Reply
 
Thread Tools Search this Thread
 
Old 21 September 2014, 05:01   #1
Member
 
Country: UK - England
Town: driffield
Length: no boat
Join Date: Jul 2014
Posts: 36
Starting old mercury 7.5 hp

Hi all just managed to get hold of a mercury 7.5hp thunder bolt.
Apparently not been started for 20 years. After a quick inspection with my limited knowhow I found that I can pull the start cord but it is very stiff to pull but it duz turn. Any advice on what my next step would be would great thaks
__________________

__________________
tooter is offline   Reply With Quote
Old 21 September 2014, 05:15   #2
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 12,837
RIBase
Well... if you want to use it, it'd make a good anchor. If you want to sell it, sell it as spares or repairs and let someone else have the inevitable problems that come with a semi-siezed engine.

Basically, if you don't know what to do with a semi-siezed motor, you shouldn't be playing with it as you'll more than likely cause damage that will result in engine failure. It's not a novice's project, no matter how much helpful advice you get.

You may have already caused irreparable damage just by turning the motor over when dry.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 21 September 2014, 05:41   #3
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,064
Nos is probably right but I guess it depends what you mean by "it is very stiff to pull but it duz turn"...
__________________
Poly is offline   Reply With Quote
Old 21 September 2014, 05:59   #4
Member
 
Country: UK - England
Town: driffield
Length: no boat
Join Date: Jul 2014
Posts: 36
I have only pulled it slowly to see if it turns not to try and start it. Just want to know if it is going to be useable.
__________________
tooter is offline   Reply With Quote
Old 21 September 2014, 06:02   #5
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 12,837
RIBase
Highly unlikely.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 21 September 2014, 10:58   #6
Member
 
Country: UK - England
Town: driffield
Length: no boat
Join Date: Jul 2014
Posts: 36
Any advice on as what procedures to take first things to check.
__________________
tooter is offline   Reply With Quote
Old 21 September 2014, 11:09   #7
Member
 
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 287
take to your local marine shop and have them look at it, I know you dont want to waste money noboady does but it could be a cost to save, spend £50 to be told its scrap or £50 could say it's a cracker
__________________
slate1234 is offline   Reply With Quote
Old 21 September 2014, 12:29   #8
Member
 
Country: UK - England
Town: driffield
Length: no boat
Join Date: Jul 2014
Posts: 36
OK thanks was hopeing for something a bit more constructive but thanks anyway
__________________
tooter is offline   Reply With Quote
Old 21 September 2014, 13:00   #9
RIBnet supporter
 
bartiny's Avatar
 
Country: UK - England
Town: Accrington
Length: no boat
Join Date: Oct 2012
Posts: 451
I sent you a PM
__________________
bartiny is offline   Reply With Quote
Old 21 September 2014, 13:13   #10
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,064
Quote:
Originally Posted by tooter View Post
OK thanks was hopeing for something a bit more constructive but thanks anyway
Actually that probably is constructive. No offence intended but without some experience in the area you are potentially more likely to do harm than good (as Nos4r2 has already suggested) and if you had that experience you probably wouldn't be asking here where to start.

Essentially any petrol engine needs the following to run:

fuel and air in the right mix
compression
a spark

all at the right time! The engine has been sitting for 20 yrs, if it was "put away" in perfect running order, winterised before being put away and stored somewhere nice then its feasible to put fresh fuel/oil in it turn it over and off she goes, but if its turned over - even slowly - without oil getting to the cylinders you can cause significant damage, all the more likely with an engine thats potentially been stored badly. Depending how it was stored the carbs may be blocked. If no fuel is getting in, then on an old pre-mix 2 stroke no oil is getting in either.

Assuming the stiffness turning over is not a trivial problem with the pull chord mechanism then its a really bad sign. If the head needs to come off (even to investigate) that is not a "beginners" job especially on an old engine with potentially seized bolts etc.

If its an easy fix £50 ish for an hour of a marine engineer's time and your engine is running. If its goosed then you find out before you've wasted a whole load of money on parts and a several hours of grief working it out for yourself. You'd also be able to sell it for spares/repair with a description of whats wrong which will get you more money than "stiff to turn over".
__________________
Poly is offline   Reply With Quote
Old 21 September 2014, 13:25   #11
RIBnet admin team
 
Nos4r2's Avatar
 
Country: UK - England
Town: The wilds of Wiltshire
Boat name: Dominator
Make: SR5.4
Length: 7m +
Engine: Yam 85
MMSI: 235055163
Join Date: Jul 2005
Posts: 12,837
RIBase
Quote:
Originally Posted by tooter View Post
OK thanks was hopeing for something a bit more constructive but thanks anyway
The thing is, we can go through lots of what you'd like to be constructive advice, but what it boils down to is this:-

You need that motor to work, every time. If it doesn't, you may be in deep deep trouble.
Your 1st post basically asks for advice for a novice on doing a job best left to the experts, on repairing a long neglected, partially siezed piece of equipment that could have any number of other faults from being left standing.Plus you will be relying on it to get you home.

