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Valve Adjustment and MPG

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Old 11-29-2008, 12:03 AM   #1  
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Question Valve Adjustment and MPG

I actually researched this before creating a post, I only found one reference to valve adjustment affecting the MPG...

Would a Valve Adjustment increase my MPG any? I'm now at 280,000 and have no idea if it was ever done before.

-Tim
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Old 11-29-2008, 06:30 AM   #2  
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I am also curious about this as I am at 108k and the book calls for adjustment at 100k. My truck runs great and gets decent mileage. I am more concerned if this should be done to prevent any damage from happening.

Do the valves tighten up over time prevent valves from seating completely?
or
Do the valves loosen up and not allow full opening?

I am hoping for the second as I would think this would have less chance of causing trouble.
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Old 11-29-2008, 06:45 AM   #3  
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Yeah, I have the same question. My truck runs fine and I've never adjusted the valves. I'm more worried about messing something up by opening the valve cover. Is there a way to tell if the valves need adjusting or not? Besides taking off the valve cover, of course....
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Old 11-29-2008, 07:41 AM   #4  
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Old 11-29-2008, 09:34 AM   #5  
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i adjusted mine recently and it did nothing for mileage
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Old 11-29-2008, 09:39 AM   #6  
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Quote:
Originally Posted by sheriffav8r View Post
Yeah, I have the same question. My truck runs fine and I've never adjusted the valves. I'm more worried about messing something up by opening the valve cover. Is there a way to tell if the valves need adjusting or not? Besides taking off the valve cover, of course....
how many miles do you have
if you worry about removing the valve cover take it to a professional
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Old 11-29-2008, 07:24 PM   #7  
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Adjustment is standard maintance item. Won't help or hurt milage or perfromace, unless really off. Just a check to compensate for normal wear of valve train. The clearence generally increases.
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Old 11-29-2008, 07:27 PM   #8  
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You need it but .....no change in milage
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Old 11-30-2008, 11:09 AM   #9  
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My truck had 188000 miles and the valves have never been adjusted so I adjusted them myself about a month ago. The tolerances are really big so everything was still within specs but I set them right on the money anyway. It seemed to me like the engine got a little better sound out of the valve train, but the engine is so noisy it is hard to tell. And as everyone has previously stated , I also had no change in mileage. The job is easy to do yourself, but it does require that you know, for sure, which valve you are on and what to set it at. If you got confused or tried to rush it and set a valve wrong it would be bad. Prolly just more the reason to do it yourself and take your time to get it just right. The valve cover is a good one on these trucks! The valve cover has a real good reusable gasket on it and that made the job a lot easier. It took me about two hours on a Saturday afternoon to do the job and that is with a lot of double checking , sipping a beer and making sure it was right. I got to use my inch pound torque wrench too which usually lays idle in the tool box. I use a little stepladder to get to the back valves. Good luck.
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Old 11-30-2008, 09:58 PM   #10  
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+1 on what Turbo2 said. The factory service manual calls for checking the valve las at 150,000 miles. I checked mine, and found only one which was very very slightly out of tolerance. Unless something is horribly wrong, they shouldn't be much out of adjustment, and if you find one or two a little loose, that's unlikely change your MPG even a little. If you find any way too tigtht, that will cause noticeable running issues, and usually indicates other problems in the valve train.
The hardest part of setting the valve lash is getting the rocker cover off. That, and reaching the rearmost couple of rockers!
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Old 07-24-2009, 12:22 PM   #11  
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It's only going to improve MPG's if your truck was losing power to begin with... I have an old 12V so I have to do this maintenance annually... but on your truck, they're supposed to be "maintenance free" (I turned wrenches at a dodge house for a short time and I know that NOTHING is maintenance free... it's usually maintenance expensive.... LOL).

I would onyl do this if you're hearing ticking or if it's just "high-time". I think the dealership i worked at said 150k miles was a good time to do it, but there was nothing in the mopar books that I recall. It's really a judgement for you.

J
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Old 10-01-2014, 06:55 PM   #12  
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I did mine at around 100,000 miles and they were within spec (just tightened them to the minimum) and haven't done it since (just under 300,000 miles now). I would like to do them again but my Uncle had the tool and is unavailable anymore from him.
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Old 10-08-2014, 01:56 PM   #13  
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I had a 1992 and it did make a small difference in performance and mileage, maybe 1 to 1.5 mpg,
I have 225,000 miles on my 2001 and they have never been, I do hear a bit more valve clatter
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Old 10-19-2014, 01:53 AM   #14  
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........I can say both my trucks a 1992 12 valve and a 2001 24 valve both picked up 2-3 miles per gallon.................kim..........
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Old 10-19-2014, 09:46 AM   #15  
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Quote:
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........I can say both my trucks a 1992 12 valve and a 2001 24 valve both picked up 2-3 miles per gallon.................kim..........
wow! must have been way out of adjustment
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