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Have 2007 mack ami370 and when pressuring up cylinders

through injector holes they don't...
have 2007 mack ami370 and when pressuring up cylinders through injector holes they don't hold any pressure is that normal
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Answered in 2 minutes by:
12/6/2019
Technician: Mike Mcmillan, Shop Foreman/Triage Tech replied 2 years ago
Mike Mcmillan
Mike Mcmillan, Shop Foreman/Triage Tech
Category: Medium and Heavy Trucks
Satisfied Customers: 6,605
Experience: Volvo/Mack Master Tech, Certified with Cummins, Eaton, GM, Hino, Detroit Diesel
Verified
Hello and thank you for using Just Answer my name is ***** ***** I will be assisting you with your question today I am sorry that you were having issues with your Mack please know that I will do everything I can to help you out my first question on this is what else is going on with the truck that would’ve let you to put air into the cylinder and the cylinder should hold air pressure some will leak off thru the crankcase.
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Customer reply replied 2 years ago
was making a really funny tapping sound in first half of engine so pulled injector unit pumps and checked all the rollers and then pulled injectors and all first three hole none are holding airwhen I pressure up cylinder 2 it bleeds out of injector 3
Technician: Mike Mcmillan, Shop Foreman/Triage Tech replied 2 years ago
did you take the rocker arms loose and all cylinders when you did it and also is the noise more of a pop or more of a tap
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Customer reply replied 2 years ago
More like a hard tapping and grinding sound ....does that make sinceMore towards the front middle of engine
Technician: Mike Mcmillan, Shop Foreman/Triage Tech replied 2 years ago

I would suspect a cam follower being out or a cam lobe. What I do is rotate the engine and measure the rocker arm lift with a dial indicator and document them as I go along. I do it this way because usually a cam only goes bad at one spot which will not show up on an overhead check most of the time. But on the lift it will.

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Customer reply replied 2 years ago
What would it sound like if a bearring was out
Technician: Mike Mcmillan, Shop Foreman/Triage Tech replied 2 years ago

Usually that will start with a screeching sound then a lower metal to metal. A wrist pin would sound like a knocking noise, A cam bearing can make that noise because it echos up thru the push tubes

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Customer reply replied 2 years ago
Should I drop the pan and take a look up at the cam
Technician: Mike Mcmillan, Shop Foreman/Triage Tech replied 2 years ago

Yes, I would, You can access it that way too and check for any metallic debris coming from other places as well. Please let me know if you have any follow up questions on this. Thank you.

Mike Mcmillan
Mike Mcmillan, Shop Foreman/Triage Tech
Category: Medium and Heavy Trucks
Satisfied Customers: 6,605
Experience: Volvo/Mack Master Tech, Certified with Cummins, Eaton, GM, Hino, Detroit Diesel
Verified
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Mike Mcmillan
Mike Mcmillan
Mike Mcmillan, Shop Foreman/Triage Tech
Category: Medium and Heavy Trucks
Satisfied Customers: 6,605
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Experience: Volvo/Mack Master Tech, Certified with Cummins, Eaton, GM, Hino, Detroit Diesel

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