DJ Truck Repair Posted May 12 Share Posted May 12 I have a 2013 mp8 Mack. Same engine as D13 volvo. Came in shop with burnt valve on number 1 cylinder. Owner decided to replace head and declined to change damaged liner due to where the damage was. After head replacement had a fuel knock on same cylinder valve was burnt on. He stated that the knock was happening even before the burnt valve and decided that since truck had almost a million miles he wanted to rebuild it. After rebuild fuel knock is still there. I swapped injecters around and fuel knock stays at number one hole. I’ve checked all rocker arms and plunger for Jake’s and everything is good. I’m out of ideas. Can someone help me here??? Thank you! Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/ Share on other sites More sharing options...
mrsmackpaul Posted May 12 Share Posted May 12 Never worked on these motors so Im not gunna be of any real help, anything I say is just thinking out aloud So I need to just ramble a bit I believe you can rule out mechanical as the motor has been rebuilt You can rule out the injector because you swapped it I think it wouldn't be unreasonable to suggest that the valve burnt because of something wrong and not wear and tare So it really only leaves the electrical side of the injection system, (I am assuming the injectors are fired eelectrically ?) Is there a high resitance connection causing the voltage to be lower than needed and as such the injector is firing a bit slower ? I have no idea if this is even possible but just throwing a idea out there Lot's more smarter people with these than me on here Paul Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/#findComment-551542 Share on other sites More sharing options...
fjh Posted May 12 Share Posted May 12 4 hours ago, DJ Truck Repair said: I have a 2013 mp8 Mack. Same engine as D13 volvo. Came in shop with burnt valve on number 1 cylinder. Owner decided to replace head and declined to change damaged liner due to where the damage was. After head replacement had a fuel knock on same cylinder valve was burnt on. He stated that the knock was happening even before the burnt valve and decided that since truck had almost a million miles he wanted to rebuild it. After rebuild fuel knock is still there. I swapped injecters around and fuel knock stays at number one hole. I’ve checked all rocker arms and plunger for Jake’s and everything is good. I’m out of ideas. Can someone help me here??? Thank you! Do you have a puter with ptt? that will do a cut out test? cylinder balance test? Jpro? Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/#findComment-551546 Share on other sites More sharing options...
DJ Truck Repair Posted May 13 Author Share Posted May 13 17 hours ago, fjh said: Do you have a puter with ptt? that will do a cut out test? cylinder balance test? Jpro? I have jpro. Every time I cut number one the knock goes away. On 5/9/2019 at 7:05 AM, nidfd112 said: Had a truck come in with one of number one cylinder exhaust valves was burnt on it. Customer wanted to replace cylinder head and we did. Finished the installation and when we started truck up it runs for 15-20 seconds fine and after turbo spools up it develops a knock in the engine. If we cut number one injector out with computer knocks seems to dissappear. We have removed pan and inspected cylinder wall, piston and bearings and also have changed out #1 injector. Does anyone have any ideas on what to check out next. On 5/3/2024 at 3:11 PM, D-Day said: I can not remember the exact location of the brake light switch for a DM of that year but its common for the spring to break inside of these little switches allowing the contact points to stick together same thing with the low air pressure switch Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/#findComment-551606 Share on other sites More sharing options...
The Heinz Posted May 13 Share Posted May 13 We see a lot of electrical faults with injectors, particularly in the harness. You may want to check the injector end of the harness on cylinder 1 for any faults, especially any oil intrusion. You could also have something up with the overhead, like the rockers themselves. We see those fail too. There's a lot of possibilities with the MP engines, but we wouldn't be able to diag over the internet sadly. Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/#findComment-551615 Share on other sites More sharing options...
fjh Posted May 13 Share Posted May 13 1 hour ago, The Heinz said: We see a lot of electrical faults with injectors, particularly in the harness. You may want to check the injector end of the harness on cylinder 1 for any faults, especially any oil intrusion. You could also have something up with the overhead, like the rockers themselves. We see those fail too. There's a lot of possibilities with the MP engines, but we wouldn't be able to diag over the internet sadly. Agree Heinz! re check the set! How ever Fuel knock is pretty distinctive! Harness is a good probability it should be coding out thou! or pin fretting was a common issue! Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/#findComment-551622 Share on other sites More sharing options...
Solution Popular Post DJ Truck Repair Posted May 14 Author Solution Popular Post Share Posted May 14 Just to let everybody know because there is another forum in here about the same issue, but there was no resolution if you replace the head on a D13 volvo or a mp8 Mack and it has a fuel knock you have to log in with ptt and reset the contribution balance on each injector. 1 2 Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/#findComment-551663 Share on other sites More sharing options...
fjh Posted May 14 Share Posted May 14 10 hours ago, DJ Truck Repair said: Just to let everybody know because there is another forum in here about the same issue, but there was no resolution if you replace the head on a D13 volvo or a mp8 Mack and it has a fuel knock you have to log in with ptt and reset the contribution balance on each injector. Good Find and good info Bro! SO , Is this the same as the trim code? or some other function In PTT!? Learned Data Reset? Just askin! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74149-rebuilt-engine-fuel-knock/#findComment-551681 Share on other sites More sharing options...
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