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Starter wonbt disengage 470 Mercruiser

boatleg

New member
"I am new to this site. Attemp

"I am new to this site. Attempted to go fishing yesterday, starter seems to be engaged and won't release. No problems starting each time, but I can hear the starter motor gear keep turning when she is running. NB: If I hit the key again I can hear the starter begin to operate but there is no grinding to suggest that it is trying to re-engage with the fly wheel. So I reckon that she is stuck in the engaged position. Giving it a good knock didn't budge it though.
Any suggestions would be much appreciated.
Thanks from Melbourne. Boatleg."
 
"If it disengages when the key

"If it disengages when the key is turned off your ignition switch may be bad. to verify this check with a volt meter or test light to see if you have voltage at the solenoid on the small wire after you release the key to the run position.

The starter converts electricity to mechanical energy in two stages. Turning on the ignition switch releases a small amount of power from the battery to the solenoid above the starter. This creates a magnetic field that pulls the solenoid plunger forward, forcing the attached shift yoke to move the starter drive so that its pinion gear meshes with the engine's crankshaft flywheel. When the plunger completes its travels, it strikes a contact that permits a greater amount of current to flow from the battery to the starter motor. The motor then spins the drive and turns the meshed gears to provide power to the crankshaft, which prepares each cylinder for ignition. "AFTER THE ENGINE STARTS, THE IGNITION KEY IS RELEASED TO BREAK THE STARTING CIRCUIT". The solenoid's magnetic field collapses and the return spring pulls the plunger back, automatically shutting off the starter motor and disengaging the starter drive. When the starter is not in use, the drive unit is retracted so that its pinion is disengaged from the flywheel. As soon as the starter is activated, the forward movement of the solenoid plunger causes the shift yoke to move the drive in the opposite direction and engage the pinion and flywheel. The pinion is locked to its shaft by a clutch that unlocks if the engine starts up and the flywheel begins turning the pinion faster than its normal speed. By allowing the pinion to spin freely for a moment, the clutch protects the motor from damage until the drive is retracted."
 
"Thanks Collin. At no point do

"Thanks Collin. At no point does it seem to disengage, even when the key is off. I am assuming that the starter will still activate from a stopped engine state, and restart the engine even if it has not retracted. So if the unit is still engaged then I may have a crook return spring? If I remove the starter will this be evident? Should I be looking at the clutch mechanism as well?
Thanks again for the advice."
 
"It's probably a bad start

"It's probably a bad starter if there is no current and it won't disengage. I got a good rebuilt starter with a warranty for my 97 4.3 v6 at S.E.A. Manufacturing in Debray, Fl. for 64.76 including shipping, no core charge (386) 668-1424."
 
"If the bendix on the starter

"If the bendix on the starter is keeping the gear engaged in the flywheel when the motor is running, that starter is going to eat itself really fast. The bearings in the starter are not meant to be run for any duration nor at engine speeds.

Pull the starter and test it on a bench. You'll see exactly what is happening then."
 
I thought the gear on the star

I thought the gear on the starter pops up when engaged and retracts when stopped. Could the pop up just need cleaning and lubrication?
 
"Seems a little odd it would b

"Seems a little odd it would be stuck in the extended position. The thing spends the majority of its life retracted... if it was going to get stuck, I'd think it would get stuck retracted.

Any chance it's miss-wired such that the solenoid is always getting power (ie. bypassing the ignition switch)?

Otherwise, pull the starter and take a look. Be careful of the shims, if it has any."
 
"Thanks for all the good advic

"Thanks for all the good advice. I haven't had a chance to pull the starter as yet. I am hoping that it may just need 'cleaning and lubrication' to get it running right, as there hasn't been any rewiring done and to date it has been working well. Shims?? Interesting. I'll keep an eye out.
I will post my findings. Thanks."
 
"Shims used to be between the

"Shims used to be between the block and the starter. Not as common anymore, but every so often you'll still find them. If the starter needs them and you leave them out, you'll hear it next time you turn the key. Terrible screaching sound. Not good for the starter gear or the flywheel teeth either."
 
"Well!! Attempted to remove th

"Well!! Attempted to remove the starter on the weekend. Neither nut wanted to budge, despite soaking for days before with CRC, however both bolts now turn freely. I'm guessing this could be a big problem, unless there are nuts behind the mounting surface???? I haven't had a chance to check that out as yet. So the starter is still in there!! Not Happy at all!
I could really do with some further advice on what to do next.
PS: I'd love to go fishin again this year?!?!?!}}
Regards Boatleg."
 
