We own a 2000 Honda CR-V.
The maintenance schedule for valve adjustment says to adjust the vales at 60,000 miles and then ignore them unless they get noisy.
So I ignored them until the Check Engine light came on at about 97,000 miles. The codes were for cylinder misfires.
The valves were out of adjustment. Adjusting them fixed the problem.
So my question: Should valves be adjusted proactively and prophylacticly (is this a word?)in spite of what the maintenance schedule says?
Thanks for any advice.
Consumers should learn to avoid cars that require periodic valve adjustments and replacing timing belts. There is simply no need to accept these burdens today…Finding competent mechanics who can perform these services is becoming more and more difficult and when found, the expense can be staggering…
Only on a very small percentage of vehicles.
Adjusting valves basically establishes the amount of freeplay within the mechanical “train” from the cam lobe to the valve stem. Properly adjusted, the lifters/tappets are then prevented from hammering the corresponding surfaces, the cam lobes themselves.
The overwhelming majority of engines today use “hydraulic lifters”. Hydraulic lifters use the pressurized oil as a hydraulic fluid to fill the lifters, expanding them to take up the freeplay in the mechanical “train” from the lobe to the valvestem. Hydraulic lifters only need to be adjusted at installation, to establish the proper dimension such that when the engine is operating the lifters will be within the range of their ability to expand and contract, enabling the liftere to compensate as the engine operates and as it wears.
Your misfire did not come about due to your valves being loose (and thus noisy) they came about from your valves being tight (and thus silent). There is a finite amount of time you can run with a valve so tight that it causes a misfire before permenant damage is done to the valve face and valve seat.
Yes, and yes! You were very lucky to escape without severe engine damage. These “first-generation” Honda CR-V engines must have their valves checked every 30,000 miles. For some unknown reason, Honda made a bad boo-boo in their owners manuals, recommending the first valve check at 105,000 miles. Unfortunately, many CR-V owners got burned with $1000-$2000 repair bills when their valves got out of adjustment and melted well before 105,000 miles. This came to be a major egg-on-face episode for Honda and a nightmare for some first-gen Honda owners. (Google Honda CR-V valves, and you’ll get an eyeful). You were lucky enough to escape without a valve job. From now on, have the valves checked every 30k miles. Also be sure to have the rear differential fluid changed every 30k. The good news is that these CR-V’s are extremely reliable as long as you avoid the dreaded valve problem and change the diff fluid regularly…do your preventive maintenance religiously and these vehicles will go 200+ miles, no problem. I just read about one guy who had 600k+ miles on his. Mine’s barely broken in at 65k!
On my first cars (A Sunbeam Imp and a VW Beetle (1970)) I adjusted the valves at each oil change. Took only a couple of minutes. Today I only have the adjustment done when there is a good reason like a timing belt job. Modern cars just don’t need them done generally.
Thanks to Jesmed for the CR-V specific answer. I’ll take your advice to heart.
When the mechanic adjusted the valves he also did a leak-down test. One cylinder shows 30-40% leakage, so we may be in for a valve job.
It’s time to replace the timing belt, so we’ll find out then.
I had to laugh, a 1970 Bug is not considered a “modern car” sure beats a Model T (unless you are that guy who thinks old cars run cleaner), he sure has been scarce after his “eye opening” post dealing with emissions.
Mechanical valve lifters should be adjusted every 30k miles and many recommendations about this issue are totally bogus. These hokey recommendations are made by the marketing people, not mechanically astutue people. Extended valve lash intervals are a joke (at least if you value your engine. The recommendation about determing valve lash audibly is downright laughable to be honest about it.
The quiet valves are the ones that can kill your engine’s top end quickly, not the noisy ones. In a perfect world they should be inspected at 1000 miles intially and every 30k after that, but this is seldom ever done.
Now to address your potential looming problem. Adjusting the valves fixed the problem; for now. However, microscopic valve face/seat damage due to tight valves will have already happened and any fix may be short term only.
An engine that is missing due to tight valves will cause those tight ones to burn a little and it does not take long to do this. Once adjusted the engine may appear to run normally but that microscopic damage will worsen over time due to exhaust gas seeping past those damaged areas. At some point it will become a full-fledged leak and the engine miss will return. At that point it’s valve job time.
I would advise having a compression test run in about 10k miles unless the engine miss returns before then but basically adjusting the valves after the fact is akin to closing the barn door after the horses ran away.
Believe it or not, the Ford flat heads valves were set by grinding the valves. To reduce the clearance the seat and face were cut, to increase the clearance the stem was cut down.
I try to avoid vehicles / manufacturers that use 1950’s design features. Modern designs do not require valve adjustments…There still must be some motorcycle engineers designing Honda engines…I see they finally fired the rubber timing belt guys…