impellor on blueband merc 50 cant split lower unit

[Nos4r2]

Right, this was beginning to niggle at me, so I went and had a good look at my seloc manual which covers from 1965 to 1985 and there's definitely never been a bolt inside it- I suspect that your driveshaft is siezed to the crank and the 10mm movement is due to bearing or spline movement in the lower unit.

[jwalker]

Originally Posted by Nos4r2

...and the 10mm movement is due to bearing or spline movement in the lower unit.

Nah. Not unless it's fallen to bits inside the lower unit.

I don't know your engine but, presuming there's nothing unusual about it and you have definately removed all the bolts which should be removed, you would expect there to be 3 connections to separate;
1) the gear select shaft,
2) the driveshaft and
3) the water connection to the pump.

If Nos is correct then 1 is taken care of unless the splines are stuck and the shaft is pulling down against the inside of the engine casing or whatever mechanism is inside the casing.

If you have 10mm of movement the driveshaft spline is free but some motors have a seal in the bottom of the crankshaft spline. Could the driveshaft spline be hooked up on this? Alternatively, could the bottom of the crankshaft be a lump of rust which the spline is coming up against?

At the water connection I'd expect a pipe to simply slide out of a rubber neck seal. Squint in with a torch and see what you can see.

Just some thoughts.

Edit; there could be a speedo pickup pipe in there too. Possibly flexible.

[Dino89]

thanx again for the posts , certain all bolts are removed and selector is not the problem the problem to my mind is around the drive shaft not coming through as i said before can feel in knocking through fly wheel and the movement of the shaft seems to be top end rather than bottem sump end although this all by feel so could be wrong as metal has a habit of transmitting through it!
so if theres no fixings holding it and its rusted and just pulling down on engine casing what is the best way to proceed to free it ,said before gave it a go with wedges and got know extra movement at all if anyone has workshop sectional picture showing the assemly of this shaft woould be useful
would like to do my own sectional view with an angle grinder to see wat the problem is !!!

[jwalker]

Originally Posted by Dino89

....would like to do my own sectional view with an angle grinder to see wat the problem is !!!

[Nos4r2]

Originally Posted by Dino89

if anyone has workshop sectional picture showing the assemly of this shaft woould be useful

I do, but I'll have to get a pic to you later when the camera batteries are charged up.

There's no speedo pickup on pre blueband model 500's.

The main driveshaft on these usually has a fair bit of movement up/down on the splines into the drive gear of the lower unit-about 10mm in fact. This is why I suspect that your driveshaft is siezed to the powerhead. The driveshafts on the red bands weren't stainless-they just had a plated area round the lower unit seal unlike the later bluebands.

This is going to sound odd, but what I'd do is turn the engine upside down on a flat surface (make sure there's no water in it 1st),block up ALL the holes that aren't in the lower unit(carbs, plugs, peehole, exhaust transfer port) and pour a gallon of diesel straight through the 10mm gap in the lower unit. Leave it for a week or two for the diesel to penetrate, maybe tapping the chocks occasionally while you wait to see if it pops apart.

This sounds loads more sensible when you bear in mind the manual seems to think the only way of seperating a siezed drive/crank joint is to drill a hole in the leg and then cut it with a gas-axe... There's realistically no easy way of dealing with a 40 year old engine that's got stuff siezed in it

Assuming it comes apart, make sure all the diesel has drained out of the engine before you try and turn it over or it'll fluid lock.

[Dino89]

thanx again ,going to give the diesal a go at weekend it does sound better than the other option !!
will feed back with results!!
Dino

[Dino89]

right engine is off and upside down filled with diesal in garage will wait and see if we get any more movement next weekend,
Nos if u get a chance would like to have a look at a picture of this shaft assembly
thanx for all the help
Dino

[jwalker]

Dino, I hope it comes apart but if it doesn't, presuming the impeller doesn't have a metal centre, I'd have a go at putting a cut right through the replacement impeller just infront of the keyway. You could put a drop of superglue on the cut area to bring it back together once fitted around the shaft. Rubber superglues particularly well. If the cut is in such a position that the impeller is trailing the keyway when it is rotating and since the rubber is always pushed inwards inside the pump housing, you'd have fair chance of it staying together.

Just another wee thought.

[Nos4r2]

I WILL get you that pic....I 'm cursing,I can't find the camera since my girlfriend packed it to take to her parent's.

[Dino89]

will check back for picys thanx,
we have got the motor upside down still filled with diesal and all fingers & limbs crossed !! brotherinlaw is going to look tonight or tomorrow c if anything gives !!

[Nos4r2]

ok, got pics- Drop me a PM with your email addy and I'll send them direct. The files are too big to post on here and I suspect you'll want as much detail as possible.

[Dino89]

pm done let me know if you dont receive it think i done it ok ,
yes would like as much detail as poss ,what manual have you got for these motors and where can one be purchased maybe worth him investing in one
thanx
Dino

[Nos4r2]

I've got 2 manuals- seloc and clymer but only the seloc covers the really early ones which is unfortunate as the Seloc isn't great. You find them on Ebay occasionally (both mine are from there) but the only one there at the moment is in the USA but will post to UK. Usually about 28 quid so grab it if you can!

http://cgi.ebay.co.uk/SELOC-Mercury-...QQcmdZViewItem

[Dino89]

went back to motor today been left upside down filled with deisal for approx 10 days ,using a hydraulic spreader between fins and two tapered chisels back and front success it came apart !! thanx to Nos4r2 and all who helped with this post have photos of it apart! the impellor blades were almost falling off so hopefully new impellor and he should be up and cruising soon,
any advice on sourceing parts would be useful we did break a nylon threaded water pipe so need new one of these as well but all in all well pleased thus far..

[Nos4r2]

Wahey! What did the top of the driveshaft look like in the end?

[Dino89]

photos attached am i right in thinking the bush at the top of the shaft should have stayed in the casing ?

[Nos4r2]

No, that bush is supposed to come out-looks like it all came out fine (were the water vents broken beforehand or did they break while taking the lower unit off? They won't make any difference to it like that anyway). It's in remarkably good condition considering it's over 40 years old.

[Dino89]

the bush is pretty firmly in place but need to remove it to get impellor houseing off shaft must say i was impressed with the condition of shaft the way it was stuck thought it was going to be a pile of rust!!
brotherinlaw broke vents before i got there! it was going to be an all or nothing result!! he also broke the nylon nut with water pipe that goes at the front of the lower unit so need to replace that as well but all in all it was a superb result
i will make a couple of ali slotted plates and pop rivet them in place to keep it all looking nice !

[Nos4r2]

Don't worry about the nylon nut and hose-it's the speedo takeoff and they aren't much good when they DO work. It means having an extra hose connected to the motor too.

You WILL need to replace that bush if it gets damaged though-it's what holds the grease into the powerhead/driveshaft joint.

[Dino89]

will a blow lamp help with the removal of the bush ,how tight a press fit are they ?