Certain models have had problems with oil consumption without the heads being removed. The most common is the early- to mid-’90s Prelude. While some techs have blamed and replaced valve seals to solve this problem, it’s usually piston ring replacement that will fix the car. I mentioned earlier that a leak-down test is a good way to check the integrity of the compression rings and valves, but that’s not the case for the oil rings. As far as I know, there is no test for the oil rings. I suspect the rings over the valve seals if the smoking persists longer than it would take to clear out the cylinders after start up. I’d still do a leak-down test on the engine before disassembly to check the sealing capabilities. When replacing rings with the engine in the car, honing is not required or recommended. It comes down to the same issue as with gasket removal – the threat presented by the grinding dust outweighs any benefit that honing offers. If the cylinders are damaged, the engine will need to be replaced or a full rebuild with a bore job and oversized pistons is in order.
Other than the problems already mentioned, most engine problems you’ll see on Hondas will be the result of poor maintenance practices. Whether it’s a bent valve, burnt valve or a blown head gasket, it’s a safe bet that it could have been avoided with proper maintenance.
I still believe that valve adjustment should be part of a 60,000-mile service. Honda has changed the valve adjustment interval on its cars to include the wording “audible inspection only; adjust only if noisy.” The problem is that we are more concerned about a tight, rather than loose, valve. This is critical on the popular CR-V model where the specs are a tight 0.003-0.006-in. for the intake and 0.006-0.007-in. on the exhaust side. There is little room to compensate for wear before the valve is being held off the seat, resulting in a misfire or, if ignored, a burnt valve.
If you’re faced with a “poor run when cold” condition or a mysterious misfire code, suspect a tight valve. You may be wondering why it would present itself as a cold-run problem. It’s the result of the aluminum head expanding at a greater rate than the steel valve. As the engine heats up, the head will grow, moving the rocker away from the valve stem. This will result in valve lash and sealing of the cylinder. It’s further proof of why it’s important to adjust the valves with the engine temperature as specified by the manufacturer. Thankfully, Honda uses a cold setting, which makes the job much easier.
In addition to allowing the cylinder to seal, valve lash is important to allow the valve to transfer heat to the cylinder head. Without the opportunity to spend some time on the seat, it doesn’t take long for the 1,400° F exhaust gases passing by to burn the valve and damage the seat, resulting in an expensive valve job. While regular valve adjustment is critical on the CR-V, it’s a good practice on all of the four-cylinder Hondas. While the larger specs are more forgiving than the CR-V, they will tend to tighten up. This is most important on cars that are driven hard, and a good practice on all models.
COOLING SYSTEM MAINTENANCE
We’re well aware that regular cooling system maintenance will prevent overheating problems and the radiator blockage that leads to head gasket failure. It’s important that we continue to educate our customers on the value of cooling system maintenance.
We all should be recommending water pump and drive belt replacement with a timing belt job, but consider adding a thermostat to the list. It’s a good time to replace it while the system is empty, it doesn’t add much to the price and, when you’re done, you and the customer can be confident that the cooling system is in good shape.
TOP-END CLEANING
The final maintenance item to consider is regular top-end cleaning to prevent the carbon buildup on the valves. In my opinion, this procedure is dependent on how frequently you see the problem. If it’s a problem you’ve seen in your area, it makes a lot of sense to do the job, not only to prevent it from becoming a problem, but also to ensure the car performs as it should. Carbon buildup will cause driveability problems that the customer may not notice since they tend to come on gradually. But most will notice the increased performance and smoother running when it’s removed.
I hope you feel more confident that you’re ready to diagnose and tackle top-end service on four-cylinder Honda and Acura engines, and will continue to educate your customers on the benefits of preventive maintenance that will safeguard their vehicle from needing these repairs in the first place. As import specialists, we win either way.
