How to tell if valve adjustment needed?


#1

I just finished replacing the timing belt, water pump, idler and tensioner pulleys, thermostat, and the 17 year old heater hoses in my 1990 Toyota Celica. I started the car and let it idle in the driveway and it seems to idle fine and still sounds fine even as I increase the RPMs. The only thinkg I notice is the exhaust has kind of an odd sound that I can only notice when I walk around to the back of the car as it idles. It’s hard to describe, but instead of being a uniform sound I guess it sounds likes it’s coughing every once in a while. I was looking through the Toyota shop manual that I have an noticed a procedure for adjusting valves and remember reading how important OK says that is to have done. Since the engine sounds ok and I took care to make sure I had the timing marks set correctly when replacing the belt was wondering if the odd noice I hear from the tail pipe could be related to needing a valve adjustment, but I have no idea what the symptoms are when that needs to be done. BTW, the car has between 110K and 110k on it.

Thanks,

Joe


#2

Oops, meant to say between 100K and 110K.


#3

What you may be hearing is an erratic ignition spit. It’s not that rare.
The usual cause is spark plugs and/or wires.

As to valve adjustment, there is no way of checking valve lash in mechanical lifters other than actually tearing into it and verifying lash with a feeler gauge or dial indicator.
Toyota even made an idiotic suggestion about valve lash being checked “audibly”.
That without a doubt is one of the dumbest things I’ve ever heard in my life, and it comes straight from Toyota Motor Co.


#4

Thanks for the help. What you describe sounds exactly like what I’m hearing. I was going to describe it as a spit, but didn’t think anyone would know what I meant. I thought I replaced the plugs and wires about 20,000 miles ago, but I’ll have to check that, maybe it’s been longer than I thought.

The procedure in the service manual showed how to check the valve adjustment. Looked like it required a couple of special tools and some shims and I think replacing existing shims if necessary. Wasn’t planning on doing that myself though as I really didn’t understand exactly how to do it.

Thanks again for the help,
Joe


#5

With concern over valve adjustment the lash could be checked with feeler guages just to verify that they’re at least on or close to what they should be.
Shim and bucket adjusters are much better about staying within specs, so it’s possible to check the adjustment without buying the tools and shims.

JMHO, but valve lash should be inspected every 30k miles. Often adjustment is not needed but that’s where the inspection part of it comes in; making sure it’s not needed. If ignored sometimes the valves tighten up due to stem stretch or valve face/valve seat wear (the exhausts are critical) and by the time the problem is noticed, the damage is done.


#6

Thanks. I think I can handle checking the valve lash, that looked easy enough to do. I don’t think they’ve ever been checked, so based on your recommendation it’s way overdue. I do want the car to last a bit longer, another 17 years would be fine by me, so I’ll try and do that within the next month.


#7

Do it! Cars with solid lifters NEED to have the lash checked with a feeler gauge every now and then. Loose valves you CAN hear. a little click,click,click sound. But a TIGHT valve is silent and can result in a burned valve…