fairly new rebuild. runs great, gets up to 190/200, lower hose still cold.
the t-stat is new: or fairly. was working when then had to rebuild: could it now be stuck. have tried to burp it, but ... it's an AR that opens at 175 I believe.
I do have an old one that opens at 190 (i have checked)
ideas
Geo
stuck thermostat??
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geospider
- Patron 2020
- Posts: 585
- Joined: Mon Mar 20, 2017 9:07 pm
- Your car is a: 1979 Spider 2000
- Location: concord, ca
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SuperCoupe
- Patron 2018
- Posts: 11
- Joined: Thu Oct 12, 2017 10:10 am
- Your car is a: 1973 124 Sport Coupe
Re: stuck thermostat??
Do yourself a big favor. Ditch the external thermostat and go for the conventional in-head thermostat. I was dealing with the same issues as you. Sometimes the thermo would open but many times the hose was cold and the thermostat wouldn't open. I just changed to an in-head thermostat and no problems. I'm big into keeping things original, but these external thermostats are finicky and troublesome. I worked at a Fiat repair shop in the 80s and 90s and we always converted the cars and that eliminated cooling system hassles for our customers. Good luck!
Current:
'73 Fiat 124 Sport Coupe
'82 Alfa GTV6
'12 500 Abarth
'18 Alfa Stelvio Sport
Previously owned:
124 Sedan and Wagon, couple of 850 and 128 sedans, 71 and 72 124 Sport Spiders, 76 Lancia Scorpion, 87 X1/9. 500X Trekking Plus
'73 Fiat 124 Sport Coupe
'82 Alfa GTV6
'12 500 Abarth
'18 Alfa Stelvio Sport
Previously owned:
124 Sedan and Wagon, couple of 850 and 128 sedans, 71 and 72 124 Sport Spiders, 76 Lancia Scorpion, 87 X1/9. 500X Trekking Plus
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MattVAS
- Patron 2020
- Posts: 225
- Joined: Thu May 18, 2017 11:10 am
- Your car is a: 1976 Fiat Spider 124
Re: stuck thermostat??
KEEP the external thermostat. It is the better unit.
1. They flow more than the internal
2. They produce better flow across the engine vs the internal (see below)
3. The reason Fiat ditched the internal and went back to the external is because the internal units can crack heads
4. External units are not finky at all, they just require good burping
5. They used to swap to the internals not due to finky nature but cost of units (externals were $60 even back in 1980 vs the $3 for an internal)
--- Current costs aren't as big a problem $30 for external vs $8 for internal. And remember external units are just a thermostat they are their own housing that is why they cost more.
Reasons for your issues.
1. air in system
2. thermostat upside down
3. it failed and is now stuck
Fixes
1. if air how did it get there
a. Either more burping needs to be down or you have a leak. A tiny tiny tiny head gasket leak can cause a never ending air pocket to occur and just ruin you day.
http://fiatparts.blogspot.com/2012/09/m ... h-way.html
2. installing a thermostat upside down
a. About once a week we get a call about just this. People do it all the time.
3. failure
a. This can happen but the only way to check is to pull the unit and boil it.
This is a simple little drawing I did a while back to be explain why the external thermostats are simply better than internal units.
1. They flow more than the internal
2. They produce better flow across the engine vs the internal (see below)
3. The reason Fiat ditched the internal and went back to the external is because the internal units can crack heads
4. External units are not finky at all, they just require good burping
5. They used to swap to the internals not due to finky nature but cost of units (externals were $60 even back in 1980 vs the $3 for an internal)
--- Current costs aren't as big a problem $30 for external vs $8 for internal. And remember external units are just a thermostat they are their own housing that is why they cost more.
Reasons for your issues.
1. air in system
2. thermostat upside down
3. it failed and is now stuck
Fixes
1. if air how did it get there
a. Either more burping needs to be down or you have a leak. A tiny tiny tiny head gasket leak can cause a never ending air pocket to occur and just ruin you day.
http://fiatparts.blogspot.com/2012/09/m ... h-way.html
2. installing a thermostat upside down
a. About once a week we get a call about just this. People do it all the time.
3. failure
a. This can happen but the only way to check is to pull the unit and boil it.
This is a simple little drawing I did a while back to be explain why the external thermostats are simply better than internal units.
Matt Phillips
Vick Auto - Manager
http://www.vickauto.com
Stock parts or Performance parts we've got what you need.
Vick Auto - Manager
http://www.vickauto.com
Stock parts or Performance parts we've got what you need.
