Help please, how do I....??

the2esses · Jun 18, 2005

How do I remove the lower gear case from a Mercury 40, appoximately 1986. I have removed the 3 bolts and the unit is still tight together. I do have a manual coming, but I'm in the UK and am having to have one shipped over from America, I have tried and failed to get one over here. So, in the meantime, if anyone could help me out, I would really appreciate it. Sarah (yep, I really am female!)

Moody Blue · Jun 18, 2005

Re: Help please, how do I....??

Should be four (4) bolts. Two located towards front of unit (1 port, 1 starboard), one nut at the center underside of antiventilation plate, one bolt located under trim tab at rear of lower unit. You will first have to remove the trim tab to access this bolt. It may take some gentle persuation to separate from the midsection. Sometimes thin wooden wedges are used to force the two pieces apart.

the2esses · Jun 19, 2005

Re: Help please, how do I....??

Hi Rod Thanks for replying to me. You were right, I've spent all morning at it, but I've finally got that trim tab off - it was seized on, the pig! Now, before I go pulling the gear box off, what's the best way to disconnect the gear linkage? Is it, how to word it, attached to the gear box in any way, or do I have to remove the pin from the top? Really appreciate you helping me out Rod. Thanks. Sarah

Moody Blue · Jun 20, 2005

Re: Help please, how do I....??

Both the drive shaft and shift shaft are splined and slip into mating splined shafts at the top end. No linkages to disconnect. Just gently persuade the lower unit apart from the mid-section. If the two haven't been separated in some time it will take a bit of effort to get them apart.

the2esses · Jun 20, 2005

Re: Help please, how do I....??

Hello again Rod, thank you for replying again, all these posters and just you.....! The gear box has come apart slightly, the drive shaft is disengaged, but the shift shaft is seized solid. I've soaked it in releasing oil and will have another go at it later. I wonder if I could be so cheeky as to ask you something else.....! Can you possibly explain props to me, if you know anything about them. Or anyone else if there is anyone else alive on this forum. Tee heel. In simplified english please! (I am only a mere female after all). I understand there's pitches and sizes. Mine is damaged, I've had a look on good old ebay, there are various sizes, how do I identify mine? I did find some numbers on it, which are 4873136A4013P and in the centre where the nut that holds it on is, is the number 14. Found one on Ebay with the numbers 4861820A114P. What's the difference?! Thanks ever so! Sarah xxx

AMD Rules · Jun 21, 2005

Re: Help please, how do I....??

Hi Sarah, Basic prop identification has two main characteristics; Prop diameter and pitch. Prop diameter is the outside diameter at the blade tips, whereas pitch is the distance the propeller would travel in one revolution assuming it does not slip in the water. Your propeller has a Mercury Black Max part number, and is described as: Black Max Propeller 10 3/8 X 13 RH Alum 3 BL Meaning it is 10-3/8" diameter , 13" pitch , rotates right hand to move forward, and has 3 aluminum blades. The selection of prop depends on the type and weight of the boat, the type and hp of motor, and includes some variation depending on how your going to use it. They need to be selected to keep the motor rpm within its optimum range at wide open throttle. Check out this link for a more detailed explanation: About Propellers

Moody Blue · Jun 21, 2005

Re: Help please, how do I....??

Sarah, two other things to be aware of when shopping for a prop is the number of splines on the prop shaft and the diam of the hub. It is possible (especially in this motor size) to find props of the same diam., and pitch but having a different number of splines or possibly different hub diam. 25hp use some of the same sized props but have 11 splines, 40hp have 13 splines, and 60hp have 15 splines. I have almost bought several props off e-bay but when questioning the spline count found they were for either smaller or larger motors than mine (also a 40hp). Here is a link to some prop numbers and specs. http://www.propline.com/Select-Boat...um-Propellers/30_40_HP_and_25_HP_4_Stroke.htm All I can tell you about the second number is that it is 11 1/4" diam x 14" pitch from a mid 1970's 40-65HP Merc. To be sure you get a prop that works for your motor, count the number of splines on the prop shaft and measure the diameter of the hub at the back of the prop (end opposite the nut). It will be either 3", 3 1/4" or 4". Ask the seller for these details before bidding. Good luck.

technostingray · Jun 21, 2005

Re: Help please, how do I....??

Sopunds like you are getting good advice. Too many cooks spoil the broth, you know.

the2esses · Jun 21, 2005

Re: Help please, how do I....??

Thanks everyone for all your replies. It really is much appreciated. There can never be too many cooks, surely...... Sarah xxxx

Moody Blue · Jun 21, 2005

Re: Help please, how do I....??

Original quote by the2esses

all these posters and just you.....!

I'm not sure if I should I be insulted or flattered ? Just you ?

Any luck getting the L/U separated yet ?

the2esses · Jun 21, 2005

Re: Help please, how do I....??

