Thermostat or NO Thermostat???

Timmmy

'87 Bertone X1/9
Ok fellow Xers, I need some feedback. I haven't posted here in awhile, but I'm still enjoying the hell out of my Exxy. I have a 1987 Bertone, 1500 FI. Last summer it was overheating so I had the radiator cleaned and rodded. This summer I have the A/C working great (at last). I realized that the thermostat I put in last year may not have been the most optimal. It was a Stant 13378. So I got a 45378 equivalent from Napa. It does appear to open up much more than the previous one.
Here is the dilemma. When I ran the radiator flush stuff through the system, I did it with the thermostat removed, then flushed with water and ran for a bit, and flushed with water again. Then I put the new stat in and filled it with antifreeze and water. When I was running it without the stat it ran much cooler, about 180 or so maybe less, yet I still had heat coming from the heater. Now that I have the new stat installed, it still runs hotter than I'd like ion the freeway or uphill, usually up around the 3/4 mark on the temp gauge. Which I think is around 225-230 or so.............
SO, the question is,....what would be the problem running without a thermostat in it during the summer months at least, especially since I do still seem to have flow through the heater core?????
Any suggestions???

TIMMMY
 
Before you change anything else

verify that the temp. gage is reading correctly. If your radiator has never had any attention then it's time to do it as sitting and age will build up deposits in the core.

If after that then think about thermostat or no thermostat. But mind you a thermostat serves for a reason. I would never recommend running without a thermostat especially with an aluminum head and cast iron block. 2 different heat expansion rates which a thermostat helps to compensate for.
 
The thermostat in most Fiats is the dual-action type, that is it opens one circuit while it closes the other. Make sure your thermostat does this. Without it in place you'll get flow through the engine even when there is some flow through the radiator, essentially short-circuiting the radiator circuit.

Perhaps you should get one from a Fiat parts vendor, but I can't say without knowing what you got is the correct type.
 
Thermostat

As pointed out, Fiat thermostats don't just control the flow of coolant from the engine to the radiator, they also close off one circuit as another opens. Pretty sure Senor Lampredi knew what he was doing, he was a pretty good engine designer.

My 2 bobs worth...

Rob
 
Like this...

This page from the factory manual explains how this works with the stock thermostat.
Vsdm8g.jpg
 
A couple of other things to check...

1. Pressure test or replace the CAP.

2. Pressure test the entire system.

3. Is this increase in temp with the A/C on? If so, I'm not familiar with what to expect... but it does not leave much margin for safety.

4. Without the A/C... your stat and PRESSURIZED system should maintain the car at about 185 degrees. If the fan(s) come on in traffic, they should cycle after a few minutes after the temp drops.

5. Do you run a front license plate... and do you not the temp rise over 60 mph versus running at 55 or so. I have PROVEN to myself that the plate deflects air AROUND the radiator at speed... and it should be moved to one side if you wish to continue to run one.

HTH...
 
Hi
GEEKY ALERT! :wink2:
The thermostat regulates the engine temperature to a value the manufacturers have determined to give best engine performance and avoids such problems as fuel wash in the bores if running too cool.

They should never open fully in normal running. If they do "hit the wall" then you have problems in other areas of your cooling system.

Indeed they should oscillate around their set temperature at a point below fully open.

Coolant needs an optimum finite time to traverse the radiator to allow maximum extraction of the heat by the airflow.

Removing a thermostat may allow the coolant to flow too quickly thru the radiator and it may result in not enough heat being extracted and indeed cause OVERHEATING as the heat energy cannot escape the system fast enough.

HTH

Cheers
Dave
South Oz
 
Whats the ideal temp?

Something I've thought about before but never delved into.
Replaced my stat a few years ago cause the old one died (engine overheating).
Bought a replacement from local Fiat supplier who said it is a slightly lower temp one so would help cooling. Good I thought.

Did I do the right thing?
How does lower temp affect engine running (performance, efficiency, emissions).
 
After what I have experienced, I would doubt the accuracy of your temp gauge, and would only trust it if checked with a second mechanical gauge reading off the same head port, and/or with a laser temp gauge used to check the temps at the head, t/stat housing, hoses, and rad inlet/outlet.

I also agree that running without a t/stat is just a bad idea.

The (Super) Stant 45378 has proven to be the most reliable, of the three different types I tried. I would not trust an 'equivilent'.
 
Cooler Thermostat?

I have used 160 degree thermostats in several X 1/9s year round with no issues. If memory serves me, the part was a Stant 13376 and it did not have to be modified to fit. It should never cause premature engine wear due to the lower temp, because this type of bypass system regulates the temperature of the coolant returning to the engine. Just my two cents, hope it helps.
 
Back
Top