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extending service intervals may be a bad idea


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so iv been doing some hopper bottom work as well as my normal dump trailer work latley between low oil prices and lots of rain road work has been slow this year. running synthetic oil in the mack hit 10k miles on my service last week witch is where i would normally drop my oil and change all filters. yesterday i was on my way in with a load of sunflowers (confection flowers light load can only get to about 75-76k gross loaded to the gills) was dropping near home. on my way in i started noticing some power loss engine was running smooth but went to pass a slow truck on a 2 lane stepped on it and it just would hardly pick up speed was in a bit of a hurry becouse i was pushing it time wise to get unloaded would of had the load stuck on my trailer till monday if i didnt make it by 5pm. so anyway i made it there with about 10 mins to spare got unloaded but by the time i pulled in i was having trouble to maintain 60mph would only get about 15psi of boost get unloaded pull out of the elevator about 5:20 all parts stores are closed decide to just head it to the house. by the time i get home i can only get about 10psi on the boost gauge had trouble keeping highway speeds with just a empty hopper bottom hooked up. boost psi was normal on the jake break. pull in its running a bit rough on acceleration had the truck idling it starts idling rough sitting in the yard looking it over but if you hit the throttle it would rev up but not smootly and then would idle smooth for a second before idling rough again then after a few mins it died out.

i think its plugged fuel filters went home went to bed. slept in this morning going to go pick up some fuel filters and service the truck and pray thats all it is. im not 100% sure because when iv gelled in trucks before they didn't develop the rough running just wouldn't rev or make power. then idle would get rough but not rev till they died out or you shut them off.

winter time is the only time i have had fuel filter problems in the past. on my truck before the mack i ran conventional oil and dropped at 5k miles and changed all filters. in the mack iv been running synthetic and a 10k intervall. i thought i would go 15k this time with doing the hopper bottom work because i am running a lot more highway miles than i would doing just dump trailer work and less gravel roads.

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Hopefully it's something simple. At work they run synthetic in all the trucks and change oil every 1000 (yes thousand) hours. I've never noticed any performance drops but than again run a DD 15 @ 515hp with a 10sp grossing 130k so I don't have much performance per say but like I said no rough running or any thing. Personally I think that's too long between oil changes but hey what do I know? Best of luck, happy Fourth of July.

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I cannot see why extended oil service intervals had anything to do with rough running or low boost pressure. IIf you want to have extended service interval on oil and oil filters fine. Just make sure you service fuel filters on regular basis. It sounds like if a simple problem plugged fuel filters or bad fuel or fuel line. Good Luck .Joe D.

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I'm seeing you are dropping full synthetc @ 10 000 miles? If it makes you feel better then fine, but that's an expensive obsession. Where is the extended drain? Did you forget a 0 in the mileage? There is NOTHING extended about 10 000 miles unless your idle time is 85%.

Edited by wiserfrombud
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It must be a western thing, 5000 mile is a standard on/off road change interval and 10,000 mile on road. So I understand the 10-15,000 mile interval that Ez rider is speaking of for synthetic oils and clean operating conditions, i will do the same thing with my farm tractors 100 hours during the summmer and 150-200 hours in the winter/early spring

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found the problem wasn't fuel filters the plastic drive gear on the fuel supply pump was spinning on its metal insert that was pressed onto the pumps shaft. they don't sell the plastic gear separate and the local mack dealer didn't have a pump on hand said they couldn't get one there till Tuesday. but they found one for me at another mack dealer 100 miles away so i did a 200 mile round trip in the pickup to go get a fuel pump. stuffed it in the truck and the dog is back up and barking again.

it was defiantly acting like a fuel supply problem but not exactly like plugged fuel filters. low boost psi is not necessarily a sign of a boost leak or turbo problem. takes fuel to make boost. low boost with black smoke and high pyro temps would indicate a boost leak. low boost no smoke and low pyro temps can indicate a fuel problem. also why i mentioned that boost psi on the jake break was normal. plugged air filter would also act simular to a boost leak although iv never seen a airfilter plug to the point that it caused a noticeable drivabiltiy problem and it wouldn't have come on that quick while running down a asphalt highway.

10k miles on synthetic is already doubling my normal service interval in my shaker before i bought my mack i was changing oil at 5k miles with conventional. oil samples would start showing some signs of viscosity break down by that point. my normal loaded weight is 96k (witch is why i said i was loaded light at 75k gross) also do a lot of slow speed driving typically and a lot of gravel roads and dirty operating conditions. had a bit over 500 hours and roughly 12k miles sense my last service. i was planing to extend it out to 15k this time as i had more highway time and some lighter loads than normal. oil samples have been looking good at a 10k drain on synthetic in the mack. the sythetic is roughly double the cost of conventional so cost is near equal at a 10k drain on synthetic vrs 5k drain on conventional. and less time spent changing oil.

although the problem turned out to not be plugged fuel filters i feel maybe i still ran too long on the fuel filters could have contributed by making the supply pump work harder. i think im going to start doing a b service and do fuel filters and air filter half way between oil drains. and keep oil drains around to 10k range.

