# Engine starts hard when hot.



## keiko (Aug 14, 2006)

Started my 67 after many years yesterday and it cranked over very easy then when the engine warmed up it was very difficult to start.Battery is brand new and super duty 1000 amps, Thanks for any help


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## geeteeohguy (Feb 2, 2008)

Possible: high resistance in starter windings, high resistance in battery cables, overly advanced timing due to sticking centrifugal weights caused by gummed up distributor shaft. (Very common on cars that have sat awhile!)


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## PontiacJim (Dec 29, 2012)

keiko said:


> Started my 67 after many years yesterday and it cranked over very easy then when the engine warmed up it was very difficult to start.Battery is brand new and super duty 1000 amps, Thanks for any help


Carb might be dried out from setting so long and needs a good rebuild - new gaskets, accelerator pump, needle & seat. You could have gas dripping into the intake and this would also cause a hard start problem - kinda like flooding the engine.


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## Anderslober (Mar 15, 2018)

Heat soaking of starter........a known Pontiac problem.....my 78 TA does this.......just let it cool down for 20-30 minutes....then it starts fine again.


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## keiko (Aug 14, 2006)

could this be a problem due to the timing be to far advanced ? if so which way would I turn the distributor to retard it ? Thanks


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## Lemans guy (Oct 14, 2014)

Pontiac distributors turn CCW........you turn against rotation to advance and with rotation to retard.....

But I doubt it is timing as timing does not change between a cold and hot start,...unless a condition like GTO guy said with sticking weights.

Rather your car started fine cold,....that means the choke and fast idle cam were able to give it a rich enough mixture so it fired right up...

But all those systems are not supposed to be in play on a hot start,.....so Like PJ said a gummed up carb, idle mixture set a bit too lean....

Also make sure the choke and fast idle cam release, because if they are stuck....the mixture will be too rich when hot and the car will not start because it is flooded,. Will smoke and idle rough if they stay engaged..

Could also be electrical resistance that does not occur until hot....

To begin with use some carb cleaner on that carb, for a quick clean, You still should rebuild it after 10 years. Look under the distributor cap and check weights and springs, a spring could be off,...and get fresh gasoline.

Leave that timing alone for the moment, it started,....investigate some other places or you will get hung up,....you can check it with a timing light.....to see where it is without moving it.>:nerd:0


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## geeteeohguy (Feb 2, 2008)

You can rule out the sticking distributor weights in 2 minutes next time it acts up. Simply pull the dist cap and see if you can manually turn the rotor. If you can, it was stuck in the mechanical position due to a gummed up distributor shaft. Very common. If this is NOT the issue, at least you've eliminated it. From your description, it is a slow cranking when hot issue, correct? NOT a crank and crank and crank, but no start issue?


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## keiko (Aug 14, 2006)

geeteeohguy said:


> You can rule out the sticking distributor weights in 2 minutes next time it acts up. Simply pull the dist cap and see if you can manually turn the rotor. If you can, it was stuck in the mechanical position due to a gummed up distributor shaft. Very common. If this is NOT the issue, at least you've eliminated it. From your description, it is a slow cranking when hot issue, correct? NOT a crank and crank and crank, but no start issue?


 Nope not a starting issue, Spins like hell when cold but when I turn it off and immediately try to re start it when hot it bogs down, almost like there is to much compression to let the pistons spin (I know this is not the case but trying to explain what it does)


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## gmjunkie (Jan 1, 2019)

Do you have headers on the car? I experienced this on my 70 skylark after I installed headers. The starter got too hot and acted like the compression was super high. Buy a heat wrap and wrap the starter. Should take care of the problem.


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## 1968gto421 (Mar 28, 2014)

There are many threads on this forum dealing with this problem. I used the google custom search in the upper right corner of the screen. Anyway here is an example of thigs I found. Check this link out:

https://www.gtoforum.com/f50/69-gto-wont-start-when-hot-107754/

Best of luck resolving this!


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## keiko (Aug 14, 2006)

thank you


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## keiko (Aug 14, 2006)

You know maybe it is the choke. Here is a picture of mine, is there supposed to be something that goes or connects where the rubber tube is. This is how it came back from the carb shop a number of years ago.


