Mazda Rotary Club

General => General Technical => Topic started by: od404 on November 30, 2007, 10:35:44 AM

Title: Over cooling?
Post by: od404 on November 30, 2007, 10:35:44 AM
Hi all,

Not sure if I\'m just being overly cautious, but here goes...


I\'ve owned my FD for just over a month now, and in the past few weeks I\'ve noticed some strange readings from the stock temp gauge.  Now it has always sat at just under 90deg once warm, but recenty I\'ve noticed that when driving steadily (say 60mph cruising on the motorway) off boost, the needle drops away and usually settles just about the second white mark (at the cold end of the gauge).

It started doing this when the weather got colder, but I\'m not entirely convinced that\'s the reason (or could it?).  The car has got a Billion Aluminium rad which may be helping keep temps down.


My current thinking is that it may be thermostat related, and I\'m going to try to get my hands on a Commander for my PFC (car never came with one) so I can see exactly what temps are being recorded.

Has anyone else experienced this in their FD?
Title: Over cooling?
Post by: nikp on November 30, 2007, 10:41:33 AM
Not seen this myself, but overcooling needs to be investigated. A Commander is a good idea as that will show the exact temps, and maybe an after market water temp gauge for the radiator. You will see slightly cooler temps this time of year, but it still shouldn\'t drop to below 80/81 when it is up to temperature.
Title: Over cooling?
Post by: RemarkLima on November 30, 2007, 11:00:11 AM
Sounds like the thermostat is stuck open TBH. Just means too much water will flow round the rad on cruise mode, where you\'ve got light load and good airflow.
Title: Over cooling?
Post by: od404 on November 30, 2007, 11:53:40 AM
Quote from: RemarkLimaSounds like the thermostat is stuck open TBH. Just means too much water will flow round the rad on cruise mode, where you\'ve got light load and good airflow.

Yeah that was my thinking too.  It doesn\'t take much to get it back up to where it should be though, just requires a bit more thought with regards driving style.
Title: Over cooling?
Post by: RemarkLima on November 30, 2007, 12:03:27 PM
Almost 100% thermostat stuck open if it goes to where it should be, especially once you\'ve slowed down.

Of course IMHO ;)
Title: Over cooling?
Post by: od404 on November 30, 2007, 12:36:27 PM
Yeah, park up and let it idle and it sits where it should.
Title: Over cooling?
Post by: neil_jdmr on November 30, 2007, 03:19:41 PM
Quote from: RemarkLimaAlmost 100% thermostat stuck open if it goes to where it should be, especially once you\'ve slowed down.
 
Of course IMHO ;)

Yes 100% agree with RemarkLima your thermostat is stuck open and more than likely new one required.
 
About £40 from mazda
Title: Over cooling?
Post by: Rzla on November 30, 2007, 03:20:44 PM
arent the stock temp gauges meant to be cr@p (cr@p) ?
Title: Over cooling?
Post by: SmbFD3S on November 30, 2007, 03:55:16 PM
Only because they aren\'t linear so if the needle sticks in the middle this can show anything from about 80 deg to 100 degrees thats all but it should remain slap bang in the centre nonetheless.... Agree with the other posts that it\'s gonna be a stuck open thermostat :Thumbs-up
Title: Over cooling?
Post by: arrouk on November 30, 2007, 04:50:00 PM
this time of year i NEVER see over 76-78\'C water temps unless i leave the car to idle for a while.

matt
Title: Over cooling?
Post by: SmbFD3S on November 30, 2007, 04:59:19 PM
Thats strange being as the standard thermostat dont actually open until until 83-84 degrees....
Title: Over cooling?
Post by: shaunwil on November 30, 2007, 05:54:08 PM
Are you sure it hasn\'t got the lower temp thermostat ??

Shaun
Title: Over cooling?
Post by: arrouk on November 30, 2007, 06:10:39 PM
no just a standard mazda.
just a thought but is the pickup for the pfc on the flow or return side of the rad?

matt
Title: Over cooling?
Post by: Jit on November 30, 2007, 06:54:24 PM
hmmm thats wierd...my first car had no thermostat in it when i removed the lump...the needle was always poiting to the same place.
Title: Over cooling?
Post by: Jono FD3 on December 01, 2007, 02:17:36 PM
My temp needle on the std gauge always sits in the middle.... but since I have had my power FC fitted the comander tells me that I am running 70 - 73c (with thte std gauge sitting in the usual position!!)

Going to check my thermostat now!!!

Jono
Title: Over cooling?
Post by: chrisJDM on December 01, 2007, 10:16:57 PM
the standard temp gauges are renowned for being crap, mine always just sits at half all the time once it had warmed up, thats if i am driving on a cold day or stuck in traffic on a hot day.  Dont trust it, ive heard stories where the gauge doesnt show that your temp is too high until it is too late.  Im much happier with the power fc commander, get a proper reading all the time which i can keep a eye on.