Starter Doesn't Want to Engage When Engine is Hot

[cleithau]

I have a 1985 F-250, 6.9, C-6, and it will start fine when cold but if I shut it off after it has warmed up or with any of the electrical accesoires on the starter grinds on the flexplate. The flexplates teeth are not reat but it seems like part of the problem is in the starter. It is a new unit from Napa. I changed it hoping it was just a bad starter when I bought it but it didn't solve the problem. Is it possible the wire going from the soleniod (on the fender) isn't sending enough voltage to the solenio on the starter? I'm hoping its just not getting enough voltage. Or has anyone else had this problem with aftermarket starters?

 

[icanfixall]

Usually the flexplate ring gear wears out in one of three places. Check the gear closely all the way around. You will probably find some teeth really worn. These motors start and stop on one of three places on the gear. Thats why they grind. Sometimes the gear can be heated up and removed and clocked back on the flexplate where there in nice new teeth to engage to. I did this once but that lasted some 5 years till I ended up replacing the gear and flexplate. Do you have the heavy cast iron flywheel and flexplate como setup or just the lite pressed flexplate setup?

 

[cleithau]

How do I tell which flywheel or flex plate type I have?

 

[icanfixall]

To find out what flexplate you have just remove the inspection cover and look in. The single flexplate will be just that. The other heavy cast iron flexplate combo will be easy to see. It almost looks like a standard clutch type flywheel setup.

 

[Mr_Roboto]

Since it is affected by having electrical accessories on, it would appear that it is primarily an electrical problem. The flex plate is probably buggered from grinding, not vice-versa.

First thing I would change out the fender solenoid. They are fairly inexpensive, under $20.

The power from the fender solenoid is what makes the starter mounted solenoid close. The starter mounted solenoid sends current to the motor itself, on most starters it is also what forces the bendix gear out to engage the flywheel gears.

 

[cleithau]

The soleniod on the fender is new as of a year ago, as is the starter. Really the only thing left is the wire from the battery to the fenderwell solenoid, and from the fenderwell solenoid to the starter. Unless it is possible the wire from the ignition which engages the fenderwell solenoid doesn't always fully engage it. Before I put a new flywheel and here it grind I want to eliminate all other possibilities. Has anyone out there had any problems with the Napa starter motors? Just wondering cuz I got a bad one from CarQuest for a Toyota years back, ground on the flywheel when it was really cold (below 0). But I am wondering if it isn't possible there are some cheap starters and after they get hot from sitting by the exhaust, the bushings expand and don't allow the to fully engage? Does anyones have a heat shield on the starter?

Are Powermaster starters good? From Summit Racing?

 

[greythorn3]

mine does that randomly cold or hot.. with a NEW starter and RINGEAR on the flywheel.. 84 6.9 i installed in my 75 crew cab ford.. its so random it drive me up the wall.. i think i will try changing the solinoid like was suggested and see if that works.

Ray

 

[greythorn3]

I would also like ot say im running dual yellow top optimas.. i dont know if anyones though if it could be a battery problem.. but then why would it be random.. ive also though maybe it could be a grounding issue.. i think i will put a large ground wire from the battery to the starter bolt also to see if this solves it..

Ray

 

[cleithau]

I just changed the wire from the fender mounted soleniod to the starter soleniod, originally a 10 gauge, to a 4 gauge, and replaced the wire that splits in two and goes from the positive terminal, to the glow plug relay, to the starter relay with 4 gauge as well. Hopefully that helps, if not Im going to add the negative from the battery to the starter bolt soon.

I'll let ya know if it works. Let me know of the ground helps?

Does your truck do it more hot or cold? Mine hardly ever does it cold, almost always hot. Does it make a difference if there are electrical accesories on?

I have the Mitsu starter. Where did you buy and what kind of starter do you have?

 

[greythorn3]

doesnt matter if hot or cold on mine.. mine is the direct drive starter not the gear reduction one.. but ive had it do it on both types.

Ray

 

[ihdieselman]

I had this problem with my 84 I replaced the auto with a manual and new ring gear and never had anymore trouble. I highly recommend this,
big improvement!

 

[greythorn3]

I had this problem with my 84 I replaced the auto with a manual and new ring gear and never had anymore trouble. I highly recommend this,
big improvement!

mine does it on the AUTO and MANUAL trucks i have, and the manual has a brand new STARTER and RINGGEAR.

Ray

 

[greythorn3]

I think its chinese solinoids that are on the remanufacuted mexico starters.. seems tehy push the gear out at the wrong time.. or push it out spinning to early..

 

[GREASE FIRE]

i have had this problem on my 6.2 step van for about a year - started when the van was 20 years old. On those, the wire from the key switch goes right to the starter solenoid on the starter (unlike the fords which have an additional solenoid) so when the wire gets old, and the starter solenoid gets hot, there is not enough power to get the solenoid to fully engage due to resistence. At least i think that is the problem. I solved my problem by wiring it up like the fords, by adding another solenoid on the fender wall with heavy wire. I also have an auxillary starter button on the dash in case the key switch doesn't work since i have no idea where the problem is with the wire that goes from it, but somewhere it must be messed up. So i used brand new wire for the starter button and ran it to the new solenoid i added.

i have a feeling you solved the problem by replacing the thin wire with the thicker stuff.

Paul

 

[RLDSL]

Napa's rebuilt anything quit being any good a number of years ago when they lost track of who their main market was. When they quit catering to the professional mechanics and started worrying more about competing with the mc parts places for the DIYer market, their rebuilt stuff got just as lousy at the mc parts places, even worse when you consider the mc parts places usually give a longer warranty. Last few rebuilt starters and alternators I got from Napa , had one dead out of the box, a couple crap out under the very short warranty, the the others croak shortly after the warranty ran out.

It's got to where on starters and alternators, the only rebuilts ones I'll buy are the Bosch Reman units, they charge a fortune for them, but you get two years free towing with them if they conk out ( now That's standing behind a product ) They basically replace everything but the case.

For the price on rebuilt starters for these things, you can get a new import Denso and be done with it.

You're better off buying one of the new import starters or taking your old starter to a real rebuilder , if you still have one in the area. They are getting hard to find these days, luckily this is still considered a commercial engine, and there are a few shops that only do diesel electric rebuilding ( they won't fool with car stuff, just trucks and dozers and such ) and they will work on these things.

Do make sure the batt cables are in good shape. if there's too much resistance, it's not going to throw that starter drive in like it should.