tricky spot, you might need to jostle the cover a little and wiggle it free before you can fully remove it. Double-check for any forgotten fasteners before getting too frustrated.
Step #3: Find the Specified Valve Clearance
Next, you’ll need to find out what valve clearance you need to target. There will be a sticker in the engine bay somewhere, or you can check your car’s owner’s manual. You’re looking for the valve clearance that the auto manufacturer requires: this will be the gap that you set during the adjustment.
For instance, your car might have an intake clearance of 0.008” and an exhaust clearance of 0.012”
Step #4: Start Adjusting the Valves
Looking at the frontmost valve, you’ll notice that the intake valve is fully open. This means that the exhaust side has to be fully closed since that’s how an engine fires. That’s where we want to start.
Slide a feeler gauge between the bottom of the exhaust valve and the surface it comes in contact with. The perfect level of tightness is when the feeler gauge can move with a little friction. If it moves too freely, the valve is too high up. If it can’t fit in the slot or you have to really shove it, then the valve is too low down.
Keep the feeler gauge under the valve, and grab a flathead screwdriver and a socket wrench. Loosen the nut on the top of the valve assembly, then use the screwdriver to tighten the flathead in the center. Tighten the nut, then check the feeler gauge.
If the feeler gauge moves smoothly with a little friction, you’re perfect.
Step #5: Note Your Progress and Continue Adjusting
The best practice is to write down which valves you adjusted already. That way, you don’t forget anything or waste time doing the same valve twice.
With that done, you’ll want to move to the next valve.
Step #6a: Adjusting Valves on Manual Transmission
With a manual transmission, it’s easy to repeat steps 3 and 4. With your car turned off, put your vehicle into its highest gear and remove the parking brake. Push your car back a little bit and continue doing so until the next valve changes position (in this case, the intake valve 3).
Stop moving the vehicle and set the parking brake. Repeat steps 3 and 4 for this next valve.
Continue the process, moving the vehicle forwards and backward until each valve moves in sequence. Make a note of every valve you adjust, and ensure you have 6 valves written down if you have a V6.
Step #6b: Adjusting Valves on Automatic Transmission
The theory is the same as everything I previously said, even if you have an automatic transmission. The only difference is that you won’t be able to throw your car into high gear and rock it around.
To get around this, use a cheater bar and socket wrench to turn the crankshaft pulley manually. This will allow your vehicle to move around and change the position of your valves in order.
It’s definitely harder to do, but you should give it a shot. If you can’t figure it out, there’s nothing wrong with going to a mechanic after.
Step #7: Replace the Gasket and Reassembly
After all the valves are done, you’re almost finished. Check the gasket on the valve cover that you removed in step #1. The gasket is the rubber ring along the bottom face of the cover.
If the rubber gasket is gray, cracked, twisted, or too firm to compress, then you need to replace it. A replacement valve cover gasket isn’t that expensive, and you can probably find it at your local auto shop.
If the gasket looks healthy, then you can put the valve cover back on.
Re-install all the bolts you took off in step #1, and make sure you tighten them so they don’t come loose while you’re driving.
Turn on the car and listen for the rattling noise. If you don’t hear it, then pat yourself on the back. If it’s still there, take your car to a mechanic for more troubleshooting.
The average valve adjustment costs less than $300 for a mechanic to do the job, but you can try fixing it yourself for less than $50. I’ve personally done it in the past, and it’s not as hard as it sounds.