Thermostat (scratching my head) - ZR-1 Net Registry Forums

Shrek · 09-23-2020

I've been chasing my bubbies heater problem in his 93. Last option was to pull the thermostat and check the feed line to the core. BINGO...it was clogged!
Now here's the strange part: the thermostat has two bypass springs and neither one is long enough to hold the disc in position.

The one on the left is from my wifes 91 that I replaced years ago when I replaced the water pump.

The one on the right is from his 93.

Wondering if anyone else has seen anything like this? Could it be some sort of test part associated with the cars original history?

The car was an early 93 production (#17) that went to a test engineer and has emissions exempt decals under the hood along with coolant temps written with grease pencil on the surge tank.

Shrek · 09-23-2020

Video of thermostat

https://www.youtube.com/watch?v=3iIZWVVfoB4

Emissions decal

Shrek · 09-26-2020

I spoke with Marc H. a few days ago about this double bypass spring and he couldn't recall ever seeing any others like it.

Guess I'll label and put it on the shelf with my stash of used LT5 stuff.
If anything It should make for good conversation when a bunch of us old guys are sitting around in the garage telling ZR-1 lies/stories.

WARP TEN · 09-26-2020

Yeah Shrek--here's what it will be like....Bob

BlackZR1 · 09-26-2020

Haha, excellent, I actually did laugh out loud!

DRM500RUBYZR-1 · 09-26-2020

as did I.
Marty

Hib Halverson · 09-26-2020

Well...I'll be damned.

Someone modified that 'stat with an extra spring to hold the bypass closed and force more flow through the radiator at higher RPM. Not a bad idea if the car has an all aluminum radiator but not such a good idea if it has a production radiator with crimped-on plastic side tanks.

I had an all-aluminum, Fluidyne radiator in Barney when I owned it and I always wanted to reduce the amount of coolant which is bypassed at high RPM in the interest of reducing ECT at high-RPM/high-load. Rather than upping the bypass spring pressure on the thermostat, I was going to try restricting the bypass flow though the hose the actually bypasses coolant around the radiator. I was going to do this with a restrictor. I actually had obtained a Delrin rod of the right O.D. and was going to drill various sized, smaller holes in it and put that restrictor in the bypass hose. I was going to combine the restrictor with a slightly higher system pressure.

But... like a lot of things, I never got around to doing it before I sold the car.

09-26-2020	#3
Shrek Join Date: Sep 2010 Location: Currituck, NC Posts: 246	Re: Thermostat (scratching my head) I spoke with Marc H. a few days ago about this double bypass spring and he couldn't recall ever seeing any others like it. Guess I'll label and put it on the shelf with my stash of used LT5 stuff. If anything It should make for good conversation when a bunch of us old guys are sitting around in the garage telling ZR-1 lies/stories. __________________ :cheers: [B][COLOR="seagreen"]Shrek[/COLOR][/B] [SIGPIC][/SIGPIC]

09-26-2020	#5
BlackZR1 Join Date: Aug 2015 Location: Pittsburgh, PA Posts: 152	Re: Thermostat (scratching my head) Haha, excellent, I actually did laugh out loud! __________________ Roger 1990 ZR-1 #2699 Black on Black 15,000 miles Full-time secondaries, 4.10 gears, C-beam plates, ported top end

09-26-2020	#6
DRM500RUBYZR-1 Join Date: Sep 2008 Location: Mullica Hill, New Jersey Posts: 2,566	Re: Thermostat (scratching my head) as did I. Marty

09-26-2020	#7
Hib Halverson Join Date: Jun 2005 Location: CenCoast California Posts: 899	Re: Thermostat (scratching my head) Well...I'll be damned. Someone modified that 'stat with an extra spring to hold the bypass closed and force more flow through the radiator at higher RPM. Not a bad idea if the car has an all aluminum radiator but not such a good idea if it has a production radiator with crimped-on plastic side tanks. I had an all-aluminum, Fluidyne radiator in Barney when I owned it and I always wanted to reduce the amount of coolant which is bypassed at high RPM in the interest of reducing ECT at high-RPM/high-load. Rather than upping the bypass spring pressure on the thermostat, I was going to try restricting the bypass flow though the hose the actually bypasses coolant around the radiator. I was going to do this with a restrictor. I actually had obtained a Delrin rod of the right O.D. and was going to drill various sized, smaller holes in it and put that restrictor in the bypass hose. I was going to combine the restrictor with a slightly higher system pressure. But... like a lot of things, I never got around to doing it before I sold the car. __________________ Hib Halverson Technical Writer former owner 95 VIN 0140 current owner 19 VIN 1878 Last edited by Hib Halverson; 09-26-2020 at 08:32 PM.