sebTeggy

I just did a valve lash on my GS-R and 4 were in spec (all intake)
all 8 exhaust were too loose (meaning they wouldn't open all the way?)
3 intake were too loose
one intake was too tight

So, if it is too tight, that means that when the camshaft expands from heat, that it might leave the intake valve permanently open? Causing a burnt valve? (although exhaust are more prone to burning).

I thought that all hondas, rule of thumb, loosen over time? Assuming this isnt a fact?

And is 12/16 valves out of spec fairly common? Unknown time since it was last done, motor has 90 thousand miles.


EDIT: Too loose means that the clearance was HIGHER than spec, meaning that I had to tighten the gap. Both feelers fit

GagnarTheUnruly

iTrader: (3)

I'd guess they might be more likely to loosen over time but it might be more accurate to say that they just change over time.

If they are loose the main problem is that the engine is noisier and rougher-running (and probably also has increased valvetrain wear). If they are tight you increase your risk of burning a valve.

But don't worry about it too much. Just keep up with it. I check about once a year.

element600rr

honda motors do tend to get loose over time as they have a rocker between the cam and the valve . combined wear of cam , tip of valve / rocker and rocker pad . there are more surfaces to wear than a shim over valve set up ( toyota / nissan ) . nissan / toyota motors tend to tighten over time as the valves wear into the seats and wear less on the cams and buckets . hondas on the other hand tend to wear more on the rockers than the valves wear into the seats thus making the valve lash looser . it is possible for a valve to wear into the seat more than the rocker / cam to wear causing the valve lash to be to tight on a honda also . i have seen it before but more likely than not most hondas are gonna wear on the loose side ..

el crapitan

^^good info

TheRealTegger

Even if the valve can close all the way, it can still burn if it can't seat for long enough. Seating-time is any valve's only method of cooling, so its duration is critical, and that's a function of lobe-shape and the clearance.



Clearances can -- and do -- go either way.

If valvetrain parts wear, clearance will increase. If the valve itself wears into its seat, the clearance will decrease.



That is an unusually high number out-of-spec, but if they were only out by a thou or two, then it's probably normal. I generally find one or two out-of-spec by a thou either way after 30K miles.

Dogginator

IIRC, my B18C1 tends to loosen, but not very much in a year. Most of my valves are still within spec when I adjust them. The J35A6 in the Odyssey tends to have the exhaust valves tighten way before scheduled maintenance.

wanabebuff

He did say that the last lash adjustment was unknown, and after 90k assuming that it might not have been done at all, 12/16 might not be that unusual. I agree with you, if 12/16 valves were out of spec by more than a feeler up or down after 30k, something is wrong.

I've known tons of people that have NEVER done a valve lash adjustment......hundreds of thousands of miles......

GagnarTheUnruly

iTrader: (3)

But what? Probably just that the locking nuts weren't tightened enough or the lash was set poorly in the first place. I don't think having a lot of valves out of spec for an engine with unknown history is cause for alarm unless one of the valves burnt.

TheRealTegger

If a nut isn't tightened sufficiently, it will come off. That's pretty alarming on account of the sudden (and very loud) noise which will occur.

wanabebuff

I wasn't making a counterpoint or anything. I was just simply saying that since he didn't know when the valves were adjusted last, it could be that they haven't been.

GagnarTheUnruly

iTrader: (3)

I think my post came off much snarkier than I intended, sorry :/