haulin-gas Posted April 18, 2015 Share Posted April 18, 2015 A couple of weeks ago the dealership changed all the injector cups because it was pressuring up the rad and blowing coolant out.That problem was solved, but now the injectors rattle and knock like an old gas pot with the distributor advanced all the way. Seems to only do it when starting out from a stop or when cruising at a constant speed and then opening up the throttle. Constant pulling under full power and it seems to be ok.No check or warning lights on and as far as I know they didn't do any program changes to the ECM.Any ideas? Quote Link to comment https://www.bigmacktrucks.com/topic/39734-mp8-injector-rattle/ Share on other sites More sharing options...
bbigrig Posted April 18, 2015 Share Posted April 18, 2015 If the dealer installed new injectors (6-Pack) with the cup replacement its pretty common. I'm not sure how bad your noise is but every one of my MP8's that has had all injectors replaced seems a lot louder (its from the high injection pressures) for the first while. Let's face it, you are now running at full fuel pressure to the injectors that you were not getting due to your leaking injector cups. Quote Link to comment https://www.bigmacktrucks.com/topic/39734-mp8-injector-rattle/#findComment-287096 Share on other sites More sharing options...
haulin-gas Posted May 3, 2015 Author Share Posted May 3, 2015 They didn't change the injectors, just the cups. After 3 weeks it started to pressure up the rad again and oil pressure started dropping. Took it in and they ran a battery of tests on it, finally changing the egr cooler. Mack had them change the oil pump and after a run-up on the dyno the oil pressure dropped well below spec again. (14 psi) at idle. They've changed all the sensors and verified the readings with manual gauges and still have no idea what's causing the loss of pressure.I'm thinking there's a crack somewhere in the oil gallery, but then I ar just a truk dryvr. This "great up-time" slogan they use needs to be put into the trash can. Quote Link to comment https://www.bigmacktrucks.com/topic/39734-mp8-injector-rattle/#findComment-288634 Share on other sites More sharing options...
bbigrig Posted May 3, 2015 Share Posted May 3, 2015 They probably did a poor job installing the cups. I've had one of our trucks in 3 times in 13 months. 3rd time was a charm and that was over 100,000kms ago. That job was cups only as well. Agreed that Mack and Volvo need to work on changing over to something better like common rail fuel systems. These unit injectors with cups are not holding up. Quote Link to comment https://www.bigmacktrucks.com/topic/39734-mp8-injector-rattle/#findComment-288647 Share on other sites More sharing options...
220cummins Posted May 4, 2015 Share Posted May 4, 2015 I hear a common rail is in the works?? Just a rumor I heard. Quote Link to comment https://www.bigmacktrucks.com/topic/39734-mp8-injector-rattle/#findComment-288780 Share on other sites More sharing options...
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