jmahoneclipse Posted October 25, 2016 Share Posted October 25, 2016 hello, i recently had an issue with my 08 mack GU813 missing on 3 CYL. after testing i found the problem was the wiring harness, so i proceeded to replace the harness and while i was in there i also changed exhaust manifold and manifold gaskets due to them leaking. once everything was back together i ran the engine and found a boost leak at the vband on the turbo. i tried a new o-ring and the factory o-rings wouldn't seal so i placed a thicker o-ring in its place and i cant get an bubbles from around the flange while idled up with about 5-10PSI of boost. but when i drive i am still getting a boost leak squeel above 15psi. i cant seem to find this with the engine running. does mack sell a kit to attach an air line to the v-band fittings for boost leak testing? Quote Link to comment https://www.bigmacktrucks.com/topic/47421-mp7-boost-leak-testing/ Share on other sites More sharing options...
Mackpro Posted October 25, 2016 Share Posted October 25, 2016 99% sure its the EGR elbow from the EGR valve to the cooler. Thoses can be a pain to get sealed . Any tme we have it loose/off , we always pressure test whole system before we put the exhaust piping back on. The end of the elbow that goes on the EGR cooler has a floating ring in it that has to be sealed perfectly. Of course you can't see if its lined up because the clamp covers it. Last week I fought with one for about an hour before I got it sealed. Quote Link to comment https://www.bigmacktrucks.com/topic/47421-mp7-boost-leak-testing/#findComment-349867 Share on other sites More sharing options...
jmahoneclipse Posted October 25, 2016 Author Share Posted October 25, 2016 i did have all of that removed and all new gaskets installed. but how do you know if that is the issue? i was thinking of commanding the egr closed and test drive, if that elbow was the issue on that case the noise would go away. but i do not have a scan tool for the bigger trucks so i cant do that. any other tips? Quote Link to comment https://www.bigmacktrucks.com/topic/47421-mp7-boost-leak-testing/#findComment-349868 Share on other sites More sharing options...
fjh Posted October 25, 2016 Share Posted October 25, 2016 (edited) Its Experience ! The u pipe on the egr cooler is the likley ( culprit Believe it )! Every one has been burned with it at one point or other! And yes they sell turbo cap off kit it anit the greatest thing but it does work. we have a home made one that works for all the engines it was built for the asset but it works on all of the engines. Edited October 25, 2016 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/47421-mp7-boost-leak-testing/#findComment-349869 Share on other sites More sharing options...
jmahoneclipse Posted October 27, 2016 Author Share Posted October 27, 2016 problem found! it was actually a loose clamp at the air box! under higher boost it was pulling more air thru causing a squealing noise! Quote Link to comment https://www.bigmacktrucks.com/topic/47421-mp7-boost-leak-testing/#findComment-350088 Share on other sites More sharing options...
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