Dan107 Posted February 18, 2022 Share Posted February 18, 2022 Need help again! So I replaced the cups on these two cylinders along with the wiring harness due to cracked wires and shorts. Loaded yesterday and the truck would randomly derate and quit. Codes are all over the place with crankcase pressure and injector 1 errors. Cylinder balance test was within tolerance, but this compression test is nasty looking. I’m lost with what to do next…. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/ Share on other sites More sharing options...
Dan107 Posted February 18, 2022 Author Share Posted February 18, 2022 2 minutes ago, Onyx610 said: Did you happen to do this test before the work was done? Also weird how number 6 is in the red but is at 80% just like number 4. Did you program the trim codes of the injectors? This was done today, three weeks after I did the work. Injector trim codes can’t be programmed on this year model from what I’ve been told. 2012 CXU613 MACK PINNACLE. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489707 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 Weird how cylinder 6 is in the red but at 80% just like number 4. I’m not sure how accurate this test is? I think the results are based off of the speed of the crank and uses the camshaft to tell what cylinder it’s on. Being that those two cylinders you did work on I’d say you may have to go over your work. Do the overhead again to start and see what happens. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489708 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 Interesting this is 3 weeks after… Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489709 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 The reason I asked did you happen to do the test before you did the work was to see if the results were the same or not. Might have another issue other then just the cups. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489710 Share on other sites More sharing options...
Popular Post 67RModel Posted February 18, 2022 Popular Post Share Posted February 18, 2022 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? 3 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489711 Share on other sites More sharing options...
67RModel Posted February 18, 2022 Share Posted February 18, 2022 Also 178 r/min seems like too low of an engine speed even at low idle... Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489712 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 (edited) 178 rpm of when he was cranking it, it shuts off the injectors for a no start. The ECM determines the results based off the cam sensor to tell what cylinder it’s on and then the sensor at the flywheel to measure the speed of the crank. Faster speed for less compression and lower speed for higher compression. Edited February 18, 2022 by Onyx610 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489713 Share on other sites More sharing options...
67RModel Posted February 18, 2022 Share Posted February 18, 2022 23 minutes ago, Onyx610 said: 178 rpm of when he was cranking it, it shuts off the injectors for a no start. The ECM determines the results based off the cam sensor to tell what cylinder it’s on and then the sensor at the flywheel to measure the speed of the crank. High speed for less compression and lower speed for higher compression. Interesting. Makes good sense when its explained. It looks like the compression test is functioning properly then. That is to say I guess you can trust that cylinders 1 & 6 have low compression since those are the two that were repaired. What would the chances be that both 1 & 6 have good compression and the test is saying they do not? So it has low compression in those cylinders. Can failed injector cups and/or repair mistake somehow bleed pressure out of the cylinders? Valves not sealing? Cracked piston? Cracked liner? Not much else could be wrong. Am I missing something? Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489714 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 Yea cups can bleed out compression. That was there main issue, not sealing. Also maybe rings/head gasket. I highly doubt it’s anything like that being it’s companion cylinders and just so happens to be the two that had work done. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489716 Share on other sites More sharing options...
67RModel Posted February 18, 2022 Share Posted February 18, 2022 I know these systems spit out all kinds of errors when one thing is wrong but he did say he is getting a crankcase pressure fault. Maybe these cylinders are putting their pressure into the into the crankcase. But like you said....doubtful. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489717 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 (edited) Haha, yea when one thing goes wrong on these you get quite the riddle of codes. The only explanation I have for high crankcase pressure would be worn rings. Also like I said earlier I find it odd that it has cylinder 6 as bad but it’s at 80 percent. So is cylinder 4 but it gets the ok? Sounds like to me something wasn’t done right and he needs to go back over the work. Which sucks but it happens….Hopefully some of the other guys can maybe give him some other options first. Edited February 18, 2022 by Onyx610 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489719 Share on other sites More sharing options...
Dan107 Posted February 18, 2022 Author Share Posted February 18, 2022 I did a follow-up test and six was green instead of a red bar! Not sure what would cause the mistake in the reading though. I've done the injector cut-out test, and the cylinder balance as well. The cut-out produced the expected results and the balance test was in the green. As to improper cup install, could be. I definitely don't do this on a daily basis like some of ya'll out there, but have done it a couple of times on this truck. I may not have mentioned there is significant pressure on the oil fill cap, and the crank-case vent cylinder on the block feels like a fan blowing out of the down tube. I'm going to pull the valve cover and check what I can. Question though; if it were a cup failure would I have coolant running by and out of the cup into the oil pan? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489725 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 Probably nothing going on with the cups and if you have done them a few times then you are probably good. So number one is still in the red? It’s safe to say you have another issue going on and it’s causing a lot of pressure in the crankcase. Hows truck running? Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489728 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 That crankcase spinner assembly has also been known to cause crankcase pressure issues… 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489730 Share on other sites More sharing options...
