Slow to heat up, quick to cool down

Re: Slow to heat up, quick to cool down (just_ace)

Sat, 14 Sep 2013 14:43:53 GMT

Surely you've had a cooling system service in that time with new thermostat, rad cap etc? How many k's in 10yrs?

Re: Slow to heat up, quick to cool down (dylmrt)

Sat, 14 Sep 2013 12:05:20 GMT

Never changed it before Jay, so over 10 years!

Re: Slow to heat up, quick to cool down (cogs)

Sat, 14 Sep 2013 11:41:19 GMT

Are Tridon thermostats still garbage?? Back in the day, every one I fitted would cock over in the plunger making the plate misalign and get stuck cracked open leading to the exact symptom OP describes.

I found that Waxstat ones were as good as OEM though. They have a dished poppet plate that guides smoothly into the seat and never jam up.

Another plus with OEM is that the supplied gasket/rubber seal tends to be a LOT better quality.

Re: Slow to heat up, quick to cool down (MR2QIK)

Thu, 12 Sep 2013 19:45:13 GMT

You don't want a lower thermostat. Would drive like the car hasn't warmed up. I'm a tad suss about what's happening with yours & hope it is just the thermostat.

When's the last time it was changed?

Re: Slow to heat up, quick to cool down (just_ace)

Thu, 12 Sep 2013 19:39:44 GMT

But trd ones will run colder around 65deg no? Not what you want for street imho.

Re: Slow to heat up, quick to cool down (dylmrt)

Thu, 12 Sep 2013 18:48:05 GMT

might have to buy some TRD ones frmo japan to keep in stock after this lol.

Re: Slow to heat up, quick to cool down (Mrskylighter)

Thu, 12 Sep 2013 18:15:23 GMT

Make sure you put a genuine Toyota one in. The aftermarket ones are ****e and don't work well.

Re: Slow to heat up, quick to cool down (dylmrt)

Thu, 12 Sep 2013 17:56:06 GMT

Haven't tinkered with the Power FC no. It really only happened last night.

It's probably still more likely thremo stat related because if I sit at a traffic light, it will get to 84deg, but then if i start moving quickly it'll start to drop.

Re: Slow to heat up, quick to cool down (MR2QIK)

Thu, 12 Sep 2013 15:38:59 GMT

Last one. That does explain it then, as I was never on boost on those times it happened (Sydney traffic driving). I monitor my AFR's quite frequently & check over a few areas before every wash (vaccuum lines, grounds, oil, coolant etc) so it's not often I'm caught out these days.

Re: Slow to heat up, quick to cool down (just_ace)

Thu, 12 Sep 2013 13:54:22 GMT

Well, yeh on an NA or when mani is under vacum you'd run rich, and then go lean when on boost. more boost=leaner, more vacum= richer.

Q:did you have this problem with the current motor, or the last one mr2qik?

Re: Slow to heat up, quick to cool down (MR2QIK)

Thu, 12 Sep 2013 12:52:10 GMT

Yes if you're on it dangerous. But I've noticed in my case at least, when the situation's arisen, it runs rich at cruising speeds. Not what I had expected, but was a reality. Or maybe I'm mistaken about where the vaccuum line was, but it kept happening around that area. Naturally I changed the hoses so the problem has been eliminated.

Just a quick thing to look out for before throwing money at it.

Another thought actually, did you tinker with the Power FC recently Dylan? If you deactivated the o2 sensor, then it'll likely run rich due at cruise. Unless mapped correctly in those areas (but I don't see many tunes other than Luans that run correctly with the o2 deactivated.

Re: Slow to heat up, quick to cool down (just_ace)

Thu, 12 Sep 2013 12:04:56 GMT

MR2QIK
You car may also be running very rich. Do you have an AFR reading anywhere? Mine does that when I have a split vaccuum hose to the MAP sensor.

If the hose is split to the map sensor it would get a lower reading and the motor would run lean, dangerously on boost, and will lead to melted pistons

Re: Slow to heat up, quick to cool down (dylmrt)

Thu, 12 Sep 2013 11:45:50 GMT

It does run a tad rich. I'll check the hoses tonight and the get the thermo stat changed tomorrow.

Re: Slow to heat up, quick to cool down (MR2QIK)

Thu, 12 Sep 2013 10:53:57 GMT

You car may also be running very rich. Do you have an AFR reading anywhere?

Mine does that when I have a split vaccuum hose to the MAP sensor.

Re: Slow to heat up, quick to cool down (Mr2gtracer)

Thu, 12 Sep 2013 10:32:19 GMT

I'm thinking thermostat also