Lower Unit not coming off

[Virginboater72]

Hey guys, I have a 1987 60hp Mercury outboard. It has never had a real strong water stream coming out of it, and it appears its not coming out at all now, or intermittently at best. I wanted to check the water pump and impeller. I can't seem to get the lower unit off. I have removed the 2 nuts on the sides, the one on the underside, the one on the top, and the one under the tab. I also took the pin out of the top of the shifting rod behind the carbs as well. The unit only comes down about a half inch or so, then it gets stuck. Any ideas? Thanks

 

[Texasmark]

Re: Lower Unit not coming off

First guess is steering linkage. Not familiar with your engine but the only things there, now that you have proven that you got all the fastners loose (allowing for the drop you are getting) are the drive shaft, water tube, and shift linkage.

The drive shaft is splined and has approximately 1" of engagement. If you got it half that it is not your problem.

The water tube is a press fit and that is into seals that do not present that much friction to the tube so it too is not your problem.

The shift mechanism is at the front of the LU and (should) consists of a short spline male of about 1" coming up from the LU which mates to a rigid shaft female just above the LU.

I'd have a good look at it and see if it looks like the splines have also separated by some amount. If not attempt to put a screwdriver in from the side of the LU and see if you can prise up on the female part of the coupling. If nothing acts like it wants to move your problem is the shifter coupling.

It would take some work, but if you can't free up the coupling with some penetrating oil, and afterward keep trying to prise it up, then you may have to go to the other end and pull the shift shaft. Probably a clamp at the top, inside the cowling, accessible just behind where the shift/throttle cables mount to the engine. You might undo the upper end and pull out the shaft with the LU. Obviously it will be long as is the drive shaft.

There is a bearing, neoprene seal and keeper on the bottom of the male spline in the LU so don't get too frisky with the pulling on that as if you pull it out of the shift cam in the LU, you will have to pull the guts out of the LU to get the cam mounted back onto the shaft.

HTH,
Mark

 

[Capt Ken]

Re: Lower Unit not coming off

Talk about getting the shaft! Your drive shaft is rusted into the crankshaft. The play you have is the small amount of play the drive has. Only thing you can do is start driving wedges between the lower unit and exhaust housing in an attempt to force them apart. I've actually in the past had to resort to cutting through the water pump and drive shaft with a saws all and pulling the power head with the remainder of the shaft still connected.

 

[Virginboater72]

Re: Lower Unit not coming off

I guess I will start with the wedges in the morning. So according to you guys, 5 nuts and the pin through the shaft behind the carbs should be all that's holding it on? If so, than it must be rusted. I have never had one of these apart, in fact, this is the first boat motor I have owned. I'm playing it all by ear. Where would the shafts be rusted together? Is it possible to get some PB Blaster on it tonight to soak?

 

[emckelvy]

Re: Lower Unit not coming off

I'd agree that if the gearcase has dropped down 1/2", it's not likely that the driveshaft is seized in the crankshaft. Even if it was, since it dropped down that far it's very encouraging and likely wedges will do the trick to get 'er dropped the rest of the way.

More likely it's stuck at the shift shaft, take a look at this thread and you'll see what happens with that problem, along with a lot of helpful suggestions. Your motor has the same type/design of shift shaft/reverse lockout so the info is directly applicable:

http://forums.iboats.com/mercury-mariner-outboards/war-lower-unit-590009.html

 

[Maxz695]

Re: Lower Unit not coming off

He removed the roll pin in the shifter lever up top the shift rod would come out in a one piece fashion. His driveshaft is stuck. JMO

 

[Maxz695]

Re: Lower Unit not coming off

Best thing to do when using wedges is to turn the fly wheel a bit here and there to help disipate the rust. I have heard extreem cases where they actually took it to the ramp and ran the engine to get it to drop as a last resort. This is not recommended by me. But it is an option if all eles fails. If the shift shaft is hanging up in a rusted steering arm you may have to cut it and replce it. I had to do that when dismanteling my 70 HP.

 

[Virginboater72]

Re: Lower Unit not coming off

Thanks guys, I am getting ready to head back out and start in on it again. I am a complete rookie at this, but you are saying the driveshaft is stuck? The drive shaft is in the lower unit correct? The long shaft that runs up under the cowl is the shift shaft? After removing the roll pin in the shaft under the cowl, it did move some, maybe a 1/4" or so, so I think it's free up there. It just didn't want to budge more than a 1/2" after that. I am heading out now, thanks again.