It's worth paying an outboard shop to spend an hour on it to see if it's worth doing. They'll tell you if it's scrap or not and should be able to tell you what work actually does need doing to it.

Realistically, I'd expect the motor to need a full strip and inspection to work out what's stiff,an internal clean, new gasket set , plus a new impeller, plugs and gear oil. That's nearing the cost of a running motor-before you even add in the cost of replacing broken bolts etc and some labour.
__________________
Need spares,consoles,consumables,hire,training or even a new boat?

Please click HERE and HERE and support our Trade Members.

Join up as a Trade member or Supporter HERE
Nos4r2 is offline   Reply With Quote
Old 21 September 2014, 13:33   #12
Member
 
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,869
Quote:
Originally Posted by tooter View Post
OK thanks was hopeing for something a bit more constructive but thanks anyway
By ''constructive'', did you mean 'false hope'?

You've had the best advice, delivered without flowers and frilly bits around the edges.
__________________
Mollers is offline   Reply With Quote
Old 21 September 2014, 14:11   #13
Member
 
Country: UK - England
Town: driffield
Length: no boat
Join Date: Jul 2014
Posts: 36
OK no prob thanks to all for replying.
__________________
tooter is offline   Reply With Quote
Old 21 September 2014, 15:36   #14
Member
 
Bigmuz7's Avatar
 
Country: UK - Scotland
Town: Glasgow
Boat name: stramash
Make: Tornado
Length: 5m +
Engine: Etec 90
Join Date: Feb 2006
Posts: 5,068
We used to have one of those when I was a boy .. I'm now 47 .. the electrics were a constant problem .. I think the advice you've had is good ..
__________________
Bigmuz7 is offline   Reply With Quote
Old 21 September 2014, 17:14   #15
Member
 
Country: UK - England
Town: Southampton
Boat name: SMH Rib / War Shot
Make: Ribtec / Scorpion
Length: 4m +
Engine: 100hp Yam/150hp opt
Join Date: Sep 2003
Posts: 1,976
RIBase
Have got one of those in my dad's garage too. Last run about 1994 I reckon!
__________________
Searider is offline   Reply With Quote
Old 21 September 2014, 17:37   #16
RIBnet Supporter
 
willk's Avatar
 
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 13,844
RIBase
Quote:
Originally Posted by Searider View Post
Have got one of those in my dad's garage too. Last run about 1994 I reckon!
LOL - reckon he's flogged it to make space!
__________________
.
willk is offline   Reply With Quote
Old 22 September 2014, 04:05   #17
Member
 
Country: UK - England
Town: Southampton
Boat name: SMH Rib / War Shot
Make: Ribtec / Scorpion
Length: 4m +
Engine: 100hp Yam/150hp opt
Join Date: Sep 2003
Posts: 1,976
RIBase
Back to the ops question - because I might dig the engine out of the garage and see if it runs.

Bearing in mind the engine is worthless - what should I do prior to trying to start it?
Oil down the bores?
Extra oil in petrol and then turn over with plugs disconnected?
Or stick some fresh fuel in the can and fingers crossed.

It was a rattle smoky thing at the best of times but might be a bit of gun on the river!
__________________
Searider is offline   Reply With Quote
Old 22 September 2014, 04:16   #18
RIBnet supporter
 
bartiny's Avatar
 
Country: UK - England
Town: Accrington
Length: no boat
Join Date: Oct 2012
Posts: 451
Quote:
Originally Posted by Searider View Post
Back to the ops question - because I might dig the engine out of the garage and see if it runs.

Bearing in mind the engine is worthless - what should I do prior to trying to start it?
Oil down the bores?
Extra oil in petrol and then turn over with plugs disconnected?
Or stick some fresh fuel in the can and fingers crossed.

It was a rattle smoky thing at the best of times but might be a bit of gun on the river!
IMO a very sensible answer, more or less what I advised him via PM except for the fingers crossed 1

__________________
bartiny is offline   Reply With Quote
Old 22 September 2014, 11:42   #19
Member
 
Country: UK - Wales
Town: abergele
Boat name: all mine
Make: ribtec 3m
Length: 3m +
Engine: tohatsu 9.8 hp 2st
Join Date: Sep 2012
Posts: 287
I had the same engine I found it very hard to link and sync, I sold for parts in the end, while you have the plugs out I would start with a compression test (leave one plug in) before trying to start it if the compression is good (should be around 90-100psi ish) and both cylinders are within 10% of each other go from there.
__________________
slate1234 is offline   Reply With Quote
Old 22 September 2014, 12:09   #20
Member
 
Country: UK - England
Town: driffield
Length: no boat
Join Date: Jul 2014
Posts: 36
OK thanks. The engine seems in quite bad condition I'm having trouble removing the top cowling it seems the latch is rusted on not going well at the most.
__________________

__________________
tooter 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




All times are GMT -5. The time now is 14:55.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.