Gravelguy413 Posted July 4, 2022 Share Posted July 4, 2022 How much boost should a 96 mechanical EM-7 300 be putting out under load? Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/ Share on other sites More sharing options...
mrsmackpaul Posted July 4, 2022 Share Posted July 4, 2022 A lot will depend on how much load and what revs your at I would expect maximum boost at the cross over between maximum HP and maximum torque under full load with a big long hard pull Paul Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502025 Share on other sites More sharing options...
Gravelguy413 Posted July 4, 2022 Author Share Posted July 4, 2022 I just bought a boost gauge and was wondering what it should read on a hard pull? Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502036 Share on other sites More sharing options...
fjh Posted July 4, 2022 Share Posted July 4, 2022 22-28 lots of variables ambiant temps load ect! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502049 Share on other sites More sharing options...
Gravelguy413 Posted July 4, 2022 Author Share Posted July 4, 2022 Great. If I don’t get that I will check for leaks thank you Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502051 Share on other sites More sharing options...
Gravelguy413 Posted July 4, 2022 Author Share Posted July 4, 2022 1 hour ago, fjh said: 22-28 lots of variables ambiant temps load ect! Shifting through the gears empty I can hit 21, with a full load going up a hill I hit 23-24 max. Should I be looking for leaks ? Truck is overheating on hills. I changed thermostat and coolant already. Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502062 Share on other sites More sharing options...
Popular Post terry Posted July 4, 2022 Popular Post Share Posted July 4, 2022 1 hour ago, Gravelguy413 said: Shifting through the gears empty I can hit 21, with a full load going up a hill I hit 23-24 max. Should I be looking for leaks ? Truck is overheating on hills. I changed thermostat and coolant already. If you have a front mounted inter cooler, take it off and clean everything real good, back of intercooler, and front of radiator. Terry 2 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502064 Share on other sites More sharing options...
fjh Posted July 4, 2022 Share Posted July 4, 2022 11 minutes ago, terry said: If you have a front mounted inter cooler, take it off and clean everything real good, back of intercooler, and front of radiator. Terry lots of variables ambient temps load ect Your in the zone ! Heating up ? Do you have a pyro? Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502065 Share on other sites More sharing options...
fjh Posted July 4, 2022 Share Posted July 4, 2022 (edited) 2 hours ago, Gravelguy413 said: Shifting through the gears empty I can hit 21, with a full load going up a hill I hit 23-24 max. Should I be looking for leaks ? Truck is overheating on hills. I changed thermostat and coolant already. lots of variables ambient temps load ect Your in the zone ! Heating up ? Do you have a pyro? Three indicators of a boost leak quick High pyro low boost . Trailing smoke while under load @ rated RPM anywhere from 1200 - 1600 you apear to have a maxidyne it may pull lower than twelve how ever key here is pyro temp 1100- 1100 deg 1200 is pushing it! with the maxidyne you have a wide power band Edited July 4, 2022 by fjh Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502066 Share on other sites More sharing options...
MACKS Posted July 4, 2022 Share Posted July 4, 2022 My 96 E-7 350 tops out at 27 to 28 on a hill if I give it full fuel if that’s any help.. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502083 Share on other sites More sharing options...
Gravelguy413 Posted July 4, 2022 Author Share Posted July 4, 2022 Ok I will clean everything and install a pyro and see where exhaust temps are at. Engine has 455k miles and over 25k hours maybe it’s just tired, uses oil and has a good amount of blow by although it used to pull steep hills loaded without overheating. Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502109 Share on other sites More sharing options...
mrsmackpaul Posted July 5, 2022 Share Posted July 5, 2022 I would think if it had blow by your gunna start to start to make boost but I really dont know about Paul Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502124 Share on other sites More sharing options...
Mackpro Posted July 5, 2022 Share Posted July 5, 2022 I found my Mack tube up /Spec book for the 1996 year models. A EM7-300 mechanical should be makeing 20-28 psi in a hard pull . Check the fresh air intake piping for the air compressor. The air compressor get it fresh air from the intake manifold. Any leak on that any you will loose boost. The original intake manifold gaskets were later updated to steel core gaskets due the paper gaskets blowing out 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502169 Share on other sites More sharing options...
mrsmackpaul Posted July 5, 2022 Share Posted July 5, 2022 (edited) 19 hours ago, mrsmackpaul said: I would think if it had blow by your gunna start to start to make boost but I really dont know about Paul That makes no sense at all Paul yah clown What I think I was trying to say was If you got plenty of blow by then your gunna struggle to make big boost Anyway, enough from me Paul Edited July 5, 2022 by mrsmackpaul Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502173 Share on other sites More sharing options...