 

[Maxz695]

Re: Lower Unit not coming off

Yes the driveshaft goes from the LU pinion gear wich turns the gears all the way up into the splines of the chankshaft an will come out along with the LU water tube and shift rod. If you can keep lifting the LU back up turn the flywheel and drop it agian. Repeat this over and over using a wedge to help it along. The less force used to get ths off the better. JMO

 

[Texasmark]

Re: Lower Unit not coming off

He removed the roll pin in the shifter lever up top the shift rod would come out in a one piece fashion. His driveshaft is stuck. JMO

If the engagement of the DS to the engine block is only approx 1" (which is is) and the top of the shaft is convex, how is it that it is stuck if it has already dropped half the engagement distance.
-----------------
On the reply by someone concerning 1/2" of slack and the DS is still stuck, must be something different than I ever experienced in my 50+ years of boating. I never measured it deliberately, but it isn't much, if any. In moving a removed LU around by the DS I never, ever, noticed any slack, course I wasn't looking for it either.

Besides if there was any drive shaft slack in the LU, the drive pinion could become disconnected from the F and R gears and cause problems. The manual states that the shaft is torqued to the (lower) bearing carrier, which is pressed into the housing, 70 ft-lbs and when checked against the maintenance tool used to check the position of the pinion, if it is off by as much as 0.25" to either add or subtract shims between the shaft and the lower bearing till the dimension is correct...... so you can't have any slop in the drive shaft to LU interface You can't rely on the interface between the top of the shaft and the engine block to determine the LU gear engagement any way. A stuck DS is not the problem.

My 2c,
Mark

 

[Maxz695]

Re: Lower Unit not coming off

The poster stated in the original post QUOTE" The unit only comes down about a half inch or so" Unquote. The driveshaft goes more than 1 inch into the crankshaft splines. Almost 2 inches. If you have ever had one hang up and have to turn the flywheel to get it up. There is approx 2 inches to go when the splines match up. Read before you correct thanks. There is 1 1/2 inches if spined area. There is still 1 inch to go. View attachment 180615 View attachment 180616 View attachment 180617 Also there is distance of play between the tapered pressed on driveshaft bearing and the housing, and is enough to let the driveshaft raise somewhat with the housing removed. The convext point of the driveshaft is not measured in the photo as there is a flat end on the ruler and that distance can be added to the splined area if you so desire making it well over 2 inches with the nipple if the shaft has one. It is what it is. Repeat 1 1/2 inch of splined area. The water pump base holds down the DS bearing to the race and centers the drive shaft. It is very important to make sure you have a base in very good condition as well as good oring and seal.. There is slight play if removed View attachment 180624View attachment 180625 This has nothing to do with the droped shaft in the post just to clearify there is slight room for the pinion between it and the case. NOTE: To the poster Viginboater72 I totally recommend a careful complete inspection of the drive shaft bearing, and the nylon water pump base as damage could be incourred by applying the pressure nessecary to remove the shaft if excessive rust is present on the splines after LU removal.

 

[Texasmark]

Re: Lower Unit not coming off

The poster stated in the original post QUOTE" The unit only comes down about a half inch or so" Unquote. The driveshaft goes more than 1 inch into the crankshaft splines. Almost 2 inches. If you have ever had one hang up and have to turn the flywheel to get it up. There is approx 2 inches to go when the splines match up. Read before you correct thanks. There is 1 1/2 inches if spined area. There is still 1 inch to go. View attachment 180615 View attachment 180616 View attachment 180617 Also there is distance of play between the tapered pressed on driveshaft bearing and the housing, and is enough to let the driveshaft raise somewhat with the housing removed. The convext point of the driveshaft is not measured in the photo as there is a flat end on the ruler and that distance can be added to the splined area if you so desire making it well over 2 inches with the nipple if the shaft has one. It is what it is. Repeat 1 1/2 inch of splined area. The water pump base holds down the DS bearing to the race and centers the drive shaft. It is very important to make sure you have a base in very good condition as well as good oring and seal.. There is slight play if removed View attachment 180624View attachment 180625 This has nothing to do with the droped shaft in the post just to clearify there is slight room for the pinion between it and the case. NOTE: To the poster Viginboater72 I totally recommend a careful complete inspection of the drive shaft bearing, and the nylon water pump base as damage could be incourred by applying the pressure nessecary to remove the shaft if excessive rust is present on the splines after LU removal.

I'll retain my position on this. Since I didn't ever measure a drive shaft when out even though I look at them and grease them prior to reinstallation. I used the dimension 1" as I recall that was about how far the LU was from the mid section upon reinstallation and having to turn one or the other to get the splines to line up...engagement stops just as the LU stud threads are passing thru the holes in the MS and you can get a couple of threads engaged. I'll give you the dimension.

