Heating issues (Page 2/4)
cvxjet JUN 03, 06:03 PM
If your water pump impeller is slipping like mine was, by removing the thermostat you eliminate drag on the system, so then the impeller will continue to spin (Unless the inside worn so it slips all of the time) This is a temporary test/fix....Also, when filling be careful that you don't have any air pockets in the heating system- that may be why yours stops overheating when you engage the heater/AC.

I don't have AC, so I have never had to deal with any special ventilation system procedures while refilling the coolant.

One other odd thing that once happened to me (But may not apply to Fieros)...My 1973 mach 1 started overheating on the freeway but as soon as I slowed it would cool down....I had replaced everything including radiator and hoses....Finally found out that on Mustangs the SUCTION side radiator hose has a spring in it to keep it from collapsing during high rpm pump operation.....Every time I got on the freeway, the hose was pinching off because that spring was SHORT! Wrecked the 351C in the car, so I installed a 5.0 FI engine.
Patrick JUN 03, 07:21 PM

quote
Originally posted by cvxjet:

...air pockets in the heating system- that may be why yours stops overheating when you engage the heater/AC.



Just so we're all clear on this, engaging the heater/AC makes absolutely no difference whatsoever in regards to coolant flow.

Sorry, but I find it impossible to believe that the tiny little bit of heat removed by air going through the heater core would make an appreciable difference in coolant temperature... especially in the span of "a couple seconds"!


quote
Originally posted by Monkeybean007:

My engine overheats until I turn on my heater I only have to leave it running for a couple seconds and then can turn it off and it won't overheat for the rest of the drive. 85 gt 2.8l


Mike in Sydney JUN 03, 09:49 PM

quote
Originally posted by Monkeybean007:


...but unless I am running ac/ heater it will start to overheat, ...




I'd be will to bet the sheep station that you have a faulty radiator fan switch in the engines water jacket. When the AC is turned on it overrides the normal fan switch and turns on the radiator fan, regardless of temperature. When the heater is used it circulates coolant through the heater core which in effect is a radiator and, yes, that small amount of additional "radiator" will lower the temperature.

Quick question for you: Does it overheat when you are driving at speed on the freeway when the AC is off or when it's driven around town in a stop-and-go method? If you don't overheat while driving at speed or the overheating doesn't happen as quickly as when you're doing stop-and-go or tooling around at low speed, you're likely to have a faulty fan switch or wiring issue.

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Mike in Sydney

Mike in Sydney JUN 03, 09:54 PM

quote
Originally posted by cvxjet:

I don't have AC, so I have never had to deal with any special ventilation system procedures while refilling the coolant.

.



Pretty sure the coolant filling procedure is the same whether you have AC or not

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Mike in Sydney

Patrick JUN 03, 09:58 PM

quote
Originally posted by Mike in Sydney:

When the heater is used it circulates coolant through the heater core..



Mike, quit spreading FALSE information!

Coolant is constantly circulating through the heater core in a Fiero. How many times do we need to go over this?!!! (This was discussed just recently in This thread.)

[This message has been edited by Patrick (edited 06-03-2020).]

Mike in Sydney JUN 03, 10:25 PM
Patrick, don't blow a gasket, Mate. Yes, coolant is circulating constantly through the heater core. Increasing airflow to the core by turning on the fan does improve heat transfer through the core so, yes, using the heater will lower the temperature in the coolant to some degree. It's the same principle as the fan on the primary radiator.

Love you, mean it. I appreciate your input and comments.http://www.fiero.nl/forum/icons/icon10.gif

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Mike in Sydney

Patrick JUN 03, 10:40 PM

quote
Originally posted by Mike in Sydney:

Patrick, don't blow a gasket, Mate.



Mike, the "tantrum" fella is still a smiley face. I wasn't choked.

But back to the issue... I cannot believe that running the heater, rad fan, or whatever for two seconds makes a lick of difference with the actual coolant temperature!


quote
Originally posted by Monkeybean007:

My engine overheats until I turn on my heater I only have to leave it running for a couple seconds and then can turn it off and it won't overheat for the rest of the drive. 85 gt 2.8l


Mike in Sydney JUN 03, 11:11 PM
Patrick, You have a PM, buddy.

Mike
cvxjet JUN 04, 11:30 AM
Patrick- That is what I thought.....But my 1972 Merc Comet had AC and had a VALVE that shut off flow thru the vent system while in AC mode.....Wasn't sure about Fieros.

Is there a (Crazy) possibility that the radiator fan is not running until he turns on the AC? How quickly does it overheat? And at what atmospheric temps?
Monkeybean007 JUN 04, 03:08 PM

quote
Originally posted by Mike in Sydney:
I'd be will to bet the sheep station that you have a faulty radiator fan switch in the engines water jacket. When the AC is turned on it overrides the normal fan switch and turns on the radiator fan, regardless of temperature. When the heater is used it circulates coolant through the heater core which in effect is a radiator and, yes, that small amount of additional "radiator" will lower the temperature.

Quick question for you: Does it overheat when you are driving at speed on the freeway when the AC is off or when it's driven around town in a stop-and-go method? If you don't overheat while driving at speed or the overheating doesn't happen as quickly as when you're doing stop-and-go or tooling around at low speed, you're likely to have a faulty fan switch or wiring issue.



Overheats at stop and go's