New radiator + Dexcool = higher temps?
Thread Starter
Racer
Joined: Dec 2007
Posts: 461
Likes: 25
From: North OC California
New radiator + Dexcool = higher temps?
2007 Z51 with a stick.....
About a month ago, my car would run 199- 203F at 70 mph on 100F summer days. Then I got the infamous crack on the driver’s side tank of the original radiator. I bought the car used, and the coolant was bright pink (think highlighter pink) and of unknown type. Could’ve been Redline Water Wetter, Toyota flavor, Cherry 7Up....no idea.
Replaced said cracked radiator with a OEM radiator. Rather than risking the consequences of mixing anything with said remaining bright pink stuff, I had my dealer flush the system and refill with the prescribed 50/50 Dex and water mix....
Here’s the thing: I realize temps of 208F under the same operating conditions as stated above are well within the acceptable operating range of these cars, but 7-9 degrees warmer temps with a new radiator and fresh Dex?! Anyone else experience this?
About a month ago, my car would run 199- 203F at 70 mph on 100F summer days. Then I got the infamous crack on the driver’s side tank of the original radiator. I bought the car used, and the coolant was bright pink (think highlighter pink) and of unknown type. Could’ve been Redline Water Wetter, Toyota flavor, Cherry 7Up....no idea.
Replaced said cracked radiator with a OEM radiator. Rather than risking the consequences of mixing anything with said remaining bright pink stuff, I had my dealer flush the system and refill with the prescribed 50/50 Dex and water mix....
Here’s the thing: I realize temps of 208F under the same operating conditions as stated above are well within the acceptable operating range of these cars, but 7-9 degrees warmer temps with a new radiator and fresh Dex?! Anyone else experience this?
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
No, but then you don't know if that's the first change of coolant since the car was new. If so, it's a little late. Altho not usual, the thermostat's just an operating piece that eventually can do funny things; I would've changed it, too. But I don't think that's the problem, nor do I think you have a problem. 208 is not something to be concerned about IMO. Just keep an eye on engine and oil temp---it never hurts to do so. That bright pink color is a bit odd since Dex is really much closer to orange. It'd take a lot of WaterWetter to change the color to pink.
Thread Starter
Racer
Joined: Dec 2007
Posts: 461
Likes: 25
From: North OC California
Neglected to mention I also replaced the thermostat with a new 187F unit during the radiator install, although I fail to understand how that would change the operational temperature without any tuning changes. Regardless if it ran at 201 or 208, the thermostat would be wide open anyway, correct?
I wouldn’t have expected to see that drastic of a difference in cooling efficiency between two OEM radiators. A degree or two, sure, but 7 degrees?
I wouldn’t have expected to see that drastic of a difference in cooling efficiency between two OEM radiators. A degree or two, sure, but 7 degrees?
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
I'll let the experts chime in but it seems a bit more but not enough to get concerned about IMO. Glad you did the thermostat! From new, my '08 always ran a little "warm" and seldom went to the mid-190s. In stop-and-go, 223 wasn't unusual, a/c on, ambient temps in the 80s, 90s or higher. I didn't worry--fans on, car cooling when open road. As I said, just keep an eye on everything.
Note: I will assume there are no air pockets in coolant which does happen after a re-do. Make sure coolant recovery tank is up to the mid-point (not too high).
Note: I will assume there are no air pockets in coolant which does happen after a re-do. Make sure coolant recovery tank is up to the mid-point (not too high).
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
What thermostat was in it before? The thermostat rating is when it starts to open. In general they will be fully open 6-10* after that. The coolant temp will be 8-10* above the fully open temp. Sounds like you’re right where you should be with the thermostat you’re using.
Air pockets can also contribute since there will be less coolant in the system.
Air pockets can also contribute since there will be less coolant in the system.
Thread Starter
Racer
Joined: Dec 2007
Posts: 461
Likes: 25
From: North OC California
What thermostat was in it before? The thermostat rating is when it starts to open. In general they will be fully open 6-10* after that. The coolant temp will be 8-10* above the fully open temp. Sounds like you’re right where you should be with the thermostat you’re using.
Air pockets can also contribute since there will be less coolant in the system.
Air pockets can also contribute since there will be less coolant in the system.
There is no air in the system, the temps are completely stable.
Last edited by ZFIDDY1; Nov 13, 2017 at 11:35 AM.
Le Mans Master
Joined: Oct 2000
Posts: 6,507
Likes: 723
From: Sausalito CA
Seems you did a good repair.
I can only emphasize as above, to check for air pockets...make sure the system is full.
Of course take a look at the front of the radiator from underneath to insure there are no leaves or paper blocking air flow. Else, again unsure if a gasket/ sealant is blocking flow at the thermostat. Check water pump weep hole for issues. Make sure electronic fans are coming on as usual. You could also buy a test stripe to calculate the water to coolant ratio.
Else, I have no other helpful comments.
Good luck.
I can only emphasize as above, to check for air pockets...make sure the system is full.
Of course take a look at the front of the radiator from underneath to insure there are no leaves or paper blocking air flow. Else, again unsure if a gasket/ sealant is blocking flow at the thermostat. Check water pump weep hole for issues. Make sure electronic fans are coming on as usual. You could also buy a test stripe to calculate the water to coolant ratio.
Else, I have no other helpful comments.
Good luck.
