Technical Fiat 850 Coupe 1967 cooling system vs 850 Sport Coupe

[vili76]

Hi! Facing some overheating problems again and was wondering are the cooling system parts different in 1967 Coupe and later Sports Coupes? Was looking for a thermostat and a thermostat housing gasket (possibly also housing), might buy a waterpump. Other stuff also, don’t know yet.

Seems that most available parts in eBay and online stores are for coupes 1968 onwards and I am not sure if they will work with my engine? Will they?

Would like to order from Europe but am willing to consider overseas options as well (depending on shipping costs to Finland).

Thanks for your help in advance!

 

[vili76]

No one knows if the thermostat for a Sport Coupe fits the 1st generation Coupe? I seriously can’t figure out if it does.

 

[dragonwagon]

I believe that the thermostats will interchange but there are two types of waterpump - three bolt and four bolt.

 

[timmycm850]

the internal part of the stat is the same.

The lower part of the stat casing is the same but the top is different as it has a larger outlet and goes a different direction into the radiator.

The radiator intake at the top is different and the early and later cars have different waterpumos and fanshrouds.

Best starting point is to take the radiator out and flush it through with a descaler and pressure wash the outside of the rad as oil deposits on the surface reduce its cooling effect. Thoroughly Wash the side you cannot see and check all the fine little veins are letting the air through. Make sure you have the direction correct rotation waterpump by looking inside it as some 600 pumps get put on early 3 bolt 850s. Make sure the fan is for the correct rotation as air from inside the engine bay will be forced through the radiator. Make sure you have the tin plate under the radiator to stop the hot air coming back into the engine bay.
A few things to check before random part changes are needed.
All assuming your running a fairly standard engine.

Tim

 

[rusty500]

Especially make sure you have the metal apron under the radiator side of the engine compartment!
I don't know if this is true of all models (mine is '68 Sport Coupe), but I can see when my thermostat first opens up when I'm driving from cold . When the cool water that's been sitting in the radiator starts circulating, it causes the needle in the water temp gauge to drop pretty dramatically. If that's not happening, it may be an indication that your thermostat isn't working as it should, or the circuit running through the radiator isn't flowing as it should.

 

[timmycm850]

Hi Rusty500.

I'm concerned the pipes that are connected from the water pump and bottom of the stat to your temp sender are blocked as these pipes should allow water to circulate before the stat is open.

Alternatively. If you drill a 5mm hole through the steel plate arround the stat it will allow the hot water to get to the stat to allow it to open.

Tim

 

[rusty500]

I know my pipes and junctions are clear because I recently flushed the whole system and even snaked the clogged portions. I'm not worried about my system because the water temp stays rock solid at 190F even when the air temp here is at/above 100F. The only time I've had problems is when I didn't put the aprons back on immediately after working on the engine.

What about my description makes you think there might be a problem?

 

[timmycm850]

Hi rusty 500.

Its the info about the temp dropping back when the radiator contents are released. In my experience with 850s it should rise to running temp gradually. Only way temp gysfe woukd fall back would be when you open the heater valve.

Some stats have a small bypass hole in them from new.

Tim

 

[rusty500]

So, Tim, you're saying that the circuit shouldn't be completely bypassing the radiator during warm-up and mine appears to be. I can look into what's interfering with it circulating through the radiator as you say it should, but I don't see why this would be a problem, given that the system is both warming up quickly and keeping the engine from overheating, even under some pretty extreme conditions.

What does it help to have some of the coolant circulate through the radiator when the thermostat?

 

[timmycm850]

There should be water flow arround partly during the warming up and to allow proper hot water getting to the stat otherwise it won't open when the engine gets hot