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Discussion Starter #1
So, before I changed my head gasket, the way it used to run was when you got in and started it, it would idle up to about 1200 to 1500 rpm and then come down to about 7 or 800 after warming up. After I got the head gasket changed and put back together, it idles up to about 1500 and stays there. Is something not functioning properly? And even odder is when I'm turning and got the clutch in moving down a gear as I'm slowing, it will idle up and down likes theres a vaccum leak. I've checked all my hoses and they are all on. I suppose I could have a puncture in one but I don't know how it could be from when I'm slowing down and turning cause it doesn't happen when the car is at a stop. So I decided to experiment with the distributor. I know there is advanced and retarded. If we are looking at the driver side of the engine facing the distributor, I am going to assume that having it turned as far clockwise is advanced. Thats just the position I've always had it. When I decided to move it counter clock wise all the way, it started up and ran right at 700 rpm without having to come down. However, the car was even more of a wimp than it already is so I will assume that is retarded. Why would that bring the rpm level down? And I also don't hear it idling while in turns with the clutch in. Should the distributor be centered? I was told advancing the timing once the car is hot, it won't start but like I said, the timing has always been advanced and started fine.
 

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Resident asshole
Corolla
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get a timing light before you start experimenting, going to either extreme is really alot of difference.
 

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Token Aussie
1998 AE102, 2018 ZRE182
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2,247 Posts
If the engine is going to a high idle and staying there (or constantly switching between high and low), then that usually means there's an air-bubble in the cooling system, which stuffs up the cold-idle valve in the throttle body and causes the idle speed to fluctuate. Bleed the cooling system and see if the idle settles down properly
 

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Discussion Starter #7
its a 91 corolla 1.6. 5 speed. 4age. how does one bleed the cooling system? I'm going to have to put antifreeze in it since there is only water at the moment and its getting cold again.
 

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Resident asshole
Corolla
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It should bleed itself.
To empty the block, theres a bolt next to the oil pressure sender you unscrew.
 

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Token Aussie
1998 AE102, 2018 ZRE182
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2,247 Posts
its a 91 corolla 1.6. 5 speed. 4age. how does one bleed the cooling system? I'm going to have to put antifreeze in it since there is only water at the moment and its getting cold again.
Easiest way to bleed the cooling system is to jack the front of the car up to make sure that the radiator cap is the highest point of the system (air bubbles naturally migrate to the highest point, which can easily be the throttle body cold-idle valve, causing the erratic idle), then run the engine with the radiator cap removed and the heater on hot (to open the heater tap fully). To speed up the process, you can tape an upside-down Coke bottle or the like to the radiator mouth with the bottom cut off, and add some coolant or water to the bottle - this adds hydraulic "head" to the system and will force the air bubbles out better (if you don't use the bottle, then the head difference between the throttle body and the radiator cap mightn't be enough to force the bubbles through).

You should only need to run the engine for a couple of minutes once it has warmed up to force the bubbles out - if the idle speed continues to be erratic afterwards then it most likely isn't an air-bubble problem.
 

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Discussion Starter #10
Easiest way to bleed the cooling system is to jack the front of the car up to make sure that the radiator cap is the highest point of the system (air bubbles naturally migrate to the highest point, which can easily be the throttle body cold-idle valve, causing the erratic idle), then run the engine with the radiator cap removed and the heater on hot (to open the heater tap fully). To speed up the process, you can tape an upside-down Coke bottle or the like to the radiator mouth with the bottom cut off, and add some coolant or water to the bottle - this adds hydraulic "head" to the system and will force the air bubbles out better (if you don't use the bottle, then the head difference between the throttle body and the radiator cap mightn't be enough to force the bubbles through).

You should only need to run the engine for a couple of minutes once it has warmed up to force the bubbles out - if the idle speed continues to be erratic afterwards then it most likely isn't an air-bubble problem.


How do you know when the air bubbles are out? Do I need to uscrew the little bleeder valve someone else mentioned?
 

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Token Aussie
1998 AE102, 2018 ZRE182
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2,247 Posts
How do you know when the air bubbles are out? Do I need to uscrew the little bleeder valve someone else mentioned?
You'll know when the air bubble comes out because, well, you'll get bubbles - they're fairly noticeable. And if the idle settles properly and stays there, then chances are you've got all the bubbles.
 

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Discussion Starter #12
Oh i get it now. We are trying to get the bubbles to the front to the radiator cap. How much water do these radiators in our little corollas hold? By December the temp around here will be down to single digits so I got to figure out the best mixture of antifreeze/water. Would 3 parts antifreeze and 1 part water be fine?
 

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1988 Corolla SR-5
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Easiest way is to buy the 50/50 mix. You just pour that in straight from the bottle, if it meets the temperature range for your region.
 

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Corolla
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heck, I live in Finland and I've never had problems with 50/50 mix and we get below -40C here
 

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Discussion Starter #15
I was told its better to get the stuff thats not already premixed cause your getting more, you just have to add water.
 

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I was told its better to get the stuff thats not already premixed cause your getting more, you just have to add water.
Sure, but with the 50/50 you are paying for the convinience of not having to measure it, and not needing a second container to store the extra that you mixed.
 

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Resident asshole
Corolla
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and considering the premixed one is from distilled water rather than tap water, its slightly better. Whatever you do, dont mix it with the distilled mineral water you get for drinking, because that contains minerals which will cause deposits to form in the water channels.
 
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