96bulldogpower Posted 14 hours ago Share Posted 14 hours ago hey guys looking for some help on this one. I’ve got a 12’ Mack granite with an mp7 that’s making oil. Oil level rises about a gallon every two weeks. I’ve put UV dye in the filter and checked to see if I could find the leak, I found nothing around the injectors or galley plugs. I then added another ounce of dye directly into the fuel gallery through one of the plugs and still nothing. I can’t find the leak even after hours of looking. Anyone have any ideas on where else these engines can pass fuel into the crankcase? Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/ Share on other sites More sharing options...
Joey Mack Posted 14 hours ago Share Posted 14 hours ago Tandem pump ? Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582109 Share on other sites More sharing options...
96bulldogpower Posted 13 hours ago Author Share Posted 13 hours ago Do you mean the fuel pump that mounts behind the power steering pump? I thought about that but fuel isn’t mixing with the power steering fluid, which I assumed was the first thing that would happen if the fuel pump seal went out. Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582110 Share on other sites More sharing options...
Joey Mack Posted 13 hours ago Share Posted 13 hours ago Fair thinking, im grabbing at straws after reading the post. Is there raw fuel smoke? Bad injector ?? Low power/missfire, stuck piston rings Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582111 Share on other sites More sharing options...
96bulldogpower Posted 13 hours ago Author Share Posted 13 hours ago 17 minutes ago, Joey Mack said: Fair thinking, im grabbing at straws after reading the post. Is there raw fuel smoke? Bad injector ?? Low power/missfire, stuck piston rings No other concerns besides the rising oil unfortunately 😞. Truck starts and runs great. No misfires or smoke. I’d hate to throw parts at it and I don’t have much time to work on it before it has to go back into service in a week and a half. If I can’t find anything else tomorrow then I may just have to put it back together and order a set of injectors to throw at it next time it come back to the shop and hope it fixes it. Meanwhile we’re changing the oil once a month Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582113 Share on other sites More sharing options...
Joey Mack Posted 13 hours ago Share Posted 13 hours ago You are sure its fuel ? Did you do a halo test or oil sample test? Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582114 Share on other sites More sharing options...
96bulldogpower Posted 13 hours ago Author Share Posted 13 hours ago It’s for sure fuel, I haven’t got an oil sample yet (going to send some off though) but I’m certain it’s fuel. Put a drop on cardboard and it leaches out. Smells like fuel too. Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582115 Share on other sites More sharing options...
Joey Mack Posted 12 hours ago Share Posted 12 hours ago Ok Good enough.. just save the sample money. I am probably not going to help much at this point, but Mackpro may see this and chime in, and a few others. I will watch this thread.. Jojo, Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582119 Share on other sites More sharing options...
Mark T Posted 12 hours ago Share Posted 12 hours ago Probably injectors. Have they been changed ? Remans often are less than perfect. Leak around the pushrod and adds up after a short time. 2 Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582128 Share on other sites More sharing options...
Joey Mack Posted 12 hours ago Share Posted 12 hours ago Glad you're here Mark.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582129 Share on other sites More sharing options...
96bulldogpower Posted 11 hours ago Author Share Posted 11 hours ago 1 hour ago, Mark T said: Probably injectors. Have they been changed ? Remans often are less than perfect. Leak around the pushrod and adds up after a short time. I’ve got a feeling you’re right about that. After inspecting it further tonight I can the the FAINTEST uv dye glow on the injector springs. I will look for new injectors at this point, looks like this is probably my best bet. Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582131 Share on other sites More sharing options...
96bulldogpower Posted 11 hours ago Author Share Posted 11 hours ago 1 hour ago, Mark T said: Probably injectors. Have they been changed ? Remans often are less than perfect. Leak around the pushrod and adds up after a short time. The truck has about 280k miles and about 20k hours. It’s got the original injectors as far as I can tell Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582132 Share on other sites More sharing options...
fjh Posted 10 hours ago Share Posted 10 hours ago 1 hour ago, Mark T said: Probably injectors. Have they been changed ? Remans often are less than perfect. Leak around the pushrod and adds up after a short time. Fairly common you need to put some dye in the fuel filter and run and check with a black light to confirm! As mentioned bOr throw injectors at it a bit of expensive amo for the parts canon on a guess! Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582135 Share on other sites More sharing options...
Mark T Posted 3 hours ago Share Posted 3 hours ago IDK that I'd be just running out replacing injectors, but it'd be a likely spot to get more involved with looking for the problem. Then there's the wiring harness, that sometimes doesn't live through it all. Like F said, it can get expensive. Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582141 Share on other sites More sharing options...
Joey Mack Posted 2 hours ago Share Posted 2 hours ago What about the cups? Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582142 Share on other sites More sharing options...
Mark T Posted 1 hour ago Share Posted 1 hour ago 1 hour ago, Joey Mack said: What about the cups? Probably conicals in it. Just a guess. Quote Link to comment https://www.bigmacktrucks.com/topic/75926-2012-gu713-mp7-making-oil/#findComment-582144 Share on other sites More sharing options...
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