cxn613 Posted January 25, 2017 Share Posted January 25, 2017 2008 mp8 485 has around 475,000 on it, has vibration under load. Rpm's fluctuate when its acting up. This is not a consistent problem. Has the same feel as an injector being cut out but power is not effected when it does this. Truck has had all new cups and injectors and cam in the last 100,000 miles. Riding the jake down a hill seems to vibrate the worst. Quote Link to comment Share on other sites More sharing options...
fjh Posted January 26, 2017 Share Posted January 26, 2017 (edited) Its Possible the engine brake slaves are coming apart they are screwed together and some times they work loose! The only way to tell is to remove the vCover and check the valve set if the brake adjustment has tightened up then you got to lift the rocker shaft and check the slaves. Edited January 26, 2017 by fjh Quote Link to comment Share on other sites More sharing options...
cxn613 Posted January 26, 2017 Author Share Posted January 26, 2017 ok thanks Quote Link to comment Share on other sites More sharing options...
fjh Posted January 27, 2017 Share Posted January 27, 2017 Another indicator related to slaves is more frequent regens if the set gets real bad! Quote Link to comment Share on other sites More sharing options...
Mackpro Posted January 27, 2017 Share Posted January 27, 2017 FJH, did you see the new bulletin that came out today on the engine brake pistons? We ordered the tools, they were not to bad on the price, I was shocked. We have been seeing alot of these come apart here lately causing lots of problems. Exhaust Rocker Compression Brake repair.pdf 2 Quote Link to comment Share on other sites More sharing options...
Mackpro Posted January 27, 2017 Share Posted January 27, 2017 If you operate in very dusty conditions Id consider installing the fuel tank air filter kit so save your injectors, Any time we install a injector kit, we install the the filter kit if not already installed. Fuel tank air filter kits.pdf Quote Link to comment Share on other sites More sharing options...
hgfdg1990 Posted January 28, 2017 Share Posted January 28, 2017 (edited) xd Edited January 28, 2017 by Bigmackdaddy77 Quote Link to comment Share on other sites More sharing options...
fjh Posted January 28, 2017 Share Posted January 28, 2017 15 hours ago, Mackpro said: FJH, did you see the new bulletin that came out today on the engine brake pistons? We ordered the tools, they were not to bad on the price, I was shocked. We have been seeing alot of these come apart here lately causing lots of problems. Exhaust Rocker Compression Brake repair.pdf Thanxz for the post MP No MP I hadn't seen that . All I got to say is what took them so long we've been having issues with this for three years or more All models ! As for the price this may be a record as well we have been repairing them with out the tools for so long they better make it worth while !Ya got to do what ya got to do! 1 Quote Link to comment Share on other sites More sharing options...
cxn613 Posted January 30, 2017 Author Share Posted January 30, 2017 thanks for input. truck is doing a regen about once a week now compared to the once a month like it usually does, so may be onto something with the jake slaves. also the truck just has a slight choppyness while cruising down the road. almost like your on a light rumble strip all the time. truck runs in normal road conditions and not any off road use. has virgin bridgestone tires on. shocks all are new, cab mounts and engine mounts seem good. Quote Link to comment Share on other sites More sharing options...
fjh Posted January 30, 2017 Share Posted January 30, 2017 2 hours ago, cxn613 said: thanks for input. truck is doing a regen about once a week now compared to the once a month like it usually does, so may be onto something with the jake slaves. also the truck just has a slight choppyness while cruising down the road. almost like your on a light rumble strip all the time. truck runs in normal road conditions and not any off road use. has virgin bridgestone tires on. shocks all are new, cab mounts and engine mounts seem good. Don t wait to long to have it looked into! Keep us up to date so others can benefit from your findings! Quote Link to comment Share on other sites More sharing options...
cxn613 Posted February 6, 2017 Author Share Posted February 6, 2017 will the jake slaves still make a vibration even at a 1200-1400 rpm high idle? You can feel the vibration up through floor board when doing this but smooths out above 1600 rpm. Quote Link to comment Share on other sites More sharing options...
