View Full Version : Coolant trouble

12-04-2004, 04:31 AM
ST185. every 6 weeks or so, the coolant is nearly dry and i get air popping through the system when i switch the engine off , i dont have any leaks, the coolant isnt bleeding into the engine, it just gets damn hot, 1200-1400 degrees F kinda hot if i'm to believe the manual, i get steam popping out of the overflow regularly. Logic tells me it's to be expected running 1 bar constant and evaporation will happen, just keep topping up, but concern says 'hey, lets see ehat the boys have to say'

So, this morning it took 2 litres of coolant, i ran it most of the day then it took 2 more litres. imagine its full now and all air pockets have bled out. i upped the coolant mix so its roughly 60 water 40 coolant.

comments please guys.

12-04-2004, 07:01 AM
have you rpessure tested your radiator and radiator cap?

12-04-2004, 10:53 AM
Any temperature fluxation on that stationary piece of crap gauge? Stay right below half like it should?

It does sound like your system is not holding pressure like it should, which does lead me to think your cap, or radiator isnt functioning properly.

Your sure you dont have a head gasket issue?

david in germany
12-04-2004, 11:22 AM
have you checked for coolant in the oil, is it blowing smoke?
maby a head gasket leaking coolant into the cylindes and burning it out. is there oil in the coolant after short trips?
I'll keep my fingers crossed that it isn't.

12-04-2004, 03:28 PM
doesnt sound good, cuz im thinking head gasket too. we just had the same symptoms on our subaru, and it was caused by the headgasket.

12-04-2004, 04:06 PM
ugh head gasket change on flat 4, ive done that

sounds like:

faulty thermostat
bad radiator cap
small leak somewhere

go over your cooling system good and also see if your plugs look wet , like if theres water or sumthing on them, ive had the smae problem twice

1st time bad radiator cap
2nd time leaking headgasket

12-04-2004, 06:33 PM
Nope, the radiator pressure is OK, has a new radiator cap, 1.4mm metal HG was fitted 6 months ago when a 57kmile engine was transplanted, it had the arp studs at the same time, not blowing smoke, temp gauge rises as should to halfway and stays there.

But AHA, guess what i noticed this morning, radiator fan wasnt turning when it should have been. Need to test the circuit/fan and associated sensors. could be just a fuse, the connector may have simply fallen loose.

So no worries, glad its a simple thing to fathom rather than a overhaul.

thanks again guys. just talking it through focuses the mind.

12-04-2004, 11:33 PM
what was the turn out?

you don't have a cylinder leakage tester, do you?

12-05-2004, 12:31 AM
that will do it

for now just unplug the fan temp sensor

fan will run consantly

thats how mine has been for awhile

12-05-2004, 09:40 PM
went to Stirling in Scotland for a meet with the Scots crew today, a 300 mile round trip, she didnt flutter at all. still havent fixed the fan, its getting VV cold in blitey, will be fixed next week though..

12-06-2004, 12:43 AM
well did u do the temporary fix like i sugested

its a lil white plug on the thermostat housing or on the bottom of the radiator

unplug it and the fan will run

12-06-2004, 01:00 AM
will do mate, tommorow, its early evening for you but it's 1am for me in blitey, I aint going out there at the moment with frost all over the car.. Brrrrr.

12-06-2004, 01:01 AM
hmm, you gave me an idea, could i wire a switch to it and choose when i want to run the fan from the cockpit?

12-06-2004, 02:48 AM
hmm, you gave me an idea, could i wire a switch to it and choose when i want to run the fan from the cockpit?

Yes, I did that on my 75 celica, now I just have it on all the time.

12-06-2004, 03:38 AM
Heh, yeah, certainly one way to do it, my engine lid fans are run that way.

12-06-2004, 04:39 AM
I've seen some swapped Celicas that use a switch for the fan, as well. There always seems to be an issue wiring them up correctly.

12-06-2004, 08:55 AM
one of the boys from aus is looking at wiring up a switch.. ill try to talk him into doing a how to. for a 184, but will be the same.

12-06-2004, 06:16 PM
i had mine as as witch for awhile but i ended up just unplugging the fan sensor (not the temp sensor, thats the green plug) this way when i turn the car on, fan is on, when i turn the car off, fan is off

12-06-2004, 08:29 PM
So, if i just unplug the sensor, and the fan constantly runs, this should increase performance? yay or nay.

