Car runs too cold after fixing heater.

A

aarpcard

True Classic
Ever since I bought my X back in March, I've been battling pretty bad overheating issues. Ended up replacing basically the entire cooling system - waterpump, rubber hoses, thermostat, all gaskets, flushed underbody tubes and block, radiator cap, and upgraded to the aluminum radiator.

Drove it for the rest of the summer and the needle on the gauge would rise to 190 and stay there no matter the type of driving. Problem fixed!

Now that it's gotton colder out, I decided it was finally time to fix the blower motor. Turned out to be a variety of issues with the electrics, but I sorted that this past weekend.

The problem now is with the colder weather, it takes a very long time to get up to temp (190F) (like probably 10+ miles of 70 mph highway driving). Once it gets up to temp, if I turn the heater on full blast, the temp drops and fluctuates between 120F and 150F.

I highly doubt the thermostat is bad since it's less than 2 months old . . .

General knowledge dictates that a car running significantly colder than operating temp will burn more fuel as the ECU tried to bring it back up to temp.

What're your opinions on whether or not I should actually worry about this? Is there something simple I can do to reduce cooling in cooler weather, but boost it in hotter weather?
 
I wouldn't rule out the thermostat and even if its good, you can always swap it out for one that opens at a higher temperature for winter driving. Aside from burning fuel, I'd be more concerned about the oil not reaching correct operating temperature. Lastly, you can always restrict air flow through the radiator by partially blocking it with sheet of cardboard, plastic, whatever.

Ed
 
I would vote thermostat. It should be holding the temperature at 190 by regulating the opening. Did you use the two stage thermostat that the X is supposed to have?

The heater is in the constant flow part of the circuit which means that even with the thermostat “closed” there will be hot flow through the heater core if desired. The heater loop returns cooled water to the water pump by way of the bypass tube and then the engine block.

That the temp is dropping so strongly suggests an issue with the thermostat.
 
kmead said:
I would vote thermostat. It should be holding the temperature at 190 by regulating the opening. Did you use the two stage thermostat that the X is supposed to have?

The heater is in the constant flow part of the circuit which means that even with the thermostat “closed” there will be hot flow through the heater core if desired. The heater loop returns cooled water to the water pump by way of the bypass tube and then the engine block.

That the temp is dropping so strongly suggests an issue with the thermostat.
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I'm using the one listed on MWB. Specifically this one: http://www.midwest-bayless.com/Fiat-X19-0_p-16545-thermostat-fiat-bertone-x19-1973-88-new.aspx

Not sure if it's two stage or not . . .
 
Funny you should mention this because I experienced a similar situation last night making the 15 minute drive on surface streets coming back home from visiting my brother's house. I had the heater on max temp (but not the blower fan) and as expected I could feel warmed air within 2 minutes of startup, and it got progressively warmer/hotter as I drove. I noted about halfway home, after I moved the heat slider to about halfway the coolant temp rose almost immediately, but still it did not get up to the full 190 degrees until I was just about home.

Here's the vital info not yet mentioned--I was driving with the roof off and it was probably about 50-55 degrees out. All the heat coming out of the heater was going right out of the car. I chalked up the slowness to come up to temp as being due to the tremendous heat loss from no roof.

If you suspect a problem with the stat and have access to one of those fiber optic inspection cameras, you might be able to snake it thru the expansion tank, down thru the fat return hose from the tank to the stat housing, and then see the business end of the stat. I think the specs on the good cameras say they are waterproof and can operate at higher temps, which would let you do this while the engine is running. That would be a neat video to watch :)
 
Dan Sarandrea (Phila) said:
Funny you should mention this because I experienced a similar situation last night making the 15 minute drive on surface streets coming back home from visiting my brother's house. I had the heater on max temp (but not the blower fan) and as expected I could feel warmed air within 2 minutes of startup, and it got progressively warmer/hotter as I drove. I noted about halfway home, after I moved the heat slider to about halfway the coolant temp rose almost immediately, but still it did not get up to the full 190 degrees until I was just about home.

Here's the vital info not yet mentioned--I was driving with the roof off and it was probably about 50-55 degrees out. All the heat coming out of the heater was going right out of the car. I chalked up the slowness to come up to temp as being due to the tremendous heat loss from no roof.

If you suspect a problem with the stat and have access to one of those fiber optic inspection cameras, you might be able to snake it thru the expansion tank, down thru the fat return hose from the tank to the stat housing, and then see the business end of the stat. I think the specs on the good cameras say they are waterproof and can operate at higher temps, which would let you do this while the engine is running. That would be a neat video to watch :)
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Yeah, that sounds pretty similar to what I'm experiencing. All of this was with the heater lever all the way open, and the blower on max with the top off.

Turning the blower off resulted in warmer running temps, but it the car still did not stay consistently at 190F. New parts do fail, but I'd honestly be surprised if it's the brand new thermostat that's responsible. I did reuse the old T-stat rubber gasket (because I forgot to order a new one =P), but it appeared to be in good enough condition to use.

The only other thing I can think of is that the radiator fans seem to kick on too soon (at temperatures that are too low). Maybe the radiator temp switch is out of spec. I think autozone rents out inspection cameras so that's also a good idea if it happens to be waterproof.
 
What condition are your electrical connections in the dash area? If the fans are kicking in early and the thermostat is new, I bet the gauge is reading low when the heater is turned on. This sounds like an electrical glitch to me.

