Technical Bleeding early coolant system (without T)

[S854]

I’m still getting to know my new-to-me, 1969 124 Spider… it has a 1608, 125BC engine/124AC head with the thermostat in the head…

I’ve searched and found many, many videos and articles on how to properly bleed the T thermostat engines but nothing on the earlier engines…

Can anyone point me in the right direction to their successful procedure on the older engines?

I’ve only had the opportunity to drive the car once for any substantial amount of time, one odd thing I noticed was heading into town, 6 or 7 miles mostly “downhill” from where we live, a slight grade, so no real throttle application necessary, just enough to keep 55 mph… the temp gauge during this run was somewhere around 120-130… later, around town and on the way home (uphill) temps were pretty consistent at 185-190… ambient temp around 65-70 that day…

Does all this seem normal?

I have a small leak from the thermostat housing-to-head junction so I’m going to reseal that soon… should I replace the thermostat while I’m in there?

Thanks in advance.

(I posted this on the Mirafiori forum… I was searching for answers to my question and Google directed me there… from what I can tell, Mirafiori isn’t a very active site… thought I’d ask here…)

 

[The Panda Nut]

Hi there. Im taking you habve a pressure cap / pressuised system. The temps you report sound reasonable not wildy unreasonable anyway. If you are getting access, I would definitely change the thermostat for a few bucks its a wise move while you can. Older type stats seemed to last a long time, but once its renewed it should give peace of mind and be one less thing to bite you. It should keep the temperature more consistent. Running cold is not as bad as overheat, but its not a great idea.

 

[bugsymike]

I agree with @The Panda Nut as above, sounds quite a rare beast you have the 1608cc was only made for a few years, I looked at an old Fiat 131 Mirafiori manual but it starts at 1975 and the 1600 engine is actually the later 1570cc I think. Many years ago I had a 1971 Alfa Romeo 1750GTV when they were still cheap to buy. The 1600 version in that manual although a different engine again but same era with old style thermostat mentions bleeding at the inlet manifold and the water pump. However if you are only disturbing the thermostat housing I would clean the gasket area for the new gasket and as I am fitting the thermostat refill the coolant to the level of the thermostat in it's housing as you assemble, that way you know there is no air below it, then once it is bolted down continue to top up coolant in normal rad and header tank if applicable. If heater hoses are higher than engine I have even removed the top heater hose and filled from their to ensure as little air in a system as possible before replacing.
Obviously warm engine up checking the hoses so you you can feel when the thermostat opens, run for a few minutes after that whilst watching temp doesn't rise any higher, then if it feels good switch off and let cool down and once cold recheck coolant levels before any road test. I know this sounds a bit "long winded", but it is best to be safe as if it overheats during a fast road test due to air locks it can get expensive.
The photos below are for the Alfa but may give some insight including thermostat temps back then as engines ran at lower temp than modern ones.
Generally older cars were easier to get the air out of coolant system than modern stuff.
Sorry if all this is "teaching granny to suck eggs", you probably already are aware of this.

 

[S854]

Appreciate you guys sharing your knowledge… snow/cold is forecast for the next week or so, won’t be getting the car out anytime soon…

I’ll order a new housing gasket, radiator cap and thermostat… I’ll fill as I go when putting things back together…

I haven’t actually placed my hand on a rad hose to check their temp… when I get it out next, I’ll bring along my temp gun and stop from time to time time to get readings from the hoses and engine block…

 

[bugsymike]

Appreciate you guys sharing your knowledge… snow/cold is forecast for the next week or so, won’t be getting the car out anytime soon…

I’ll order a new housing gasket, radiator cap and thermostat… I’ll fill as I go when putting things back together…

I haven’t actually placed my hand on a rad hose to check their temp… when I get it out next, I’ll bring along my temp gun and stop from time to time time to get readings from the hoses and engine block…

Usually on starting engine from cold I put my hand on the cold top hose then as thermostat opens it soon gets to where you have to let the hose go, roughly high 80s Centigrade for me.
I do have a laser temp gun , but I am old school.