Mariner 4hp 2 stroke - what am I doing wrong!

[stepaway]

Hi all - finally got the outboard out after long term covid storage

I thought I’d best change the impeller - I did it a few years ago and it hasn’t been used since, but thought it may as well be done again to be sure.

Now, my brain isn’t as good as it used to be, so even though I’ve changed it with no problems before this time I’ve half arsed it and can’t for the life of me remember a few things.

I’ll put my hands up and say I rushed into it and should have been a bit more patient so sorry to now come here asking for favours!

Firstly, it’s a 2004 4m 4hp 2 stroke Mariner (so a Mercury/Yamaha I believe) I used to have the workshop manual printed off, but now I can’t find it and I can’t find it online anywhere’ - does anyone have a link to it or a copy anywhere please?

Secondly, I undid the selector rod inside the leg behind the rubber bung to get the lower unit off, and seemed to have done something to the F/N/R rod. The gearbox now seems to be stuck in gear, and although the rod moves up and down it doesn’t seem to be selecting correctly? (The prop turns the shaft that goes up into the main power head when I spin it by hand) Amy thoughts on what I may have done anyone?

Lastly, does anyone know which way the impeller needs to sit. I just replaced it like for like last time and all was fine. I forgot to check before I removed it this time so for the life of me can’t remember which way it was

I’m in Bedfordshire, if anyone was local who knows their outboards that could cast their eye over it that would be much appreciated and I’m sure some beer tokens would be provided!

Many thanks in advance

Si

[jeffstevens763@g]

Here you go



https://youtu.be/5-mUC8Wunn4

[stepaway]

Thanks for that, I’ve just watched this incidentally! Answers some of my questions thanks regarding impeller orientation so that’s helped.

Anyone have any ideas on the gear selector / box not going in neutral? Should I be able to manually do this with the lower unit removed just by moving it with my hand? As I said it goes up and down, but there doesn’t appear to be any resistance. If I swivel it round it feels as though it’s making contact with something so not sure if it’s got something on the end that should locate into something that’s fine out of sink?

[jeffstevens763@g]

Put your gear selector so it shows the block and nut in the hole behind the rubber bung he says its at the bottom for connecting can’t remember if it’s in reverse or not so you will have the set the rod on the gearbox before you put it on that’s what you’ve probably done move that rod gearbox end

[TmMorris]

You can usually engage the gearing by hand, I've resorted to using mole grips before.

To be honest, if you can move it up and down easily and not feel any kind of mechanical action then I guess the stepped end on the bottom of the rod could have come off? I'm not sure you're normally able to turn the rod as the selector at the bottom is squared and set in a channel/guide.

Are you saying that you can move the rod up and down, you neither hear nor feel any mechanical action and at no position does the gearbox go into neutral or the opposite gear?

Is it possible that you've pulled the rod up and subsequently pulled the selector away from the pin and channel? If this has happened then it might not be possible to push it back into place as the spring will have pushed the pin to the back and there is usually too big a step on the selector to winkle it back down behind the pin.

When I had the problem where I hadn't refitted the selector properly after a rebuild of the lower leg the quick fix was to whip out the gear box, refit the selector correctly and put the gearbox back in.

I spent ages last Spring trying to get the lower leg of my 15 2s Yam/Mariner back on but the gear selector was too high and I eventually realised that it was seated so took the gearbox back out to get it seated.

Or have I misinterpreted the symptoms?

[stepaway]

Thanks Jeff (again ) I’m fine with the lock but behind the rubber bung connecting the two selector rods.

The problem is where the selector rod goes into the gearbox on the lower unit. I might be imagining it but I thought that rod could be used to manually select if the gears are engaged or if it is in neutral? Or am I imagining that and if I put it all back together it will work?

[stepaway]

Originally Posted by TmMorris

You can usually engage the gearing by hand, I've resorted to using mole grips before.

To be honest, if you can move it up and down easily and not feel any kind of mechanical action then I guess the stepped end on the bottom of the rod could have come off? I'm not sure you're normally able to turn the rod as the selector at the bottom is squared and set in a channel/guide.

Are you saying that you can move the rod up and down, you neither hear nor feel any mechanical action and at no position does the gearbox go into neutral or the opposite gear?

Is it possible that you've pulled the rod up and subsequently pulled the selector away from the pin and channel? If this has happened then it might not be possible to push it back into place as the spring will have pushed the pin to the back and there is usually too big a step on the selector to winkle it back down behind the pin.

When I had the problem where I hadn't refitted the selector properly after a rebuild of the lower leg the quick fix was to whip out the gear box, refit the selector correctly and put the gearbox back in.

I spent ages last Spring trying to get the lower leg of my 15 2s Yam/Mariner back on but the gear selector was too high and I eventually realised that it was seated so took the gearbox back out to get it seated.

Or have I misinterpreted the symptoms?

Ah ha, this is exactly what I’m talking about, thank you 👍🏻

So - it sounds as though your explanation is right of the problem, I’ll go take a look now and see how I access the gearbox. Any pointers please?

