Acura TSX Spark Plug Replacement/Valve Adjustment

Hello again,

I took my 2007 Acura TSX with 100k miles in for service a months for an oil change/tire rotation. At that time, the Service Advisor recommended that the spark plugs be replaced and a valve adjustment be done. Currently, the car is at 105k miles (wife drives a ton). Anyway, it will be due for service in the near future, and I am not sure what really should be done. What’s the longest I can go with spark plugs? I was going to have them replaced this next service visit if truly necessary.

Also, the engine makes no noise. Is a valve adjustment really necessary? I am on a tight budget, so I really don’t want to have to do maintenance that isn’t really necessary. Plus, the valve adjustment is pretty pricey.

Any advice/guidance would be greatly appreciated!

Tight valves don’t make any noise, they just burn exhaust valves. Spark plugs should be done at the intervals shown in your owners manual. I would be shocked if it was over 100,000 miles.

If you don’t like the price of a valve adjustment , you will absolutely hate the price of valve replacement.

Here’s what the manufacturer of your vehicle specifies.

“Adjust valves during service only if they are noisy.”


What is the worst that will happen if you wait 10k over the recommended replacement interval for spark plugs? The car seems to be running fine.

Anyway, I am hoping to have them done ASAP, but was wondering what will happen if you postpone changing them?

Gas mileage suffers.

Your car has an information display which will tell you when to do maintenance items. You can look up its codes on the internet (so, for instance, you’d google “2007 TSX service 1A”)

At any rate, the 100,000 mile service on your car calls for changing the oil, rotating the tires, and inspecting a bunch of stuff. It also recommends that you change the cabin filter.

The 110,000 mile service calls for an oil change, tire rotation, valve inspection and as @Tester said, only adjust them if they’re noisy, and a spark plug change.

If this were my car I’d do the spark plugs, oil change, tire rotation, and cabin filter. I would personally inspect everything myself but if you don’t know what you’re looking for you should have them do it. If they claim something needs fixing, I would want them to show me how it is broken first.

Assuming the service adviser told you the valve adjustment needed to be done based on the car’s mileage and not because he heard them making noise, I would also find a new place to take it, because this one is trying to drain your wallet unethically.

If you wait on the spark plugs, probably nothing bad will happen. But I wouldn’t personally want to take the chance at wrecking the engine just to put off a relatively inexpensive maintenance procedure for only 10k miles, especially since if your wife really does drive a ton, it’s going to happen very soon anyway.

Given the many discussions we’ve had about valve adjustment, and how they can be out of adjustment without being noisy (if they’re tight), I’d get them checked (valve cover off, check that they’re in spec) even if they aren’t noisy. I don’t blame the dealer.

IMHO, if the manufacturer doesn’t recommend a service unless it’s required under certain conditions, why would anyone pay for that non-required service?


So you’re a believer in lifetime ATF?

ATF is a consumable.

A valve adjustment isn’t.

From experience, and all the Honda’s I and my family have owned, and other peoples Honda’s I’ve serviced over the years, there have only been two conditions where I’ve had to adjust the valves.

If the valves are noisy. And in one case the valves were noisy because two of the locknuts for the valve lash adjustment screws were missing.

Or if the head was disassembled and brought to a machine shop for service.

Once the valve lash was set and the valve cover was installed, the vehicles went 100,000’s of miles without ever touching the valves again.


Now you bring in actual experience, don’t confuse me with the facts!

Since you’ve dealt with multiple Hondas, haven’t found an issue with ‘tight’ valves, I’ll withdraw my recommendation. No need for a valve adjustment if they’re not noisy.

That audible valve lash recommendation is absolutely, 100%, without a shadow of a doubt one of the biggest loads of mechanical bull excrement ever placed out there for consumption.


Did you design the engine?

And write the recommended service specs?

In all the years I’ve serviced Honda engines, I have never seen a problem with valve recession due misadjusted valves.


My opinion is based on 40+ years of working with mechanical lifter engines (both nut/screw and buckets) and that includes time served at a Honda dealer. The vast majority of those checked needed some adjustment and that applied to other techs in the shop besides myself.
A couple of buddies of mine whom I used to work with at Honda still work for a Honda dealer to this day with 30+ years in and their position on lash is the same as mine.

As to cylinder head problems due to improper lash I have seen failed cylinder heads due to tight lash. In some cases the heads were not even worth repairing as not only was hunks of the valve and valve seat missing but chunks of aluminum around the seat.

