Oh the woes undercooling (Page 1/1)
jon m DEC 13, 03:46 PM
Right after yesterdays antics coil and module change out the car starts and runs good except for one thing (he says hoping).

Undercooling - I think either the thermostat is stuck open or its O ring is leaking - when I drive the car the temp needle doesn't move when stopped for a while the needle starts to move up un till the fan kicks in at 190 ( have rodney's low temp switch fitted which I may swap out until the summer) when I start the car from cold after about 5 minutes the radiator cap at the starts to get warm so cooling is circulating.

I am bearing in mind that it is -2 degrees C here but the needle should still be in a good range
Took the spark plugs out and they are sooted up so running rich - which brings me to the conclusion of undercooling and to be honest the car has stood still for 5 and half years.
The Temp gauge is working as it should no pegging etc.

So with this in mind I plan to get a new thermostat (will try and look around my garage for an old one I may have in the meantime) and a new oem fan temp switch for this winter period.

I was looking at Rockauto at the Stant 195 thermostat could anyone recommend a fan temp switch ?

Also can anyone give me the Dorman part numbers for the 2 PCV grommets that fit in the valve covers.

Many thanks for any opinions

Jon

P/s Been a while since I was on here and its still a great forum with great people thanks for all the help much appreciated
Patrick DEC 13, 04:26 PM

quote
Originally posted by jon m:

the fan kicks in at 190 ( have rodney's low temp switch fitted which I may swap out until the summer)



The 190°F fan switch has little to no bearing on your engine's apparent slow warming up period. If it did, every time you moved forward, your engine would cool down (below optimal operating temps) from air being pushed through the radiator. My advice would be to just leave the fan switch alone. It's the thermostat that makes all the difference.
jon m DEC 13, 05:06 PM
Hi Patrick - Many thanks for your reply - I will concentrate on the thermostat and report back.
Thanks again
Jon
theogre DEC 13, 06:54 PM
Assume the Coolant System works 100% for now....

Idle vs driving means engine RPM changes often a lot.
That slows/speeds the Water pump affecting coolant flow.

Plus in winter the T-stant "slams" open and shut & w/ slow coolant flow can slug the engine w/ cold "water" and is not a problem but some people w/o a clue freaks out and vendors sell many "fixes" to take money.

Stant is gone see https://www.fiero.nl/forum/Forum2/HTML/146523.html
So very unlikely to find anything other then "factory spec" T-stant like Super stat covered in my Cave, Thermostat
Stant Super was made different to slow or stop the temp swings you see on temp gauges.

But 10 to 30+ years old vehicles the radiator has crap plugging it, Fiero & others w/ crush pipes, heater loop w/ problems and more and people putting bandages like low temp fan switch or worse rad fan is On all the time...

Some common coolant problems See my Cave, Heater, Crushed Pipe & rest of section.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

jon m DEC 14, 02:29 PM
Thanks TheOgre - As an update I took the T stat out and noticed the o ring was off and also the end of the spring within the T Stat wasn't sat fully with the base more in fresh air - So I twisted the spring around so it sat correctly and put another o ring on coated with Vaseline and re seated.

Again the car wouldnt start it was -1 so after a few turns of the crank there was a smell of petrol so I removed the plugs and waited about an hour and pottered about on returning I replaced the plugs and she fired back to life -I am thinking is this because she ran rich previous causing a flooding situation ?

Anyway as a positive the car was ticking over nicely (i did disconnect the battery beforehand so the ecm could learn fresh) and within 5 - 7 minuets the temp needle started to move.
I drove it for a few miles at different speeds and the temp needle stayed around 140 degrees without dropping bearing in mind the cold weather I'm thinking the undercooling is solved Hopefully.

Jon