Damaged Thermostat?
 

Hi all,

Long time lurker, first time poster...I drive a 2017 MT Toyota 86

I was doing an oil change and everything seemed to be going fine, until I forgot to use a piece of timber between the front jack position of the car and the jack. It seemed as I was letting it down it slipped for the last bit and dropped maybe 10cm. I think when the jack slipped it went forward and might have damaged something...Stupid of me to not do the most important part right (securely jack the car)

The issue I'm experiencing now is that the thermostat seems to be broken.. I'm thinking maybe this is due to the force of falling that 10cm and possibly the jack slipping forward to the area the header plate is...

The reason I say thermostat is because the following things are occurring:

- Fans for radiator only switch on if I turn on the air conditioning

- when idling without the a/c on the coolant temperature creeps up (I read through this thread - https://www.ft86club.com/forums/showthread.php?t=76948) thus, idling, I let it climb all the way till 101C/214F before I turned on the a/c to cool it down) - the fans never cycled on/off

- Also upon normal start up I notice the coolant temperature takes long than usual to heat up. This to me is also indicating thermostat. As the valve should only open from 90C or something like that. But instead its "broken" open and the the coolant is constantly flowing and when I drive and the wind flows through the radiator (fans still not on) the engine coolant dips to around 88C (prior to this whole situation it would stay at 90C pretty solidly regardless of idling/driving -and then only after constantly shifting at redline on hot days, it would climb to a max of 92C/198F meanwhile the oil would be at 109C/228F) The service manual details how the thermostat should restrict flow till 86 to 90°C (187 to 194°F) then cycle fans once it reads at 95°C (203°F)

Attachment 184714

- the "idiot proof" radiator gauge shows the progres of the coolant getting warmer as I start-up and drive, so this tells me the coolant sensor is working (also I'm getting an accurate reading in TorquePro)

I use 5w30 oil cause Australia is hot af. All the temperature readings came off Torque Pro app

Being a newb to all this I'm just wondering if it is possible I have missed something and it is not infact the thermostat?

Do you have any pictures of the part(s) of the car that you believe were damaged?


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Welcome to the forum, malkduds - :clap:

:slap: that's for not being careful jacking up your car.

I have a feeling that the operating temperature of your car is within "operational limits".

I wouldn't worry about unless the car overheats.

However, if you would feel better, just change the thermostat, they aren't very expensive.

Back in the day if we suspected a weak or bad thermostat, we would take it out, put it in a pan of water on the stove along with a candy thermometer, turn up the heat to see if and at what temperature it would open.


I hope you get it sorted out.


humfrz

Did that more than once.

Thanks for all your recommendations.

I drove up on some ramps today and took some snaps of the undercarriage. It seems I was being somewhat of a hypochondriac...Anyway here are the snaps (looks fine to me apart from all the driveway scraping - :bonk:)

Attachment 184910
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I've been been looking into the electronics more (since the official coolant is so expensive). I've checked the two fuses for the cooling fans. They both operate under a/c and the fuses were also intact.

I've been reading up some articles on what causes the fans to cycle on/off

https://www.subaruofpueblo.com/07-03...er-driving.htm
https://www.alldrivesubaroo.com.au/e...ooling-system/

Both these sites mention a thermostatic switch, so I guess I'll look into that if the dealership denies my warranty claim

So I've had a read in the service manual. I think I might have found my issue. It is in fact the temperature sensor...

Attachment 184914

The bottom warm up test fits my description perfectly..

Have you had any luck resolving this? There are a lot of pieces to the "fans coming on when engine hot" puzzle, as well as logical steps to accurately diagnose the issue.

If you haven't figured it out yet, and want to be able to repair/maintain your car on your own, investing in a infrared temperature gun is instrumental to determining the current operating state of your cooling system. The coolant temp sensors are only in so many locations (if there are multiple), and reading the "live data" even then is only as reliable as the temp senders themselves.

Sorry to be so late to reply on this..

In the end I let the coolant temps creep up.. now it reaches 101C/214F then the fans turn on, and it comes down. Once I saw it go to 96C/205F then go back down, but every other time so far it is 101C/214F and then it will go back down till 88C/190F. This is several mornings, AC off and oil at ~100C/212F (after revving it out when traffic breaks up), idling in traffic on an average day (26C/79F)

So fans probably are kicking in at 96C/205F but some sensor is reading 101C/214F? Or maybe I need to use a more thorough tool to check the engine coolant, like a temperature gun as mentioned above.

All my coolant readings were with the BAFX OBII bluetooth adaptor and torque pro

It seems fine to me, never goes past 101C/214F and it drives fine :thumbsup:

Another "cold case" resolved by the ever helpful "mechanics"..

It sounds like you might be ok. I tried looking up when the fans are supposed to turn on but didn't see anything. Maybe more digging would help. My main thought with the temp gun was it would enable you to determine if your thermostat is stuck open or opening too early. Otherwise all you can do is feel the hoses. That and let you know if there are major discrepancies between coolant outlet temp and the coolant temp reading by the ECU.

Glad to hear it hasn't been acting up.

Did you fix your problem?

Yeah no such problem, like others have alluded to, the gauge for coolant is a rough estimate of a safe range (even though the needle might not move).

It can go up to 110C before fans kick in and it goes back to 92C (or something there of) - which you can see if you check OB2 readings.

Haha silly me :bonk:

Thread title: "Damaged thermostat"
Thread contents: "Jack slipped while doing an oil change"
Pictures: no damage

Yeah nothing to see here.