penberth3
Well-Known Member
No, you have to heat the prop to expand it. And remember you've got two different materials.
Suzuki 2.2 outboard how to remove stuck prop..?
- Thread starter Captain Crisp
- Start date
No, you have to heat the prop to expand it. And remember you've got two different materials.
RichardS
N/A
You need to remember that when you heat a metal nut or ring (an annulus) the diameter/circumference of both the inside and outside planes increases. When you cool an annulus both of the diameters/circumferences decreases.
Richard
reeac
Well-Known Member
I assume that the prop. is made of a polymer. The coefficient of thermal expansion of polymers is typically 10 times that of metals so you're better off heating the prop than cooling the shaft
. I recently had to change a ceramic disc tap cartridge, the tap knob being firmly stuck on. I applied Plus Gas and then managed to get the claws of a claw hammer between the knob and a wooden block which rested on the wash basin and similarly used one jaw of water pump pliers on the opposite side to provide an axial separating force. A bit of impulse on both tools shifted things
. I recently had to change a ceramic disc tap cartridge, the tap knob being firmly stuck on. I applied Plus Gas and then managed to get the claws of a claw hammer between the knob and a wooden block which rested on the wash basin and similarly used one jaw of water pump pliers on the opposite side to provide an axial separating force. A bit of impulse on both tools shifted things
HissyFit
Well-Known Member
That is true for a thin annuli that behave like a wires which contract along their length. This does not necessarily hold true for items of increasing cross-sectional area.
HissyFit
Well-Known Member
Everyone has used heat for a long time, and everyone has struggled. Someone needs to try the counter-intuitive. The application of cold is becoming the preferred method for removing certain stuck parts amongst cycle mechanics at least.
RichardS
N/A
It holds true for all metal ring structures (nuts, washers, spacers, bushes, bearings, hollow shafts etc) that we are likely to be dealing with as marine or auto engineers. I can show you the underlying thermal expansion coefficient effects if you need proof, although you will be able to find it online.
Richard
RichardS
N/A
I've been pressing and removing bearings and bushes into and from housings for decades. I, and every other engineer, always heat the housings and freeze the bearings. Where significant heat cannot be applied, a cycle of gentle heating and cooling is sometimes employed, but that does not change the physics.
Richard
Greenheart
Well-Known Member
If you do that, be sure to video the process, with coloured lights and slow 1980s music for the full Top of the Pops effect.
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penberth3
Well-Known Member
"Cold shock" might work for small cycle parts, it's not going to do anything on a large mass of metal.
simonfraser
Well-Known Member
waterproof grease, and remove it once a year to clean up and re-grease, no more drama
Topcat47
Well-Known Member
Heating the prop makes the whole, thing expand. This applies to the internal diameter of the prop as much as the external. Aluminium and brass expand more than steel for a given temperature rise, so applying heat will loosen the prop. It is advisable to use a heat shield to protect the leg outboard casting when doing this. Cooling the prop has the opposite effect of tightening the prop onto the steel shaft. Corrosion is the most likely cause of the pro jamming on the shaft. Repeated heat cycles and spraying Penetrating oil on any part of the shaft you can get at is the solution. WD40 is a water dispersant with very poor lubricating properties.
THIS IS NOT RECOMMENDED FOR PLASTIC PROPS.
Jim@sea
Well-Known Member
Jim@sea
Well-Known Member
Warm it up with a heat gun then stick bottom end in a bucket of paraffin for a week then give it a smack with a rubber hammer.
(years ago you could buy Penetrating Oil which was just paraffin with a bit of graphite in)
(years ago you could buy Penetrating Oil which was just paraffin with a bit of graphite in)
RichardS
N/A
Surely we're still buying penetrating oil now? I use Plus Gas but there are many other brands.
Richard
Caraway
Well-Known Member
Just as a thought. Too late now, but if you had been really stuck. Could you have removed the gearbox from the leg and then undone the two bolts behind the prop and withdrawn the prop/bearing holder/propshaft to give good access to the prop/shaft interface?
Slightly different motor as this has the impellor above the gearbox.
Slightly different motor as this has the impellor above the gearbox.
VicS
Well-Known Member
No
Not with the one you illustrate nor with a DT2.2
The propshaft is integral with the gear which is behind the pinion which you cannot release until you are able to access and remove the clip on the bottom of the driveshaft and pull that probably.
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179580
Well-Known Member
You need to read the report on the Doxford crankshaft repair on the MV Eastern Rover. This happened back in 1968 so not new tech. 4000 litres of liquid nitrogen to restore crank alignment!
Adios
...
One key thing about successfully using heat is needing to get the heat into the heated part as quickly as possible and whack it before the shaft has had a chance to take heat and also expand. Might have been worth trying putting the engine prop facing down and dunking the whole prop in a pan of boiling water, rather than pouring from kettles
RichardS
N/A
Maybe that repair needed contraction rather than expansion. I use the freezer for bearings and bushings but I could use liquid nitrogen if I had any so it's not really proof of anything.
Richard
C08
Well-Known Member
My understanding is that the expansion co-efficient of aluminium is much more than the steel shaft so the prop will loosen on the steel shaft with heat. On a small outboard with a shear pin that should work but not a bigger engine where the prop has a rubber/metal bush where the heat could soften the rubber.