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Guest Message by DevFuse

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How to avoid air in system when changing the coolant temp sensor?

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3 replies to this topic

#1 Impreza_WRX_STi


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Posted 06 October 2003 - 09:31 PM

I plan on installing a coolant temp sensor, soon. I want to avoid getting air into the system while changing it. Is there any trickery or simple guidelines to follow?

Any knowledge or thoughts will probably help.


#2 cookie


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Posted 06 October 2003 - 10:57 PM

Wouldn't hurt to bleed it later on one of these pancakes.
I used to clean the area with ether after wire brushing and prep the sender I was going to change. By prep I mean if I was going to put a line of tape or sealer on it so it would be ready to go. Many of the new ones come with a sealer on them.
why did I use ether to clean? In the old days when you started Greyhound busses you had to do it from the rear with ether.
I noticed the area where you used the ether was always clean and since then it has been in my toolbox.
Make sure you have a socket ready for both the sender you are removing and the replacement. They are not always the same size due to production changes.
Remember to have enough of the sender thread exposed to give you a good ground and swtch em.

#3 MorganM


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Posted 07 October 2003 - 04:24 PM

The temp sensor in the intake manifold is one of the highest points of the coolant system. You will have to drain very little from the coolant system to swap it out with out a big mess.

My trick to bleeding the coolant system is this:

Take it slow. Be patient in letting it settle down, then add more, settle, add... Use the lower radiator hose like a hand pump. You can force out air and suck in coolant with it. Once she gets almost full you squeeze it in, pour in a bit of coolant, then let it out and watch it suck all that in. Repeat this untill it simply will not burp out any more air or suck in any more coolant. Make sure the overflow is properly filled and you shoudl be good to go. There should be a bleed valve on top of the radiator also that you can use to get the final little bit of air out. This method has worked very well for me. Ive never had to use the bleeder screws to bleed the system doing it this way.

HOpe it makes sense and helps :)

#4 lmdew



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Posted 08 October 2003 - 07:04 AM

Install a coolant flush tee in the heater hose and then fill with the cap off. This speeds the filling process and lets the air out. Finish up the fill as the manual recommends.

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