"I've never seen a starter

"I've never seen a starter mounted with through bolts and nuts. I don't have first hand knowledge of this particular engine though. Starters are typically mounted directly to the block with capscrews (or bolts) threading into tapped holes in the casting... you may have stripped the holes out or broke the bolts.
Rust sounds like a pretty big problem here. Find the source, if it's getting wet the next starter may face a similar fate.
If there is in fact no nuts on the back sides of the bolts (which I expect is the case), try pulling the bolts out using a pair of vise grips then give the starter a good couple of whacks with a hammer... it may be rusted to the block."
 
"STOP... don't take a hamm

"STOP... don't take a hammer to that aluminum block or you will not get on the water for a long time, the bolts are attached with two nuts on the back side, that is why it was so tight getting them loose, now they are all just spinning together, get a wrench on the back side and you will be in good shape, hope this helps, David"
 
"he didn't say wack the mo

"he didn't say wack the motor he said wack the starter which I wouldn't do with a regular hammer either. I would wack it lightly with big rubber mallet on put a piece of wood on the starter and wack the wood.

This shows you that a maunal would make a big difference. If you can't buy one, here in the states some of our local libraries have have them to borrow. I have manuals for all my motors and they are a huge help.
good luck"
 
"You know, I almost added some

"You know, I almost added some words to my above post like "using a soft face hammer" or "using a block of wood" but I really didn't think anyone would take a 5lb. sledge to their starter unless, as may be the case here, it argravated the individual enough to do so.

David does shed some light on the specifics of this engine though... which should do the trick, without the need for additional force."
 
"yeah i just wanted to get a l

"yeah i just wanted to get a little point across cause i have seen people hit the starter and the aluminum be soft or cracked cause it the only thing holding the massive force a starter puts out let alone it's weight and they hit it only to have a corner or ear break off and then no more starter mounting... these engine's are famous for being hard on the starter so it's got to be hard on the little aluminum area holding it... didn't mean to offend anyone or any other posts just wanted everyone to be careful about working on these older engines especially dealing with the aluminum block on these, hope you get it all apart and fix her up so you can get some fishing in this year
happy.gif
"
 
"No offense taken, David. I&#3

"No offense taken, David. I'm glad you piped up!
It's all about getting smarter."
 
"I am having a similar (if

"I am having a similar (if not the same) issue with my I/O 898 Mercruiser. When I turn the key to the 'on' position, the starting cranks intermittently. Turning the key to 'start' does nothing. I pulled the starter to find the top 1/8" of the starter gear (Delco Remy) worn off and the tops of the each tooth mushroomed. Most likely from the starter cranking when the engine was running (and the reason it wont' start anymore).

I bench tested the starter and it works fine. I'm going to get a new ignition switch this week and will post results.

Who I bought it from put in a new shifter but did not hook up the wiring (starter cut off, on/off switch). Could this be part of the problem?

Boatleg, is this the same issue you're seeing?

Thanks."
 
"Finally found the time and fr

"Finally found the time and frame of mind to remove the starter yesterday. It took a lot of leverage and 'persuasion' to dislodge it from the block. I would say it has not been off for some time (if at all). The boat is a 1987 build, with only now 260 hours running, so this is possible.
Anyway, I think that clearly I have a problem with the solenoid. Some internal surface rust on the 'plunger'(clear lack of libricant) due to time spent in the bilge. Not surprising that the gear was kept engaged on the flywheel. So I believe that I don't have an ignition problem.
Thanks to all for your help."
 
"Starter is back in. Always a

"Starter is back in. Always a little worried about the first turn of the key. Got lucky I guess. No Problems. Running like a dream again, 'til something else lets go.
Managed a rebuild from a neighbour(Mechanic) for a bottle of scotch.
Thanks again for the help all.
Back to fishing in style."
 
I have a 1986 Merc 470 that I

I have a 1986 Merc 470 that I replaced the carb and installed a breakerless ignition. Problem is when on a cold start I can crank the engine for about 3 to 5 seconds and as soon as I let of the key it will pop of and start running. I have experimented with hold they key longer and it won't start until I let off the key. When the engine is warm it starts imediatly. The engine has had a full tune up and runs great otherwise.

I was told by a local mechanic that there is a second positive voltage wire that goes from starter relay to the coil. This wire supplies a full 11 to 12 volts bypassing the resistance wire durring starts. To compensate for the high voltage drop to the coil on cold starts.

I was going to test by jumping a test lead form the positive on the battery to the positive on the coil to see if it starts up on first crank on a cold start.

Any ideas if this is a common issue or a good test?
 
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