I’ve also done a lot of my own cylinder head work with valve/seat grinding and so on. Some of that head work was due to sheer miles. In other cases it was premature valve leakage due to tight lash.

One Subaru that came into the shop (screw/nut like Honda) had both cylinder heads trashed beyond repair due to tight lash. This car was less than 1 year old and had 7k total (yes, a single 7…) miles on it.

Car makers put out a lot of recommendations that are crap. Much like the the Subaru owner who asked Subaru corporate when to change his automatic trans fluid and he was told by the “technical department” to change it “when it’s black and smells really, really bad”. Pretty damned pathetic.

The only way I can see valve damage occurring on a Honda engine when doing a valve lash adjustment is if it’s done while the engine cold.

The valve lash must be performed while the engine is hot.


It has to be taken under consideration that when the engine heats up the valve lash adjusting screw is going expand along its length along with the valve stem.

So if the valve lash is performed while the engine cold, the adjustment screw along with the valve stem will get longer due to thermal expansion. And this will cause the valves to hang open.

But I’ve never touched the valves on a Honda engine once the valve lash has been adjusted properly after a service or repair.


Tom & Ray’s take on the subject.

Here’s an earlier thread

I’ve owned 4 Hondas ('75 Civic, '81, '85, '88 Accords).
Did valve adjustment at the recommended intervals (15 or 30k miles).
Most of the time clearances increased, but occasionally I’d find valves going tight.

Thanks for all of the information and recommendations. You are all very knowledgeable on this site, and I am glad that I came across it! Thanks again for all of your help!

If you plan to keep the car for any length of time, suggest you have all this work done.

Many manufacturers are specifying 100K for spark plugs. Here’s the problem. Part of their motivation for this high number is the car rating magazines include how much maintenance expense is to be expected if you own the car. And the magazines use the manufacturer’s suggested intervals to cost that out. Now if you wanted your car to come in showing a low cost maintenance in comparison to other cars, what would you do?

100 k is too many miles in my opinion for spark plug changes. It’s not that the newer-type plugs won’t last that long so much, but that they can get coated with very stubborn carbon deposits and can become difficult to remove without damaging the threads in the cylinder head. If that happens the replacement spark plugs might not be able to form a tight seal, so expensive cylinder head reconditioning will be needed. The other problem is that the plug gap can widen over miles driven. Modern fuel injection/electronic ignition systems compensate for this by raising the spark voltage. But that can overheat and damage the coil or coil packs. Coil packs are a lot more expensive to replace than spark plugs.

Valve adjustment. Think positive. It’s possible all that needs to be done is measure it, all the valves will remain within specs, and no adjustment will be needed. That won’t be very expensive. Ask what they’ll charge if no adjustment is required. On my 4- banger Corolla that job takes about 45 minutes to do. A pro could do it in 30 minutes or less I suspect. If it turns out no adjustment is needed, then you’ll know the valves are fine, plus you’ll have a baseline to compare with for the next valve measurement.

If you don’t do the valve measurement, since it isn’t in the manufacturer’s maintenance schedule apparently, most likely no harm will be done. I’ve measured the valves for years, first on my 70’s VW Rabbit, and my 90’s Corolla, and never once has an adjustment been required. I just write the numbers down in the book, verify they resided within the spec limits, and put it all back together.

But what if you don’t measure them, and one or more actually they are out of spec? If the valves are a little too loose, the worst that happens usually, besides some noise, is you lose some engine power. Takes longer to accelerate. But if the valves are too tight, especially one the exhaust valves, that can be a bigger problem. A tight valve wouldn’t properly seat, and some combination of loss of compression and improper heat transfer could occur, the latter of which could badly damage the valve and/or the seat.

So what would I do? At 100 K, I’d measure the valve clearances.

If you want to take a chance, and haven’t noticed any performance loss, and tend to not do hard accelerations or other driving styles that might be causing hotter than normal conditions inside the engine, you can probably get away with skipping the valve clearance measurement. But I wouldn’t.

I’ve been to the mechanical lifter rodeos (aircraft, motorcycles, and foreign brand cars) my entire life and believe my comments are 100% accurate.

It’s claimed that lash is fine for the duration so I ask this. If you’re never checking them then how in the hxxx do you KNOW what’s going on inside the valve train?

It’s claimed that audible lash inspection is fine. Tight valves make no noise. So how do you KNOW any valves are not tight?

Just one of countless sources speaking to the issue…

I have burnt the heck out of tight valves on air cooled VWs but I guess an air cooled VW isn’t a water cooled Honda.