Pre-Alpha drive won't go into reverse.

[cjray03]

Hi, I have a 1970 Fiberform with the 120hp Mercruiser in it. Pretty sure it's pre-alpha. It was running flawlessly. Then it ran hot. The first thing I did was drop the lower unit and check the impeller. It was perfect. I put the lower unit back on and realized the hose from the outdrive to the transom was loose. Fixed the overheating issue, but now it won't go into reverse. I have set and reset the shift shaft so that I am positive it is in forward ALL THE WAY, before I slide the lower unit up into the upper. I have changed the intermediate shift shaft because it was visibly worn. there is a tremendous amount of play around the intermediate shift shaft, don't know if that will cause it or not. Anyways, it was running and going into reverse just fine before I dropped the lower unit. I am at my wits end with it, it makes no sense that it won't go into reverse. I can turn the shaft with my finger and the lower unit goes in reverse, so I know it isn't that. Anyone have any ideas?

 

[ScottinAZ]

you may have something out of place where the cable interacts with the bellcrank. Very easy for that to fall out of place when re-installing the drive. If it isnt that, your lower cable may have packed it in and need replacement.

 

[cjray03]

you may have something out of place where the cable interacts with the bellcrank. Very easy for that to fall out of place when re-installing the drive. If it isnt that, your lower cable may have packed it in and need replacement.

I have taken off the drive to check the cable. I checked the upper shift shaft and the cable. It appears ok. I took the lower shift cable loose from the transom and pulled out on it to see if it would go into reverse and it doesn't, so I know its between the cable and the lower unit. The only things in there are the cable end, shift lever, upper shift shaft and intermediate shift shaft. It simply isn't turning far enough to go into gear. Is that a symptom of a bad cable? It goes in and out smoothly. I know about the "off by one spline" thing too. I have checked and double checked that it is fully engaged in forward before sliding it up.

 

[ScottinAZ]

ok, I think I know what the issue is.... I did something similar last year when I reassembled my drive (1980 vintage Mercruiser) only mine I couldnt get out of forward..... check this thread out, specifically post #4.

Almost back together, but a shifter issue

Ok, after a bit of a hiatus waiting for exhaust parts, I have the 120 in my boat back together and tuned. running great now and no water in the oil from a burned out riser. Give it two pumps of throttle, and it starts right up, happy as a clam with this. \ now for the issue. Installed the...

forums.iboats.com

I am thinking that you have the upper and lower shift shafts misaligned. Its damn easy to do, there is nothing that holds the upper section in place if the whole drive is off, and the lower section jumps out of place almost immediately unless constant pressure is on the prop.....

 

[Scott06]

ok, I think I know what the issue is.... I did something similar last year when I reassembled my drive (1980 vintage Mercruiser) only mine I couldnt get out of forward..... check this thread out, specifically post #4.

Almost back together, but a shifter issue

Ok, after a bit of a hiatus waiting for exhaust parts, I have the 120 in my boat back together and tuned. running great now and no water in the oil from a burned out riser. Give it two pumps of throttle, and it starts right up, happy as a clam with this. \ now for the issue. Installed the...

forums.iboats.com

I am thinking that you have the upper and lower shift shafts misaligned. Its damn easy to do, there is nothing that holds the upper section in place if the whole drive is off, and the lower section jumps out of place almost immediately unless constant pressure is on the prop.....

This above when you split the halves to do the impeller east to misalign the shift shaft that is cotter pinned in the upper with the splines shaft in lower. Upper shift shaft needs to be straight ahead and lower shaft needs to be I think turn all the way clockwise to be in fwd

 

[cjray03]

This above when you split the halves to do the impeller east to misalign the shift shaft that is cotter pinned in the upper with the splines shaft in lower. Upper shift shaft needs to be straight ahead and lower shaft needs to be I think turn all the way clockwise to be in fwd

Yes I made sure that the intermediate shaft was forward, I had to hold it interlocked with the upper shift shaft, then I turned the shift shaft clockwise while holding the prop counter clockwise to lock it in forward. Everything slid into place. I thought I had it, but no reverse... like I said I changed the intermediate shift shaft (that's the one with the cotter pin and washer) because it was worn and slightly bent. It still won't turn far enough to take it into reverse. There is a whole lot of play around that intermediate shaft, when it's separated from the lower it moves around a lot. I have to hold it up and in the upper shaft otherwise it just flops around while I try to put the lower in. I have looked for the bushing for that intermediate shaft, but I am unable to find one.