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## geeteeohguy (Feb 2, 2008)

Yep. Your heat tube is missing. Supposed to be a tube from the intake manifold to the choke to heat up the choke spring and open the choke. The vendors should have them. A five minute fix.


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## geeteeohguy (Feb 2, 2008)

You have a '65 Tripower intake on your '67....the hole for the choke tube is hidden in the pic by your strange fuel line!!


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## pcguy (Jul 7, 2014)

I cured this same problem with my SBC in my 75 Vega. It was the contacts in the solenoid; took it apart and cleaned/filed the mating surfaces. At the same time I added an external relay that took the load to start the solenoid off the key switch; ie now when the key is turned, the relay activates and it activates the solenoid.

Never an issue after that...


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## Lemans guy (Oct 14, 2014)

Yes and ditch that clear plastic tube if hooked to the hot exhaust crossover it will melt. Use rubber.

Another track is to add an electric choke very easy set up 1 wire to key on power....

Either way with no choke, and you have no choke set up like this the car will be a hard start cold....


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## 71 Lemans Sport (12 mo ago)

Hi Guys, 

I was looking for answers on what I think might be the same problem and came across this thread. Trying to see if someone can tell me what I am experiencing so I can get it fixed.

I have a 1971 Lemans Sport with a 350 with an Edebrock manifold and 4 barrel edelbrock carb. A month ago my starter was making a winding noise not engaging the flywheel right and I fixed the problem by installing a shim. After installing the shim the winding noise went away and it actually cranked as it should, two pumps on the gas pedal and it would start on the first try, could drive it to the store and while hot would crank perfectly and start up on the first try.

Fast forward to this week. I converted my clutch fan and stock shroud and installed a duel electric fan setup and while running the relay sender to the manifold I think I might have bumped something which was disconnected which I don't know about, also to add I swapped out the negative battery cable with a new one and grounded to the same bolt as previous one on the engine block.

I took the wife out for a beer to test out the new electric fans and car cranked normal and started on first try, however when we arrived at the brewery realized it was closed so when I went to start the car up again heard a whinning noise and it took about three tries for the car to start and I had to give it a couple pumps on the pedal. I know the starter is engaging the flywheel because the car starts just doesn't crank normally once hot now for some reason.

Hoping someone can help me out.

Thank you!


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## Lemans guy (Oct 14, 2014)

Starter solenoids often fail “intermittently” they whine, and spin free. But then they can catch and the car will start as normal. It can be exacerbated by heat, like after a drive. As heat causes electrical resistance.

It sounds like you need a new starter solenoid. Depending on what starter you have some can be removed and replaced and some are integral with the starter and they are changed together.

If you shimmed it you should be able to change it. Disconnect the battery first so it is not hot, two long bolts hold it on and take it out. Get it rebuilt, or buy a rebuilt one, or buy a new version of one depending on what you prefer.


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## 71 Lemans Sport (12 mo ago)

@Lemans guy, thanks for the advice and I’m going to replace the starter this weekend. I’ll let you guys know if that fixes the hit start problem.
Thank you!


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## PontiacJim (Dec 29, 2012)

71 Lemans Sport said:


> @Lemans guy, thanks for the advice and I’m going to replace the starter this weekend. I’ll let you guys know if that fixes the hit start problem.
> Thank you!


You also said you replaced the ground battery cable. Often, the parts store replacement cables are of a much thinner gauge. I was in a store recently and they had a larger selection of the thinner 4 Ga., and just a few of the better 2 Ga.. In reality, 1/0 Ga would be better. The larger gauge has less resistance which is very important as when the engine/compartment gets hot, heat creates added resistance and the engine cranks hard. But when cold, you may have no issues starting the engine.

Make sure you have all your grounds, engine to frame and engine to firewall.

So look into this as well.


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## 71 Lemans Sport (12 mo ago)

@PontiacJim thanks Pontiac Jim! I will also look into the gauge size of my negative cable. I’m planning on taking the car out Sunday if it’s nice out so I’ll test multiple cold and hit starts to see what feedback I get and will let you guys know.

thank you!


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