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i will say though even though the mack kinda let me down and cost me some money today at least it got me home without a tow. it wouldn't start this morning to pull it into the shop just sputter a spit for a few seconds before dieing. so i had to fix it where it sat working outside in the dirt. but could have been worse. although i wore a trail between where i park the truck and the shop today...lol

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Good to hear it was a simple fix. Pulling a hopper will plug an air filter quicker than most applications due to the dust at point a and b.

this is true. the run i was doing was loading out of grain bins on a farm rather than out in a field 325 mile round trip to the elevator back to the same farm making 2 trips per day and the onset of the problem was on the highway about 30 miles from the elevator and progressively worse from there to the point it died after i parked it outside my shop and wouldn't restart.

defiantly could have been a worse repair. fuel filters would have been a much simpler fix lol. i don't know why they decided to make the fuel pump drive gear out of plastic. several hours of diagnostics to find the problem 3 hour drive to go get parts my simple fix pretty much ate up the whole day today. i wont complain though, glad someone had the part within a distance i could make before they closed and not be down till Tuesday waiting on parts.

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Lucky you made it home... Usually when the supply pump quits, it is complete and without warning. I got in the habit of carrying a spare in the toolbox.

As far as drain intervals, call me crazy but I ran my 2000 427 E-tech at 20,000 mile intervals using Mobil Delvac 15w-40. The Mack service manual allows 25,000 mile intervals. This engine had bearings rolled in once and now has over 1.5 million miles without overhaul. Not bragging but I must have been doing something right all that time. Mack's 3 filter system is far superior to other engine brands and IMHO allows longer drain intervals.

Gregg

Sent from my XT1254 using Tapatalk

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Lucky you made it home... Usually when the supply pump quits, it is complete and without warning. I got in the habit of carrying a spare in the toolbox.

As far as drain intervals, call me crazy but I ran my 2000 427 E-tech at 20,000 mile intervals using Mobil Delvac 15w-40. The Mack service manual allows 25,000 mile intervals. This engine had bearings rolled in once and now has over 1.5 million miles without overhaul. Not bragging but I must have been doing something right all that time. Mack's 3 filter system is far superior to other engine brands and IMHO allows longer drain intervals.

Gregg

Sent from my XT1254 using Tapatalk

how many times have you had this problem with the fuel pump. the fuel pump was a little spendy to carry a spare in the side box (about 300+ 100 core charge) mine s a 2000 460

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how many times have you had this problem with the fuel pump. the fuel pump was a little spendy to carry a spare in the side box (about 300+ 100 core charge) mine s a 2000 460

I think twice in about 10 years... Not too often but I am anal about getting stranded lol I carry lots of spare parts and tools.

Sent from my XT1254 using Tapatalk

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I agree with underdog. My last 2 trucks got the oil dropped at the first 5000 miles and then after put in 5w40 full synthetic and then it stayed in until an oil sample showed something abnormal to change it. Every 25 000 miles, change filters and pull a sample that is tested at a lab and run it. 150 000 mile oil changes were pretty typical. I have always used aftermarket bypass filtration as well however, and all of my trucks have been OTR. Just another opinion and point of view, that's all. I noticed the term "viscosity breakdown" I have never seen that in any sample of 100 000+ miles unless contaminates such as fuel are introduced. Base however will drop over time. It's just a matter of replacing a half gallon or so occasionally to freshen things up.

Edited by wiserfrombud
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I think twice in about 10 years... Not too often but I am anal about getting stranded lol I carry lots of spare parts and tools.

Sent from my XT1254 using Tapatalk

i certainly feel you on carrying lots of spare parts and tools i do as well. i found a used pump on e-bay for $40 + shipping i may order something like that in the near future to throw under the bunk. twice in 10 years for something that can leave you sitting where you are is probably grounds to carry a spare. tow trucks are expensive. i still say its a bad design almost like its designed to fail.

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  • 3 weeks later...

My local CAT service shop manager, who I trust, suggest I go by my hour meter. Every 300 hrs. A National crane, with by far the majority of my time spent idling in PTO and slightly above. If I can't make enough money in 300 hrs of running the crane to afford that oil change schedule, I'll retire!

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