npoutre

So my timing belt snapped while going 70 on the highway in my 2001 CRV 160k miles (last done at 90k). A mechanic mentioned that "more than likely" the engine was fine. So I decided to replace the timing belt/water pump/tensioner, etc myself. The belt was completely shredded. I thought it would be a good idea to adjust the valves while I was in there with the cover off. I don't recall the values being bad, but I did have to adjust a couple that were maybe at most .002" out of spec (not sure if that's a lot or not). When I fired it up for the first time it ran fine, but I could tell the valves sounded a bit rough from what I was used to hearing. The sound was only noticeable at idle and very low speeds. Because of my OCD I ended up pulling the valve cover off the next day and doing another valve adjustment. I was surprised one or two valves needed tweaking. Not sure why they moved, but again maybe at most 0.002" out of spec. This did not seem to fix the noisy valve issue. So I've been commuting with it for the last two weeks now and she runs great, but I can't stand the sound at idle.

I did a compression test today and all cylinders came back fine from what I can tell. No obvious issues. Is it possible I have a bent valve that I can't get adjusted? Maybe I'm adjusting wrong? I have the shop manual with all the specs so can't imagine I'm doing it wrong...but that's certainly possible. If I had a bent valve would it run fine with a good compression check? Try adjusting valves again?

Ryanthegreat1

Use a go no-go method with the feelers. If you are shooting for 0.010" of clearance use a 0.010" and a 0.011" feeler. The 0.010" will just fit and the 0.011" will not fit.

npoutre

When I did the valve adjustment on the two previous attempts I did use feeler gauges. I was shooting for 0.004" +/- 0.001" on intake and 0.007" +/- 0.001" on exhaust (B20Z2 engine). For most valves the feeler measured dead nuts, but there were a couple that were on the high or low side of the middle. I recognize y'all can't hear my engine, but would a gap that measures only 0.001"-0.002" out of spec cause the engine to sound rough? Any idea if an out of spec valve gap on the high side vs on the low side is worse for the noise? How close to TDC do I need to be? In other words, if my TDC mark is off by say 1/2 cam tooth, will that result in being 0.001"-0.002" out of spec on the valve clearance? I see videos where people just stick a screwdriver or dip stick in the spark plug hole to find TDC and can't believe me lining up timing marks on the cams is worse than that.

I may be psyching myself out, but recently I'm noticing that occasionally at idol the rpms are dropping from around 750 to 500. Might be nothing and doesn't happen always. I think I'll pull the cover this weekend and give the valve adjustment another shot. I recorded the gaps last time so if things have moved on me again I'll know.

npoutre

Ok not getting a lot of action on this thread, but I think I have some more information. I pulled the valve cover off again to check the valve clearance. First of all, the clearance was in spec for all valves before any adjustment was done. The previous two times I only adjusted the valves that were out of spec which was only a couple. This go around I decided to adjust all valves to the upper limit based on a youtube video I saw....so 0.005" on intake and 0.008" on exhaust. Had no issues with cylinders 2-4. Each valve adjusted just fine. On cylinder 1 though, I was able to adjust both intake valves, but only one of the exhaust valves. On the second exhaust valve (closer to cam), I was not able to adjust the clearance over the 0.007" gap. The clearance would not increase and actually started to decrease as I continued to unscrew the adjusting screw.

Why would I not be able to increase the gap on this one valve? I'm guessing this is the reason for my valve noise and rough sounding idol. Appreciate any help.

1999 Civic Si

There is a good chance when the belt snapped or skipped teeth the pistons may have kissed the valves a bit. If they are bent out of shape they can cause rough idle or misfires and can get noisy. Pretty sure a leak down test should help confirm that or you just rip the head off and take it to a machine shop and have them check the valves and head. Any reputable machine shop should be and to check and make sure the valves aren't bent and that nothing on the head is damaged.

npoutre

Thanks for the feedback. I'm pretty sure my issue is the one exhaust valve on cylinder 1. Probably a combination of being slightly bent and recessed into the head. The good new for me is it's driving "fine" right now and I'm not having any timing issues.

Found a company, Cylinder Heads International, that sells a rebuilt head for $350. That's probably the route I will end up going. Can anyone think of something bad that could happen if I continue to drive this car for a while (or until it finally stops) that a rebuilt head won't fix? Figured I would wait on the head replacement if I can. It's a bigger job than I've done before and don't want to be down a car for a long time (you know how it is, always takes longer than you originally thought running into little issues and making 10 trips to the hardware store).

Can anyone recommend a quality head gasket kit from Rock Auto? Looks like they have MANY to choose from (Ultra Power, ENGINETECH, SKP, APEX, FEL-PRO, AJUSA, ITM, MAHLE). Looks like similar kits in terms of pieces included, but from $40 - $100.

Ryanthegreat1

If there is a bent valve there is a chance the head of the valve will snap off from constant flexing trying to seat.

OEM Honda gaskets.

Smackin

I would recommend an MLS (multi-later steel) head gasket. Not sure what the OEM gasket material is, but graphite based gaskets are a bitch to deal with if you ever have to remove them.

And why not have the one valve replaced instead of
doing the entire head? You could even have that done at a machine shop.

npoutre

It's a fair question. My first thought though is that I'm likely to spend nearly the same amount to take the head into the shop and have them fix the head and that one valve. With a rebuild head I have all new valves, seals, etc. I would probably spend the little extra money for the peace of mind knowing the entire head is good. On top of that, I'm not out the time it takes the shop to diagnose and fix. The rebuild head is delivered to my doorstep. If you were to tell me the machine shop will fix for $100 that would be a different story but my gut says it's more than that. Point taken though, I'll investigate. Thanks.

1999 Civic Si

Depends on your machine shop, I had my b16 head decked, hot tanked, some threads heli coiled, old valves checked for straightness (I had some bent) and a 3 angle valve job for $250 and like a 3 day turn around (they were very busy when I dropped mine off). They are local to me and do some great work for good prices. The cost of valve seals is fairly small considering. I went oem on mine and they weren't that expensive.

npoutre

I called two local machine shops today to get quotes on repairing the head (3 angle valve job, resurface, new seals, valves/guides as needed, etc.). One shop was going to come in a little over $350 (cost of refurbished head from CHI) and the second shop was a little under. Doesn't appear there are any real savings in taking the head into a local place and the $350 is about right to have the head repaired.