Re: 5.0 Merc stalling problems
Well, it's a little long, but here is something I copied off another site a couple of years ago. It's fun to read, but it's also factual.<br /><br /><br />Mercruiser Shift Cable Replacement<br /><br />Shift System Theory:<br /><br />The shift system of a Mercruiser Alpha system is really very simple BUT it must all be working properly.<br />The remote control will pull the dash shift cable when placed into forward gear.<br />The dash shift cable attaches to a shift plate mechanism back on the engine.<br />The shift plate mechanism will then move the drive shift cable.<br />The drive shift cable will move a slide mechanism in the bellhousing which in turn will rotate the upper shift lever.<br />When the shift lever is turned, it rotates the upper, middle and lower shift shafts.<br />This shift shaft system ends up turning a bellcrank in the lower unit.<br />The bellcrank will slide a spool assembly which is attached to the clutch.<br /><br />Lost yet?<br />Actually, it's not too bad!<br /><br />On the shift plate mechanism up at the engine is a little micro-switch which is called the shift interrupter switch.<br />Most people call the shift interrupter switch the "kill switch" or "shift switch".<br />This kill switch is very important! It should never be altered, bent or disabled.<br />Basically, the kill switch helps the clutch go into the neutral position.<br />When the driver is pulling back on the remote control, to shift from forward to neutral, a tension will be placed on the drive shift cable.<br />This tension is a result of the clutch ramps being "locked" into the gear face.<br />The tension of trying to pull the clutch into neutral will activate the shift plate mechanism and actually stall the engine for a second.<br />The stalling of the engine will "jumble" the clutch away from the gear and the drive will be in neutral.<br /><br />More on this later.......<br />When working properly, the shift will be almost smooth and effortless.<br />Failures in the shift system do occur......<br /><br />Typical Failures:<br /><br />As time puts wear on the shift components, certain failures are bound to happen.<br />The most common failure symptom is <u>stalling while shifting</u>.<br />The reason an engine will stall while shifting is because the kill switch is "over-killing".<br />This doesn't mean the switch is bad!<br />Stalling is usually due to a stiff drive shift cable or shaft.<br />The shift system has bushings and seals in certain locations which keep water out of the shift areas.<br />If any of these seals (or gaskets) fail, then water will seize the components and cause the kill switch to stall the engine.<br /><br />Another symptom is difficulty in shifting.<br />If the "kill" system is not operating properly, then the drives wants to stay in gear.<br />The driver will have to pull hard on the control to get the drive out of gear and<br />when it finally DOES come out of gear it might pass neutral and slam right into the other gear.<br /><br />This will cause serious damage.<br /><br />In either case, shifting problems are not only a nuisance but they can be dangerous as well.<br /><br />Recommendations:<br /><br />Have any shift problems repaired before using the boat.<br />A good Mercruiser tech should be able to diagnose and repair any and all shift problems.<br />We recommend that the mechanic be Mercruiser Certified and experienced.<br />The shop should be an authorized Mercruiser Dealer and all parts that they use should<br />be original Mercruiser made. Aftermarket parts are NOT recommended!<br />Now, that being said, we KNOW that some of you just HAVE to do it yourself!<br />I hope the following tips help.<br /><br />Cable Replacement:<br /><br />Before we start. This can be difficult and sometimes next to impossible to do if you have no experience.<br />The service manuals are vague and having a good friend with the right tools to help would be great.<br /><br />Place the control in forward gear.<br />The drive (and it's shift shafts) MUST be in forward gear to remove the drive.<br />Note: A counter-rotation drive (left hand turning prop) must be in reverse.<br />Remove the trim cylinders and let them hang.<br />Remove the six nuts that hold the drive to the bellhousing.<br />Lift the drive a little and let it drop to break it free and assist in removing it.<br />Careful! The drive is heavy and you might screw up your back!<br />Now, I made that sound simple but in many cases the drive can be stuck on.<br />Lifting the drive higher and dropping it a little harder each time might help.<br />If it's really stuck, then a series of chisels carefully and gently wedged between the drive and the bellhousing might help.<br />Sometimes removing a drive is just like work!<br /><br />Now that the drive is off and out of the way, you can inspect the bellhousing area.<br />Was there water in the U-joint bellows?<br />Is the u-joint assembly rusted?<br /><br />Reach into the large hole and try to turn the gimbal bearing.<br />It's center should turn easily and smooth. If it's loose or stuck then replace it! (another story)<br />You will also be able to view the "shift cable cavity" where the shift slide is protruding.