Hey all,

Long time lurker, first time poster. Just bought a gold 2000 CRV auto AWD with 198k km and dealer maintence records that go back to 2009, but it had a check engine light. I was pretty stoked, until I took it to my mechanic to get it checked out. The valves were sooo tight for such a long time that it wore down the tappets in the head. Now my question is: replace the tappets, or replace the head? Please advise

Cheers,
Michael

 

You should be able to find a complete head for pretty cheap. People practically throw them away because they only want the VTEC heads.

 

Thanks for the reply. Would replacing the entire head be a better route to go than replacing all of the tappets in the existing head? If I do replace the whole head, should I be looking for something specific? If the head has to be replaced, I'd been keen to get more power if possible.

I've read that Integra manifolds are a good upgrade, should I go for an Integra head too?

 

The integra head should be the same. Its a P75 casting. Not sure about the cams, but Id bet theyre the same.

The intake manifold thing is a bit of a fallacy I think. The B20B manifold is too fall to fit in a civic, and the B20Z manifold has that big box on it which people think is "ugly", so of course everytbody thinks the Integra manifold is the only way to go, and "makes so much more power, bro."
A P75 Integra intake manifold will put a hole in the torque curve, and maybe make a couple extra horsepower. You will feel the hole a lot more than you feel 3 hp at 6500rpm.

If you want to make any kind of significant power improvement, youre really looking at doing cams, header, and tuning. Then that Integra manifold would actually start to show some gains.

 

That is all super informative, thanks very much. I was thinking about a full exhaust system, but I think cams and a tune are out of the picture, at least for now.

So in your opinion the new head is the way to go vs. replacing all tappets/lifters? Is there anything j should get done to the new head before getting it installed?

 

The valves get tight as the valves wear into the seats in the head, effectively the valve stem protrudes further into the heads. That's not unusual. I don't see the connection to the cam followers wearing out being an affect; makes no sense.
The PCM will set a code if the valves are tight as you may get misfires from unsealed valves. I have 400, 000 km on a 98 so i know the routines. If you don't want to blow a bunch of money, just do the valve adjustments and carry on. I have seen this "tight valve" scenario before even of 3.5 v6 engines tripping codes. Valve's adjusted fixed it.

 

There was a CEL when I purchased the vehicle and when scanned it showed misfire codes for all cylinders and random multiple missfire. The valves were then adjusted to spec by a friend/Honda mechanic I trust. The codes are gone, but the valves are now noisy due to what he described as material being worn from tappets due to them being tight for a long time. He said I'm fine to drive it as is, but should think about replacing them in the future. I'm just trying to do my due diligence and keep this vehicle in good running order. Are these b20z honda engines known to be noisy when valves are adjusted to spec?

 

No, once adjusted to spec they are not noisey. Some valve train noise is unavoidable however. You can replace the rocker arms , or what your refering to as tappets (they are not really tappets...tappets usually are in a pushrod engine. But in a pushrod engine, those are called "lifters" , either solid but usually hydraulic as in hydraulic lash adjusters which Honda does not use...tappets is so old school terminology). I am curious where the wear is. It would only be on the cam side where it follows the lobe and unless the rocker arm is completely ruined, it should be adjustable with no issues. Once adjust to spec the noise should be acceptable. If not then something is incorrect. Valves should only be adjusted on a cold engine. If they are adjusted above normal ambient temperature ( in other words adjusted after running the engine to normal operating temperature) they will be wildly out of spec. Have you been shown the valve train?

 

What year is this CRV ?

 

The CRV is a 2000 with 198k kilometers on it.
Sorry for the old school terminology, my first vehicle was an 84 Dodge Ram with a slant 6, and my next one was a 91 Chevy Caprice with a 305. I'm used to those old engines and the associated terminology that my father used. I'm not sure where the wear is, and I have not seen the valve train but was told it is quite dirty and gummed up. The mechanic who services it is reputable and I trust he did the service on a cold engine etc. Valves were adjusted to spec with no issues, but it is just a little loud. He said they were incredibly tight. Maybe I'm being picky. But he did say there was material worn away and that the parts would eventually need to be replaced.

 

If your keeping the head inspect the cam lobes for wear (measure)...h may be telling you the cams are worn.
These are really more likd cam followers than rockers. They pivot on screw in studs opposite side of the cam to the valve.
They are under the cam. On an engine with hydraulic lash adjusters, the screw in studs with the pivots would be hydraulic lash adjusters with the ball pivots. But since honda loves high revving engines, they're all mechanical solid valvetrains. Rock Auto sell reman heads . $570USD

 

If, at some point in the future, your valves are not able to be adjusted into spec (a pretty common situation), you can remove material from the rocker arms to make room for the ***** to be screwed further into the rocker, so the valves can be adjusted into spec again. I had to do this on my B20 exhaust rockers. It took some care and patience with the bench grinder, but it was much simpler than replacing the entire head. And it cost zero dollars.

 

I would pull the head at that point and replace the valves. If the valves are wearing that much into the head they are worn out and the exhaust valves will eventually burn a piece off. New valves aren't spendy. A machine shop can cut the seats or replace the seats and then set the valve stem to the correct height by machining the stem if required.

 

I have not heard a good explanation for why the situation of insufficient clearance occurs. It's not an issue with the valve/head seats, no loss of compression. I don't know if they are wearing into the head. They are definitely not leaking though.

