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56mercuryman

en401 gas engine troubles- clutch not engaging.

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I recently installed a en401 in my b42, it has a 5-2 duplex. the engine went together with the transmission incredible well. it bolted together with no problem. however now there is no clutch pedal at all, you can push the clutch pedal and it does nothing, if you turn the engine over with the trans in gear the engine turns over freely and the truck does not move. I am stumped as the engine and the trans bolted together with no trouble and it appeared the splines slid together easily. I am thinking perhaps the spline on the 5-2 was smaller than the clutch disk and is now just spinning inside. are all the splines on these transmissions the same? is there something i may have missed? I hate to pull it apart again. any suggestions?

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I recently installed a en401 in my b42, it has a 5-2 duplex. the engine went together with the transmission incredible well. it bolted together with no problem. however now there is no clutch pedal at all, you can push the clutch pedal and it does nothing, if you turn the engine over with the trans in gear the engine turns over freely and the truck does not move. I am stumped as the engine and the trans bolted together with no trouble and it appeared the splines slid together easily. I am thinking perhaps the spline on the 5-2 was smaller than the clutch disk and is now just spinning inside. are all the splines on these transmissions the same? is there something i may have missed? I hate to pull it apart again. any suggestions?

Can you shift the truck into gear with the engine running and the clutch pedal released, (foot not depressing the pedel)? If so, the input shaft may not be spinning and the problem could be as you suggest; I doubt it however. If the trans will not go into gear because of grinding, the back section of the trans may be either in neutral, or not shifting into a gear to drive the output shaft.

When you operate the shift handle is there any free play. or does if feel like the lever is moving something inside the transmission? Take the driveshaft loose, put the transmission into a gear with the engine shut off, and try to turn the output shaft. If it turns, move forward with the diagnosis.

I would never install a trans without placing it in each gear and turning the input and output shafts to ensure it is operable.

Rob

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the motor is not running yet I had just installed it. the transmission shifts fine however when you put it in gear and manually turn the engine over with a socket wrench the trans binds up and you cannot get it out of gear, if the truck is rocked it pops out. I do not think the trans is the issue its in between the clutch and that it is already engaged somehow. My guess is that somehow the throwout bearing is binding up and has disengaged the clutch already when the engine and trans went together. upon doing this there is no contact between the pressure plate and clutch thus allowing the engine to turn freely with the trans in gear and again why there is no clutch pedal. I have planned to use longer bolts on the bellhousing to allow me to seperate the engine and trans and see if i can free up the clutch or throwout bearing and then regain the proper clutch clearance. i just really do not want to pull the engine out again and really just wanted to know if the input shafts on mack 5-2 and mack 5-3 are the same or are bigger.

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imput shafts should all be the same as long as both are a 77 series transmission. sounds like you have an issue with the throw out bearing. Matt

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Hey. I am still learning, but on other stuff I have worked on (light trucks, tractors) it does matter what way the clutch plate goes in. Not sure if this is even possible in these trucks, but just a thought

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I think I found the problem, the clutch disk is not quite on the splines correctly and is binding up, its pushed by the splines and is opening the pressure plate causing them to disengage, not sure how that is possible when the transmission and bell housing went together fine. I am not sure if perhaps there is a burr on the spine or not or why it did not slide on correctly. I am now having difficulty getting it loose enough to put it on the splines correctly. I have loosened off the transmission and still no go, these parts are extremely heavy and not easy to "jiggle" them into place. I am going to try and loosen off the pressure plate and try to move the disk around through the grease fitting plate on the bottom. If that does not work, then the motor will have to come out again and the clutch will have to be centered again. Any ideas on any easier ways?

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If the splines are tight you either have a worn clutch disc, worn input shaft to the trans, (probably twisted), or the wrong clutch disc. You should have about .005-.012 clearance in the input shaft splines to the clutch disc splines or things are really shot. Are you forcing this onto either part that is rusty?

Rob

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nothing is rusty, it looks ok, no twists or bends, not sure why it will not go on properly, am planning to pull it apart again, remove the clutch disk and then try it on the trans splines just to be sure.

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Just adding two cents to the equation; wouldn't it be easier to get a good trans jack on a good flat level surface and remove the trans? may be a little less iron to handle, and may be a little easier to troubleshoot.

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