-
SuperCoupe
- Patron 2018
- Posts: 11
- Joined: Thu Oct 12, 2017 10:10 am
- Your car is a: 1973 124 Sport Coupe
Re: stuck thermostat??
I agree that the external/mixing thermostat is a better system when it works.
The issue is that the system can be difficult /tricky/finicky, etc. to bleed for many people, as is documented by countless posts here and ~ 50 years of on the road experience. Add in if the unit fails, it is not readily available for most people, name brands are not cheap, and the system caused headaches for dealers even when the cars were brand new, and it is a viable alternative to folks that don't want to deal with the hassles. If your car bleeds out without an issue than go for the external unit, but if don't want the hassles an internal/conventional thermostat is literally install and forget.
According to the SAE paper filed on the Twin Cam engine by Lampredi in 1969, the mixing thermostat primary function is to cut down on warmup time and to have more even temperatures. This comes into play particularly in cold climates. It's important to note that Fiat didn't equip some cars with the external thermostat and used a convention internal thermostat, so it is not a hillbilly fix. The way most people drive these cars (in nice weather, Sunday drives, etc.) they will likely not notice any downside. If you are racing that may be another story, but I just saw a post by Guy Croft saying to install an internal thermostat, and looking at homologation papers on the Fiat Abarth 124 Rally they show an internal thermostat, so I'd say if you go for it even in that situation, you'll also be fine.
You'll see there is a coolant flow even when the conventional thermostat is closed (albeit much less than the externat thermostat system) through the engine and there is a bypass built into the engine via the cooling jackets in the block and head.
The issue is that the system can be difficult /tricky/finicky, etc. to bleed for many people, as is documented by countless posts here and ~ 50 years of on the road experience. Add in if the unit fails, it is not readily available for most people, name brands are not cheap, and the system caused headaches for dealers even when the cars were brand new, and it is a viable alternative to folks that don't want to deal with the hassles. If your car bleeds out without an issue than go for the external unit, but if don't want the hassles an internal/conventional thermostat is literally install and forget.
According to the SAE paper filed on the Twin Cam engine by Lampredi in 1969, the mixing thermostat primary function is to cut down on warmup time and to have more even temperatures. This comes into play particularly in cold climates. It's important to note that Fiat didn't equip some cars with the external thermostat and used a convention internal thermostat, so it is not a hillbilly fix. The way most people drive these cars (in nice weather, Sunday drives, etc.) they will likely not notice any downside. If you are racing that may be another story, but I just saw a post by Guy Croft saying to install an internal thermostat, and looking at homologation papers on the Fiat Abarth 124 Rally they show an internal thermostat, so I'd say if you go for it even in that situation, you'll also be fine.
You'll see there is a coolant flow even when the conventional thermostat is closed (albeit much less than the externat thermostat system) through the engine and there is a bypass built into the engine via the cooling jackets in the block and head.
Current:
'73 Fiat 124 Sport Coupe
'82 Alfa GTV6
'12 500 Abarth
'18 Alfa Stelvio Sport
Previously owned:
124 Sedan and Wagon, couple of 850 and 128 sedans, 71 and 72 124 Sport Spiders, 76 Lancia Scorpion, 87 X1/9. 500X Trekking Plus
'73 Fiat 124 Sport Coupe
'82 Alfa GTV6
'12 500 Abarth
'18 Alfa Stelvio Sport
Previously owned:
124 Sedan and Wagon, couple of 850 and 128 sedans, 71 and 72 124 Sport Spiders, 76 Lancia Scorpion, 87 X1/9. 500X Trekking Plus
-
geospider
- Patron 2020
- Posts: 585
- Joined: Mon Mar 20, 2017 9:07 pm
- Your car is a: 1979 Spider 2000
- Location: concord, ca
Re: stuck thermostat??
Reburped; then allowed it to get up to temp. prob nervous since all is rebuilt.
Matt, thanks for the reminder that the gauges arent perfect.
At 190; lower hose hot, then fan came on.
what a blast to finally drive. damn they pull well around a corner. (Ar springs and Konis; and 205 Hankooks help) People love to wave at us in these (it's the car,, not me)
Geo
Matt, thanks for the reminder that the gauges arent perfect.
At 190; lower hose hot, then fan came on.
what a blast to finally drive. damn they pull well around a corner. (Ar springs and Konis; and 205 Hankooks help) People love to wave at us in these (it's the car,, not me)
Geo