Thermostat

[henry]

Is it possible to just disconnect the stat and by pass it? will it wok? No over heath?

[rlux4]

Yes, it is possible. It's not a good idea though, here's why.
During last year's overheating episode on the trip up to Oregon, the first thing I did was take out the thermostat. Turns out it was a waste of time, because as it turned out a PO had drilled out the valve cone in the stat, so it wasn't working anyway. However, what I found out was A) of course, there is no temperature control for the engine coolant. And B) the flow through the radiator is too fast for there to be enough heat transfer to dissipate the heat in the coolant.
What would happen is; the coolant temp stayed on the high side of normal until I hit a grade and then the temp would go up. From there it wouldn't go down (as per "B" above) and at the next grade I hit, the temp was already at the upper limit of acceptable. The only time the temp would go down would be at a fairly long downgrade. I made the plumbing for the stat eliminator out of galvanized pipe, so the flow was pretty much unrestricted. Maybe some kind of restricter could be incorporated, which would slow down the flow through the radiator, but that function is handled perfectly by a good working thermostat and a properly burped cooling circuit. I don't know if you caught it, but my new stat and airless coolant circuit was able to handle towing a trailer up two of the worst mountain passes in the west without going over 195°.
Ron

[Foster48x]

Henry, Ron's right. I would replace it. It's there for a reason. The PO had bypassed the thermostat on mine and drove it like that for who knows how long. Like you, after wondering whether or not to replace mine I found out (from the knowledgeable members of this site) that the inline thermostat is there to regulate both high and lo temp extremes. Consistent coolant temperature is needed to run the engine efficiently.

I replaced mine for $20 from one of the vendors from this site and it works great. I found it at PerformanceFiat.com. The thermostat on the site is plastic but he also stocks a metal one for the same price.

Rick

[henry]

thank you for the info. What do you think about this stat modification?

http://www.international-auto.com/fiat- ... in-cam.cfm

[rlux4]

In my opinion, an absolute necessity. I could not get my system to bleed the air out that was trapped between the bottom of the radiator and the bottom leg of the stat no matter what I did. I actually drilled the hole in the stat before I had ever heard of the procedure as a means to get that final air pocket to get pushed up past the closed stat and rise to the top of the system to be expelled. I also did the "T" in the topmost heater hose to fill the system from the highest point. By doing these two things, I never have to worry about burping my system.
Here's the thread from last year when I posted what I thought was an original solution to the air pocket problem:
http://www.fiatspider.com:16080/f08/vie ... ole#p25546
Ron

[mbouse]

i prefer to plaguerize the work of another forum member and show off his talent.... and, i don't mind repeating that either.

much simpler than removing the 'stat, drilling holes and replacing the modified 'stat is to simply install a flush system T-fitting to the heater core hose. this becomes the highest point in the cooling system, and when used to final fill the antifreeze.. will 100% ensure that there are zero air pockets.

(drum roll....) presenting Balto-Bernie's T-fitting:

[eugrides]

having thermostat problems ordered new one my car sat for 15yrs. understand tTin heater hose to vent air at highest point please explain how to fill system after i install new stat and T

[rlux4]

Mike, I have that modification on my car, but it doesn't address the problem of the lowest point in the system. The line coming out of the bottom of the radiator to the stat. It has air in it that has no where to go. The coolant from the bottom of the radiator goes up to the stat. It pushes the air ahead of it towards a closed stat. This air doesn't dislodge unless the stat opens to allow the air to rise. The problem is; with air against the stat it will never open. Burping won't work, it only compresses the air against the closed stat. The little hole in the stat allows not only coolant to dribble down into the other side of the stat, but it gives a place for the air to rise past the stat. A lot of car's stats come predrilled for this very reason, and I've heard some Fiat stats are coming that way now.
Ron

[So Cal Mark]

the best way is to fill the system as you add parts. For instance fill the radiator and lower hose, then install the thermostat. Then fill the hoses going to the stat and the upper hose. A very small hole in the stat is a great idea, not only for filling the system but as a safety in case the stat ever sticks shut. That small hole will allow a small amount of circulation preventing a complete meltdown. Keep the hole smaller than 1/8" though or your heater won't work very well

[deacon]

I have been trying to burp the system now for three days. I have the T installed in the heater hose, filled all of the parts while assembling, jacked the car up and burped it through the radiator and then burped it thriough the T and have been letting it sit and filling it each time the level goes down at the T. I have a hole drilled in the new Tstat and checked the orientation as directed onn the forum (blow into it, blocked leg towards the lower rad hose). I have run it four times and it runs for a few minutes and the gauge goes up near the red zone before I shut it off. I let it cool down and then open the T to check the level. I top off the coolant and give all the hoses especially the lower rad hose a good massage to work any bubbles out. Before running it a few minutes ago, the level hadn't been dropping and I had not seen any air at the T.

The catch bottle and the radiator have maintained at their correct levels. I am not looking for a magic solution, just venting I guess. I have never experienced a car like this before........I don't know if I should just keep bleeding or take it all apart and start again, and it's running SO nice I just want to drive it! Whew.......

[rlux4]

With the "T" installed at the highest point in the system it shouldn't be necessary to jack up the front end. That was only necessary when the radiator filler neck was the filling point. Your temp gauge is showing high temp, is it accurate? Have you checked the lower radiator hose to see if it's gotten hot? With the filler T on the highest loop of heater hose, and the hole drilled in the stat, you shouldn't have air in the system at this point. You may have to take out the stat and check it in hot water to see if it's opening.
Ron

[deacon]

Here is what I just did. I pulled the thermostat and put it on the stove in a pan of water with a thermometer. It DID open at between 180-190 which is in spec. I did check the radiator as well. Now I did not let the gauge go into the red although it was still creeping up. At this point, I figure that the gauge is off or? I hesitate to just run the car figuring the gauge is wrong and wait for the tstat to open. I will try to see if there is a way to test the gauge.

[So Cal Mark]

is the water pump actually pumping coolant? It shouldn't get that hot that quickly if there is any circulation

[deacon]

It appears that it is. I does take five minutes or more of idling for it to approach the red zone on the gauge with an outside air temp of about 45. it is a brand new water pump, timing belt, etc. The car had the same symptom with the old water pump, but it needed to be replaced for the noisy bearing if nothing else.

[So Cal Mark]

so you were having the same trouble before replacing all of those parts? Have you checked flow through the radiator. Hard to believe the engine is overheating at idle at 45 degrees