Joey Mack Posted February 18, 2022 Share Posted February 18, 2022 I never really understood compression tests without a stem and a gauge in the injector hole... however, I have used cyl. cutout and balance tests, with some succes...jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489731 Share on other sites More sharing options...
Dan107 Posted February 18, 2022 Author Share Posted February 18, 2022 3 minutes ago, Onyx610 said: Probably nothing going on with the cups and if you have done them a few times then you are probably good. So number one is still in the red? It’s safe to say you have another issue going on and it’s causing a lot of pressure in the crankcase. Hows truck running? Truck runs rough, when it will continue to run. That was my issue last night, it would run for a mile or two, then derate. Then the next restart, run for 15 or 20 miles. Also, on the radiator fill side of the reservoir, there is a small hose that connects to the bottom of the tank. When the engine is idling, there are bubbles coming up through that tube into the coolant. When the engine is at 1000 rpm's or better, the bubbles disappear. It's crazy! Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489732 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 (edited) Aeration of coolant or fuel is a symptom of cups. It just depends on if the combustion gas goes up through the cup and around the injector or it goes up around the outside of the cup. Edited February 18, 2022 by Onyx610 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489733 Share on other sites More sharing options...
Joey Mack Posted February 18, 2022 Share Posted February 18, 2022 did you swage the cups correctly? is the oil level rising? this would be a good reason to take an old valve cover and cut the top out of and mount it to your engine and run it to see if there are bubbles coming from the cups... I havent done it on a Volvo but i have done it on my chevy engines. jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489734 Share on other sites More sharing options...
Onyx610 Posted February 18, 2022 Share Posted February 18, 2022 (edited) I also don’t see one bad cup causing it to run as bad as you describe, especially if the bubbles clear up over 1k rpm. The weirdest thing is the amount of blowby your describing. Only other thing I could think of for crankcase pressure would be turbo or air compressor. Air compressor could also cause bubbles in coolant but I don’t see any drivability issues with it. Edited February 18, 2022 by Onyx610 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489736 Share on other sites More sharing options...
Dan107 Posted February 19, 2022 Author Share Posted February 19, 2022 I guess, I'm pulling the valve cover in the morning and seeing what I can see and go from there...I'll update when I figure something out. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489746 Share on other sites More sharing options...
Onyx610 Posted February 19, 2022 Share Posted February 19, 2022 Good luck 🤞🏻 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489748 Share on other sites More sharing options...
JoeH Posted February 19, 2022 Share Posted February 19, 2022 Valve covers and oil pan show you most of what's going on mechanically. With pressurizing the crankcase I'd pull the oil pan and look at cylinder #1. That's pretty far off on compression, could be something serious going on with that piston/liner. Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489761 Share on other sites More sharing options...
Joey Mack Posted February 19, 2022 Share Posted February 19, 2022 I see you replaced the wire harness.. When you start the truck, does it turn over for about 10 seconds before it fires? My point is that if the harness is not plugged in correctly, you will get multiple codes and extended crank times. this would indicate that the cam and/or crank sensor are not plugged into the correct sensors. For some reason, VOLVO, uses the same type of plugs and duetch connectors on the harness, so it is very easy to plug into the wrong sensor.. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489763 Share on other sites More sharing options...
Dan107 Posted February 19, 2022 Author Share Posted February 19, 2022 14 minutes ago, Joey Mack said: I see you replaced the wire harness.. When you start the truck, does it turn over for about 10 seconds before it fires? My point is that if the harness is not plugged in correctly, you will get multiple codes and extended crank times. this would indicate that the cam and/or crank sensor are not plugged into the correct sensors. For some reason, VOLVO, uses the same type of plugs and duetch connectors on the harness, so it is very easy to plug into the wrong sensor.. jojo LOL...you are right!! When I originally put the new harness on I got the oil pressure and crankcase plugs crossed, as well as the cam and crank sensor. When I tried to start the engine it would make a quarter turn, like one cylinder at a time would come up. I was wondering why I was getting the improper voltage codes to those sensors then it dawned on me....(hey stupid, those plugs are crossed!!!!) I switched everything and she fired right up. Didn't make sense to me why the plugs would be the same with sensors that close together, but I'm just a lowly owner not a high powered engineer..... 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69251-compression-test-with-tech-tool/#findComment-489765 Share on other sites More sharing options...
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