Stuart Turner P5M rebuild

Hi folks,

Next project is a Stuart p5M - currently with a seized piston, but everything seems to be there... apart from the magneto.
At some point in its life it has been fitted with a starter motor, a coil, presumably a battery, and a contacts set in the old magneto drive housing.
The mag drive now has a blanking plate over the refitted points.

Questions:
Can I refit a mag to this?
If so, what do I need? (Replace blanking plate, fit a drive shaft, fit an SR1 mag?)
Has anyone got them??

Presumably, if someone has fitted a coil and contacts set to their engine, they may have the old bits somewhere??

Some P5Ms (a lot of the later ones) came with battery/coil ignition as standard.

StuartTurnerSteve wrote:Some P5Ms (a lot of the later ones) came with battery/coil ignition as standard.

I believe I have a leaflet describing the coil ignition.

Might be worth a look here... https://www.facebook.com/pg/stuartturnerengines/posts/

I've probably got a copy of the manual somewhere, got Stuart stuff over 4 hard drives.

So - we managed to get the flywheel off before Tier 4, but the only movement on the crank is when it lifts the head off the block!
The piston is seized solid right at the top of its stroke!

We've done the rubber mallet thing, the block of wood and a heavy lump-hammer thing, and we're currently doing the rust-eating acid thing and giving it an occasional tweak with an inverted pulley-puller.
Steel plate now ordered to make a stronger rig over the top to give us a bit more push on the piston.

Any other suggestion gratefully received!

Some heat on the piston crown?

Alan

Hi Alan
yes I've seen various methods from welding torches to a petrol rag in the top of the bore.
We've been reluctant so far, as I assumed that the piston would expand too and wedge itself even harder??

Don't think I would use a welding torch! Although the idea is to heat (propane burner used with care) on the piston which expands and compresses the rust and upon cooling there is 'in theory' a gap which allows it to come out.

Alan

How big are the water inlet/outlet ports? If big enough, could you direct a gas torch in through those and heat the cylinder that way? I've done it that way on a Lister d when the piston is stuck part way in the cylinder!

I had a piston stuck in a hopper cooled Lister A, building a fire in the bore didnt work, so I smashed the top off the piston from inside the piston and with a hacksaw blade mounted in a handle I carefully cut the piston in half trying not to damage the bore, when I got the piston out I found the reason it was trapped, the rings had eaten there way into the bore and it was them that stopped the piston coming out, the barrel was also scrap because of the damage so a new barrel and piston was found.

Maryalice

So - we're still trying to get the piston out of the bore on the Stuart P5M, and I've drilled a 10mm steel plate to mount over the cylinder studs to take a threaded bolt and try to press it out - though temperature and covid restrictions at present are making it a low-priority activity!

We want to try to get into the crankcase through the front now - so flywheel is off... but how do we remove the tapered collet that sits behind the flywheel??
Sorry - I guess silly question for those of you who have done it before, but help needed for novices!

What is the piston made from, I would place a 10mm piece of plate on top of the piston so you dont poke a hole in it.

Maryalice

maryalice wrote:What is the piston made from, I would place a 10mm piece of plate on top of the piston so you dont poke a hole in it.

Maryalice

contoured block of oak already cut for the job!

Any tips on the crankshaft collet?

So - the old P5M project ground to a halt on the workbench while we played with some of our other engines. However, wife's away for a few days, so chance to get a box of bits out on the kitchen table to see what's there!

So, how did you free up the piston and remove crankshaft collect in the end?

Never managed to free up the other engine, I'm sorry to admit. We left that and got distracted by other engines and the one rally we've been able to visit this year.

This is a different box of bits from a P5ME - apparently all complete and ready for restoration. Bit I haven't really got a shed big enough and warm enough for winter renovations, nor the time really, and I discovered its the electric start version - so I think we're going to move this one on.

Happy New Year engine lovers!
So - we sold the box of bits to someone who is going to enjoy putting them all together.
The seized piston remains seized and tucked away out of sight and mind in the back shed.
Meanwhile...
we bought another P5M which is not seized, turns over nicely (once I'd soaked the starter chain and freed all the links) and has a good spark. However - it does not seem to be drawing fuel into the cylinder.
Any ideas??
I've had the carb off and thoroughly cleaned it, and I've sprayed a bit of fuel directly into the spark hole and got the thing to 'cough' a couple of times when I turned her over again. But nothing doing when I put a bowl full of fuel in the carb.
I've not connected up an actual fuel tank yet - but it doesn't need that head of petrol above it does it??