<br />This cavity should be free of ANY corrosion and water.<br />The lever should be in good condition and the roller should spin free.<br />Most of the shift components in the shift cavity should be greased and clean.<br /><br />Here is where you get your exercise, climb back into the boat AGAIN.....<br />Disconnect the drive shift cable from the shift plate.<br />Remove the two little itsy bitsy set screws from the sides of the end of the drive shift cable.<br />Remove the black plastic cable end and loosen the brass lock-nut on the stainless tube.<br />Unscrew the stainless tube from the end of the cable sheath.<br />Now, this is important!..... slide your hand down the cable sheath as far as you possibly can.<br />SOMETIMES you will feel a plastic spiral wrap on the cable sheath.<br />This spiral wrap is to protect the cable from melting against the exhaust pipe.<br />You MUST REMOVE the plastic spiral wrap or you will live a "hell" trying to get the cable out.<br /><br />More exercise....... climb back out of the boat......<br /><br />Wait! You forgot to turn the steering to the left....<br />Climb back into the boat and turn the steering to the left. (sorry about that)<br /><br />Climb BACK out of the boat again and look at the shift cable bellows.<br />You MAY have one of several types of small clamps on the small end of the shift bellows. Remove whatever it is.<br />Now, grab the gray slide and pull the cable core out of the cable from behind.<br />Pick up your special 9/16" socket and........ oh..... I didn't tell you about the special 9/16" socket that you must have?<br />To remove and install the shift cable sheath, you will need an extra deep 9/16" socket which has been turned down to have thin walls.<br />Snap-On tools sells a great extra deep 9/16" socket but it will absolutely NOT WORK unless you have the walls thinned.<br />Take the $72.00 socket to a machine shop and have them turn it on a lathe so it will fit perfectly<br />into the bellhousing as so it will fit straight on the cable nut without binding on the side of the cavity.<br /><br />IF you attempt to install the new cable without this tool OR if the tool is not milled correctly, then you will destroy your new shift cable during installation<br />AND you might destroy your $300.00 bellhousing as well.<br />Mercruiser does NOT sell this tool.<br /><br />OK, now that you have the correct socket, go ahead and unthread the cable sheath from the bellhousing.<br />After it's all the way unthreaded, pull on the cable and it should slide right out.<br />IF it pulls out almost all the way but then gets stuck... it's because you weren't paying attention<br />when I told you to remove the spiral wrap from the sheath inside the engine compartment.<br />Good luck if it's stuck. You will just have to spend the next few hours trying to get it free.<br /><br />Now that you smart people have the sheath out, you need to inspect the shift cable bellows as this is the only time<br />that you can replace the bellows. If needed, remove the old cable bellows and install a new one.<br />Make sure you clean the aluminum where the bellows seat. Also, you need to apply Bellows Adhesive to the inside of the bellows.<br /><br />Maybe I just got a little ahead of myself....<br /><br />Let's try to stick to removing things first.<br /><br />Get a small but good screwdriver and remove the little stainless set screw that is holding the shift lever in place.<br />Sometimes this screw is just plain stuck or stripped and you need to take a chisel and crack the aluminum lever in two.<br />Note: Sometimes it's better to just destroy stuff and replace it then to spend an hour trying to remove a $14.00 part.<br /><br />Slide the stainless shift shaft down and out.<br />Now, below that lever SHOULD be a white plastic washer. Remember that!<br />If you forget that washer when you reassemble then it won't shift right.<br /><br />Cool! Everything is in pieces!<br /><br />Ya' know where that little stainless shaft pulled through? Well, if you look, you SHOULD see<br />a small shift shaft seal pressed up in the bellhousing.<br />This seal could leak water into the shift cable cavity and in most cases this is the reason<br />that your cable failed!!!<br />ALWAYS replace the shift shaft seal!<br />Mercruiser changed the seal to a brass barrel shaped bushing which press fits up into the bellhousing<br />and hangs down in the exhaust passage. It's about the diameter of a quarter and hangs down about one inch.<br />IF you have the cheesy old style little shift shaft seal, then pop it out and knock out the upper brass bushing as well.<br />Go to your Mercruiser Dealer and get the new style, dual lipped, brass shift shaft bushing assembly.<br />When you press the new bushing into place, make sure you sealed it with loc-tight!<br /><br />So now you have the new shift seal in place. Good job!<br />Clean up the stainless shift shaft and grease it up.<br /><br />Note: A word about grease.... Special Lube 101 by Mercury Marine is great.