 

[ScottinAZ]

there are only so many points of contact in the system. If the drive goes into reverse when you manually move the shift linkage, its not inside the drive. If the intermediate shaft is not SLOPPY loose on the splines going into the lower, it likely isnt your issue either. This leaves the linkage in the upper and the lower shift cable. What is the fit between the shoes on the upper and lower units? It goes into forward, so it "should" be good enough. To my knowledge there is no bushing that tightens up the slop in the intermediate section of the shaft, it relies on the interface of the splines on the bottom and the shift shoe up top for stability

By chance, when you are shifting from the helm controls, is the shift interrupt tripping? (this shouldnt be happening out of the water, nor when shifting INTO gear) This would be indicative of a bad lower shift cable.

When you have the lower cable disconnected from the shift linkage, is there any excess slop in the cable where there is no movement in the other end of the cable?

You may want to look up the lower shift cable adjustment procedure and go through that, and see what happens. I wouldnt move anything, but it should highlight if there is excess slop, or if the cable just picked this particular time to go bad. You can find the procedure (or a similar one that should work for you) in Service Manual #4 page 4-14 through 4-16

The problem is, the system has now been "disrupted" so a marginally working part may have crapped out at exactly the same time as you were working on the transom hose. Its not that you CAUSED the issue, but you did highlight it.... its the nature of working on old boats.

 

[cjray03]

there are only so many points of contact in the system. If the drive goes into reverse when you manually move the shift linkage, its not inside the drive. If the intermediate shaft is not SLOPPY loose on the splines going into the lower, it likely isnt your issue either. This leaves the linkage in the upper and the lower shift cable. What is the fit between the shoes on the upper and lower units? It goes into forward, so it "should" be good enough. To my knowledge there is no bushing that tightens up the slop in the intermediate section of the shaft, it relies on the interface of the splines on the bottom and the shift shoe up top for stability

By chance, when you are shifting from the helm controls, is the shift interrupt tripping? (this shouldnt be happening out of the water, nor when shifting INTO gear) This would be indicative of a bad lower shift cable.

When you have the lower cable disconnected from the shift linkage, is there any excess slop in the cable where there is no movement in the other end of the cable?

You may want to look up the lower shift cable adjustment procedure and go through that, and see what happens. I wouldnt move anything, but it should highlight if there is excess slop, or if the cable just picked this particular time to go bad. You can find the procedure (or a similar one that should work for you) in Service Manual #4 page 4-14 through 4-16

The problem is, the system has now been "disrupted" so a marginally working part may have crapped out at exactly the same time as you were working on the transom hose. Its not that you CAUSED the issue, but you did highlight it.... its the nature of working on old boats.

Thank you for the input. I actually had the boat in the shop and the shop said that there was an issue with the drive. I do not believe there is because with the lower off I can manually turn the shift shaft and it goes into gear both ways. I think they monkeyed with the adjustments on the transom between the upper and lower shift cables. The interrupt does move when you are shifting into reverse. I didn't think that it was an adjustment because if the lower cable is off I can push it into forward, and pull it into neutral, but that is as far as it will go, it won't pull back far enough to go into reverse. It will pull back far enough that you can hear it dragging the dogs of reverse, but the shift lever just doesn't go around enough to lock it in. There is room for it to go, but it stops. I don't know if this is a cable issue or not, it shifts smoothly by hand and by the helm shift lever. Prior to it running hot and me dropping the lower unit it ran great and shifted forward and reverse just fine. I'm just stumped. It makes no sense that it isn't working. Thanks again for your help

 

[ScottinAZ]

ok. We have found the proverbial smoking gun. The shift interrupt should not be moving at all during shifting INTO gear, nor on land. Its only purpose is to momentarily shut off the ignition so the drive comes out of gear. The way the dogs are cut, they pull into each other under load, and without this, you would play hell getting the drive into neutral without the momentary cutout unloading the dogs.

That said, the shop may indeed have messed with the adjustments. You can TRY and go through the adjustment procedure to get the system to work, but likely since the cable is tripping the interlock, it is fried. When the cable gets old and crusty, the internal friction is enough to couple the core to the sheath enough to overcome the spring on the interlock, and you have issues such as what you are having. (the pivot on the interlock effectively "changes" the length of the cable throw when it trips, and then resets when the load on the trip spring resets)

If it were my boat, I would try adjusting the cable system to spec (6" center to center on the brass piece to where it connects to the shift lever), once this is set, the stud where the shift cable attaches is adjusted in its slot to match the cable. If this does not work, and it likely wont, you need a new lower shift cable. DO NOT GO AFTERMARKET ON THIS..... I just went through that PITA, and the difference in cost isnt worth the hassle..... (check my factory parts thread from yesterday for some pics of a 15 hr used aftermarket cable)

 

[cjray03]

Ok, so I accept that the shift cable is probably bad. Now the problem is that I can't seem to find one that will fit. Seems that the cables out there are for 1978 and newer. I know that the one I have threads in from the motor side of the bell housing and all the newer ones go in from the other side. I have a 1/4 NPT tap ready to thread the front side. I just need to know which cable to buy. If you have any knowledge on that it would be very helpful. Thank you.

