MA7008O

Well, that my question....

DaveK

I think the sensible answer is : If it's due in the service schedule (considering the mileage you've done since the last time they were checked).

If they are noisy (tappety tappety sound) then that means they need adjusting - it means the clearance is too big.

On the other hand - if they don't make any noise - it doesn't mean that they don't need adjusting, 'cos it might mean the gap is too small. And that's when they might say hello to the pistons......

ThomasC2

Like Dave says, you have to measure the gap to know.

MA7008O

Thanks for the answer. I ask because there are many rumours, for example for my Honda Translp, that just say that until they "sound a bit" there is no need to adjust.

Considering that it’s very time consuming I just was wondering if this opinion was logical …

Again, I thing Dave is perfectly right: sound means the gap is too big, but no noise could either mean correct gap or too small.

Thanks again

botoo

{{On the other hand - if they don't make any noise - it doesn't mean that they don't need adjusting, 'cos it might mean the gap is too small. And that's when they might say hello to the pistons......}}

Since I don't know too much about this, how would the gap get too small? I can see wear causing noisy valves, but I don't understand the gap getting too small. Are you saying they might not have been adjusted properly in the first place?

Michael Delaney

One thing that could cause tightening of the valve clearance is wear of the valve face or the seat it contacts. Moves the valve up and closes the clearance. You are only talking .004 in. here.

Gus

To me, the concern is more towards " not hearing the tappets" as the normal wear factor would be for valve face (seat) wear making the valve clearnace tighter ( less noise), not greater ( noiseier). I think it is best to check the valve clearnace within the recommended mileage regardless of noise you hear ( or don't hear).

ddz

Rather than the valves running into the pistons, the real concern with improperly adjusted valves is the potential for them to "burn." The exhaust valves are cooled through contact with the valve seat when they are closed and through the oil film surrounding the valve stem in the guides. Exhaust valves are particularly vulnerable when the clearances are too tight because the face of the valve is exposed to the hot exhaust gasses passing by for longer periods of time. Larger clearances make a lot of noise and can end up damaging the contact surfaces between the valve stem and rocker arm but only in the most extreme conditions. As valves wear into the seats the clearances tighten up and start a chain of events that can lead to disaster unless and until a valve adjustment makes things right. It's cheap insurance to follow the recommended intervals to check on things...

garrett376

Just to add a bit of info to clarify - it's the seating of the valve into the valve seat that cools the valve off by transferring the heat to the head; if the valve does not get to seat properly, or long enough, it will burn. Exhaust gas contact duration is not a big deal - consider race cams with greater duration... but it is correct that too tight is worse than too loose. Too loose, you just get crappy performance, versus damage. I would think you'd have to really screw up the adjustment to cause a problem, though.