The jet on these has a tendency to put up all a lot of junk. On the bottom side of the carb, a nut with a flat head screw in the middle. unscrew the nut which is the jet, I normally blow them out with an airline or carb cleaner.
You air cap (screw in bit with holes) is wound all the way in. These were set would out about 1/4" from the factory, slight changes could be made for variations in fuel quality. People tend to try to use them as a choke but they don't work the same, the manual says hold a rag over the intake while trying to start.

hth,

Cheers, Steve

Thanks for the tips Steve.

I've now rigged up a little bottle and a line to keep the carb full of fuel, and with a bit of petrol or 'EasyStart' through the spark hole - I have managed to get it to cough and splutter for a half a dozen turns or so.  
But that could be just the residual fuel in the chamber.
It just doesn't seem to want to fire from the carburetor.
It may have tried once when I had a rag over the carb air intake - but it didn't last more than a 3 or 4 turns.

I've had the carb off and cleaned, and even replaced it with one from another box of bits. I've even had a sheet of paper against the open intake port on the crankcase so I can see the paper 'suck in' in when the piston draws air to the bottom. But it stubbornly refuses to fire!
(Dumb question - is it possible it's not transferring to the top of the cylinder for the compression stroke??)

The only other thing to note is that the engine is very hard to turn over when the spark plug is in.
With the spark plug out (i.e. when checking for a spark) it turns over freely.
But cranking against the compression and the impulse mag is giving me shoulders like Popeye!!

Any ideas?

If you put your thumb over the spark plug hole is there any suck on the down stroke? Crankcase compression could be a down. Have you tried a squirt of oil down the bore?
What is the mag like? main issue with poor starting/running of Stuart's in a past it's best magneto.
If it's an impulse mag would should be able to flick it over compression to start.

Hi Steve et al,

No further forward I’m afraid
Nice spark, and plenty of suck and blow when I put my thumb over the spark hole.

I was hoping to get it all going without too much intervention – but took the head off this week so I could check that (a) the transfer port was not blocked, and (b) the piston was in the right way around.
Both seem fine, and having taken the carb off, I tried a squirt of easy start through the intake port, which managed to produce a ‘cough’, but no more.
I also tried filling the removed carb bowl with water and blowing through to see if I could prove a spray out the other side!
Maybe it did – but who knows what’s going on in that chunk of brass??

I thought modern carbs with all their idle jets and bleed screws were complicated – but the Stuart is defeating me!
Any more thoughts would be gratefully received

Might Help...only other thing would be timing.
Out of interest what resistance are you getting on the magneto secondary windings?

Thanks Steve et al

this engine is sooo frustrating!
Head has been off to check transfer port clear. New gasket cut and fitted (leaving a hole for transfer!)
Carb taken off, inspected, cleaned, swapped, swapped back.
(I even filled the bowl with water and blew through the air intake to check it was pulling up fluid!)
1/2 ltr fuel bottle installed to ensure feed to carb. Clean fuel put in.
Compression seems good.
Spark seems good (5.5kohm across secondary coil, Steve)
Experimented with long and short length spark plugs (what's the recommended make/model??)
Timing set between 'spark' and TDC marks.

With much perseverance, and a squirt of 'EasyStart', I get an occasional kickback and a flooded carb.

What am I missing???!!!!
The only videos I've found online are either (a) rusty unfinished projects, or (b) working warm engines that fire up with a single flick over TDC!

Any more ideas guys?
(Or anyone want to buy a Stuart P5M??   )

Mark
(just back in from small cold shed smelling of petrol!)

Sadly there is not much else to try. They are a simple engine as long as they have fuel, compression and a spark they should go.

They should start with a flick over compression as the IIRC they are fitted with an impulse magneto. So the magneto trips at TDC for easier starting at slow speed thanks to the spring helping wind it up. It then self adjusts the timing to so many degrees before TDC. Trying to remember now but I think you set it for the points top open at TDC, been a while since I've done one. It's also easy to set the 120 degrees out so they fire at BDC.

My K was basically a 4 stoke P5 which has the same starting procedure.


If you want easy starting get a Stuart diesel