Mark

 

[Maxz695]

Re: Lower Unit not coming off

1 1/2 inch studs. I,m not knocking you read the tape based on fact not guessing thats all It isn,t about wheater or not it,s the shift shaft or the drive shaft just you absurd attack on my post and your wrong. There is a big difference between 1/2 inch and 1 inch esspecially if it is a steel driveshaft. That info has not yet been revealed. Your basing your assumption that it is 1/2 inch down with 1/2 inch to go this is not Fact. There again is a big difference between 1/2 rusted stuck driveshaft and 1 full inch of rusted driveshaft. I even stated in a prior post here that it could be the shift shaft hanging up in the rusted pivot shaft. but my assumption is based on the amout of drop bing 1/2 inch. In my experienc if there where corrosion in the pivot shaft if would be more in the center of the shaft well beyond 6 to 8 inches, not 1/2 inch. Thats what I based my assumtion on. I,m not attacking your post or your opinion but you surely feel comfortable attacking mine. Time may tell if the poster posts the results. In any case You should not attack anothers post based on guessing but fact. That I would respect. To try to use my post to justify your assumption is totally irresponsible on your part. Just the posters update for you to re read Quote" After removing the roll pin in the shaft under the cowl, it did move some, maybe a 1/4" or so, so I think it's free up there. It just didn't want to budge more than a 1/2" after that. I am heading out now, thanks again" Unquote

 

[Virginboater72]

Re: Lower Unit not coming off

Well, I didn't want to start a war, but all of your input is appreciated. The LU is still stuck on. I have broken a prybar, and several knuckles! The LU has dropped a total of maybe 3/4" of an inch. I don't know what to think now. I have broken a couple pieces of the fins above the LU studs, as well as a piece of the LU housing. I guess a new LU is going to be needed if I can get the old one off. Do you guys think I have unhooked everything? I have removed the 5 nuts that hold it on, and the roll pin on the top of the shift shaft behind the carbs. I can't find anything else. Any ideas would be great. Thanks. I will attach a pic.

 

[carholme]

Re: Lower Unit not coming off

Have you checked to see if yours has the stud in the front? What is your engine s/n?

Gerry

 

[Virginboater72]

Re: Lower Unit not coming off

I believe I got them all carholme, there was for the tab, one under the tab, and another next to that. Then there was the other 2 on the sides for a total of 5. Here is the serial# OB226481. Thanks.

 

[carholme]

Re: Lower Unit not coming off

That s/n comes up as:

MERCURY - ( 60 H.P. (1987 ))
Serial No: 0B226481 Model No: 1060717

Parts List for model 1060717:

50/60 HP (3 CYLINDER) - Mercury, Mercruiser, Force, etc. Parts Lookup

OEM Service Manual P/N: 90-86135--5

Mercury Mariner Outboard Service Manual 45 50 60 70 P N 90 86135 5 | eBay

Here is a link to the condensed version of the Clymer service manual. Download soonest to your computer as the link is short lived

EBSCO Publishing Service Selection Page

See LU removal on page 248.

Gerry

 

[Virginboater72]

Re: Lower Unit not coming off

It appears that I have removed everything that needs to be removed in order for that LU to come out. I didn't see any other clips or anything holding that shift rod in place. I guess I will keep prying away! Thanks for that info Gerry, it's good to have on hand.

 

[carholme]

Re: Lower Unit not coming off

You say that you have removed the roll pin at the top of the shift shaft. If you have done that, do you see any separation of the shaft from the lever or are they still solidly connected? You could remove nut, item 8, under SHIFT LINKAGE AND EXHAUST PLATE and see if the shift shaft is free at all. As well, in the broken out piece at the RH front side of the LU, you should be able to see in there and see the reverse lock cam and the connection between the upper and lower shift rods. You might even be able to get a punch in there and see if you can tap the upper shift rod upwards just to make sure that the shift rod is not holding things up, ie; corrosion.

Gerry

 

[Moody Blue]

Re: Lower Unit not coming off

Stop the madness. That lower unit is being destroyed. Don't use pry bars because they will only apply a LARGE force over a VERY small area and break things. Those lower units aint cheap. A pry bar will also force the lower unit down at an angle, maybe further adding to the problem.

Use any kind of wedges, forced between the lower unit and the driveshaft housing. Place them equally from either side and from front and back. You can even use shims for hanging doors etc. Hammer them in gradually and evenly until they are TIGHT. This will apply a huge downward force. Watch carefully as you are doing this to see if any of the linkages are moving/bending. Stop if something doesn't look right.

Are you able to easily shove the lower unit back up into position or is there resistance?