So my Fiero died... (Page 10/12)
Cliff Pennock AUG 21, 05:59 AM
I've tried to find a coolant flow diagram of the V6 but were unable to find one (other than a very, very basic one). So I looked at the service manual an now I'm even more confused.

Looking at this picture:



that tells me hot coolant from the engine travels the pipes on the passenger's side of the car to the front of the car. And that cooled coolant travels the pipes from the radiator to the engine on the driver's side of the car.

But then I look at this picture of the radiator:



It says the inlet tank is on the driver's side, and the outlet tank on the passenger's side. So hot coolant is coming in on the driver's side en cooled coolant is coming out on the passenger side - which is completely the opposite of the first drawing. Or do they mean that the inlet tank is actually the radiator's outlet tank but is connected to the inlet pipe of the engine? I'm confused.
Rick Vanderpool AUG 21, 12:25 PM
I can see why the confusion, but if you think of both pictures in terms of the radiator they make sense. The thermostat controls flow out of the engine, and it allows hot coolant to run through the pipe on the driver's side, into the inlet tank on the driver's side of the radiator. The water pump pulls cool coolant from the passenger side of the radiator and pipe and pushes it into the block. To simplify hot to the radiator on the drivers side and cold from the radiator on the passenger's side.
Rick
sleek fiero AUG 21, 01:43 PM
Yes the first drawing is wrong .#2 is the outlet from the thermostat and the #3 is the inlet from the rad. sleek
Cliff Pennock AUG 21, 02:12 PM
Cool, thanks Rick & sleek!

As for the transmission lines, which of the two is the inlet (on the radiator)? The upper or the lower?

Also, looking at the design, you can clearly see that it's designed to keep the transmission oil temperature at engine temperature. And not to cool it. If that's the case, why would you want to introduce a transmission oil cooler in the system? That defeats the design of the cooling system.
theogre AUG 21, 02:16 PM

quote
Originally posted by Cliff Pennock:
A few months ago, I replaced the dash and that didn't make a difference. So I know at least the problem is not in there.

Does Not = this dash is any good or even same as old unit.
Even a brand new dash put in a 30+ year old car can have big problems.
Gauge Senders ground to body etc & 1 Iffy ground connection anywhere can make gauges lie. Iffy Power connection can do same.

Is Why ECM have Regulated 5V &or Ground to almost all sensors. Only "1 wire" O2 "grounds" thru the exhaust.

My Temp Gauge reads Lower then ECM ECT because of same problem somewhere in that wiring.
But Fuel gauge is close to accurate now when cleaned the clips etc in link page. Cleaned the sender & connectors when replacing F-pump didn't help much even test for 0-90Ω on the sender & C502 connector w/ Ω meter.

OP gauge "pegs" and replace it & senderS & still "pegs" most of time even w/ Fix Resistor close to 45Ω (42 or 48) should be close to middle gauge range but "pegs" @ little over 80PSI.

"Bigger"/"Better" Rad often makes Temp Swinging "Worse" because cools down more in Cool/Cold Weather and slug the engine when T-stat opens fast.
Depending where, how long, and more the engine temp may Never stabilize. Super stat may look same as OEM but had different temp curve to operate in & far less Temp Swings that "people" see as "a problem" when often is nothing. Even if you order by Stant PN, very likely only get "OEM" type since Motoraid buyout.

Many Big Trucks have Shutters in front of Rad to manually or auto close in cold weather for same reason. Even then some trucks still have covers over the grill for more protection in cold weather. Because those Huge radiators often needed in warm/hot weather but works against the engine in cold weather & can't make enough heat just to run right.
Cliff Pennock AUG 21, 03:22 PM
Yes, I understand the second dash could be iffy as well. But it didn't make any difference as far as the erratic temperatures were concerned. I've ordered another temp gauge sending unit but since it's shipped from the US, it might take a few weeks to arrive.
sleek fiero AUG 21, 06:51 PM
Hi Cliff . Yes you could have a bad gauge but it is more likely a bad sender. I replaced my sender and the gauge always was in the normal range but the idiot light was glowing after 5 minutes of driving .I changed it out with the Standard replacement unit and no more problems. I am sorry to say the 1st 0ne was from the Fiero store . Don't trust Chinese parts. sleek
theogre AUG 21, 07:16 PM

quote
Originally posted by sleek fiero:

this is what you need Cliff

Won't work w/o extra parts.
see Coolant Pressure Testing for Fiero http://www.fiero.nl/forum/Forum2/HTML/145505.html

And doesn't help looking for problems causing temp swings or other "over heating" problems.
theogre AUG 21, 07:20 PM

quote
Originally posted by Cliff Pennock:
Yes, I understand the second dash could be iffy as well. But it didn't make any difference as far as the erratic temperatures were concerned. I've ordered another temp gauge sending unit but since it's shipped from the US, it might take a few weeks to arrive.

New sender may help, or not, for gauge that reads low.

E2A--> Because iffy wiring that add resistant or cause low volts make Temp gauge to lie because sender is NTC thermistor so less resistance = higher temp

[This message has been edited by theogre (edited 08-21-2023).]

Cliff Pennock AUG 21, 07:24 PM

quote
Originally posted by sleek fiero:

Yes you could have a bad gauge but it is more likely a bad sender.



Which is why I ordered a new one. 😄


quote
Don't trust Chinese parts.



Not to sound stereotypical or anything, but it seems to me China can only produce "complete and utter crap" or "I can't believe they can make this for so little money".

Anyways, I have no idea what I will be getting but if it is the sending unit that is causing the problems, I should at least see some change with the new sending unit.