fjh Posted February 7, 2017 Share Posted February 7, 2017 (edited) Usually noticed in the higher rpms! Know engine codes but anything is possible like MPro said lots of different symptoms! You may have injector or injector harness issues If its coding / hard to tell till you look! Edited February 7, 2017 by fjh Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 7, 2017 Share Posted February 7, 2017 Any guess in what I'm doing today? 2014 CHU MP8 with 215,000 miles. Vibration under a load (97,897 pounds) . Exhaust brake pistons were tight. Quote Link to comment Share on other sites More sharing options...
fjh Posted February 8, 2017 Share Posted February 8, 2017 WELL Looky there a performance six pack GOOD JOB just pop those babys in there! Like I said AND there's your proof! Only six grand! cheap a twice the price! Are we doing a complimentary Cup Job to top it off! Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 8, 2017 Share Posted February 8, 2017 Thank God for extended warranty! LOL. I got this one done in under 8 hours but if I'm not bothered and feeling good and can do one in 6 hours. The kit comes with every thing , cups, injectors, o-ring and hold down bolts. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 8, 2017 Share Posted February 8, 2017 I will say, this is one of the best pulling trucks I have ever road in or drove. The owner picked me up and we took a load of corn to the grainery last friday. Grossed out at almost 98,000 pounds and bad injectors we had no problems in the hills or in heavy traffic. I thought it was awesome but he said it was no where as good as it usually is. Truck is a CHU daycab with a 505 PLUS MP-8, T-310 trans , Meritor rears with 3.21 gears and disc brakes all the way around. Running super singles on the back 445/50 R22.5 . No speed limiting and he dont baby it at all and still getting 6.1 MPG on his trips. I have pulled up some of his other longer and lighter trips and they were in the very high 7's . Quote Link to comment Share on other sites More sharing options...
fjh Posted February 8, 2017 Share Posted February 8, 2017 (edited) Wouldn't it be nice if this fixes his problem for good! Yup If your an O/O these days You Don"t dare NOT Buy A super Warrenty And hopfully you earn enough to be down while its being repaired Don't matter whos truck you own! Cummins is everybit as bad for not giving the rats ass if your unit is down . unless you happen to have a fleet! then THEY MITE kiss ass a little! Edited February 8, 2017 by fjh 1 Quote Link to comment Share on other sites More sharing options...
cxn613 Posted February 10, 2017 Author Share Posted February 10, 2017 Got to drive the truck today with a load. I do believe it is in the engine. Pulling a hard grade with rpms up it seems fine, but cruising over a knoll or just interstate cruising the engine will flutter. Really notice it if the cruise is on and you hit your target speed and the engine backs off then when it starts to come back it will flutter and tach needle will bounce. Coming home empty it runs perfect. Did get rid of the "hope" in the ride fixed by using those centering pins to center the wheels and drums. Quote Link to comment Share on other sites More sharing options...
Sharkbiteray Posted July 29, 2017 Share Posted July 29, 2017 (edited) Thanks for this Thread, this last week, noticed vibration under load with full jake, loud clunk when I throttle out of Jake. Also a load noise(sounds like air rush to clunk) when downshifting on hill quickly, if I throttle down a little and then shift no noise... Half Jake no symptoms. Trying get home, be ok if I drive no exhaust brake? I just bought this truck with 461k and have put $15k into parts and repairs so far...this exhaust problem is a 8 hr fix? Edited July 29, 2017 by Sharkbiteray Quote Link to comment Share on other sites More sharing options...
Mark_Robinson Posted July 29, 2017 Share Posted July 29, 2017 I think the problem is with the fuel pressure regulator. Try changing the fuel filter. Quote Used Trucks In Australia Link to comment Share on other sites More sharing options...
Hellcatheavyhaul Posted August 25, 2017 Share Posted August 25, 2017 Mines doing the same thing so far we think injectors which turned into a head. #6 exhaust valve is being greedy. Be nice to see how things go with the other ones Quote Link to comment Share on other sites More sharing options...
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