Question: No reverse in my mericruiser inboard.?

(Posted by: edward m on 2010-08-12 18:48:15)

I recently bought a used lower end for my boat i installed it with no problems everything slid right in but no reverse now foward works great but when shifted to reverse its like its goes back to neatural. I have had the cable adjusted and checked out and are fine, is there anything i could have done when installing that would cause this. i made sure it was in foward the only way it will line up. any suggestions????

Posted by: frank m on 2010-08-13, 08:08:53

When you installed the lower unit to the upper unit you messed up... When installing the lower the lowers shift shaft has to be in the same gear position as the upper shift shaft, meaning that now you installed the lower shifted in reverse while the upper was in still in neutral.(or some other combination). Drain the outdrive oil and drop the lower, shift the upper into fw gear by the controller in the boat, turn the shift shaft on the lower unit so the prop does not move counter!! clockwise, and keep some force on the prop or propshaft shaft so the lower stays in fw gear and remount the lower, so now they`r both in relation.. ..in fw gear. You can also do this in reverse or neutral but there is a fw rule on a mercruiser. Also when removing or remounting the complete outdrive it always must be done shifted in fw gear on a mercruiser!. Good luck! Oh yeah, and dont forget the quad o ring in between the oil passage

Posted by: Girly Brains on 2010-08-12, 19:52:27

I take it that you mean the inboard has an outdrive unit. I have never worked on one of these, but assuming that the gearbox works the same way as a regular outboard, you may find the following, which I wrote in answer to this same problem, but on an outboard, helpful: The two gears on an outboard are selected by sliding a dog-clutch forwards or backwards along the short prop shaft in the gearbox (lower unit). This dog clutch is made to slide by a shift-cradle on the end of a shift-rod attached to the controls. The shift-cradle is two-pronged, like holding out your thumb and forefinger. These 'prongs' run in a channel in the clutch in order to gain their purchase on it and move it forwards or backwards along the shaft, while the clutch itself is free to rotate on the shaft within their grasp - swinging one way or the other, as required. And sliding the dog-clutch either way along the prop-shaft to engage the desired gear. Like moving your wrist back and forth while holding out your thumb and forefinger! The tips ('fingers') of the prongs eventually become worn by the revolving clutch and loose their grasp in the channel. And reverse, for obvious reasons of helpful design, is the first to go - this is selected by the arm pushing the clutch, whereas fwd is selected by pulling it - so taking longer to wear out and fail. (Easier to get back home in forward gear, as long as you remember that the brakes have gone!) If there is no fault with the linkage, this could be the cause of your problem. Check the state of the shift-cradle. It is by no means a difficult or expensive task but must be carried out ashore. You will need to split, but not completely remove the gearbox and hence obviously, replace the oil. It is also worth obtaining a new 'o' ring, or seal for when you re-assemble the gearbox. Not expensive usually. Take great care when removing and re-tightening the screws. they are like cheese! -|--) Edit: Lima's point also raises a very distinct possibility.

Posted by: LIMA 45.05.18.77 on 2010-08-13, 06:12:49

The shift crank was in the wrong position when you installed the outdrive. The remote control needs to be in fwd gear, and the shift crank (or shift shaft if you have a Gen II ) should face fwd.