Gravelguy413 Posted July 6, 2022 Author Share Posted July 6, 2022 The overheating issue has been solved thanks to all the Pedigreed Bulldog members who responded and told me more than once to take CAC off and clean in between radiator etc. I guess it had to sink in. Poor dog was running a fever on the hills due to all the dirt clogging the radiator fins. I get no more than 24 lbs of boost on a hard pull but sounds like it’s within spec? Probably time to freshen up the engine considering the miles / hours as a dump truck. It probably is what it is considering what is is. Lol. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502200 Share on other sites More sharing options...
mrsmackpaul Posted July 6, 2022 Share Posted July 6, 2022 That's a good result So the next things I have learnt that effect boost are a squashed exhaust or a restricted air intake I know when I re-bearinged my tip turbine it added a couple pounds of boost Little bits help Maybe check if a intake rubber connection is collapsing in or gone real soft Paul Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502206 Share on other sites More sharing options...
JoeH Posted July 6, 2022 Share Posted July 6, 2022 13 hours ago, Gravelguy413 said: The overheating issue has been solved thanks to all the Pedigreed Bulldog members who responded and told me more than once to take CAC off and clean in between radiator etc. I guess it had to sink in. Poor dog was running a fever on the hills due to all the dirt clogging the radiator fins. I get no more than 24 lbs of boost on a hard pull but sounds like it’s within spec? Probably time to freshen up the engine considering the miles / hours as a dump truck. It probably is what it is considering what is is. Lol. My e7-350 used to only hit 25. Finally pressure tested the CAC and it had a crack vertically along the seam between the passenger side and the cooling crossover tubes. Symptoms were low boost, high pyro temps, 1000-1200 degrees easy. I'll bet your CAC issues aren't over, I'll bet you have a cracked CAC. You can buy PVC pipe end caps from Home Depot, install a valve stem in one and put each one in one of the rubber hoses on the CAC. Try pressurizing it. Don't go above 35 psi, but if it's cracked you'll hear it right away. My truck makes 31 psi now, pyro tops out around 900 degrees. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502242 Share on other sites More sharing options...
fjh Posted July 6, 2022 Share Posted July 6, 2022 3 hours ago, JoeH said: My e7-350 used to only hit 25. Finally pressure tested the CAC and it had a crack vertically along the seam between the passenger side and the cooling crossover tubes. Symptoms were low boost, high pyro temps, 1000-1200 degrees easy. I'll bet your CAC issues aren't over, I'll bet you have a cracked CAC. You can buy PVC pipe end caps from Home Depot, install a valve stem in one and put each one in one of the rubber hoses on the CAC. Try pressurizing it. Don't go above 35 psi, but if it's cracked you'll hear it right away. My truck makes 31 psi now, pyro tops out around 900 degrees. Or you can look it most often happens on the top RH of the cooler due to hot incoming air! You should also be trailing smoke under load!! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502248 Share on other sites More sharing options...
JoeH Posted July 6, 2022 Share Posted July 6, 2022 Mine didn't trail smoke, but it did run hot. Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502266 Share on other sites More sharing options...
Gravelguy413 Posted July 7, 2022 Author Share Posted July 7, 2022 Great will def check this out. I should have done this when cac was off but needed the truck the next day. I really don’t notice any smoke trailing but some blue haze prob because she uses oil 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502278 Share on other sites More sharing options...
JoeH Posted July 9, 2022 Share Posted July 9, 2022 Mine didn't smoke either; don't need to remove from chassis, just need to undo plumbing at either end. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502456 Share on other sites More sharing options...
Gravelguy413 Posted July 10, 2022 Author Share Posted July 10, 2022 On 7/8/2022 at 10:03 PM, JoeH said: Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502616 Share on other sites More sharing options...
Gravelguy413 Posted July 10, 2022 Author Share Posted July 10, 2022 Found no visible cracks will put the air to it. If a crack is found can it just be welded or does the entire cac need to be replaced? Don’t want to chase cracks all the time either Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502617 Share on other sites More sharing options...
Joey Mack Posted July 10, 2022 Share Posted July 10, 2022 a radiator repair shop may be able to weld it up, I have had a few repaired, I guess it depends on how long the crack is or if its in the viens.. typically it is at the top right corner at the inlet. jojo Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502624 Share on other sites More sharing options...
Gravelguy413 Posted July 11, 2022 Author Share Posted July 11, 2022 I put the air to it today and did not hear any leaks. The sticker on top of the cac looks a lot newer than 1996 so I assume it has been replaced at one time. How can I tell if the intake gasket leaks? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70051-boost-q/#findComment-502776 Share on other sites More sharing options...
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