'51 Pontiac flathead 8 starter won't spin fast enough

[Andy J]

New 6v battery that has been tested and it's fine,2/0 positive cable,woven copper negative cable,starter has been rebuilt,so I'm at my wit's end with this thing. The woven copper cable is 7/8" wide and 1/8" thick and gets hot to the touch after about 15 seconds of cranking.

 

I put 2 different cables on and tried it again...same results. Tried jumping it with 12v from my truck...same results. Everything has been thoroughly cleaned,negative cable bolted to the block and positive cable directly to the solenoid. I am thinking a new starter is in my future.The engine has been completely rebuilt and has been started and run several times.The starter just isn't doing the job,even with 12 volts.Any suggestions or advice will be greatly appreciated.I have never had this problem before and I'm getting pissed about this.

[dl456]

Andy,

You need to check the amp draw of the starter.

If within specs, It is most definitely a bad ground circuit.

Dennis

[Oldtech]

If the ground cable is getting hot and it is the ONLY cable getting hot, it has a problem.  That said, It's likely the starter has some issue. Rebuilders can miss things.  As Dennis said, an amp test would be very interesting.

[dodge28]

A good test is to remove the spark plugs and crank the engine. If it is a rebuilt engine , it may be a little tight. Otherwise recheck the starter for faults. It is also possible that the grounding spots needs cleaning. 

[marcapra]

It could also be a bad starter solenoid.  

[john hess]

if starter was rebuilt, one or more of the brushes may be sticking also...

rebuilt and spun on a bench is different than under load...

[john hess]

4 hours ago, marcapra said:

It could also be a bad starter solenoid.  

if starter was just rebuilt, ...solenoid may be positioned wrong.. there are 4 slotted holes on solenoid base... may need adjustment... yep, been there...

[NailheadBob]

If recent rebuild on engine and starter motor, and has only been started 2 or 3 times and has this condition, possibly engine is tight from all new internal engine parts causing extra drag on engine and needs to be driven to break it in.

 

Bob

[Andy J]

Alright,I've cleaned the new cables and new battery posts again. I've cleaned the block where the negative cable is connected. I loosened the solenoid and slid it back a little,it wouldn't engage the ring gear so I put it back where it was. I've had trouble with that before. I had the new 850 CCA battery checked again and it is reading 1020 amps with a load. The negative cable is still getting hot,indicating excessive amp draw. I don't have any way to check this until I can borrow or rent a meter to check it.

 

I hit the starter with a hammer,no change. That has worked for me in the past. As NailheadBob suggested,maybe the engine is just tight because it was just rebuilt and hasn't been ran more than about 15 minutes.

 

I really appreciate everyone's responses and suggestions,but I believe a new starter is the solution,If I can find one. I've got to get the car driving because the upholstery man said I'm about 2 weeks out.

Edited July 27, 2023 by Andy J
spelling (see edit history)

[dl456]

Andy,

Starter amp draw reading will answer most questions.

Something often overlooked however: since the engine and starter have been rebuilt, has the paint been removed from the attaching surfaces. 
I still think you have a ground issue.

Dennis

[dodge28]

No need to buy a new  starter. I see on UTUBE how restorers take starters apart to to bone and rebuild them like brand new .The generator for my 28 DB was restored .  Everything rewound.  Check with Jason @ AER ,866 228 o218, 517 345 7272.  It will not hurt to get professional advice. 

[EmTee]

If the ground cable is hotter than the positive one then the ground cable is bad.

[Andy J]

This morning I cleaned everything again.I also cleaned the mounting surfaces of the bell housing and starter by sanding them shiny until they looked like new money.Put it all back together.....same thing.It may have gained a couple of rpm's,but still not fast enough to start the engine. As stated before,the negative cable is woven with the ends molded onto the terminals. It's brand new,no corrosion,so I just don't believe that it is bad. I still haven't found a meter to check the amp draw from the starter.

 

I believe tearing the starter down is my next move. I'll probably wait until tomorrow morning because it is so hot in my shop that it is almost unbearable.I worked all my life outside in the heat and in the sun for 46 years and got more than my share of heat. I don't have to do that now,so I ain't.

 

I'll report back when I figure this out.

[EmTee]

16 hours ago, Andy J said:

I still haven't found a meter to check the amp draw from the starter.

Use a volt meter to measure the voltage drop across the negative cable while cranking before you take anything apart.

[PONTIAC1953]

your battery cables need to be either #2 or #0 gauge wire, I hope you're not using the smaller gauge 12 volt battery cables.

[Andy J]

EmTee,I just read that in the shop manual.Late this afternoon,when it cools off some,I'm going to do that.The manual says there should be no more than 1/10 of a volt drop.

 

PONTIAC1953,My cables are 2/0 so I'm covered there.

 

Thanks,everyone,for your help. I've been fooling with cars all my life,rigging up junk and half-assed pieces of crap,and I've never had a problem like this before.

