muncieman Posted April 10, 2017 Share Posted April 10, 2017 I have a 65 Mack with a 673 turbo and at idle it has a distinct huff,huff,huff,huff sound I tried sending a video but the file is too big. It also smokes a whitest gray smoke. It doesn't seem to be at a loss for power so I'm wondering what anyone thinks. I'm thinking it could be a valve not seating itself right or possibly all the injectors need rebuilt. I have tried standyne injection cleaner and running it as hard as I can but it did not change anything. Quote Link to comment https://www.bigmacktrucks.com/topic/49472-engine-has-a-miss-at-idle/ Share on other sites More sharing options...
theakerstwo Posted April 10, 2017 Share Posted April 10, 2017 Many things it can be.Just to name a few is maybe a valve has cracked or burnt or a cam go down or maybe a bad injector or a bad cam in the injection pump.Or a burnt piston. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/49472-engine-has-a-miss-at-idle/#findComment-366905 Share on other sites More sharing options...
muncieman Posted April 10, 2017 Author Share Posted April 10, 2017 Do you think it could still run Ok with something like that? Quote Link to comment https://www.bigmacktrucks.com/topic/49472-engine-has-a-miss-at-idle/#findComment-366913 Share on other sites More sharing options...
fjh Posted April 10, 2017 Share Posted April 10, 2017 Sounds like a valve or if it has dyntard slave stuck 1 Quote Link to comment https://www.bigmacktrucks.com/topic/49472-engine-has-a-miss-at-idle/#findComment-366914 Share on other sites More sharing options...
Casper1988 Posted April 10, 2017 Share Posted April 10, 2017 They really smoke nasty when that Dynatard is on and fuel is rolling. Other than that its beyond me. Quote Link to comment https://www.bigmacktrucks.com/topic/49472-engine-has-a-miss-at-idle/#findComment-366936 Share on other sites More sharing options...
muncieman Posted April 10, 2017 Author Share Posted April 10, 2017 It doesn't have a dynatard. Im thinking it may only be the injectors. I'm fairly certain they have never been rebuilt. A while ago I did take the valve covers off and did not see anything broke in the upper valve train. In fact the engine look pretty clean for 51 years old.. I'm hoping it does not have a piston broke. Quote Link to comment https://www.bigmacktrucks.com/topic/49472-engine-has-a-miss-at-idle/#findComment-366945 Share on other sites More sharing options...
muncieman Posted April 10, 2017 Author Share Posted April 10, 2017 So I did take my Mack to a reputable shop and the guy there said it could possibly be the timing of the pump or the pump is wore out. Anyone know where I could find a used one? He said it could cost over 1500 to fix it. Another thing he said it could be is a valve seat may of come un-done. Another costly repair. Might be selling. Will know more next week. Quote Link to comment https://www.bigmacktrucks.com/topic/49472-engine-has-a-miss-at-idle/#findComment-366966 Share on other sites More sharing options...
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