Reply
 
Thread Tools Search this Thread
 
Old 25 February 2012, 12:39   #1
Member
 
Country: UK - England
Town: Manchester
Boat name: Quaaack
Make: Zodiac
Length: 4m +
Engine: Yamaha 40 O.B
MMSI: 235093362
Join Date: Nov 2011
Posts: 32
HELP - ive broken it!

Hi folks - come seeking your collective knowledge and help on this one.

I have a Yamaha 40HP 2 stroke outboard 1991.

Today (following the instructions for once) I set about it with intent to change the impeller to complete the service on it before the season starts.

In the process of removing the lower unit one of the larger side bolts shearer as did the bolt hiding under the trim tab anode.

The side one doesn't appear to be a problem as some slight movement can be seen when trying to prise the halves apart.

The sheared bolt under the trim tab is a) sheared flush with the case and b) most probably full of oxidation as none of the other bolts removed show anything other than the white powder I associate with being aluminium oxide.

I have tried WD40, wiggling it, hitting it from side and the exposed end to no avail. Obviously with the case being aluminium heat isn't an option.

Im rather hoping there is an obvious solution to this that the collective has come across over the years.

Any help/suggestions gratefully received.

Cheers

John
__________________

__________________
LHTEC is offline   Reply With Quote
Old 25 February 2012, 12:53   #2
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,267
RIBase
If there's no way you can get mole grips on it, then you'll probably have to drill it out. Try Duck Oil Penetrating Release on it. It may be possible to drill a recess in what's left of the bolt so you can put a decent large flathead screwdriver on it. Worth a shot anyway.
__________________

__________________
Is that with or without VAT?
spartacus is offline   Reply With Quote
Old 25 February 2012, 13:27   #3
RIBnet supporter
 
mick's Avatar
 
Country: UK - England
Town: Wakefield
Boat name: Bouncer
Make: Redbay Stormforce
Length: 6m +
Engine: 2x Honda 90Hp
MMSI: 235025718
Join Date: Jun 2009
Posts: 3,984
Can you put a photo up if you know anyone who is a good welder get a nut welded on and sometimes the heat from the weld will help loosen it and won't damage the casing.
__________________
mick is offline   Reply With Quote
Old 25 February 2012, 13:44   #4
Member
 
Country: UK - England
Town: Manchester
Boat name: Quaaack
Make: Zodiac
Length: 4m +
Engine: Yamaha 40 O.B
MMSI: 235093362
Join Date: Nov 2011
Posts: 32
Photos as requested

Top photo an over view the larger hole is for the trim tab

Click image for larger version

Name:	photo.JPG
Views:	203
Size:	135.0 KB
ID:	65890

The lower is a closer up of the actual damage itself.

Click image for larger version

Name:	photo2.JPG
Views:	204
Size:	159.6 KB
ID:	65891

As you can see there is nothing to weld onto. I had hoped that none of the threaded part would be involved in holding the lower case on but sadly it won't part so I'm assuming there is some thread involved there.
Cheers
__________________
LHTEC is offline   Reply With Quote
Old 25 February 2012, 13:49   #5
Member
 
Country: UK - England
Town: Sompting
Make: quicksilver 310
Length: 3m +
Engine: Yamaha 15HP
Join Date: Nov 2011
Posts: 190
i would say your going to have to drill that out drill a small pilot hole slowly with lots off coolant then open it out with a bigger drill until you can collapse it in on itself.
but its going to be a pig i bet
__________________
ukprometheus is offline   Reply With Quote
Old 25 February 2012, 13:53   #6
Member
 
Country: UK - England
Town: Manchester
Boat name: Quaaack
Make: Zodiac
Length: 4m +
Engine: Yamaha 40 O.B
MMSI: 235093362
Join Date: Nov 2011
Posts: 32
Cheers,

I had a feeling this was going to be a pig, all because whoever serviced it last time. couldn't be bothered putting some grease on the threads. I guess this explains why dole fins have been fitted over a broken cavitation plate, right about where you might reasonably hit the case to separate the two halves!!
__________________
LHTEC is offline   Reply With Quote
Old 25 February 2012, 13:56   #7
RIBnet supporter
 
mick's Avatar
 
Country: UK - England
Town: Wakefield
Boat name: Bouncer
Make: Redbay Stormforce
Length: 6m +
Engine: 2x Honda 90Hp
MMSI: 235025718
Join Date: Jun 2009
Posts: 3,984
A good welder would sort that easy I have seen them brake an inch in and still come out
__________________
mick is offline   Reply With Quote
Old 25 February 2012, 14:24   #8
Member
 
Ribochet's Avatar
 
Country: UK - N Ireland
Town: Rostrevor
Boat name: Ricochet
Make: Redbay
Length: 7m +
Engine: Twin F115 Yams
MMSI: 235083269
Join Date: Oct 2011
Posts: 910
By coincidence I removed the lower leg of the exact same engine today.
I can tell you that your sheared bolt is in no way threaded to the lower unit.

As you know the problem is that electrochemical corrosion has siezed the bolt to the housing of the lower unit. The good news is if you can free the lower unit then you will have no bother removing the broken stud.

The bad news is how to free the seizure? - I had a look and there is a chance that if you apply heat - be careful - each side of the lower unit between the anode and the water slats that the subsquent expansion will help break the corrosion - you need to be very careful and patience
__________________
Maximum Preparation - Maximum Fun
Ribochet is offline   Reply With Quote
Old 25 February 2012, 15:20   #9
Member
 
Country: UK - England
Town: Manchester
Boat name: Quaaack
Make: Zodiac
Length: 4m +
Engine: Yamaha 40 O.B
MMSI: 235093362
Join Date: Nov 2011
Posts: 32
Ribochet,

Thanks for this. Approximately how much of the bolt is within the area of the lower leg?

if the corrosion is holding the bolt to the lower leg then drilling the centre of the bolt might give a degree of flexibility to free it up and once the lower section is away deal with the remaining bolt accordingly.

Just me thinking out loud, shoot me down if in talking rubbish.
__________________
LHTEC is offline   Reply With Quote
Old 25 February 2012, 15:55   #10
Member
 
Ribochet's Avatar
 
Country: UK - N Ireland
Town: Rostrevor
Boat name: Ricochet
Make: Redbay
Length: 7m +
Engine: Twin F115 Yams
MMSI: 235083269
Join Date: Oct 2011
Posts: 910
There is about 47mm of the bolt in the lower leg with only about 10mm screwed into the leg itself.

It is a stainless steel bolt and IMHO it would be extremely difficult to drill it out - I certainly couldn't do it.

It is a tricky one and the broken antiventilation plate gives the impression that this has been a problem for a while.

I have used heat on aluminium castings a lot in the past to great effect - but you do need to be very careful.

If you need any pictures let me know
__________________

__________________
Maximum Preparation - Maximum Fun
Ribochet is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 08:36.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.