Dishy
 
Dishy said:
What condition are your electrical connections in the dash area? If the fans are kicking in early and the thermostat is new, I bet the gauge is reading low when the heater is turned on. This sounds like an electrical glitch to me.

Dishy
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They're not horrible, but I'm sure they could benefit form a cleaning. I have a whole list of electrical gremlins to sort out. Part of that process is cleaning/replacing all connectors and contacts on basically everything as I go along. I do have an issue where the temp gauge will instantly jump up two ticks if the headlights are turned on, and then jump back down when they're turned off. The delay is too fast to be anything other than an electrical interference.

However, the rise/fall time for the temperature after turning on/off the heater is too slow to make me automatically think it's just electrical interferrence on the gauge.

Poor conductivity in the thermal switch circuit would lead me to believe that it would close late - not early. Could be an issue with the switch, maybe the metals inside have started to separate (although I think that would still result in it closing late - not early, but who knows).
 
I put an aluminum radiator in my 85 about a year ago. The aluminum rad seems to be much more efficient than the original and I can drive a very long time before it ever reaches 190F. On the move, it rarely reaches 190F, close, but not quite. Since it is a hobby car I don't worry much about MPG, but it sure is nice no longer needing to have a staring contest with the temp gauge when I do go for a drive.

A little background on this 85. It came to me with a slight overheating issue. It has a 1500 with a MWB performance head and Vick's header if that makes a temp difference? I think that Stant has dual action stats for the X rated at 160F, 180F and 195F. (Maybe Amazon's parts checker is wrong?) So there is a chance the PO went with a lower temp thermostat on my X trying to alleviate the overheating on the cheap.
 
aarpcard said:
They're not horrible, but I'm sure they could benefit form a cleaning. I have a whole list of electrical gremlins to sort out. Part of that process is cleaning/replacing all connectors and contacts on basically everything as I go along. I do have an issue where the temp gauge will instantly jump up two ticks if the headlights are turned on, and then jump back down when they're turned off. The delay is too fast to be anything other than an electrical interference.

However, the rise/fall time for the temperature after turning on/off the heater is too slow to make me automatically think it's just electrical interferrence on the gauge.

Poor conductivity in the thermal switch circuit would lead me to believe that it would close late - not early. Could be an issue with the switch, maybe the metals inside have started to separate (although I think that would still result in it closing late - not early, but who knows).
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The cooling fan switch as installed in the X radiator was a common item on contemporary European cars, so given your car's history of running warm/hot, it's possible that a PO installed a switch from another FIAT or possibly from another Euro make of car rated to activate the fans at a temp lower than specified for the X. With a flash light and an inspection mirror you might be able to find stampings or markings on the switch that provide a part number for reference or a temperature value to indicate when the switch closes. Stock values according to FSM: close at 92°C (+/-2°C) aka 198°F, open at 87°C (+/- 2°C) aka 189°F.
 
aarpcard said:
What're your opinions on whether or not I should actually worry about this? Is there something simple I can do to reduce cooling in cooler weather, but boost it in hotter weather?
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It's slow to warm up but stable until you turn on the heater and then the temp drops? Two months young or not, either the thermostat is bad or something is wrong with the installation. (It wouldn't be a waste of time to check the temps with an IR gun to verify that the gauge and sender are telling the truth, but slow/stable warmup is not what you expect of a lying gauge).
 
aarpcard said:
The only other thing I can think of is that the radiator fans seem to kick on too soon (at temperatures that are too low). Maybe the radiator temp switch is out of spec.
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Fan on early won't make much difference if the thermostat is doing its job. Do you see the problem at highway speeds? If so, you can be fairly sure that the problem is not the fan temp switch because the airflow at speed is pretty much the same whether the fan is running or not. (However, if you have the wrong fan switch in there you do want to replace it with the right one).
 
Having had endless woes based around cooling system, my 2cents is that the engine temp drops (or stays lower, depending on how you look at it) with the heat on full no matter what. This happened for me with stock rad, aluminum rad (custom, much larger than ones on the market), old hoses, new hoses, two different water pump varieties, varied pulley diameters, a range of t/stats, standard coolant, Evans Waterless, etc...

But... I only see about 15-20f difference with the heater on (mine is on/off), not 40-70f.

I ended up buying the expensive t/stat MWB sells that is closer in spec to original equipment as opposed to the Stant variety.

With my current setup I use the stock fan switch, and the fans kick on just over 190 (based on the gauge) and go off when gauge drops just below the line. Temp stays a touch below the line all the time, with the exception of sustained high(er) rpm load driving (say 80-10mph range in 5th, ambient temps over 90) and short traffic stops after sustained highway driving.
 
Just a bit of an update to this in regards to the radiator fans.

I traced the issue to (strangely enough) an intermittent closed fault in the condenser fan thermoswitch for the air conditioning.

When that switch closes, it turns both the radiator fan and the AC condensor fan on. I have no idea what the condition of the AC system is on my car (the belt isn't even hooked up) so I just disconnected the condensor fan thermoswitch and I'll troubleshoot that system later as it's a very low priority.

It seems that switch would frequently, and randomly close causing the fans to come on when they shouldn't be on. Now the radiator fan is operating normally (turning on and off at the right temperatures. However I haven't driven the car enough to see if it has impacted the excessive cooling issue.
 
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