Starter disengaging too soon

[ProjectManaia]

I recently ran into some starting issues with a Ford Sabre 250. The starter bearings were worn and replaces by a professional. After putting the starter back in (and replacing the battery) she had trouble starting and the starter disengaged too soon for the engine to fire up properly. After a few attempts the ran like a champ again and several attempts after war going great, firing up like a small car.
now, after 2 days on anchor I tried to start and the issue reappeared. After a few tries she fired up but before the starter simply disengaged too soon.
Would appreciate any ideas on troubleshooting the issue!
Thank you all already!!!

[skipperpete]

Thats quite possibly a voltage drop in the solenoid wire. By “disengaged” do you mean stopped cranking as though you’d released the key( or button) ….or is the starter still whining but not in mesh??

[ProjectManaia]

Hello SKipperPete,
thanks for the response first of all.
What I mean the starter is still turning but disengaged as in it stops turning the actual engine (just about a second before it would fire up) and retracts, so the Revs on the starter go up until releasing the start position of the key.

This morning it fired up perfectly again (which personally I find almost worse than the problem persisting)

So my next act would be to double check, actually triple check by now, all connections, clean them, reconnect, tighten and measure resistances...
but any other ideas would be welcome!

[skipperpete]

“Turning but disengaged” is a little more difficult to explain, it means that the solenoid is active and holding the contacts together so not voltage drop in the “activate solenoid “ cable. Maybe the overunning clutch is toast? Or the pinion yoke. Hopefully someone who’s had this problem before will supply an answer.

[Fuss]

it can be a few things…
the motor is old and down on compression
starter is taken by a large draw for unknown reasons
motor wiring is old and has a big resistance
anyway… the starter relay thinks the motor has started and disengages the starter…
i never try to diagnose this xxxx when i see this problem
i get the captain to run a wire direct to starter bypassing all relays and cabling so the starters can run on and on.
the motor then starts
hope this helps

[Bowdrie]

Starter motors us a "Bendix" drive, it's basically an "overrunning clutch".
I would check-out the mechanicals.

[Pete7]

Originally Posted by Bowdrie

Starter motors us a "Bendix" drive, it's basically an "overrunning clutch".
I would check-out the mechanicals.

Agreed, plus should be clean and dry, no oil etc. Take it out and have a good look.

Pete

[deblen]

First post-"starter bearings were worn & replaced..."


Perhaps the flywheel ring gear is worn or damaged.
Remove starter & look in hole while manually turning engine 360.
Cheers/Len

[flightlead404]

Originally Posted by Bowdrie

Starter motors us a "Bendix" drive, it's basically an "overrunning clutch".
I would check-out the mechanicals.

concur, this does not sound electrical to me.

I have had my share of starter problems.

What is the mechanism by which the pinion gear retracts from the ring gear, is it centrifugal?

Are you reaching starting revs but not firing or not firing quickly enough?

[ProjectManaia]

Originally Posted by Fuss

it can be a few things…
the motor is old and down on compression
starter is taken by a large draw for unknown reasons
motor wiring is old and has a big resistance
anyway… the starter relay thinks the motor has started and disengages the starter…
i never try to diagnose this xxxx when i see this problem
i get the captain to run a wire direct to starter bypassing all relays and cabling so the starters can run on and on.
the motor then starts
hope this helps

So with all the feedback my current (best) bet would be this:
The starter was serviced about a week ago, so all was greased and oiled etc. So maybe the little gear simply jumps back too easy. Our starter does not have the "switch solenoid" on the side, there is a solenoid connection on the main cylinder of the starter, so from the drawings I think the momentum of the turn of the starter motor is pushing the gear into place with a worm drive. So that the only reason for it to stop engaging really could be bad contact somewhere, so yesterday I cleaned all contacts nicely and recrimped everything that looked questionable. Since then 4 starts ran without any issues.... yet to be found out if it solved the problem for good though....
Thank you all for the feedback!

[Pete7]

The problem with grease and oil on the starter bendix is that it creates drag, the very last thing you need. Then over time dirt is added to the mix and the bendix won't slide quickly or fully to engage with the flywheel. Hence why they should always be clean and dry.

Peter

[Cheechako]

Not familiar with the Ford Sabre. Does that engine use a solenoid engaged gear by any chance? Aren't there some starters that the solenoid thrusts a lever engaging the gear to the flywheel? If so, I would say that solenoid is weak or bad electrical contact.

[deltaten]

New Bendix, older engine. Starter runs up, spins engine. Engine achieves enuff speed to unload the Bendix but not to start. Bendix/starter run on, not engaged 'till you lay off the key switch. Used to be common for older, pre electronic everything cars....click, r-r-r, wheeeee ��

[Bowdrie]

Originally Posted by Cheechako

Aren't there some starters that the solenoid thrusts a lever engaging the gear to the flywheel?

Yeah, I kinda like them myself, and they are still quite common on larger engines, but it seems that for newer/smaller applications they've gone the way of the Dodo bird.
You could manually engage them, they worked kind of like a clutch fork lever on a manual transmission.
The new ones just use a fast thread that pushes the pinion up the shaft with a spring to push it back when you release the key.

[CMH]

I have the identical situation with my 50 hp Yamaha outboard. Bendix engages the flywheel for only a second then disengages. Replaced the starter with a used one I found in LaPaz and still have same issue. Been putting up with it for a year now. Takes several tries to start when cold🤨