Checking Valve Clearance

[Killick]

One thing that I've avoided on my engine is checking the valve clearance.

Manual says it should be done every 400 hours, but I've never done it in fear of messing something up. How difficult is this?

Fist step involves setting TDC for cylinder 1. I don't remember seeing the alignment marks. I'm guessing that they must be there, I'm just not looking carefully enough?

I have values for Intake and Exhaust, how to tell which is which? Would the exhaust valves be on the same side as the exhaust manifold? These are measured with a feeler gauge right? Under the rocker thing?

Step two: Rotate shaft 240 degrees to check cylinder #3. How do I measure this 240 degrees exactly?

Step three same as step 2, measure at cylinder #2. I have three cylinders.

To change a setting, a fuzzy image shows a wrench holding a nut while a screwdriver turns the adjustment bolt. How does this all lock in place? Is there a lockring somewhere?

I think the "turning 240 degrees" concerns me me the most.

[PEACETIME]

My suggestion would be to hire a mechanic locally who has a good rep. Ask the mechanic to show you exactly how to do this procedure. You might get charged a little more as knowledge does cost. I'm sure if you explained that when you are "out there" and needed to check/adjust valve lash it would be a good thing to know the correct procedure. I also would tell the mechanic that they would be the first you would call for any further repair or maintenance work. Be sure to take good notes in your maintenance log.

[DeepFrz]

Killick, take a marine diesel course or hire a good mechanic and watch him do it.

[atoll]

such a simple procedure to set the valve clearances,but if you get it wrong the results can be pretty harsh on the engine,even catastrupic when the rods fly out the side of the engine!
judging by your post,and with your level of expertise i would definitely get someone in who knows what they are doing.!

[sailorchic34]

Odds are its a push rod engine, so all the valves are on one side. You can usually figure which is intake or exhaust by looking at the intake manifold. The valves that line up with the intake runners are the intake valve. Me, I learned from my shade tree dad. Don't worry about tdc, just watch the valves,

Intake opens first, then closes at bottomish of the compression stroke. When both valves are even that should be near tdc. both be just a little loose, turn too far and the exhaust valve will open on exhaust stroke. Intake will start to open before the exhaust is closed completely... normally.

So just watch the valve movement. when the valves are equal they are at or near tdc for that cylinder. No messing with degree wheels and finding tdc.

Or you can do what I do and just adjust the valves that are closed and rotate around till you've got them all. Its a blonde thing.....

You also want to adjust the valves with the engine cold, overnight cold... Also many engine manuals list the valve clearance in metric (yanmar for one). OK so most of the world uses metric, except the US... Just make sure your sure that your feeler gauge size equals the size indicated. (metric or imperial)

[sailorchic34]

BTW when you adjust the screw for loose tight and tighten the jam nut, recheck the valve clearance. It should slide through with a just a little binding with the nut tight. to much and its too tight. slips thru easy it's too loose. I will use the next smallest and larger gauges to check to make sure I'm spot on.

Too tight and you'll burn a valve, which gets expensive. To loose and you'll loose power and have chatter. To tight is so not good. A thousand loose will not hurt though, though 5 thousands wound affect engine performance.

My dad always checked the valve clearance with the engine running.

The intent of valve clearance with the engine cold and is to allow for expansion of the valve stems. When hot the clearance will be just about nothing to .001. Why the exhaust and intake sometimes have different clearances.

Still not sure, hire someone. Its easy to do but easy to do wrong too..

[bobconnie]

I was taught, just open the exaust valve, then set the intake valve, open the intake valve all the way and just start to close it,then set the exaust valve. it's easy at least is always has been for me, and everyone Ive shown this method to ! Just my 2 cents

[Cruisingscotts]

Follow the engine manual instructions to a "T" there are no generalizations when it comes to setting engine specific tolorances. If you are not 100% sure spend the money for 1 hr of labor and have a prof mechanic show you how. This is a very easy procedure once you know how to do it, however done incorrect it can cause big problems, think valve saying hello to piston. You most certainly should not be intimidated by this task and a lot of the above advice is good, however this is a task that should be done to manufactures spec and you should understand how and why as it is explained on your manual, otherwise your manual is pretty useless to you.

[perchance]

A few tips: Divide the number of cylinders into 760 degrees. This will give you the number of degrees you have to rotate the engine to bring the next cylinder to TDC. When number one cylinder is at TDC the timing marks on the vibration damper should be close to being aligned. To test for this you should be able to move both rocker arms slightly to indicate TDC. Hope this helps.

[roverhi]

Valves tend to tighten up not loosen with use in Gasoline engines. Assume that's the same with diesels. That's the reason that you want to adjust the valves regularly to keep them from tightening up and burning. Best to err on the loose side rather than the tight side. Loose won't hurt the engine unless they are way loose, just affect performance slightly and be noisy.

If your engine doesn't have compression releases have fun adjusting the valves. You are going to have to use the starter to turn it over and take what comes up. You can adjust the valves with the engine running but it's a messy process that takes some agility. Easiest way is take what the engine gives you and adjust the valves that are at TDC after you hit the starter momentarily. Just try and slip the gauge into the gap between the valve and rocker arm. Adjust the ones that you can get the gauge into. Eventually all the valves will present themselves at the proper position for adjusting. As a final check, be sure you can slip the gauge in on all the valves with the engine running.

Valve adjustment is not a zero tolerance job. Plenty of room for error especially on the loose side.

[Blue Stocking]

Depending on the firing order of a 4 or 6 cylinder engine, the "rule of 9", or the "rule of 13" may apply.
Google it for explanation.

[Canibul]

He said he had a three cylinder.

[Blue Stocking]

Originally Posted by Canibul

He said he had a three cylinder.

Ooops, Sorry.
Fingers ahead of brain

[Killick]

Awesome information everyone! I also found a few videos on YouTube that filled in the "gaps". Sailorchic34 I like how you think!

Valve Adjustments - YouTube

I'll give this a go in a few days. What a great group of people, I can't believe how many responses in such a short amount of time. What did we do before the internet?!

[atoll]

if the engine is fitted with a decompressing system don't foget to check that as well!