[Andy J]

I braved the heat to conduct the tests. Three tests performed:negative battery post to starter body .23 volt drop;positive battery post to battery terminal on the solenoid .06 volt drop;across the big terminals on the solenoid .28 volt drop. So,2 of the 3 tests failed. Should have been no more than a drop of 1/0 volt drop. Surely this means the starter has crapped out,right? The battery reads 6.5 volts.

 

A new or rebuilt starter is in order to get this car to run. 

[Andy J]

Well,after trying to find a starter and talking to several old mechanics in my area,I have drawn a blank again. I took the starter back to the shop and told the man to go through the thing with a fine tooth comb and figure out what is wrong. This problem has got the whole project at a standstill. There's got to be a starter on this planet somewhere. If these folks can come up with parts for these 100-120 year old cars,especially makes that only a relatively few cars were made,certainly I'll hit paydirt some time.

[95Cardinal]

On 7/27/2023 at 3:26 PM, dodge28 said:

No need to buy a new  starter. I see on UTUBE how restorers take starters apart to to bone and rebuild them like brand new .The generator for my 28 DB was restored .  Everything rewound.  Check with Jason @ AER ,866 228 o218, 517 345 7272.  It will not hurt to get professional advice. 

 

@Andy J I agree; there's probably something wrong with the starter.

Jason IS great, but he's a long way from Mississippi and you would have to check with him to see if he could turn it around quickly enough to meet your 2 week window.

 

BUT, you still might have a bad ground cable and/or starter solenoid.

Negative battery post to starter body should have essentially 0 voltage drop. 0.23 volts indicates there is a problem in the ground connection and/or cable.

Same with the drop across the solenoid.

 

All the ideas above make sense; tight, new engine, potentially bad solenoid, internal starter issues creating excessive current draw.

If you can't check the current draw when cranking, try pulling all the spark plugs and measure the torque required to turn over the engine by hand.

In my experience, 30 to 45 lb.ft. of torque should turn over the rotating assembly.

If it takes much more than that, the engine might be too tight.

[R Walling]

 If my ground cable was getting hot, I would make up a ground cable that is extremely too large and attach it directly to the bolt that holds the starter on. If it still gets hot or doesn't do any good, I definitely suspect the starter or a tight engine.

 

What are the five things that could cause a starter motor to have high current draw? Shorted Armature, grounded Armature, bent Armature, shorted field Armature, worn bushings.

 

 

[JACK M]

3 hours ago, R Walling said:

 If my ground cable was getting hot, I would make up a ground cable that is extremely too large

You could use half of a set of jumper cables for this, you keep saying that the ground strap gets hot, that tells me that it won't carry the current efficiently. (Should be bigger)

[EmTee]

If there's an issue with the starter internally (e.g., a 'short'), then both the positive and negative cables - and possibly the starter itself should be getting hot.

[Andy J]

R Walling,an extra ground was one of the first things I tried.

 

EmTee,the starter does get hot. The positive cable is a 2/0 and doesn't even get warm. As I stated before,the negative cable is a new woven strap,plenty heavy enough for the job. The engine has been run several times before the starter crapped out on me.

 

I took the starter back to the man yesterday to check all these things,shorts in the field coils,armature,brushes,bushings and anything else that might be faulty. He said,"I'll have to take it apart." So that tells me when I took it to him before,all he did was put a new starter drive and solenoid on it. I told him to do whatever it takes to fix it,just do it! Maybe I'll get results this time.

 

I wish that I didn't have to depend on anyone to work on my stuff. I don't know how to do some things,but I'm going to learn how.

[Andy J]

The latest on my starter dilemma.The man said he found the problem.When he put the new solenoid on,one of the bolts he used was too long and it screwed into the field coil,causing a short. He put a shorter bolt in it to fix the problem. He admitted that it was his fault,no charge,and that it should work just fine.I put it back on,tried it,no difference whatsoever. I've been bummed out ever since.

 

After another search,I found this shop in Texas,gave them a call,and talked to the man there.I told him exactly what it was doing and he said I'll guarantee you the armature has a short in it. I gave him the part number and he said "that starter is for a 6 cylinder car. It has two field coils where the one you need has four coils and has 30% more cranking power.I can fix you up in a couple of weeks." I told him to get on it and I'll be waiting for your call. So,that's where I am today.Hopefully this will get me going.

Edited August 13, 2023 by Andy J
spelling (see edit history)

[EmTee]

54 minutes ago, Andy J said:

I gave him the part number and he said "that starter is for a 6 cylinder car. It has two field coils where the one you need has four coils and has 30% more cranking power.

Now your battery, cables and connections will get a real workout! 

[Oldtech]

GM used to do that. The chevy cars had 2 poles. Trucks had 4. It was popular to put the 4 pole on the car that had to start in the winter. They had noticeably more crank. I still have one for a 50 Chev. 

You needed a new starter guy. A shorted armature is very easy to check with a growler. If he cant at least do that he can't fix much. If he ran a bolt into a field ( I don't know how he would do that, it could damage the coil internally.  Your Texas guy sounds a lot more hopeful.

Edited August 14, 2023 by Oldtech (see edit history)