Still having hot start issues
 

Hi all, I have a 75 TA with a standard low comp 400 with headers only. I started having hot start issues a while back and have done the following:
-wrapped the headers near the starter
-put a metal heat shield over the headers
-wrapped the starter with a versa shield and then a metal heat shield over the top
-new 4g starter wire
-new optima yellow top 34 battery
-new battery terminals
-0g ground from battery to original ground point at top of hearder
-extra ground from battery to other side of motor

I spent all day today redoing the wiring for the battery and it still cranks like it's dead when it gets hot. After I let it sit for 2.5 hours or so it cranked and started perfectly.

I don't know how old the starter is, but it has been replaced at some point. I've checked the timing and that is fine. It doesn't run overly hot either. My only thoughts at this point are to move the ground somewhere else on the engine and/or a mini starter.

Is there anything else anyone can suggest? Thanks in advance.

Sounds like you've taken the right steps. Heat shield on a stock starter w headers did the trick on my old 70 GTO after cooking a few stock starters. Since originality isn't a concern I would try a ministarter. I've had great success with a Power master w heat shield on my 69.

Hook up a meter to the battery and see how many amps the starter is drawing during start up. (may want to disconnect power to distributor to avoid starting)

I think these starters should not draw more than 250 amps?? (can anyone confirm) If it does, your starter needs replacing.

Get the ground cable off the exhaust. The factory did it there, but that is a very poor place to do it as the connection will get worse over time. Maybe relocate to a hole in the front of the head, or one of the bolt bosses right under the valve cover rail. A good GM starter should have no issues what so ever turning over your engine.

Take a volt meter and when it is cranking slow, connect the neg lead of the voltmeter to the negative battery post, and the positive lead to the other end of the negative battery cable where it bolts to the block. Crank engine over and read the voltmeter. There should be no reading if the cable and connection are good. If it reads .3 volts or more, you have a ground issue. The higher the reading, the worse the connection. If you get a reading of 1 volt or more, that will cause a serious starting issue.

200-250 amps would be a normal reading, and the battery voltage should not drop below 10 volts during cranking.

Is it having trouble turning over, or turning over and not starting?

I had the "slow/not turning over when hot" issue with the factory starter. Mini-starter cured it.

Your solenoid is bad. Either replace it, or replace the whole starter. A mini starter would be a good choice if you replace the whole thing. I've replaced the solenoid several times when I had T/A's for daily drivers.

Does that 4 awg starter cable try to melt the insulation or replacement cable ends while cranking hot?

IMO 4 awg is budget part store junk. When it comes to cranking a hot Pontiac V8. Even on the low compression engine. IMO, 2 awg would be a minimum, at best, if the cable is short. Would prefere 1/0 (0) or 2/0 (00) for + & - ..

Takes a lot more amps to crank an engine that's hot than it does cold. Voltage drop from heat and cylinders ready to fire wont let the starter spin the engine fast enough to start. Acts like a dead battery when it's just not enough amps going to and from the starter.

Clay

Not enough information to diagnose but if all other items are good the armature could be swollen from heat cycles. Go to a mini, it will solve you start issue if it is the starter.

If the starter has worn bushings that allows the armature to drag on the winding shoes it will cause a hot start issue, as heat seems to multiply the issue, but will still work find when cold. Sometimes the reman starters today aren't much better or don't seem to last as long.

I usually rebuild them myself with a good quality kit and feel it's a better result than some of the reman stuff out there now.

I run a stock starter on my Pontiac that I rebuilt 20 years ago, and have had both headers and RA manifolds on the car with no heat shielding on anything at all.....drive the car all the time and never an issue, even with initial timing jacked up.

You've done everything else but the starter.....I'm betting it's worn inside and pulling too many amps.

Try this simple test.
With some drivers side headers you can get to the terminal / solenoid end of the starter between the header tubes with a long enough screw driver and place a short across the Crank terminal and the battery terminal.
In doing this when the motor is hot soaked and it Cranks then it's the solenoid, if it still does not Crank then the starter can not pull enough current thru the wire or ground to do its job.
Another simple test it to have someone watch your headlights when you go to Crank the motor when it's hot, if the headlights dim then the solenoid is working and you should be hearing the starter trying to crank the motor some.
If the head lights do not dim then once again the starter is current starved by wiring or grounding!
If you do the screw driver test be sure to not short it out to the header tubes or other things at ground potential.

FWIW, I went through all of this with my GP. I spent the money, put in a Powermaster XS Torque mini, and 20 years later haven't given it a second thought. Smaller, lighter, easier to handle, easier to wire, easier to install, and it cranks better, especially when hot (I live in Texas). For me, this is one of those "why didn't i do this sooner" things.

The problem with factory starters is its really hard to find a good one. They don't make new ones and the rebuilt ones are generally crap. IMI makes a good mini starter. Had great luck with them in street cars and race cars. Here in Phoenix Az it gets really hot in the summer and I have no problem with hot starts since going to a mini starter.

There are some companies out there now claiming to make all new OEM type starters for Pontiacs. I see them on Rock Auto anyway. Not sure if they are any better than rebuilt though.

Is the wire from your ignition switch to the solenoid the original one? I've had the same problem with several GTO's in the past, and the final fix, after trying EVERYTHING else, was to replace that wire. It degrades over time, and when hot, gets super high resistance. Am running stock GM starters in both GTO's, and they've been in there for decades with no issues. And it gets HOT where I live. It only took me about 20 years to figure out the problem with my '67, and after the wire replacement, no issues at all.

^^^^^^^
Probably this, it doesn't take too much wear on the bushings to drag the armature on the fields and as has been said they will crank fine when cold, and the armature will slow down with heat soak. Good way to tell is tear the starter down and see if there are witness marks on the armature where it's dragged on the fields.

I also rebuild my own starters, so I know what's in there and it's done properly. I've never used a mini starter on any of my cars race or street, but from what's been said on PY they seem to work fine.

Make sure you have the high torque GM starter because the low torque one will not crank any Pontiac engine well, no matter what compression it is. The high torque starter has the long screw with a copper tubing spacer between the solenoid and the field connection.

Other than making absolutely sure all your connections are clean so there is a minimum amount of resistance. You can't just look at the connection and think it's clean, you must disassemble them and clean them. They can look just fine until you take them apart.

I agree 4 G is pretty small wire for a Pontiac V8, probably at the edge of being too small of a gauge wire. The crappy cables sold at most parts stores may look new and shiny, but many times aren't nearly as good as OEM cables were.

GeeTeeohguy has a good theory also, the wire going down to energize the solenoid gets a lot of heat and people drop the starter and let it hang by those wires breaking strands inside of the insulation. If that wire is degraded it will also affect the starter when hot.

I had a nagging hot start issue for A while that turned out to be a bad ignition switch.

In terms of the 69 and up lower steering column mounted switches they fail far less then the earlier ones, but they can go out of adjustment on there slide mount and make for a no hot start issue!

First disconnect the battery.

Next Drop the column down so you can get at the rectangular switch on the top side .

Next loosen the two 5/16" headed machine screws that hold down the switch at each end.

Once you have the bolts looose enough to move it back and forth have another person turn the key to the Crank position and at this point you should move the switch as far up towards the steering wheel as if will go , then tighten down on those two 5/16" nuts and. You then have it adjusted right.

Yes, but it is a dry heat. ;)

Time to step up to a mini starter