 

[dubs283]

Mercury only makes one style alpha cable these days, threads into the bell housing from the aft side. A few options as far as kits go from just the cable assembly to a full kit including bellows, clamps, gaskets, orings, etc.

FYI the threaded portion of the bell housing that accepts the cable is straight pipe thread. You'll need a 1/4 × 18 NPS tap, not NPT

 

[ScottinAZ]

I had the same issue with the shift cable. Get the tap. Rethread the hole for the newer style cable and all will be right with the world.

 

[nola mike]

. I have a 1/4 NPT tap ready to thread the front side.

it's not an NPT tap, it's a straight thread tap

 

[ScottinAZ]

I found mine for fairly cheap on eBay, I think it was under 10 bucks shipped.

 

[cjray03]

So I took a couple of pics so you can see what I am working with. As you can see what I believe is the throttle kill switch is pegged out while the throttle is in reverse. That would be the switch on the right with the roller on it. There is also a switch on the left, but I think that one is the neutral switch. I may be mixed up, but even if I am both of those switches are active while it's in gear. Anyways, the point being that if it isn't supposed to move out of water then the cable is definitely the issue. I ordered a kit today and a 1/4" NPS tap, all mine are too small or NPT. Thank you all for your input.

 

[ScottinAZ]

the cutoff switch, which is on the left in the pic being activated is typical for a bad shift cable. the inner wears enough to jam up, that friction, and the loss of motion is what is causing you to lose reverse. Yours just seems to have picked the time to show itself right after the other work.

 

[cjray03]

Update: Changed the shift cable and everything is working as it should. At least for the shifting...I checked the oil and there's water in it now. Hopefully it's just a blown head gasket. I really would hate to have to scrap the boat. I did see a 3.0 for a couple hundred bucks, 400 with the entire outdrive and all. It really is a nice boat. Was perfect before it ran hot... and BTW I actually used the 1/4" NPT Tap, had to weld it to a bolt to get the length to turn it in, but it worked beautifully. The cable wasn't tough to change.

 

[ScottinAZ]

Update: Changed the shift cable and everything is working as it should. At least for the shifting...I checked the oil and there's water in it now. Hopefully it's just a blown head gasket. I really would hate to have to scrap the boat. I did see a 3.0 for a couple hundred bucks, 400 with the entire outdrive and all. It really is a nice boat. Was perfect before it ran hot... and BTW I actually used the 1/4" NPT Tap, had to weld it to a bolt to get the length to turn it in, but it worked beautifully. The cable wasn't tough to change.

I wouldnt freak out about the water in the oil YET.... I had a similar issue last year, and it was the manifold riser elbow being rotted out, and water getting in through the exhaust system. Yours is even older than mine by about a decade, so you may well have a similar issue. What you really need to do is clean the water out of the engine before it does any damage. (drain/fill the oil, change filter and hit the cylinders with some WD-40 ASAP) then you can start looking to see where the water is coming in from. Pressure test the engine to see if the motor is the issue, and if that tests good, pull your manifold and fill the water jacket with acetone. That will creep through any cracks that may be in there, and the level of acetone will drop. In my case, I was pouring chunky rust out of the riser elbow, so it was a pretty sure thing where the issue was coming from.

others will be along shortly that can assist with the setup for pressure testing the engine. My issue was found before I got to that point.

 

[cjray03]

Well, I know there's a crack in the exhaust manifold. The guy at the boat shop told me as much. Said he put JB weld on it to try and keep it from leaking. I didn't think about it leaking into the block. I don't know if I can find an exhaust manifold that will fit the engine. It's the 120hp 2.5l. But it's a 1970 vintage. I will check the compression before I go into buying the manifold though. Thanks for the input. Didn't mean to change the subject of the thread, I guess I can start a new one about the water problem.

 

[ScottinAZ]

Well, I know there's a crack in the exhaust manifold. The guy at the boat shop told me as much. Said he put JB weld on it to try and keep it from leaking. I didn't think about it leaking into the block. I don't know if I can find an exhaust manifold that will fit the engine. It's the 120hp 2.5l. But it's a 1970 vintage. I will check the compression before I go into buying the manifold though. Thanks for the input. Didn't mean to change the subject of the thread, I guess I can start a new one about the water problem.

the manifolds are still available. IIRC you take the same one I do. I checked into this when I had my issues..... I forget who offhand was the aftermarket supplier, but they are still out there.