<br />You can use 101 as the only grease for this entire job BUT Mercruiser recommends that you<br />use a special Spline Grease in the driveshaft splines before installing the drive unit.<br /><br />Slip the shaft up into place and install your new roller lever and set screw.<br /><br />Now, think back..... what did you forget?<br /><br />The white plastic washer!!!! The white plastic washer must be installed before the lever!<br /><br />Ok...... the shift shaft assembly is now installed and all greased up.<br /><br />Now we can start on the hard parts.<br />Open the package for the new Mercruiser cable and separate the sheath from everything.<br />Take some Perfect Seal or Permatex 2B or good pipe sealer and coat the brass threads on the sheath.<br />Take some Special lube and coat a little on the other end of the cable to help it slide through the new cable bellows.<br />Slide the cable end through the bellhousing and work it through the bellows.<br />This can be a ***** to do.<br /><br />When you slide the cable through.... it will soon stop and it will hit the back of the engine.<br />This is when you need your friend.<br />Hopefully he isn't to drunk from drinking beer as he was watching you do all the other work.<br />Have him climb into the boat with a long, thin screwdriver and a flashlight.<br />He will have to look down behind the engine and locate where the cable is coming through.<br />You can be moving the cable in and out while he is looking to help him see it.<br />When he sees the cable, he needs to guide it over towards the stb. side of the engine.<br />This is tough to do the first time or two and it helps to have a thin screwdriver that is REALLY long.<br />As he pushes the cable to the side, he needs to tell you when to push.<br />If it's done right, the cable will miss the engine and slide in easily.<br /><br />DO NOT FORCE, KINK or BEND the cable!!!!!!<br />If you bent the cable, then it's RUINED.<br />If you try to straighten the cable and finish the installation you will be upset to find your engine will stall!<br />Throw out the damaged cable and startover. Trust me on this. I know.... from experience.<br /><br />Now......... keep your drunk friend in the boat. Just keep him happy with another beer or something.<br />Recheck to make sure you put thread sealer on the cable threads.<br />Have your friend gently pull on the cable while you use your new special 9/16" socket to thread the cable in.<br />Don't thread the cable all the way!<br />Leave one thread showing.<br /><br />Now get the small parts bag that came with the cable and locate the new aluminum slide, the allen set screw, and the small piece of wire.<br />Take the cable core and slide it into the aluminum slide.<br />The lead end of the core will be recessed in the slide.<br />Thread the allen set screw into the slide until it JUST BARELY TOUCHES the lead.<br />Adjust the allen screw so the slide has no end play BUT will still spin freely on the core.<br />IF you over tighten the allen screw then the drive wont shift right.<br />Twist the little wire piece to lock the allen in place. <br /><br />Slide the cable core slowly and carefully into the sheath from behind.<br />If you kink the core then throw it out and buy a whole new cable assembly.<br /><br />DO NOT GREASE THE CORE!<br />IF you grease the core then it will stall the engine when you shift.<br /><br />Time for some exercise. Your friend is too drunk so climb in the boat with the other small pieces that came with the cable.<br />You will also need a 7/16" open end wrench, an adjustable wrench, lock pliers, a new small cotter pin and a beer for the drunk guy.<br /><br />Thread the stainless tube into the end of the cable all the way and then back it off two turns.<br />Lock it down with the 7/16" nut.<br />Now slip the little anchor thing into the plastic tube and slip it over the end of the core.<br /><br />Install and tighten the little, little set screws.<br /><br />Take the spiral wrap and install it on the sheath down low where the cable gets close to the exhaust pipe.<br /><br />With the control in forward, install, temporarily, the cable to the shaft plate mechanism.<br /><br />This will help hold the slide and shift shaft in the forward position for installing the drive.<br /><br />Exercise time......... jump out of the boat and make sure that you have cleaned off all the old gasket material from both the drive AND the bellhousing.<br /><br />Glue (with bellows adhesive) the new water passage o-ring and the large u-joint hole o-ring into place.<br /><br />Place the new drive gasket on the studs of the bellhousing.<br />Get this....... use NO SEALER. That's right. It KILLS us Mercruiser mechanics when we see Silicone sealant squishing out from the drive gasket. It's not right. DON'T use sealer!<br /><br />Take some 101 grease and put some on the drive mounting studs and on the large o-ring.<br /><br />Let's inspect the drive before we install it.....<br />Do the splines look clean? Have you greased the cross bearings?<br />Take a good look at the lower shift shaft and make sure in moves free.<br />Take some Mercruiser Spline grease and grease up the splined shaft.