77 running hot

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Rupesy
Posts: 66
Joined: Thu Apr 29, 2010 10:20 pm
Your car is a: 1977 Spider
Location: Houston, TX

77 running hot

Post by Rupesy »

I am all out of ideas. Not sure if I really have an issue of not. I had have read all posts and have followed many of the suggestions. Ambient temperature at this point is 100F+. While sitting in the driveway idling, it runs past the 190F mark and the needle sits over the "0" of the 190. The fan cycles on and off at this point normally and the needle stays fairly steady. I have switched out the fan switch and thermostat both known working prior to installation. I tested the fan switch in a pot of the stove and I got continuity around 185-190F. Both thermostats working as they should, Upon start up, hot water travels from the pump through the thermostat to the t-fitting. As it approaches 190F on the gauge, I can feel hot water going from the T to the top of the radtiator. The hose form the bottom of the radiator remains cool for a while and the needle parks at 190F for a while. Hose from top of head and hoses running to carb all are hot. Eventually I can feel hot water coming from the radiator into the thermostat. That is when the temp starts to climb until the fan switch kicks in. I bought a infrared temp gauge as I have been going crazy. Best I can tell the temp gauge matches the temp of the engine at the sensor. The temperature of the engine seems to settle out at around 205-210F. I checked the temp at the bottom of the radiator near the fan switch and best I can tell it is coming on at around 190F-ish in that area. I checked the opposite side on the bottom and it was around 200F-ish. Keep in mind I was doing the best I could with the infrared temp gauge. I took it for a drive yesterday and driving around in stop and go traffic the temp climbed a little but never into the red. At the hottest point, I stopped and checked the temp with the gun and it was around 215F on the head. I felt like the temp should have dropped while I was driving, but heck, it's pretty hot out. Car ran normal and didn't run funny. So I decided to jack up the car to make sure I didn't have a bubble and no change. I do have the T-fitting on the hose coming off the head for filling. I drilled the hole in the thermostat. Heater core is open during the fill and first start. New radiator cap. Water pump is maybe a year old. Radiator is about a year old and I pulled it and flushed it as well, but seems wide open. The overheat sensor is new and I am waiting on a new temp sensor just in case.

Is the radiator fan switch supposed to be set at 190F? or should I have one set lower?
Any other suggestions other than replace the pump?
'77 Fiat Spider
'79 Porsche 928
'83 Jeep CJ7
'04 Chevy Suburban
'04 BMW Z4
'00 Porsche Boxster
User avatar
Rupesy
Posts: 66
Joined: Thu Apr 29, 2010 10:20 pm
Your car is a: 1977 Spider
Location: Houston, TX

Re: 77 running hot

Post by Rupesy »

Forgot to mention I checked the fan thermostat on the stove with a temp sensor and continuity meter and I got around 190F when I got continuity.
'77 Fiat Spider
'79 Porsche 928
'83 Jeep CJ7
'04 Chevy Suburban
'04 BMW Z4
'00 Porsche Boxster
redcars
Patron 2020
Patron 2020
Posts: 487
Joined: Sat Jul 31, 2010 9:36 pm
Your car is a: 1981 Spider 2000
Location: Collinsville, IL

Re: 77 running hot

Post by redcars »

Your car is running exactly as it was designed to. Drive it and enjoy it.
1987 Lotus Super 7 clone
1981 Fiat Spider 2000 AT
1982 Fiat Spider 2000 5sd
1970 Fiat Coupe
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courtenay
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Posts: 1321
Joined: Mon Nov 30, 2009 11:41 pm
Your car is a: 1980 Spider 2000
Location: Courtenay, BC, Canada

Re: 77 running hot

Post by courtenay »

I'm with Redcars - sounds completely normal to me.
Bruce Shearer
'80 Spider Fi
'10 Volvo XC70
'06 GMC 1 Ton PU
'72 Spider a long, long time ago
So Cal Mark

Re: 77 running hot

Post by So Cal Mark »

water does not travel from the pump to the thermostat. That is the inlet side of the pump. Water at the pump gets pushed through the block, up to the head, from the tee into the top of the radiator, out the bottom of the radiator to the thermostat. That's the progression if the t-stat is open. An engine will normally run 10-15 degrees hotter than the thermostat rating temperature
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