Onyx610 Posted February 22, 2022 Share Posted February 22, 2022 Pictures and updates please! If you have the time haha… Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-489976 Share on other sites More sharing options...
Onyx610 Posted February 22, 2022 Share Posted February 22, 2022 (edited) So this is kind of double edge sword…Yea it sucks it came to this, but at the sametime look at the knowledge your gonna have when your done. On top of that a close to new engine! Edited February 22, 2022 by Onyx610 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-489977 Share on other sites More sharing options...
Onyx610 Posted February 22, 2022 Share Posted February 22, 2022 Also if anyone decides to machine any metal off that head, if it comes down to it…You will need shims for whatever was taken off to correct the backlash of that cam gear. They go In what I believe is called the cam tower. Basically just raises the cam. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-489978 Share on other sites More sharing options...
Joey Mack Posted February 22, 2022 Share Posted February 22, 2022 this is interesting... I have wondered what was done if an MP head was machined.. Because of the cam gear meshing in the back of the engine.. There is only .004" backlash allowed. so how would you account for that? thicker head gasket? I dont know, seems to me a new head would be the answer.. what do you think? jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-489980 Share on other sites More sharing options...
Vmac3 Posted February 22, 2022 Share Posted February 22, 2022 On 2/18/2022 at 2:30 PM, 67RModel said: I don't know how these new systems work but I'm curious as to why cylinder compression is measured as a percent (%). A percentage of what? What it was when it was new? What instrument or sensor is determining % compression? Did you mess with the valves during your repair? Maybe you could check the valve lash on cylinders #1 & 6 to make sure they are sealing properly? Sorry I am late to the party. How these compressions tests work is, the engine ecu measures the speed of the crankshaft while the starter motor is engaged. The ecu will see what cylinder is coming on the compression stroke by looking at the camshaft and synchronizing it with the crankshaft. Then the ecu will see which cylinder has the slowest speed during the compression stroke and compare the others to the slowest cylinder. If you do back to back compression tests, often times a weaker cylinder can sometimes be at 100%. This test should be used with a cylinder balance test. V 2 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490004 Share on other sites More sharing options...
Popular Post Vmac3 Posted February 22, 2022 Popular Post Share Posted February 22, 2022 11 hours ago, Joey Mack said: this is interesting... I have wondered what was done if an MP head was machined.. Because of the cam gear meshing in the back of the engine.. There is only .004" backlash allowed. so how would you account for that? thicker head gasket? I dont know, seems to me a new head would be the answer.. what do you think? jojo You would be correct. These cylinder heads should not be machined because this will change compression ratio and injector protrusion. V 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490005 Share on other sites More sharing options...
Onyx610 Posted February 22, 2022 Share Posted February 22, 2022 54 minutes ago, Vmac3 said: You would be correct. These cylinder heads should not be machined because this will change compression ratio and injector protrusion. V I thought it was supposed to be avoided but could be done within a certain limit. If it was done the shims on the cam towers would be needed? Never done it so I ask you for your opinion 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490008 Share on other sites More sharing options...
Vmac3 Posted February 22, 2022 Share Posted February 22, 2022 3 minutes ago, Onyx610 said: I thought it was supposed to be avoided but could be done within a certain limit. If it was done the shims on the cam towers would be needed? Never done it so I ask you for your opinion It is possible to correct the gear backlash with this method but the injector protrusion will be an issue. V 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490009 Share on other sites More sharing options...
fjh Posted February 22, 2022 Share Posted February 22, 2022 1 hour ago, Vmac3 said: You would be correct. These cylinder heads should not be machined because this will change compression ratio and injector protrusion. V I still have a concern here that we are over looking the original post combustion in coolant! I would scrutinize these liners for cracks and pin holes as well did you have an oil sample done ? As Joe mentioned post sum picts of the scuffed liners These Rarely fail head gaskets from what we have seen at our shop . not saying it can't happen ............ Real heavy scuffing may be caused by a pin hole or crack ! Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490015 Share on other sites More sharing options...
