Valves leaking air into intake manifold.
 

Nevermind, no text. ^_^ I did a leak-down test on TDC exhaust stroke instead of compression stroke. *facepalm*

Re: Valves leaking air into intake manifold.
 

:_doh:

Well at least you don't have any issues with it lol

Re: Valves leaking air into intake manifold.
 

Cylinders 2/4 were leaking the most past the intake valves, while 1/3 not so much. I did a valve adjustment recently to minimum spec, but it was based on valves that had carbon deposits on them. After inspecting the clearance today, a few of the intake valves had no clearance, causing the valves to be open.

So I adjusted the clearance to maximum allowable so that I can clean the valves through hard driving, allowing them an opportunity to seat in. (.009/.011) The car is already idling properly, which it wasn't before. After about 2 weeks of hard driving, I will do another valve job and put them back to minumum spec. (007/.009)

Yeah, nothing serious. At 165k I've got really good compression:

160
160
155
155

Re: Valves leaking air into intake manifold.
 

I'm curious why you are setting them at the minimum. I would think the increased chance chance of burning a valve wouldn't be worth it.

Re: Valves leaking air into intake manifold.
 

I set Hondas valves to the loose end of the spec range because most of them tend to tighten over time and miles.

They aren't noisy when I do it, and it allows more time and miles before they need adjusted again.


Loose valves might be just noisy.
Tight valves are quiet..... BUT too tight can also lead to P0172 rich codes and burned valves.

Re: Valves leaking air into intake manifold.
 

What are some of the signs that lead to needing a valve adjustment?

Re: Valves leaking air into intake manifold.
 

Honda says to listen for valve noise during maintenance checks...... But tight valves don't make noise.


Symptoms of tight valve issues can vary, depending on the severity of the condition.

Re: Valves leaking air into intake manifold.
 

Some of the things that tight valves can cause: Low vacuum, low fuel trim numbers, high MAP voltage, low compression, misfires, stalling, burned valves, codes related to any of the above, and probably more I didn't think of right now.




Tight valves caused excessive engine vibration in trucks like mine LOL.

Re: Valves leaking air into intake manifold.
 

You're not going to burn a valve or get any of the issues ezone mentioned when you're adjusting to minimum specs. That's why honda says it's in spec, because there will be no issues there.

Any way, the reason I set them low is because the engine is significantly more responsive and tight. You can tell on these low HP engines. But you have to push the car hard before a valve job or you will not adjust properly.

Re: Valves leaking air into intake manifold.
 

Correct. Anywhere within the specified clearance adjustment range is still "in spec".

Re: Valves leaking air into intake manifold.
 

Ohhh, you were saying below minimum spec; getting it to as close to no clearance as you can. (like .001) Probably a bad idea. ^_^

And the torque on the nuts is very important. Don't hand-tighten. 13 ft. lbs. is the spec, and it's very tight for such little nuts because they will come loose if you torque lower due to the excessive movement and the oil on the threads.

Re: Valves leaking air into intake manifold.
 

There must be adequate clearance allowed because certain things GROW as they heat up to operating temperature.



I adjust to the loose end of the specs simply because so many of the engines tend to tighten the valves as they wear. That hopefully allows more miles between needing adjustments.


Setting them at the tight end of the spec causes an increase in both overlap and duration, which can sometimes be felt on the butt-dyno.

(My average dealership customers don't employ the butt-dyno.)

You really don't want to strip the threads off either.

Everyone doing this should look up the correct specs for their particular engine before the job begins.


"Too loose is too loose, and too tight can be too loose too."