Replace thermostat?

Dough

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Hi, I've noticed that my car takes a long time to warm up these days, I drive ~32 km (20 miles) a day to work, let the car warm up for a minute or two before i start moving. I park in a garage overnight, on the colder days, roughly -10 degrees celcius (sorry don't know that in Fahrenheit) or lower, the car doesn't warm up by the time i get to work, its barely moved from where it is when it is off.

The car is a stock 99 dx, no mods. I read/heard someone saying replacing the thermostat would help the car warm up. Is this true? Is there a write up on this? How much would the parts be?

Any other suggestions?
 

Civic2007

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yup......sounds like your thermostat is stuck open
 


xxsenceo89x

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follow the upper radiator hose from the radiator. take off the hose on the motor side and take a look. dont try to take it off the radiator side or the radiator might break.
 

JohnS.

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The part runs about $20-$30 (USD) inc. tax. The job takes less than 30 minutes to do. I changed mine last week. My car used to take more than 30 minutes to warm up in this freezing weather. Now it only takes 7 minutes to fully warm up :thumbs up.

I wrote a quick How-To. No pictures are necessary. It's straight forward.
http://projectjaydem.com/forum/viewtopic.php?t=472
 


Dough

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thanks for the help thus far, i got a few more noob questions:

should i be worried about air bubbles in the cooling system after?
where would i top off coolant mixture? rad or overflow bottle?
how easy is it to have leaks? I am worried i will mess up something when putting it all back
lastly, i dont need to get under the car at all except put something to catch the coolant that drips out... right?
 

JohnS.

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thanks for the help thus far, i got a few more noob questions:

should i be worried about air bubbles in the cooling system after?
where would i top off coolant mixture? rad or overflow bottle?
how easy is it to have leaks? I am worried i will mess up something when putting it all back
lastly, i dont need to get under the car at all except put something to catch the coolant that drips out... right?
No need to worry about air bubbles if you're just changing the t-stat.

Top off coolant in radiator cap.

You can't mess anything up when changing the t-stat unless you take a hammer or sledge hammer to something. It's separate from the radiator. If you do, I highly suggest not working on your car anymore.

Correct.
 

Civic2007

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there should be a bleeder screw somewhere near the thermostat.....im not positive on that but i know for a fact there is one on 94-95 tegs so you should have one......when you refill use 50/50......if you find a bleeder screw then have the engine running and turn your heater on then loosen the screw until all the air is out and tighten it back up....
 

Billy.

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so far the coldest ive cranked my motor on was about 3*C. from there it takes about 15-20minutes to reach 85*C. during warmer weather it goes from like 15*C to 88*C in about 15minutes flat. are you properly warming up in the morning? you should let it idle for a few minutes before you hit the road

when i replaced my tstat and radiator it was as simple as filling up the reservoir, then the radiator, and cranking up the motor with the heat fully on. no bleeding required :what:
 

Civic2007

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i recommend bleeding it.....the air bubbles can put cracks in your block....better safe than sorry
 

Dough

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i usually let it up warm up until idle rpm slows to the ~750 rpm nromal rpm... it idles higher when its cold.


Usual morning routine is:
Turn on, wait ~20 seconds, back out onto driveway using reverse, put back in park, get out sort the garbage or w/e in the garage (bad to leave idling car in garage, pushes CO2 into the house), close the garage and sit in the civic for a bit, if it doesnt begin to idle at 750 rpm, i drive softly to the main roads, and sometimes it doesnt even warm up enough to drop to the 750 rpm idle, when i stop at the lights i put it in neutral to let it spin freely... other days i drive normal as it warms up.

Its ridiculous tho, I drive ~45 minutes on a busy highway and the car still doesnt get to ideal operating temp (middle of temp guage), usually fluctuates below 1/4....

I gotta try doing the thermostat thing, but worried about the bleeding thing now :s
 

Billy.

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i actually think the bleeding thing depends on which motor and year you have. i couldnt find a bleed screw anywhere when i changed out my tstat. the tstat itself actually have a little hole on the rim of the housing with a screw like plug inside of it. im thinking the thermostat itself automatically bled air out of the system. other tstats that ive looked at were lacking that hole

the screw that says BLEED BOLT was non existent on my thermo housing :what:


 
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Dough

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my d16y7 doesnt have the bleeder bolt according to the service manual or by visual inspection.... i gotta do this still, only problem is i dont have any of the parts and tomorrow is sunday ... d'oh!
 

Dough

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I finally did this, getting at those bolts is a b***h when you have a cheapo socket set and ratchet! I got it done in about an 1 hour. opening and closing the housing is where i spent most of my time!

I took some pics of the old thermostat, one of the rubber seals is torn up. Here's some pics





Now i just gotta monitor my coolant levels, I didn't flush the entire system as it was done a few months ago. I filled up the reservoir to the max mark and let the engine run for 15-20 min, drove to a store nearby and back, let it run, checked the level, it was still where I had filled it up to. I warmed up the car 9 hours later (warms up alot quicker ~10 min and it was almost at half on the gauge, its -4*C or 24*F outside) checked the coolant levels and it had gone down a bit, so i topped back up to the full mark. Now i just gotta monitor it for a few days.

Thanks for the help guys!
 
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matt9112

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hey would my thermo be the problem if my car has no heat? never had heat?
ive emoved the Ac but i would like the heat
 

Dough

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I got a few more questions:

Anyway to bleed or get rid of all the air bubbles without a complete flush? The air bubble thought scares me :S

How warm should the lower radiator hose get? The upper rad hose is quite warm, not burning hot though, i could hold it comfortably. But the lower feels very cool. It is -2*C or 28*F outside today.
 


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