1968 FP Renovation Problems

[mikep]

Hi all. I am trying to renovate a friends FP that has not been used for 20 years or so. Problems so far:-

1. Removing screws to drop gearbox, is it OK to use heat as well as penetrating oil?

2. Removing dome nut. How to lock flywheel while tapping spanner? Would heat help?

3. Compression check gives 75psi and I suspect rings are stuck in grooves. Is it easy to remove crankcase to get at piston?

4. Tank is brass but with much solidified tar inside. Any suggestions for chemical to remove it.

Have to say this is a very nice site but am getting into trouble with her indoors for the length of time I spend on the computer.

[RickUK]

Hi Mike

1. Use a lot of heat - best thing on aluminium.
2. Use a tourniquet or a purpose made rubber strap wrench as sold in auto accessory shops to remove oil filters - set up to pull in opposite direction to spanner. Don't use heat here because of the electrics under the flywheel.
3. 75 psi compression is good - may improve with running and when oil gets around the bore.
4. Best chemical is Sodium Hydroxide, but which will also remove any paint, and you would need to take a lot of care against skin burns. Tank may need several days to clean up - immerse in solution in a bucket and leave. If the 'tar' is not too bad, maybe a long soak with petrol in the tank may work.
5. Her indoors will be less amused when you are spending time playing with the Seagull!!

[40TPI]

Hi all.

2. Removing dome nut. How to lock flywheel while tapping spanner? Would heat help?

Oil filter strap spanner is a great idea however a quick sharp whack on the tommy bar in well fitting box spanner on the dome nut has never failed here..... simply rely on the inertia of the flywheel, no need to hold it. However a tight box or ring spanner is a must ; open enders fly too far!

If the "tar" shows signs of softening with petrol then a handful of nuts/driveway stones in half a pint of petrol and a rhythmic maracas session very hour or so may work wonders. Flush and repeat as necessary

Peter

[mikep]

Success!! Had previously tried with large socket spanner but have just tried with 23mm ring and bingo it worked. Many thanks.

[Jerry In Maine]

i've used household drain cleaner in a grubby tank with good results. remove fuel valve, plug hole, fill with hot water, add drain cleaner and let 'er bubble for a couple hours. don't put the cap on...the reaction gives off a gas that'll want to get out.

[Horsley-Anarak]

1. Removing screws to drop gearbox, is it OK to use heat as well as penetrating oil?

I have found that giving as much heat as you feel safe with is a good idea (don't melt the ally).

Also if you find a punch the same size as the top of the screws. Then give the screws a few good taps with a hammer the shock will help to loosen the corrosion.

If that fails and you loose the slots in the screws (I have had one side of the screw head shear off) you will need to drill out the remain head of the screw. Try and leave enough of the screw sticking out of the gearbox, so that you can use grips and more heat to get the bits out.

Good luck

H-A

[mikep]

Thanks for all the tips. I have been experimenting with various stuff to clean interior of fuel tank tar. Petrol no effect, acetone turns green but little effect on lump of tar, hydrocloric acid turns lump brown but remains as lump, cellulose thinners turns green but little effect and finally caustic soda which does seem to dissolve the lump so I am tempted to try this in tank. I have three reservation though:-

1. Effect of caustic solution on brass?

2. Is the filler cap likely to be caustic proof?

3. Best way of disposing of solution afterwards?

[blue]

i have used dishwasher tablet+boiling water+something to rattle around inside --then 1/2 hour of south american music and and maracas---worked for me

[Jerry In Maine]

1. Effect of caustic solution on brass?

2. Is the filler cap likely to be caustic proof?

3. Best way of disposing of solution afterwards?

1) didn't hurt mine. brass was nice shiny afterwards.

2) don't put the cap on while the stuff is in the tank. leave the tank top open so gases can escape.

3) caustic soda = Sodium hydroxide (NaOH) = drain cleaner; so it can go down the drain. it gets so diluted in the sewer that it won't hurt anything.

[mikep]

OK have cleaned out petrol tank with caustic soda. It took about 8 washes! Have got gearbox cover off and am cleaning it out at the moment.

I am having trouble seperating the gearbox casing so would like to take the whole gearbox off. Despite searching the forums I am unable to decide if I can remove the casting from the shaft by just undoing the pinch bolt or if I need to split the gearbox casing first.

Would appreciate advice.

[RickUK]

You can take the whole gearbox off by undoing the pinchbolt, but it probably won't be straightforward.
Best advice is to take the pinchbolt right out, and you may be lucky in being able to put the bolt in from the opposite side if the thread will start -if you have a 5/16" BSF tap, run this through to clear the thread first.
The object of this is to wind the screw in and put a thick washer in the slot under the screw, and gently wind the screw in to expand the joint. Only do this for one turn or less when the screw has loaded up, otherwise there is a risk of cracking the casting at the bottom of the slot. Some heat around the collar will also help, and use a rubber mallet to get the gearbox moving.
You might also feel a bit of resistance if the water pickup pipe (inside the exhaust tube) has seized into the casting, but this should move with a few friendly thumps.
The gearbox will come off with the square driveshaft in place, as it is held captive by the water impeller until you are able to split the gearbox and water pump casting.
When you have eventually separated the two castings, clean the bore of the water pump casting (which fits onto the drive tube) so reassembly is easy, and smear it with grease (I like coppergrease) in case of any future dismantling.

[mikep]

Thanks for all the help. Have seperated the gearbox from head complete with square drive shaft. Managed to get one of the screws out but not the centre one. Have tried heat but so far will not move. I guess I will just try more penetrating oil. Would stuff it all back together except the lower half of the drive shaft is rusty and could do with a clean.

How is the water pump impellor fixed to the shaft?

[billyboy]

the rotor is simply friction fitted to the shaft....boil in water for a few minutes to soften....push on....allow to cool.....done.

[mikep]

Do I take it the waterpump impellor is plastic? If so am I likely to damage it using a blowtorch to try and get the centre screw out?

[Jerry In Maine]

it shouldn't melt. you'd have to get the entire assembly very hot in order for that much heat to get that far.

i have a lower unit on the bench right now that's just as stuck. will race you...first one to get his off wins!

just keep the torch on the screw. heat it up, let it cool and heat it again. i found that several hot/cold cycles helps. in between add some penetrating oil. position an old screwdriver on the screw and tap hard with a hammer as the vibration can help the penetrating oil seep in between the threads.

you need a screwdriver that fits well. grab the handle with a pair of vicegrips to give you more turning power. the grips also let you push downward harder to keep the screwdriver blade from slipping.

a few expletives spoken at the right moments also help. i have a few that are known to work but i can't list them here.