12-06-2004, 08:46 PM
I can't see it improving performance at all. It will just keep you running a bit cooler (not always better!) The additional load on the alternator actually causes a loss of power (although minimal) and the fan running all the time will decrease the life of the fan.

12-06-2004, 09:28 PM
I thought about fan motor load and alternator having to be driven more, but i got confused between cold intake and colder engine cooling.. lol..

i think i may just create a switch for when in heavy traffic and stationary, but a constantfan during the hot summer days would be an edvantage.

12-07-2004, 03:12 PM
so now it's running constant, i take it i need a new fan sensor?

12-07-2004, 08:02 PM
relay went bad

wait what did u do?

mine would just randomly go on and off then one day didnt come on

relay went bad

im not really worried about the fan dying due to i have 5 of em

12-07-2004, 09:48 PM
no dude, i mean i disconected it, so now it runs constant.. lol

si i guess i need a new relay sensor thingymebob

12-07-2004, 09:54 PM
yeah new relay...that should fix it

12-09-2004, 05:59 AM
ummmmmm.... if you disconnected the fan thermal switch at the radiator (by the lower radiator hose) and the fan constantly runs then you need a new thermal switch, not a relay. If the relay was bad it would not operate constantly while the ignition was turned on. That thermal switch is usually about $80.

12-09-2004, 06:54 AM
sorry i was told relay but that makes sense

see why ive been running consatant fan

most money im gonna spend on this car in the next month or 2 is to get a good tps and a new o2 sensor

07-10-2005, 07:59 PM
thought I'd update this thread as Ive just done a Yahoo search for 'coolant thermostat st185' and this thread cam up :D

so... I ran until late Feb this year without a fan relay.

then, late Feb - I fitted fan relay and knock sensor and drove about 200 mile round trip, the day included 10 drag runs... temps at least 17 degrees C.

I had carried out a coolant change to toyota for life when the fan relay was put in, on the way home on the freeway, I overheated... heater on hot - pulled over, opened hood and let idle for 2 mins, listening and watching... swithc off engine on side of free way and waited 10 minutes.

opened rad cap with rag and topped up slowly with spare water only...from my etsimates, the tank took about 50% water with the remaining 50% toyota red coolant... it had simply evaporated out of the overflow, and the relay fan was, again, fried.

When the coolant was changed initially, it was definately vented and topped up accordingly.

I suspect the rad fan relay got fried again with high charge temps at 1 bar on stock ATAIC and CT26.

Car has ran fine since - havent had to add a drop of coolant, no overheating at all. rad fan is still disconnected.

I've looked in chiltons but can't find any thermostatic valve info...

I believe a combination of air pockets and charge temps fried the first fan relay, it fries soon after I purhcased the car, whilst the car was running very poorly and had been messed with.

I believe that incorrect coolant to water mix and high charge temps failed the second relay.

still open to suggestions for other causes.... but I believe its just boosting outside of thermal efficiency and air pocket/incorrect mix...

unless you have any other ideas?


07-10-2005, 09:40 PM
Have you replaced the fan switch yet?
It's the sensor you unplugged. And most likely the reason the fan won't run.

engine/coolant/charge temps should have no effect on the fan relay. If it's the relay, something [electrical] is frying it. Have you checked to see if the connections are tight?

07-10-2005, 11:12 PM
yup, I changed it and it lasted 1 day, stopped working - on the day in question, temps must have been around 15 degrees celcius outside ambient temps, i was travelling at a steady 80-90 mph on the freeway - lots of airflow.

mbc left at 1 bar. no creep, spikes or overboost...

less than 1/4 mile form home - on freeway - I realised I was boiling coolant as I saw steam escaping by the head light - then saw the temp gauge rise.

stock ATA - stock ct26 with mbc at 12 psi. 3.25" aussie DP - stock manifold and wastegate, 2.75" full new style st185 mongoose with flexi...

does anyone think I may be suffering too little head flow at any point? making heat spots?

anyhow - i believe that temp of coolant re-entering the rad (right where the relay is) is cooking the sensors ... (shrug)

or I have an electrical fault.

any info on thermostatic valve?