Hard start when hot
Thread Starter
Teching In
Joined: Dec 2003
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From: chicagoland
Hard start when hot There have been times after some spirited driving my Ls1 doesn't want to start. It turns over very slow. After 10-15 minutes of cool down it will start. The engine is cammed, Texas Speed CNC'd heads, and Kooks headers. Any thoughts? Is the starter getting too hot near the headers?
There have been times after some spirited driving my Ls1 doesn't want to start. It turns over very slow. After 10-15 minutes of cool down it will start. The engine is cammed, Texas Speed CNC'd heads, and Kooks headers. Any thoughts? Is the starter getting too hot near the headers?
Thread Starter
Teching In
Joined: Dec 2003
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From: chicagoland
Thanks. While the Formula is 15 years old it only has 65K miles on it. I realize age can be a factor but usage shouldn't be. In your opinion is the starter weak and need replacement or could I get a heat shielding wrap to go around the starter?
Heat shield with headers is always a good idea. How old is the battery?
Thread Starter
Teching In
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From: chicagoland
It's actually 5-6 years old however it's always had plenty of cranking power. It's an Optima Red top. During the winter it's always on a trickle charger. Maybe it's time to replace the starter, the Red top and the get a heat shield for the new starter. With the stock compression ratio I'm thinking an OEM starter should be OK.
I'd try battery first. At that age, I would expect the battery to struggle a bit when very hot. Even new a battery will put out less power when either very cold or very hot. Worth checking/cleaning your grounds as well.
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It's actually 5-6 years old however it's always had plenty of cranking power. It's an Optima Red top. During the winter it's always on a trickle charger. Maybe it's time to replace the starter, the Red top and the get a heat shield for the new starter. With the stock compression ratio I'm thinking an OEM starter should be OK.
And when a starter gets hot from radiant heat off the headerers...they usually will not even spin at all till they cool off. The heat doesn't just make them weak...they disable them completely while they are hot.
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In my 20+ years of stock car racing experience, its the starter. We always have hard start, slow cranking conditions after a race due to the starter being hot and the amount of ignition advance we run. We replaced the weak starter with a good high torque unit and problem solved. Our cars get a new optima battery almost every year.
You can have the battery tested but they need to use a high load on it to duplicate a hot engine.
You can have the battery tested but they need to use a high load on it to duplicate a hot engine.
TECH Apprentice
Joined: Jan 2004
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Not to hijack the thread but my engine is still stock and my car is difficult to start usually in the summer months. This issue has been going on for the last few years. First two or even three start ups during the day will work. Third or fourth and it will either crank for a while and start up or I give up, wait a second or two, try again and it will start up fine.
I did suspect the battery but I had it tested when I let it die during my suspension overhaul. I suspect either the starter or fuel pump but am leaning more towards the starter since the fuel pumps sounds like it is priming fine during start up and operates fine when the car is running. Or is there something else I need to look at?
I did suspect the battery but I had it tested when I let it die during my suspension overhaul. I suspect either the starter or fuel pump but am leaning more towards the starter since the fuel pumps sounds like it is priming fine during start up and operates fine when the car is running. Or is there something else I need to look at?
I had this problem. Early on it was annoying but after a while I had to let the car sit there and cool off a lot to be able to start it. Replaced the starter (PITA with headers) and issue went away completely.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
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From: So.Cal.
Not to hijack the thread but my engine is still stock and my car is difficult to start usually in the summer months. This issue has been going on for the last few years. First two or even three start ups during the day will work. Third or fourth and it will either crank for a while and start up or I give up, wait a second or two, try again and it will start up fine.
I did suspect the battery but I had it tested when I let it die during my suspension overhaul. I suspect either the starter or fuel pump but am leaning more towards the starter since the fuel pumps sounds like it is priming fine during start up and operates fine when the car is running. Or is there something else I need to look at?
I did suspect the battery but I had it tested when I let it die during my suspension overhaul. I suspect either the starter or fuel pump but am leaning more towards the starter since the fuel pumps sounds like it is priming fine during start up and operates fine when the car is running. Or is there something else I need to look at?
There is a difference... the first one is what is happening to to op.