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Old 08-17-2019, 06:30 PM   #1
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Valve Clearance Adjustment

I installed a new valve cover gasket yesterday and considered a valve clearance check or adjustment. I chickened out and went with ďif it ainít broke donít fix itĒ. Engine is running fine, a Perkins 4-236. My questions is this: how can you tell if your valves need adjusting?
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Old 08-17-2019, 06:37 PM   #2
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Imagine two tap dancers out of sync. I dunno, I made it up.
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Old 08-17-2019, 07:10 PM   #3
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Originally Posted by Gulf Comanche View Post
I installed a new valve cover gasket yesterday and considered a valve clearance check or adjustment. I chickened out and went with ďif it ainít broke donít fix itĒ. Engine is running fine, a Perkins 4-236. My questions is this: how can you tell if your valves need adjusting?
Unless they are way out of adjustment you can only tell by measuring them.
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Old 08-17-2019, 07:22 PM   #4
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Unless they are way out of adjustment you can only tell by measuring them.
Thatís what I figured but was hoping there would be some kind of racket that I should listen for. It ainít broke so I wonít fix it.
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Old 08-17-2019, 07:27 PM   #5
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It's not rocket science. Either get a knowledgeable friend or pay a mechanic to adjust the valves and learn. The valve clearance has to be done periodically because of wear on the top of the valve stem and the rocker that operates it. Letting it go too long means a bigger gap, the rocker hits the valve stem with more force and you get more wear, faster.
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Old 08-17-2019, 07:33 PM   #6
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We did a valve adjustment during Bob Smithís Lehman seminar. Bob told us we had done a good job after he fired it up and listened to it. I am not sure what he was listening for but apparently he heard what he wanted to hear. After having participated in one valve adjustment, I would not feel comfortable doing it on my own. I would pay to have it done.
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Old 08-17-2019, 07:35 PM   #7
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You won't know the difference until you get them adjusted. Not sure how your Perkins will behave, but my Cummins always runs quieter and seems to idle smoother after adjusting the valves. It's not a bad job, if you ever take the injectors out, adjust the valves since the motor will be so much easier to bar over without any compression.
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Old 08-17-2019, 07:47 PM   #8
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Thatís what I figured but was hoping there would be some kind of racket that I should listen for. It ainít broke so I wonít fix it.
It is also possible to have a valve that is too tight, not only is that worse than too loose but it won't make any extra noise.
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Old 08-17-2019, 08:31 PM   #9
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OK, thanks to all y’all.
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Old 08-17-2019, 09:00 PM   #10
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sounds pretty good to me @ about 2:43
If it sounds like this, then adjust them
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Old 08-17-2019, 11:33 PM   #11
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Adjusting valves on big diesels is really not hard. Compared to the tiny adjustment screws and nuts of a gas auto engine, the diesel adjusters will be much easier. Turning the engine may be the harder task.

Didn't any of you adjust valves on a foreign car or motorcycle in your youth? Identical process, just bigger.

The U Tube videos should help.
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Old 08-18-2019, 01:42 AM   #12
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I'm not sure about a Perkins, but most small diesel manufacturers recommend a valve check & adjustment every 500 hours. Engines often experience valve recession and need to be compensated by adjusting the valve lash.

It's not much more complicated than doing an oil change, and can be done in less than an hour.
Don't wait until it's broken and you've dropped a valve. That will take a lot longer than an hour.
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Old 08-18-2019, 06:27 AM   #13
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The simplest method to decide if the adjustment is OK is the GO-NOGO method.

If DA Book sez 12 thousands is required , you first select an 11thou feeler gauge and see that it slips by very easily.

Then a 13 thou feeler is used to measure that it does not fit easily, only with modest force.

The measurements can be made either with the engine running , fine for a check, or stationary.

If stationary DA Book (workshop manual) will frequently have instructions like "when # 6 exhaust valve begins to open adjust intake and exhaust of cylinder #2.

This is done to assure the cam is not lifting the valves you are setting.


DONE,
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Old 08-18-2019, 07:51 AM   #14
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If you have the rocker cover off, at least measure the lash and see if any are far off from spec. Anyone that owns one of these things should know how to measure and set lash. Super easy.
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Old 08-18-2019, 09:48 AM   #15
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Hi gang I have a Ford Lehman 80 HP that I have inherited. Do not have a manual yet but need a spec for valve adjustment. It has rotates on the tops. Anyone know the spec? Thanks Dan Timms
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Old 08-18-2019, 09:55 AM   #16
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Quote:
Originally Posted by FF View Post
The simplest method to decide if the adjustment is OK is the GO-NOGO method.

If DA Book sez 12 thousands is required , you first select an 11thou feeler gauge and see that it slips by very easily.

Then a 13 thou feeler is used to measure that it does not fit easily, only with modest force.

The measurements can be made either with the engine running , fine for a check, or stationary.

If stationary DA Book (workshop manual) will frequently have instructions like "when # 6 exhaust valve begins to open adjust intake and exhaust of cylinder #2.

This is done to assure the cam is not lifting the valves you are setting.


DONE,
Checking valve lash while the engine is running is not a good idea.
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Old 08-18-2019, 10:21 AM   #17
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I don't think FF was suggesting doing valve adjustments on diesels while running. However, doing just that was common practice with high output solid lifter v8s in the 60's because the lifter ramps on the cam were so long. Done with deflectors you do not lose a lot of oil.
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