'86 Elky 305 Hi Temp issue, any ideas?

[oldelky]

I have an '86 ElCamino, and have been using it as a daily driver for +/- 8 years now. It is a 305, 700R4, OEM car with 120K on it.
I put a radiator in it 6 years ago, and just replaced that one with the parts house replacement part, which happens to be an Aluminum core, weird looking thing, but it did bolt right up.
The issue:
Before replacing the Radiator, the water temp was running higher than normal on the OEM gauge. Instead of sitting at the 200 mark, it was cycling between 200 and 220. Since the Rad did have a small leak, I thought that maybe there was enough pressure loss to explain the Temp increase, so RR'd the radiator as mentioned. No Joy, it still runs hotter than "normal".

Now I was thinking that maybe the thermostat is the issue, but would a faulty Thermostat just change it's Operating Range ? I would expect a bad one to just stick open or closed.
Anyone have that happen to them? Ideas welcome !!! 🙂 :!: :|

 

[Mx372]

I have an '86 ElCamino, and have been using it as a daily driver for +/- 8 years now. It is a 305, 700R4, OEM car with 120K on it.
I put a radiator in it 6 years ago, and just replaced that one with the parts house replacement part, which happens to be an Aluminum core, weird looking thing, but it did bolt right up.
The issue:
Before replacing the Radiator, the water temp was running higher than normal on the OEM gauge. Instead of sitting at the 200 mark, it was cycling between 200 and 220. Since the Rad did have a small leak, I thought that maybe there was enough pressure loss to explain the Temp increase, so RR'd the radiator as mentioned. No Joy, it still runs hotter than "normal".

Now I was thinking that maybe the thermostat is the issue, but would a faulty Thermostat just change it's Operating Range ? I would expect a bad one to just stick open or closed.
Anyone have that happen to them? Ideas welcome !!! 🙂 :!: :|

do a coolant flush and replace the thermostat. if the old one isn't opening like it should its holding hot coolant in the block. witch would lead to higher temps. Also when the cooling system has a leak it loses pressure. When it loses pressure the boiling point drops. so also check your cap, and for any other small leaks. i have an ford truck and i fought this same problem. come to find out the head gasket was bad so it was blowing my coolant out of the reservoir,

 

[gbondo57]

Had a truck with a temp guage. Watched the average temp range rise as the thermostat got older. Your post sounds like the temp rise was caused by the rad change. On mine, a flush and stat change brought it back. My obsevation was that a stat operates higher before it sticks. Good luck. P.S. a sending unit change is cheap, on these old rollers.