thermostat diag help

[10thAnnivCB7]

i think my thermostat is open ,, i have 5 minutes of warm up ,, does not matter what the temperature is ,, also when i step on the gas when it warms up my rpms shoot up 500 more which puts me at 1500 and depending on the temperature it goes down ,, if its cold it goes down slowly ,, if its hot it goes down fast ,, i dont put it into drive until it reponds quickly because the car just keeps pushing hard like it wants to go but i have to stop so i hold the brake a bit harder ,, any clue if it is the thermostat or what else can it be ,, any help would be appriciated

[oyajicool]

Make sure cooling system is filled with coolant mix and no air.

You can remove thermostat and perform functional test to see if it is closed when cold and opened when hot by cooking in a pot with thermometer.

[JDMDriver]

Just change it... not that expensive.

IMO a thermostat should be changed every timing belt.

Why? because contrary to popular belief (since they last so long) they dont last forever and do also break down.

However, when they do break down, they either break down by staying open or worse they break down by closing shut and this is serious.

My brothers CD accord's thermostat broke down in the closed position while on the road. It led to a blown radiator cap, overheating on the road and essentially limping to get home (risking warping the engine or cooking the valve seals etc).

In short as I said it should get changed and changed every long intervals (as much as the timing belt) but should be changed preemptively.

[10thAnnivCB7]

i did a coolant flush last week so i guess ill just replace it and see if the problem goes away ,, thanks ,, ill also do the test with hot water and a thermostat

[oyajicool]

If you were to do hot water test on old thermostat, I would say do that first before replacing it with new unit. The new one you just bought can be a handy spare if the existing unit fails.

New parts do not mean good working parts. Sometimes, you get a bad part right out of box.

If the existing thermo fails the test, you know this was possibly the cause of your issue.

If you change it to new without testing either one and the issue was still there, you would be thinking "it can not be the new thermostat,,, or is it?"

[oksleeper]

keep in mind if you buy a "fail safe" thermostat that it needs to be put in the water before heating or it may fail by testing

[oyajicool]

keep in mind if you buy a "fail safe" thermostat that it needs to be put in the water before heating or it may fail by testing

Since I have no idea what you are talking about here, can you explain it more in detail?

[userix]

Possible thermostat issue?

I have a related issue. Recently, my temperature would sometime rise to the 3/4 point during idle at a stop, but it never goes into the max red zone. I popped the hood while the car was still idling and notice that both fans are not spinning at all. I know the fans work fine, because they spin as soon as I turn on the A/C. But as soon as I turn off the A/C, both fans stop spinning even though the radiator is super hot. I searched and read some thermostat related posts and cannot find if the thermostat controls the fans turning off or on. I know there is a thermoswitch that is connected to the thermostat housing as well. In my case, is the thermostat the cuplrit?

Let's say the coolant level was low, the fans should still come on regardless? My coolant level is low, so shouldn't my fans be on a lot quicker, since the engine is heating up faster with a lower level of coolant?

Also, how do I use the bleed valve on the thermostat housing correctly? Thanks.