<br /><br />Before the drive is installed, think..... is it time for a new water pump?<br />Is the drive ready to be resealed?<br /><br />Does your drunk friend happen to have an engine alignment tool?<br />The engine alignment should always be tested before the drive is reinstalled. Always.<br /><br />The Mercruiser tool is about $100.00<br /><br />Now your ready to install the drive. Your drunk friend MIGHT be able to help you.<br />First place the drive into forward gear. To do this, turn the little shift shaft clockwise<br />as viewed from the top. While turning the little shaft clockwise, turn the prop COUNTERCLOCKWISE until it locks.<br />The drive MUST be in FULL forward before and during installation.<br />IF the drive comes out of forward while you are struggling with it, then stop and put it back into forward.<br />IF the drunk guy accidentally bumps the prop, then recheck to make sure it's in forward.<br />Also, make sure that the little bellhousing shift lever roller is in the fork of the slide!<br /><br />All of this HAS to be perfect before installing the drive.<br />IF one thing is out of place then your screwed.<br /><br />Have the drunk one lift the drive in place while you guide the splined shaft though the hole.<br />It will go "so far" and then stop.<br />You now need to rotate the prop IN THE REVERSE direction to turn the drive to line up the splines.<br /><br />Note! If you turn the prop in the "ratcheting" direction then it will pop out of gear!<br />Remember.... it MUST be in forward to be installed.<br /><br />When the splines get aligned, the drive should slide on more.<br />Every so often a drive will slip right on and you will be done.<br />MOST often, the drive will stop just a little short of all the way.<br />IF the drive has stopped and seems stuck from going all the way on, you need to check something.<br />You NEED to confirm that the shift shafts are in the proper positions.<br />IF you force the drive on and the shafts are wrong OR the roller is not in the slide right then damage will occur.<br /><br />After you are POSITIVE that the shafts are correct.... then a good kick can help.<br />I like to "bump" the drive on gently with a soft log.<br />Theoretically, if the splines are in good condition, and the engine is aligned, and the shafts are aligned, and the splined shaft is in good condition.....<br />then the drive will slide on easy. NOT always the case.<br /><br />Be suspicious if the drive is hard to install.<br /><br />Get one of the nuts tightened in place to hold the drive and let the drunk guy rest.<br /><br />At this point, you have the drive mated up nice but the shift cable is NOT properly adjusted yet.<br />What you need to do, is confirm a few things.<br />Did you rip the gasket during the installation?<br />Did you loose any o-rings?<br />Did the roller stay in the slide?<br /><br />Have your drunk friend climb back into the boat to test the shift.<br />Have him remove the drive cable and push the end in all the way while you turn the prop.<br />It should lock in one direction and ratchet in the other.<br />Then have him pull the end out a little till you get neutral.<br />If you get a smooth neutral then have him pull the cable out for a reverse test.<br />With the cable pulled out... rotate the prop again. It should lock in one direction and ratchet in the other.<br /><br />IF you find that it's not shifting as above, then remove the drive and check it again.<br />Practice makes perfect.<br /><br />If your right on the money then install the rest of the drive nuts and cylinders.<br /><br />Cable Adjustment:<br /><br />Remove the dash cable from the shift plate.<br />Adjust the stud in the slot to the bottom of the slot.<br />Push the drive cable inwards while someone locks the prop.<br />It is VERY important to make sure the prop is fully locked.<br />Measure the drive cable so you have a 6" distance between the hole at the end<br />and the brass barrel. (center to center!)<br />Adjust the brass barrel so it measures 6" center to center. Don't move it!<br />I sure hope that prop was locked in forward (the reverse direction).<br /><br />Place the drive cable onto the shift plate assembly being careful not to move your 6" adjustment!<br />Now you have the drive in forward AND the shift plate is in forward too!<br />Adjust the plastic barrel on the dash cable to match the plate studs so the cable will go right on<br />without moving the shift plate or the drive cable.<br />Install the nuts and the cotter pins.<br /><br />You can now do a static shift test.<br />Place the control in forward. The prop should lock in one direction and ratchet in the other.<br />Take a notice of the ratchet tension.<br />Now go into neutral. The prop should turn both ways free and no noise should be heard.<br /><br />Shift into reverse and feel the ratchet tension. Also make sure you get a good "lock" in the other direction.<br />IF the reverse is weak in the ratcheting, then adjust the stud in the lever slide on the shift plate.<br /><br />The final test is how it shifts in the water!<br /><br />Just go out and have some fun.<br />IF you need to adjust the shift, ONLY adjust the DASH CABLE BARREL.
