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"If there's ever a nuclear holocaust, the only thing left will be cockroaches and Isuzu diesels." (author unknown) This site is dedicated to the humble little Isuzu P'up.
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PostPosted: Mon Feb 04, 2008 2:06 pm 
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I am learning how to adjust my valves for the first time on my new 1981 LUV 4WD with the 2.2L Isuzu diesel engine and have two questions.

1. Should I believe the valve clearances on an Isuzu sticker on the hood of the vehicle or the clearances in the Series 11 Shop Supplement (which contains the diesel engine info?)

On the hood it says the valve lash (cold) should be 0.016 (0.4MM limit) for both intake and exhaust valves. In the shop manual it says the intake valve clearances are 0.039-0.068 and the exhaust valve clearances are 0.064-0.093 (0.20 limits for both.)

One exhaust valve was in a position where we could check it, and it was at 0.016.

BTW, I have no idea if this is the original hood although I see no evidence of a front-end collision (I'm no expert, of course, but one of my Mercedes 300DTs is a front end wreck and I know what that looks like.) I don't know if this is the original engine, either, although with the odometer only at 123k it would certainly seem like it should be the original.

2. What's the best way to turn this engine? There doesn't seem to be much space to work in at the front of the engine or from underneath.

Thank you!

Maud


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PostPosted: Mon Feb 04, 2008 4:31 pm 
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1. Valve lash is .016. The other number from your manual is for the valve guide, and that's the side-to-side wiggle. It's not an adjustment, when it gets too loose you replace the valve guide. Usually part of an overhaul, not a tuneup.

2. Park on a level surface, put it in forth gear and push a few inches. One revolution of the engine is about 18" of forward motion.

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PostPosted: Mon Feb 04, 2008 7:07 pm 
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Thank you, CharlieB!

Maud


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PostPosted: Tue Feb 05, 2008 10:38 pm 
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My friend JimBob, who has previously adjusted the valves on his Mercedes diesels and is helping me learn how to adjust these valves, has told me that he would like to turn the engine by turning the power steering pump pulley. Our friend Terri, who for years did all the work on her Isuzu P'up diesel, has mentioned it is one of those things people say not to do but tend to do anyway although very carefully.

What do you all think?

Personally, JimBob's idea makes me nervous because I don't know what could go wrong if we tried turning the pulley and made a mistake. Is this high risk? What's the worst case scenario?

TIA.

Maud


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PostPosted: Tue Feb 05, 2008 10:56 pm 
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there are a couple of ways to get the engine turned over, it your in for a serious tune up and have the injectors out that would be super easy to turn by hand. If you just decided today i'm going to adjust my valves then i would do it by putting it in gear and shoving it. A way that i found that works well is to put a wrench in the IP nut and your other hand on the crank. together you get enough force to do what you want. Its really just a personal preferance that the more you work on it you'll develop your own ways of doing it.

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PostPosted: Tue Feb 05, 2008 11:17 pm 
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The ps pump will only turn the engine if the belts are really tight. Just put it in 4th and push it. I actually "pull" from the front so I can look at the timing mark and see when it hits tdc. Pushing requires one person at the back to push, one at the front to holler STOP! If you go past the mark, don't push backwards and turn the engine backwards. Just keep going around again. For adjusting valves, you only need to be close, not exactly on the timing mark.

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PostPosted: Wed Feb 06, 2008 5:07 pm 
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MaudEssen wrote:
I am learning how to adjust my valves for the first time on my new 1981 LUV 4WD with the 2.2L Isuzu diesel engine and have two questions.

1. Should I believe the valve clearances on an Isuzu sticker on the hood of the vehicle or the clearances in the Series 11 Shop Supplement (which contains the diesel engine info?)

2. What's the best way to turn this engine? There doesn't seem to be much space to work in at the front of the engine or from underneath.

Thank you!

Maud


I don't want to overcomplicate things here but . . . Isuzu gives the general valve-lash specs for a cold C223 engine as: Intake 25 mm (.010") and exhaust 35 mm (.014"). You will find some slight variations in these very general specs. Anything close to that will be fine for most purposes. But - there have been many arguments about this for many years - dating back to the early 1900s, Henry Ford, and Model T racing.

Many people tend to adjust their valves to quiet the engine down a bit - especially when they get a bit loose and noisy. The true meaing of valve-lash specs is to get the valve timing where it was designed to be. So - to be technical, an engine adjusted for best performance is likely not to be pefectly in specs with the general lash specs as posted. An engine tuned to run it's best is adjusted with a degree wheel and the said clearance is totally ignored. Remember, the looser a valve is adjusted, the later the valve timing. The tighter the adjustment, the earlier the timing.
Since few people are willing to spend time with a degree wheel, valve-lash is a shortcut that puts an engine in "the ball park" to run well enough.

So - to be very technical - intake valves are supposed to be adjusted so they just start to open 32 degrees BTDC and close at 60 degrees ABDC. Exhaust must just start to open at 65 degrees BBDC and close at 29 degrees ATDC.

I don't use a degree wheel by the way. If I was entering some sort of contest ,I would. Any race engine - where everything needs to be perfect - is always adjusted with a degree wheel.

I find it kind of interesting. Back around 1918, there was a race between two Ford Model Ts. The race was based on a long standing argument about valve-lash adjustment. The guy who adusted with a degree-wheel won the race.

For your valve-lash adjustment going by clearance specs, you do so by getting the engine at TDC of the compression stroke for #1. Then adjust I and E on #1, just I on #2, just E on #3 and none on #4.

Then turn the crank one full turn and do the following:
Adjust none on #1, adjust E on #2, adjust I on #3, and adjust I and E on #4.

To turn the engine, I usually stick a socket and wrench on the crankshaft bolt. Another way is to remove the glow-plugs and then turn easily by hand.

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85 Isuzu 4WD diesel PUP, (2) 81 diesel Chevettes, (2) 91 diesel Volks Jettas,(22) Chevy 6.2 diesel Blazers/trucks/Suburbans, 85 Ford 6.9 diesel truck, 94 Ford 7.3 TD truck, 92 Dodge 5.9 TB diesel truck - over 20 diesel backhoes, tractors, dozers


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PostPosted: Wed Feb 06, 2008 11:10 pm 
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Not to oversimplify things, but...

Set them to .016" as the Isuzu sticker advises.

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PostPosted: Sat Feb 09, 2008 12:13 am 
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Location: '82 shortbed dsl 5-speed North Carolina
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PostPosted: Sat Feb 09, 2008 1:57 pm 
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Woohoo! JimBob and I have adjusted the valves! We're just about to put the head cover back on...JimBob has gone to get the torque wrench he forgot. As soon as we close it up and put the glow plugs back in, we're going to do a compression test.

We started to turn the engine by pushing it in fourth gear. But with the glow plugs out we found we could turn it by pulling on the pulleys. It was very easy...we just had to go around twice although because we are like Laurel and Hardy we ended up going around a total of four times.

The valves were definitely in need of adjustment. We didn't record the actual specs where they began, but they were pretty much all over the place...about half the valves too tight and some too loose and two in spec. We adjusted all intake and exhaust valves to 0.016".

I'll let you know what the compression test shows.

Thanks for all your help!

Maud


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