trouble starting when hot

[nickjames138 15]

I've been trying fix this issue for a few months now. My car starts right up in the morning. I drive around town and make a few stops and my car gets harder and harder to start until it just won't start anymore. The starter tries to start, but it sounds TIRED! If I let it sit for 20 mins or so it cools down and starts up again. I never used to have this issue until I blew my intake gasket and got water in my block. I rebuilt the engine with a new comp cam and new distributor. Since having this problem I've gotten a new starter (didn't work). I wrapped the starter with a heat shield/blanket (still no luck). I replaced the factory alternator with a 150amp and big gauge charge wire. It runs like a beast it just doesn't want to start again once I turn it off after driving around town. I've even ran to the gas tank and opened the cover...no hissing/vapor lock. My next guess is to wrap the headers with a heat shield. The starter is very close to the headers...not much I can do about it.....OR IS THERE? 

[nickjames138 15]

The strange thing is that I never had this issue before the rebuild. I also want to check the coil. 

[1969_Mach1 333]

I guess you are talking about slow cranking when the engine is warm or hot.  If so, that problem has been around for decades on Fords, especially after headers are installed.  Heat shields will help once in a while.  Sometimes the positive cable to the starter is getting too hot if it's also near the header.

If all your cables and connections are good, I'd say you likely need a permanent magnet gear reduction starter (PMGR)  My headers are not very close to my starter on my 351W, but I tried 4 stock type starters in a couple of months.  Same issue as yours, cranked fine cold, but would crank very slow after running the engine for anything more than about 20 minutes.  I eventually spent the money on a PMGR starter from Powermaster.  Without changing anything else I have never had any more issues.

Before buying a new starter, again make certain your all your cables and connections are good.  The ground from the battery should go to the engine block.  Then another good ground from the block to the body of the car.  Probably in the end, you'll need a better starter.

[nickjames138 15]

3 minutes ago, 1969_Mach1 said:

I guess you are talking about slow cranking when the engine is warm or hot.  If so, that problem has been around for decades on Fords, especially after headers are installed.  Heat shields will help once in a while.  Sometimes the positive cable to the starter is getting too hot if it's also near the header.

If all your cables and connections are good, I'd say you likely need a permanent magnet gear reduction starter (PMGR)  My headers are not very close to my starter on my 351W, but I tried 4 stock type starters in a couple of months.  Same issue as yours, cranked fine cold, but would crank very slow after running the engine for anything more than about 20 minutes.  I eventually spent the money on a PMGR starter from Powermaster.  Without changing anything else I have never had any more issues.

Before buying a new starter, again make certain your all your cables and connections are good.  The ground from the battery should go to the engine block.  Probably in the end, you'll need a better starter.

This is the exact issue I'm having. I don't understand why it just started to happen, but I think just buying a new PMGR starter is best. So, just to clarify...this completely fixed your issue? 

[1969_Mach1 333]

Yes, on my car it completely fixed the issue.  What motor and trans do you have?  Sometimes you get a starter for a late model Mustang or F150, early to mid 1990's.  They are not as high torque as something from Powermaster.  But, they are a still a small permanent magnet gear reduction starter and will work fine unless you have a high compression ratio motor, 11:1 or higher.

I think what happens with the older style starters is they use electrical field windings attached to the case on inside that create the magnetic fields needed to rotate the armature (through Faraday's laws for magnetism).  When these electrical windings get hot, like with any electrical wire, at higher temps the resistance to electrical current flow increases.  Less current flow through the electrical field windings means a weaker magnetic field.  A weaker magnetic field means a slower turning starter.  Older GM starters had the same problem.  These problems stopped back in the late 1980's and early 1990's when car manufacturers replaced the electrical field windings with permanent magnets.  Also, starters that use permanent magnets are physically smaller so they are further away from heat sources.

[barnett468 418]

are you using the same carburetor?

where is the float level set on the carb?

what is your initial timing set at?

does your intake have a port from the exhaust to heat the intake?

for now as a quick and free test you can reduce the timing 3 - 4 degrees and try that.

 

the powermaster starters 69 mach mentioned are good but you need to wire the pmgr starters differently at the starter or the solenoid.

 

 

 

 

[1969_Mach1 333]

Some of the Powermaster starters are wired differently, not all.  The model I bought was their Mastertorque series and it didn't require any wiring changes.  I think their lower torque models, the Powermax series requires a small wiring change between the stock inner fender mounted solenoid and the starter.  It's a simple change and they come with instructions that are easy to follow. 

[nickjames138 15]

13 hours ago, barnett468 said:

are you using the same carburetor?

where is the float level set on the carb?

what is your initial timing set at?

does your intake have a port from the exhaust to heat the intake?

for now as a quick and free test you can reduce the timing 3 - 4 degrees and try that.

 

the powermaster starters 69 mach mentioned are good but you need to wire the pmgr starters differently at the starter or the solenoid.

 

 

 

 

Hey Barnett, I have a FiTech carb. Would the timing make it hard to start once it's hot but easy to start when it's cold? I'm still confused on how timing curves work. 

[nickjames138 15]

7 hours ago, 1969_Mach1 said:

Some of the Powermaster starters are wired differently, not all.  The model I bought was their Mastertorque series and it didn't require any wiring changes.  I think their lower torque models, the Powermax series requires a small wiring change between the stock inner fender mounted solenoid and the starter.  It's a simple change and they come with instructions that are easy to follow. 

Awesome! I'll definitely give this a try. Cant hurt at this point. What do you think the life expectancy of a power master is? Is it the same as a factory starter or do you think it's much longer since it's a more updated starter? 

[barnett468 418]

2 hours ago, nickjames138 said:

Hey Barnett, I have a FiTech carb. Would the timing make it hard to start once it's hot but easy to start when it's cold? I'm still confused on how timing curves work. 

Yes it can in some instances. Is that carb fuel injected?

[1969_Mach1 333]

3 hours ago, nickjames138 said:

Awesome! I'll definitely give this a try. Cant hurt at this point. What do you think the life expectancy of a power master is? Is it the same as a factory starter or do you think it's much longer since it's a more updated starter? 

I honestly don't know how long Powermaster starters will last.  They are made here in the USA if that helps you.  They look more robust and the quality looks much better than a stock starter.

Retarding the ignition timing like Barnett mentioned might be a work-around.  You'd might notice the motor doesn't rev up as quickly.

You mentioned you had an intake leak so rebuilt the motor then the problem started.  Typically a new or rebuilt motor will have more cylinder pressure which can contribute to slow cranking problems.

[nickjames138 15]

On 11/18/2018 at 12:10 PM, barnett468 said:

Yes it can in some instances. Is that carb fuel injected?

yes its a throttle body style fuel injection carb (Fitech). 

[aslanefe 333]

When it is hot and it turns slow, remove the wire from the coil to distributer, then see if starter turns faster.