Hi Rod, and guys It was a compliment of course! As for the gear box, things have gone slightly pear shaped, but only slightly, I think, hope! The gear selector was still seized together on the spline, as I've tried removing the gear box, I've pulled the linkage out of the gearbox, I think I may have broken a little pin somewhere. Any ideas what I might have broken?! I knew I shouldn't have looked this morning, didn't have much time, but there you go. Ms Impatience. I've removed the engine from the other end and the gear selector off the other end of the selector shaft, thus, enabling me to remove the gear box. I wanna know what I've made a pigs ear of in my gear box! More to the point, how do I strip the gear box down to put it back, it doesn't seem to select gears anymore. Yes, I know, women belong in the kitchen. I'm still having trouble getting a manuel for this engine, recipe books are so much easier to find. Sigh! But I'm sure someone will guide me through whilst I'm waiting........I hope! Sarah xx

Motor Boater Bill · Jun 22, 2005

Re: Help please, how do I....??

Sara, You can find a parts list with blow up pictures of all the parts in your motor here: http://www.mercruiserparts.com/selectModels2.asp?type_id=MERC This may help you figure out what's come undone in your lower unit. I'm not familer with your particular motor, but I believe you'll find that there is a cam in there that moves a pin that runs through the center of the propshaft. This pin moves the clutch dog to shift the gears. Usually a clip or some such holds the shaft and cam together. I have read in another post that you may be able to "fish" in there and get the shaft back into the cam, but that it is a long shot. I have no personal experience on this. You may also want to post over on John's Old Merc Q and A board, I can't remember on which of these sites I previously encountered this problem. Johns Old Mercs: http://www.pfs-ware.com/kwast/mercboard/index.htm Good luck, and don't give up! If you need to take the lower unit apart to fix it, you should probably wait for the manual. It gets a bit tricky, and you may need a few special tools, some of which can be fabricated, and folks here or at John's can help with that also. It would be a good idea to replace the seals while you have it apart, so you would at least get the benefit of a newly sealed lower unit in the process. Has this motor been used in salt water? If so, the lower unit will likely be a bit more difficult to disassemble. And no, women don't just belong in the kitchen! Glad to see you're willing to dig into this!

the2esses · Jun 22, 2005

Re: Help please, how do I....??

Hi Bill And where have you been hiding these last few days?! That is a great site, the first link you gave me, thanks very much, and thanks also for the encouragement! Sarah xxx

Motor Boater Bill · Jun 22, 2005

Re: Help please, how do I....??

Well, I'm not one of the true experts here, so I read more than I post, but I've been following your saga. When I jump in it's mostly to share links to other good sources that I've found to keep my old motors going. Mine are both older and smaller than yours (1962 9.8 hp and 1976 20 hp) so as I said above, I don't have hands on experience with your motor. One thing that will help everyone here in assisting you will be to post the serial number of your motor, as there were often mid-year changes in various components, so serial numbers are more useful than model years. The serial number should be on a plate attached to either the leg or the transom mounting bracket. By the way, if this is a salt water motor, it may be necessary to drill and chisel out the ring that holds the lower unit pieces in (it is threaded on the outside) as this often corrodes in place on salt water motors (so I've read). Hence my question about that. That is the piece that requres a special tool to remove, even in the best of circumstances. And, sorry I got your name wrong this morning, Sarah!

the2esses · Jun 22, 2005

Re: Help please, how do I....??

Hi Bill Sara/Sarah, both the same really! I've been called worse! Don't actually know if the previous owners used the motor in salt water. The serial number is 3406830. Would I be able to find out the year from this? Thanks guys Sarah xx

Motor Boater Bill · Jun 22, 2005

Re: Help please, how do I....??

Yet another useful link: http://www.maxrules.com/merc_contents.html And also: http://www.oldmercs.com/models.html Now, I confess I am confused. First, are talking about a Merc 40 (4 hp) or a Merc 400 (40 hp)? Either way, with that serial number, we are talking early 1970's rather than 1986. Now really, no need to hedge about age...

Motor Boater Bill · Jun 22, 2005

Re: Help please, how do I....??

With the prop size you mentioned above, this must be a Merc 400, 40 hp, right?

Motor Boater Bill · Jun 22, 2005

Re: Help please, how do I....??

How about a 1972 Merc 402, 40 hp, 2 cylinder? http://www.oldmercs.com/197273merc402.htm

danie · Jun 22, 2005

Re: Help please, how do I....??

Sarah Where are you in the UK? My friends (and enemies) have all resettled in different parts of the world (due to the SA government's racist legislation and policies) and I might know someone around the corner from you that may be of help. Of the guys I correspond with I can think of two guys in Londen and one in Scotland that were boaters who liked to work on their outboards years ago. D

Motor Boater Bill · Jun 23, 2005

Re: Help please, how do I....??

A bit more reading in my manual seems to indicate that you should be able to reassemble this without tearing down the lower unit. You will have to remove the shift shaft bushing, then replace the "E clip" on the shift shaft that is below the bushing. The manual shows a special tool to remove the bushing. Maybe someone here can advise on an alternative way to remove it or perhaps you can take the lower unit to a shop and have them remove that item--shouldn't take five minutes with the right tool. I can send you a file with that page of the manual if you like. Email me at hillep@berea.edu.

Help please, how do I....??

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