Vmac3 Posted February 22, 2022 Share Posted February 22, 2022 18 minutes ago, fjh said: I still have a concern here that we are over looking the original post combustion in coolant! I would scrutinize these liners for cracks and pin holes as well did you have an oil sample done ? As Joe mentioned post sum picts of the scuffed liners These Rarely fail head gaskets from what we have seen at our shop . not saying it can't happen ............ Real heavy scuffing may be caused by a pin hole or crack ! Yes you are correct. I have never seen these head gaskets fail on a Volvo. The liners may be cavitated and a pin hole may have developed. V 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490016 Share on other sites More sharing options...
Onyx610 Posted February 22, 2022 Share Posted February 22, 2022 So some of you guys pry know this stuff, but Dan may not so hear is some decent info. A lot of it standard procedure… There are seven main caps made of nodular cast iron. Each cap is marked for its specific location starting with No. 1 at the front. Main caps No. 4 and No. 7 are not marked and have a specific purpose. Main cap No. 4 houses the thrust washers to control axial movement of the crankshaft and main cap No. 7 is the attaching point at the rear of the block for the oil pump. When removing the main caps of the crankshaft, make sure that they are installed back in the correct position. The same thing applies with the rod caps as they are fracture manufactured When removing and installing the cylinder head, make sure to use the alignment screws and washers on the side of the head and block to maneuver the head while lowering it back onto the cylinder block. Because the head gasket has elastomer sealing rings, if the head is lowered onto the gasket and then slid into place, damage to the gasket may occur and result in improper sealing. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490017 Share on other sites More sharing options...
fjh Posted February 22, 2022 Share Posted February 22, 2022 2 hours ago, Vmac3 said: Yes you are correct. I have never seen these head gaskets fail on a Volvo. The liners may be cavitated and a pin hole may have developed. V never seen cavitated liners on these either HOW ever! shit happens! So point being here suspect and rule out everything because you still may have a cup or cracked head issue ! Just sayin! Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490018 Share on other sites More sharing options...
Onyx610 Posted February 22, 2022 Share Posted February 22, 2022 I guess when he takes the head to the machine shop they can magnaflux/pressure test the head. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490024 Share on other sites More sharing options...
Vmac3 Posted February 23, 2022 Share Posted February 23, 2022 16 hours ago, fjh said: never seen cavitated liners on these either HOW ever! shit happens! So point being here suspect and rule out everything because you still may have a cup or cracked head issue ! Just sayin! I had a customer with a D12D with 2 million k wanting an engine overhaul because it was consuming oil. So we overhauled the engine, replacing all the internals with new cylinder head, camshaft and injectors. Truck ran fine until we road tested it. Once under boost the cooling system was being pressurized. I ruled out the head gasket because I have never seen one of these head gaskets fail. Anyway, I used the Fleetgaurd combustion leak detector and confirmed combustion gases in the coolant. I didn't hook up PTT because it ran great at idle and the cooling system was not being forced out of the recovery tank. So, I took an educated guess and pulled out the injectors. Bingo, #5 injector had traces of carbon on it. Removed the cup and cleaned the mating surface. Using a pen light, you were able to see a very fine hairline crack propagating from the injector tip hole. Who knew? So for sure, Unexpected things like this do happen. Took it all apart replaced the head and the truck ran fine afterwards. With the original posters issue that has an egr delete, I'm wondering if the higher cylinder combustion temps and possibly injector timing changes are causing these engines to fail like this? Dunno?? V 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490063 Share on other sites More sharing options...
fjh Posted February 23, 2022 Share Posted February 23, 2022 3 hours ago, Vmac3 said: I had a customer with a D12D with 2 million k wanting an engine overhaul because it was consuming oil. So we overhauled the engine, replacing all the internals with new cylinder head, camshaft and injectors. Truck ran fine until we road tested it. Once under boost the cooling system was being pressurized. I ruled out the head gasket because I have never seen one of these head gaskets fail. Anyway, I used the Fleetgaurd combustion leak detector and confirmed combustion gases in the coolant. I didn't hook up PTT because it ran great at idle and the cooling system was not being forced out of the recovery tank. So, I took an educated guess and pulled out the injectors. Bingo, #5 injector had traces of carbon on it. Removed the cup and cleaned the mating surface. Using a pen light, you were able to see a very fine hairline crack propagating from the injector tip hole. Who knew? So for sure, Unexpected things like this do happen. Took it all apart replaced the head and the truck ran fine afterwards. With the original posters issue that has an egr delete, I'm wondering if the higher cylinder combustion temps and possibly injector timing changes are causing these engines to fail like this? Dunno?? V So in this case he is having the head checked and possibly planed cracks in theory should show up at the machine shop cups may not! You installed New cylinder head it had cracks that is scary !That I would expect with a reman head not new nothing surprises me with reman stuff ! The egr delete is a wild card here ,seen a few of these most do ok as long as the ecm has been tweaked properly! We have seen lots of ISX heads turned into shower sprayers with out a proper tune! The heat just cooks them! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490084 Share on other sites More sharing options...
