Why do valves get tight?
 

I keep hearing about "tight valves" discovered at adjustment time. I looked, there are endless threads about tight valves, but I can't find one that tells me why.
On the gassers, top engine things seem to get loose.
Why do they get tight on these beasts?

I don't know when the last time my valves were adjusted; not since I have owned the car. And I don't know how many miles I have gone; odometer no-function.
Call it blissful ignorance.
I change my oil often, and she starts great (even though I still have to change a dead glow plug), and though it is non-turbo, she is really fast, just purrs, smooth enough at idle.
So, I haven't been too worried about valves, but when I keep reading about tight ones, I got to wonder.....

The Valves get tight on our cars (and many others!) becuase the valve wears and beats away on its seat and actually move further into the head to actually seal after time. This "further in-ness" results in the stem stick out further which results in your valves getting "tight" and/or the valve getting held slightly open.

Ignorance may be bliss, however ignoring the valves for too long will result in one of them not fully closing. This is going to burn the valve and your ignorance will turn to :mad:

Even if you don't want to adjust them, you can check them in less than one hour to determine how "tight" they really are.

or bring them to a mechanic to do it for you

I do want to know how to adjust them, I am just afraid of screwing something up. I have so many issues right now with the car, that it running good has been my crutch....
But I will do some research on this check, and ask around at how much this costs, were I to take it in...

I adjusted my valves, and my wagon has smoked badly ever since. I don't think it started at that exact time, but shortly afterward. I went back and checked them 3 times to make sure I didn't do something wrong, and it really would be hard not to get it right. Hard at first to get the wrench situation handled, but it's not rocket science.
I also couldn't check chain stretch as my "marker" situation doesn't look right (protruding mark at scale area).

Here is a helpful tip for your first time adjusting valves:

1: Adjust the valves once.
2: Repeat step 1 at least twice in the same day.
3: Go over each valve with the correct feeler gauge to make SURE they are at the correct setting.

By the second go-round you may find some "tricks" to make it less brain damage for you. Me for example, I found using a long, stiff flat blade screwdriver works in place of the third wrench since I only got the two bent wrenches to prevent the collar from turning.

The first time I adjusted my valves to took me over 1.5 hours. By the foruth time I had done them as maintence, I was down to 15 minutes from valve cover off to valve cover on! :D

If this is what causes it, wouldn't this phenomona have to slow down and eventually come to an end sometime? I can't imagine this kind of surface wear going on forever.

Dave

1976 White 300D W115 "Pearl"

Has anyone else heard about this "rule of nine" system for valve adj.
Say if you see valve 2 is open you would adjust valve seven. Valve five open adjust valve four. They talk about it all the time in Brit DIY car mags. I might try it next Fall when I'm due.

I just adjust the valves that have the high spot of the lobe opposite the valve.... the base circle of the cams are consistant for a portion on every cam out there.....except possibly top fuel.

You can adjust all valves on the motor within a single 360 degree rotation of the camshaft.

The Rule of Nine....

That is the method devised by the British for adjusting valves. Any of the British shop manuals, whether it be for Triumph, MG, Austin or whomever, all suggest using the Rule of Nine when performing "tappet" adjustments.I go through it every spring and fall with my TR6. Not hard, just as you stated, check valve #1 with #8 open, 2 with 7 open and so on and so forth. As so many of the English powerplants are OHV, there is a marvelous tool called the Clickadjust which makes checking and setting clearances a snap.

To properly perform a valve adjustment on a Mercedes diesel, you will need the three special wrenches (one for loosening the locknut, one for turning the adjuster nut and the third one for holding the valve spring collar). They can be had through any of the German tool dealers such as Samstag Sales http://www.samstagsales.com

On the old, pre-hydraulic lifter gasser engines, there is a special crows foot 17mm used to turn the ball stud to set the clearances. That is also available through Samstag or through any MB dealership.

[QUOTE=Aaron]The Rule of Nine....

That is the method devised by the British for adjusting valves. Any of the British shop manuals, whether it be for Triumph, MG, Austin or whomever, all suggest using the Rule of Nine when performing "tappet" adjustments.I go through it every spring and fall with my TR6. Not hard, just as you stated, check valve #1 with #8 open, 2 with 7 open and so on and so forth. As so many of the English powerplants are OHV, there is a marvelous tool called the Clickadjust which makes checking and setting clearances a snap.


Is the "Clickadjust" only used on Brit cars? Sounds like an interesting tool. How does it work?

First time valve adjustment.
 

Hey,
I adjusted my valves for the first time today. I took me about 3 hours.
When I started the car afterwards it made noises I never heard before. It got me a little worried but I'm pretty sure of my mechanical abilities and I'm sure it went well. But man! It was humming and shaking.
It smoothed out after it warmed up. I just took it on a 40 mile ride and it runs beautiful.
I'll have to see what happens when it fully cools down again.

Some of the valves had no gap at all!

Danny