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Ramzfan · 11-17-2015, 07:22 PM

I am curious...I was just reading a question in this month's Motorhome magazine and the fellow said that he had had his valves adjusted and it improved his fuel mileage by about 1 mpg. Has anyone here had this same experience? I am thinking that I should have mine adjusted if that claim is accurate. My rig is a 2006 Itasca Meridian 36G with a 350 Cat. It presently has 36000 miles on it.

GraySeal65 · 11-17-2015, 07:25 PM

No experience with a Cat but it made no difference on my Cummins.

jroan · 11-17-2015, 08:02 PM

My advice is if you don't hear any valve tappet noise don't have them adjusted-I don't think you will see any increase in fuel mileage. I had mine done at 50K and they really did not need it. My mileage was between 7.2-7.8 before and it is the same after.(Cat C7 year 2007)

Jroan

MaverickBBD · 11-18-2015, 04:00 PM

Been a while since I had the CAT manual out but if memory fails me as usual I think they call for an initial adjustment around 14k or something. Haven't heard of a lot of people doing think. Then the next is around 100k which is around top end time. If for any reason they are in there have them done anytime around 60k+.

scampers227 · 11-19-2015, 08:54 AM

330 Cat adjusted first time at 50k. Minute adjustment required. No gain in MPG. 8 before 8 after.

mel s · 11-19-2015, 09:18 AM

Quote:

Originally Posted by Ramzfan

I am curious...I was just reading a question in this month's Motorhome magazine and the fellow said that he had had his valves adjusted and it improved his fuel mileage by about 1 mpg. Has anyone here had this same experience? I am thinking that I should have mine adjusted if that claim is accurate. My rig is a 2006 Itasca Meridian 36G with a 350 Cat. It presently has 36000 miles on it.

Ramzfan
I did not notice any MPG increase however I do recommend you follow Caterpillar's maintenance schedule for your particular engine.
Mel
'96 Safari, 3126 Cat, (8.5 MPG average in 144k miles)

movin-on · 11-19-2015, 12:03 PM

Same here...Adjusted at 40,000 miles at a Cat shop and they were spot on...

bigdog · 11-19-2015, 02:06 PM

According to Cat, 45-50K and they pulled the records and we found that mine had been done at 47K. I was gonna have it done at 110K, but they found that I had one dead cylinder and my engine was toast , so we didn't do it. They say that the engine problem probably started before I got it and has finally gotten to the point that I noticed it. They said that the first signs started showing up on the computer records at around 70k with some overheat and engine check codes. It's dusted from some dirt getting in through a air filter with a hole in it.

I bought the rig at a bit over 80K and no signs of engine trouble.

1ciderdog · 11-20-2015, 06:04 PM

WOW, That's a bummer. I just had to replace the C7 in mine and it sure hurt the pocket book.

twinboat · 11-20-2015, 06:50 PM

I would follow Cats recomendations on valve adjustment.

Valve don't just wear to a bigger clearance.

Sometimes the valve face and seat wear, diminishing the clearance.

When this happens and the engine temp climbs, it could cause an exhaust valve to remains slightly open. That will cause rapid valve failure or a dropped valve.

Cat is not just trying to take your money.

JPMaly · 11-26-2015, 11:13 AM

Yes, I am seeing an increase in fuel economy. As high as 2 mpg, but 1 mpg seems on average for this trip, which, in all honesty is the first trip after the valve adjustment. It's routine maintenance, and a whole lot cheaper than a new engine.

rver98 · 02-02-2016, 05:44 PM

CAT recommendations are at 30k, then at 100k. As others have stated follow the manufacturer's instructions.

CAT Lover · 03-07-2016, 09:39 PM

Adjusting the valves on my rigs always helped restore diminished MPG's.

twinboat · 03-08-2016, 05:54 AM

I have adjusted valve on diesel engines many times thruout my career.

What you are doing is checking the valve clearance for need of adjustment.

I have found that most times the wear is so slight and within specs that adjustment is not needed in every valve and the ones that need it only need a slight adjustment.

So unless your engine has extremely high mileage with no past maintance, I find the claims of 10% to 20% increase in fuel economy, from just a valve clearance adjustment, questionable.

A valve clearance check is often incorporated in a major service with many other checks, services and adjustments being performed.

That, I believe is where the return of lost power and fuel economy may be realised.