Tunafish

So, I was leaving the toll booth this morning and went to shift into 3rd but got rejected and got the grind instead. So I tried to shift into 4rth but I get 2nd for a moment and let the clutch out.

Of course I revved it way too high for comfort, not sure how high. I have a rev limiter at 8k, I've only hit 7k a hand full of times. I guess it could technically still rev higher than 8k that if you let the clutch out in 2nd at higher speed, but idk.

I notice as I'm driving up to my office (more slowly, off the toll road) that I can hear a tapping sound, so I pop the hood to check it out. It definitely sounds like its coming from the valve cover area, I can't really tell beyond that.

The car seems to be running alright. Actually, aside from the noise I can't really feel a difference in acceleration or any lopeyness, it's not missing or idling any rougher, and it's still burning the usual amount of oil. It taps on start up, and then my illegal exhaust drowns it out as I accelerate. Either way, it doesn't seem to get much louder than it is at idle only a little faster. At idle, it's more of a "tap...tap...tap..." then a "tap.tap.tap.tap." if that makes any sense, it taps about as fast as you can count at idle.

The car is a 94 Integra RS , stock B18B motor (180k), CAI, full exhaust, running on Neptune Demon on stock JDM B18B tune +.5 degree on 91 octane.

I just tightened the timing belt and did a valve lash adjustment and it was running great. Getting about 28-29mpg average.

So what is causing the tapping? Am I hearing mechanical sounds from having to much play between components, or am hearing exhaust escape though the valve seat or valve seal, OR both?

It could be...?:

1. I bent a valve - It's a non interference motor (or at least it's supposed to be) so I'm having trouble understanding how this happens unless I had crazy valve float and the spring was compressed more than the Honda engineers accounted for, allowing it to contact the piston.

2. Messed up the rocker/lifter - Bent, cracked?, lifter pad was hammered down?... maybe the adjustment nut backed off and it loosened?

3. The retainer cracked - Only read of one instance where this was the culprit.

4. Valve spring - The spring is worn somehow. Of course a worn spring would be likely to cause more float and could have helped bend a valve.

5. Something else - Rod knock (don't really know what that sounds like first hand)? Exhaust leak caused by higher than normal back pressure for a second, blowing out sealant/gasket? really messed up valve seal or something?

So, what is it?

If it's a bent valve, could I fix it by dropping in a new valve and lapping it, or do I have to go to the machine shop for a satisfactory job? I have a whole B20 head for parts, so if i can fix it myself, that's ideal.

Do I need to replace the spring? rocker? valve? retainer? Should I try another valve lash adjustment and see if it helps?

What has the fix been for other people with tapping B18Bs/B18a?/B20x?

Dough_Boy.

Well a rev limiter isn't going to stop the rev on a downshift it just shuts fuel off. So if you did downshift to the wrong gear you could have over revved the engine. Or it could just be the rockers.

Tunafish

Yea. Just didn't happen to be looking at the tach when it happened.

I know that what ever happened, it happened when I missed the shift I'm just trying to figure out exactly what damage was caused. If I was running any vtec motor, I wouldn't even be asking this question, because I know the answer is that valves are bent.

Has anyone here ever fixed a tap caused by over revving with a valve lash adjustment?
(primarily on a non-vtec b series, or another non interference motor)

Smindustries

What makes you think that it's a non-interference engine?

Pull your plugs and use a borescope to look at the pistons. You'll see where one (or more) was struck.

Dough_Boy.

Is it a knock or a tap? From how your saying it's a slow tap i'm guessing maybe a rod or cam bearing.

Tunafish

Good question, I can't remember where I heard it from. I'll check.

... and according to HT it seems that it it is an interference motor, but that because of the lower compression and piston distance from the head that quite a few people get away without bending valves when timing belts break.

So... probably a bent valve or two

Dough_Boy.

If it had a bent valve it would run like shit. It's really hard to give a solid answer without being able to hear it myself.

Smindustries

Not necessarily. I've seen a number of bent valve scenarios ranging from barely running to intermittent misfire codes (one CEL per month). It depends entirely upon the level of damage.

Tunafish

it's definitely a tick or tap sound

I hope it's not a cam bearing because the B18B doesn't have them.

Tunafish

It sounds like this:

http://www.youtube.com/watch?v=6EiJn...eature=related

But, his is ticking more than mine and has some extra sounds that i don't.

It was pretty chattery before I did the valve adjustment and tightened the timing belt, i felt a big difference in performance/reduction in noise afterwards.