[TmMorris]

Two bolts on the face plate behind the propellor. Once off you'll then spot two relatively useless slots where that face plate meets the casing. You have to winkle the plate off. Drain the oil from the lower casing first! The gearbox just comes out in a few pieces so have a tub ready and just take each bit out one by one and either lay in a line or stack in reverse. I can't quite recall but you may need to remove the cog from the drive shaft to get the rearmost gear out. That's held on by a spring/cotter/c clip that pings off with a screwdriver. Make sure you watch where it goes . Of I recall there will be a few shims in there as well so make sure you keep those in order as they'll be either side of a roller bearing at the back. The last bit is a pin, aboit an inch long and 7mm thick. That sits in the assembly and is what the steped selector pushes in and allows out when you pull it up and down.

Anyway, once that's all out you'll see the gear selector rod at the back. Check that the selector hasn't somehow come off the rod but otherwise it should have gone back into position when the gears came out. Just make sure it's sitting at the bottom of its travels and then put the gears back in, the front plate and then tear to see if it's working but without pulling too hard!!!

Best practice would probably be to replace the rubber seal on the front plate but I've never done so. No harm in a bit of Emory around the sealing faces if they aren't shiny and smooth but if that's needed then the telltale would have been that the face plate would have been a bigger to remove.

I have a 1984 4hp Yam 2s and it's in pristine condition and it all comes apart smoothly.

There will be YouTube vids on removing the gears. YouTube makes this stuff so much easier.

[stepaway]

Originally Posted by TmMorris

Two bolts on the face plate behind the propellor. Once off you'll then spot two relatively useless slots where that face plate meets the casing. You have to winkle the plate off. Drain the oil from the lower casing first! The gearbox just comes out in a few pieces so have a tub ready and just take each bit out one by one and either lay in a line or stack in reverse. I can't quite recall but you may need to remove the cog from the drive shaft to get the rearmost gear out. That's held on by a spring/cotter/c clip that pings off with a screwdriver. Make sure you watch where it goes . Of I recall there will be a few shims in there as well so make sure you keep those in order as they'll be either side of a roller bearing at the back. The last bit is a pin, aboit an inch long and 7mm thick. That sits in the assembly and is what the steped selector pushes in and allows out when you pull it up and down.

Anyway, once that's all out you'll see the gear selector rod at the back. Check that the selector hasn't somehow come off the rod but otherwise it should have gone back into position when the gears came out. Just make sure it's sitting at the bottom of its travels and then put the gears back in, the front plate and then tear to see if it's working but without pulling too hard!!!

Best practice would probably be to replace the rubber seal on the front plate but I've never done so. No harm in a bit of Emory around the sealing faces if they aren't shiny and smooth but if that's needed then the telltale would have been that the face plate would have been a bigger to remove.

I have a 1984 4hp Yam 2s and it's in pristine condition and it all comes apart smoothly.

There will be YouTube vids on removing the gears. YouTube makes this stuff so much easier.

Thanks very much, so so helpful - an hour in the shed stripping it all down, taking the prop off etc and once it was apart I could see what was going on. Selector Rod fully down, re-fitted the gearbox and bobs yer uncle it’s working again 👍🏻

Def owe you a few if we ever meet in person, and a virtual high five on its way to you

Thanks again, I’ll put the rest of it back together tomorrow and it should be ready to go again 😎

Regards, Si

[Tommy c]

Before you reassemble the box back onto the leg, make sure both the gearbox and gear selector are both in reverse.

[stepaway]

Originally Posted by Tommy c

Before you reassemble the box back onto the leg, make sure both the gearbox and gear selector are both in reverse.

Will do!!! And put some fresh oil in the gearbox of course!

[TmMorris]

Good stuff. Glad it was a relatively simple fix.

[Tommy c]

Originally Posted by stepaway

Will do!!! And put some fresh oil in the gearbox of course!

Looks like we was typing at the same time.

[stepaway]

All done, up and running, fresh gear oil and a super strong tell take stream 👍🏻

Thanks all, appreciate your help

[TmMorris]

Good way to start the weekend!

[stepaway]

Originally Posted by TmMorris

Good way to start the weekend!

Yup, will be heading up the river tomorrow for a test run

Weathers looking pretty good for it ☀️

[Twyfordbridge]

Hi Stepaway. I have exactly the same engine and exactly the same problem. Impeller changed successfully but gear rod is standing too high and moves about one inch up and down freely but won't shift out of gear. I just found your post after 4 hours of frustration in the garage. I've read TmMorris very helpful reply and taken good note. Had enough for today but will attempt again tomorrow having read your very helpful post. Many thanks to both of you ��

[Twyfordbridge]

Originally Posted by TmMorris

Good stuff. Glad it was a relatively simple fix.

Thank you TM, I have exactly the same problem and engine. Will try your helpful suggestion tomorrow when my stress levels have returned to normal. Thank you again. 👍