Dan107 Posted February 26, 2022 Author Share Posted February 26, 2022 Hey all! On the question of the head, I ordered a new, fully loaded one! Had an old diesel tech take a look at it and thought it best. I didn't want to take a chance on there being something damaged we couldn't see. Plus, I spent nearly $3k having the old head serviced when #2 cylinder cracked a couple of years ago. With that being said, I think I may have really screwed up! My assumption was that with the cam gear having timing marks on a couple of teeth, that the idler gear would also have a corresponding single tooth marked...we all know what happens when we assume! Now I can't find an understandable solution on how to get this set correctly without excess work and expense. So, once again I come to ya'll for help. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490364 Share on other sites More sharing options...
fjh Posted February 26, 2022 Share Posted February 26, 2022 (edited) Unfortunately there is a specific tool to achieve this! It is hoeky as hell and a crap shoot to use ! we normaly make our own marks when removing the cam gear for ease of assembly! Mac pro Or Joey may have some decent advice on this! This here is one job you just don't want to be winging it! The only thing I can do is sit back and watch and wish you luck I am a sidewalk superintendent when it comes to red engines! ! They MAY be able to talk you guys thru it! 😡 Edited February 26, 2022 by fjh 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490365 Share on other sites More sharing options...
Dan107 Posted February 26, 2022 Author Share Posted February 26, 2022 On 2/21/2022 at 8:10 PM, Onyx610 said: Pictures and updates please! If you have the time haha… Cylinder 1 pic. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490366 Share on other sites More sharing options...
Onyx610 Posted February 26, 2022 Share Posted February 26, 2022 as I thought it looks to just be a backlash adjustment. It is just an idler gear… https://f01.justanswer.com/Mikemcmillan77/e8702f01-27ef-4360-a632-19792eaa15ef_PV776-88941026.pdf Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490394 Share on other sites More sharing options...
Joey Mack Posted February 26, 2022 Share Posted February 26, 2022 'FJH' Im about to learn something as well... Ive only built 3 of these MP's and done 6+ cam jobs.. and cup's, cup's cup's... I guess I missed the part about how to adjust the idler gear enough to account for a machined head. I too will sit back and watch.. One thing for sure.... I will not be building any of these in my shop.... I will stick to E-6, E-7, and E-tech's.... I have 2 in my shop now.. plus a 3cyl. John Deere diesel.. Jojo 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490396 Share on other sites More sharing options...
Onyx610 Posted February 26, 2022 Share Posted February 26, 2022 He got a brand new head 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490397 Share on other sites More sharing options...
Dan107 Posted February 26, 2022 Author Share Posted February 26, 2022 (edited) Hey, on this engine is there a hole in the flywheel for a dowl alignment tool like on a CAT engine? It supposed to assure the engine is TDC. Or, is there some mark on the flywheel that is visible from the bottom? Edited February 26, 2022 by Dan107 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490398 Share on other sites More sharing options...
Joey Mack Posted February 26, 2022 Share Posted February 26, 2022 no... a '0' on the flywheel, and a TDC mark on the front of the cam... jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490399 Share on other sites More sharing options...
Joey Mack Posted February 26, 2022 Share Posted February 26, 2022 sorry... MP-8 is on the front.... MP-7 is on the rear.. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490400 Share on other sites More sharing options...
Dan107 Posted February 26, 2022 Author Share Posted February 26, 2022 1 minute ago, Joey Mack said: no... a '0' on the flywheel, and a TDC mark on the front of the cam... jojo Is the "O" where a person can see it, or is it in front of the transmission? Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/page/4/#findComment-490401 Share on other sites More sharing options...
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