Replacing (moving) the rockers does not solve the problem. So it does not appear to be a problem with those. Some people suggest that the valve seats move into the head. But I seriously can't see a mechanism for that occurring.

I personally believe it's a situation that was created at the factory - I think it's an issue with the head casting. I think the heads with issues have had issues since they were made. But I have never pulled my head to inspect the valves and seats to say for sure what the condition of my seats is.

Replacing valves requires pulling the head. I would want a guarantee that that would solve the problem.

Replacing seats is, for me, strictly machine shop work and cost-prohibitive. And again, I would want a guarantee that it would solve the problem. It's probably cheaper to buy another head.

I thought about machining the valve stems. But that requires machining the surface that rides on the rocker. I don't know for a fact, but I also worry that the valves might be surface-hardened and I would remove the hardened surface by machining.

Seriously, it's so much easier to just take some material off of the rockers to add some more adjustment to the ball/screw. You are machining a surface that is not in contact with any other surface, so the grinding can be done by hand. It can be done and still leave plenty of material for threads. All the wear surfaces remain intact. I haven't had any problems with my ground rockers and I know others have had success doing it as well.

 

That's what i am saying . The valve stem moves further into the valve seat as it wears . Its a normal condition as I've mentioned before. Some may wear quicker for a variety of reasons and a casting issue could be one but its not the definitive answer. I have been in the honda business for 19 years and valve adjustments are routine maintenance.
Think about it . So the cam wears down a wee bit, the follower a wee bit and the valve a bit as well. All get smaller ( increase clearance) except the valve gets smaller at the seat and slowly retracts into the head as a result ( decreases clearance) this is normal.
This is one of the " whys" lead was once in the fuel; to lubricate the valve seat and valve and mitigate wear. When lead ended, other additives where not able to duplicate and so hardened valve seats inserts became a thing.
I have seen many a B20 series with burnt exhaust valves from being left tight and unadjusted too long.
moving the follower pivots will create the desired effect cheaper. One could get s machine shop the turn them in a lathe perhaps as well.

 

To give some more info..
"I thought about machining the valve stems. But that requires machining the surface that rides on the rocker. I don't know for a fact, but I also worry that the valves might be surface-hardened and I would remove the hardened surface by machining"
Machining the valve stem is part of a valve recondition service. Not and issue. Your only removing few thousands of an inch and cutting oils are being used so no surface hardness changes. Thus is a common practice, its called resizing; After grinding a new surface on a valve and head, and hand lappping it into the seat, the valve height is measured and adjusted with the valve grinder as required to keep it in spec. You do not machine the followers as thed tips are non critical. If, on inspection, the followers are worn, then they are replaced; same goes for the cam. Normally never this severe.
But as CRV vales are under $10 apiece, new ones are cheaper than a machine shop.
"Replacing seats is, for me, strictly machine shop work and cost-prohibitive. And again, I would want a guarantee that it would solve the problem. It's probably cheaper to buy another head."
Usually valves are the culprit. The seats are hardened. Valve/ head service will cut new seats unless they are beyond limit of wear. It will 100% solve the issue. Machine work is not cost prohibitive and it can be cheaper than a new or reco head... That said, a used head will work but it too should be check, and reconditioned to an acceptable degree to ensure service life. At the least, the head should be tested for leaks and inspected for cracks and warpage and valve seals replaced. Its cheap to plane a head in a machine shop

I have not heard a good explanation for why the situation of insufficient clearance occurs. It's not an issue with the valve/head seats, no loss of compression. I don't know if they are wearing into the head. They are definitely not leaking though.

If you missed it earlier, the OP answered my post about misfires and codes. This can occur as wear continues in the valve. He did say this was beginning to happen in his case.

This is not rocket science; its basic mechanics 101. Nothing is mysterious.
Doing a proper head service will eliminte the issue and perhaps the new valves would be an asset and in severe cases, required. I have 400, 000 km my 98, and I bought it with a burnt valve and tight others, but easily adjustable. The machine shop said the valves were still good but I bought all new exhaust valves for about $5 each for good measure.
You can certainly do the stud adjustment routine as well for a band aide. There's an awful lot of adjustment in the lash adjuster however so your valves are for sure worn considerably.

 

You explained a lot of things very well. Thank you. I took Gas Dynamics (aka Rocket Science) but I am not a professional mechanic, so I don't have your experience, I rely heavily on what I read on forums. For those of us who didn't take Mechanics 101, could you clarify why valve wear is an issue in B20 heads, yet valves rarely, if ever, wear in other B-series heads?

 

These heads (and quite a few other older Honda heads) are notorious for sinking exhaust seats. It's just the way they are. Lack of valve adjustment maintenance seems to aggravate the issue, along with the fact that if you let them get tight enough, the exhaust valve won't close fully and you will eventually end up with a burnt valve.

These rockers are stupid easy to replace. P75 heads are not worth much on the used market - you should be able to pick one up for < $100. Strip the rockers out of it, lift up the cams in your running engine, swap in all the rockers from your 'new' head, adjust to spec and go on your way. Should be less than a two hour job even if you've never done it before. If that doesn't fix your issue, then you might consider swapping heads or sending yours off to the machine shop.