[Supras] Coolant and rad (Bob)

[Jim Jobe]

It's entirely possible that the waterpump could be the problem.
The blades could have rusted away, simple enough.  It could be the
cap - it could be letting air back in if it's not sealing properly or
not allowing pressure to build in the system.

Water Wetter has given me nothing but problems, similar symptoms
in fact AND seeps out everywhere.

The best way to test a t-stat is in a pot of water on a stove to
see exactly when it starts to open.  Use a thermometer to ensure the
t-stat is opening at the proper temp.  It should be 50% or greater
(mine are usually nearly 100% open) by the temp stamped on the outer
ring.  I would also suggest using a standard OE temp t-stat (88C) as
that is what the EFI program is designed for.  Yes there are different
temp t-stats available but that will only mask your problem and cause
other problems.

You have to remember that the temp sender for the gauge is in the
top of the t-stat housing.  Any amount of air will collect there and
cause the gauge to spike.  Any amount of air in the cooling system
will cause these symptoms, be it a pinhole leak in a hose, a bad cap,
incorrect mixture of coolant (thus too low of boiling point), or a
user pulling the overflow hose out of the bottle.

I recommend filling the cooling system with the decent mixture of
coolant and distilled water.  Squeeze the upper hose a few times
to get out any large air bubbles.  Then clean and fill the overflow
bottle to within 1" to the top.  Then heat cycle it (ie drive it).
It will burp out a lot of air and likely spike the gauge as the
t-stat opens.  I will then let it coast and eventually pull over
to refill the overflow ONLY, taking care not to expose the end
of the hose.  Sometimes it will take 2-3 times.  After this I
LEAVE IT ALONE and monitor the coolant level from the outside
of the bottle (see above about cleaning it).  It should
eventually settle in to the marked cold and hot levels.

The let it idle uphill with the rad cap off while holding
one butt cheek crap never worked for me - the 7M always
boils over without pressure.  Plus it's much easier to just drive
it and let it cycle the air out itself.

On Wed, Aug 08, 2007 at 01:43:24PM +0000, jason estell wrote:
> Maybe I didnt pay enough attention with all the bickering, you did say the 
> temperature was going to red correct.  In this case it is not an issue with 
> the cap, well could be but this will cause bubling without overheating,  
> unless too much coolant leaves the system.  I will assume also that the fan 
> and clutch assy is also working ok, also a side note the clutch has a stall 
> rpm which it will only be able to acheive whithout going any faster.  
> Typicaly 4200 to 5400 rpm.  Need to know what % of what you are running.  
> Water wetter and coolant actualy have little cooling properties.  They just 
> raise the boiling and freezing points.  You can get thermostats from 160 to 
> 210 for these cars aftermarket, and I have had no problems with any of the 
> temps and i have used them all in my supras.  As far as running no 
> thermostat you will be running too cool which means running rich in return. 
> Water pump is also not culprit, they dont go out like that they just leak.  
> (exception a 72 impala i worked on impeller blades eaten away from 
> corrosion.  On the radiator though, u replaced, was it at least a dual core 
> radiator, they do sell single core rads for these cars and i have see that 
> that will overheat a car at loads.  Advanced timming will make overheat 
> under loads.  Note: thermostat temperature ie 162 deg is the temp the 
> thermostat starts to open not when it is fully open.  Bhg will cause 
> oveheating and it dosent matter what mileage you have on gasket mine blew 
> completly in 180 miles.  To test a thermostat fill a cup with water and put 
> it in microwave till temp gets high place thermostat in cup and watch to 
> see if it opens should be smooth motion.  Water wetter is a good thing to 
> have btw will lower head temps average 10 degs, but will not stop 
> overheating.  Also check boost level, overboosting?  Also if your radiator 
> in reman in may not flow enough if they didnt clean the cores will enough.  
> So allice how far does the rabbit hole really go.  Message me and ill see 
> if i can help more through im instead of tag.      Also for all who read 
> this and read of the auto computer in a manual mine is a converted manual 
> and am still running the a/t comp,  you need to jumper the neutal safety 
> swith to clutch switch or constant, and you also need to hook up the 
> reverse lights to the trans by running a hot to it.  I dont know of the 
> auto comp in manual car.  My auto trans comp ran these and i took it out to 
> make engine light go away. Hope this is helpfull.
> 
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