Coolant Temp spike
Thread Starter
Le Mans Master
Joined: Sep 2002
Posts: 5,235
Likes: 898
From: Myrtle Beach SC
Coolant Temp spike
Ok, so my 41.5k 2000 LS1 coolant temp spiked to 218 while waiting in beach traffic (50 degree outside temp). The first time I've noticed it but over the years the temp has consistently pegged at 190 so this was a deviation. I checked archives so have read the many comments that 218 isn't anything to worry about and proceeded to follow the guidance listed in the archives. I'll described what I've found and done...if I've missed anything...feel free to offer suggestions and thanks. I also reviewed the shop manual but found the archives much more "user" friendly! 
Checked the baffle and found only minor grass debris. Used compressor with extended blow gun to clear.
Removed K&N filter that I hate to say but I failed to maintain. Debris had pretty much caked up but with a few bangs and the K&N recharger kit cleaned and oiled it...have just finished with it.
It's been five years since I last changed coolant but have only put probably less than 500 miles on the motor. I plan to change it as well but the level seemed fine, perhaps on the low side but doesn't seem enough to cause the temp to go up.
Should I remove the air duct between manifold and baffle and double-check to ensure no debris got sucked in?
Ok...thx!
Checked the baffle and found only minor grass debris. Used compressor with extended blow gun to clear.
Removed K&N filter that I hate to say but I failed to maintain. Debris had pretty much caked up but with a few bangs and the K&N recharger kit cleaned and oiled it...have just finished with it.
It's been five years since I last changed coolant but have only put probably less than 500 miles on the motor. I plan to change it as well but the level seemed fine, perhaps on the low side but doesn't seem enough to cause the temp to go up.
Should I remove the air duct between manifold and baffle and double-check to ensure no debris got sucked in?
Ok...thx!
Melting Slicks
Joined: Sep 2012
Posts: 2,217
Likes: 784
From: Fort Myers Beach Florida
Mine also gets hot in beach traffic. I found it will cool off a bit if the A/C is turned on. I don't think my cooling fans operate properly but they come on when the a/c is on
Drifting
Joined: Mar 2010
Posts: 1,628
Likes: 15
From: Seattle WA
Ok, so my 41.5k 2000 LS1 coolant temp spiked to 218 while waiting in beach traffic (50 degree outside temp). The first time I've noticed it but over the years the temp has consistently pegged at 190 so this was a deviation. I checked archives so have read the many comments that 218 isn't anything to worry about and proceeded to follow the guidance listed in the archives. I'll described what I've found and done...if I've missed anything...feel free to offer suggestions and thanks. I also reviewed the shop manual but found the archives much more "user" friendly!
Checked the baffle and found only minor grass debris. Used compressor with extended blow gun to clear.
Removed K&N filter that I hate to say but I failed to maintain. Debris had pretty much caked up but with a few bangs and the K&N recharger kit cleaned and oiled it...have just finished with it.
It's been five years since I last changed coolant but have only put probably less than 500 miles on the motor. I plan to change it as well but the level seemed fine, perhaps on the low side but doesn't seem enough to cause the temp to go up.
Should I remove the air duct between manifold and baffle and double-check to ensure no debris got sucked in?
Ok...thx!
Checked the baffle and found only minor grass debris. Used compressor with extended blow gun to clear.
Removed K&N filter that I hate to say but I failed to maintain. Debris had pretty much caked up but with a few bangs and the K&N recharger kit cleaned and oiled it...have just finished with it.
It's been five years since I last changed coolant but have only put probably less than 500 miles on the motor. I plan to change it as well but the level seemed fine, perhaps on the low side but doesn't seem enough to cause the temp to go up.
Should I remove the air duct between manifold and baffle and double-check to ensure no debris got sucked in?
Ok...thx!
That being said, 5 years is the lifespan for coolant; time for a flush and fill.
Lets put it this way:
Too Cold-------Perfect---218--------------Getting warm-------230--------Too Hot(240)--Pull OVER!
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Good advice by 8VETTE7 - and I would go ahead and change the coolant just to be up to date with the maintenance.
Thread Starter
Le Mans Master
Joined: Sep 2002
Posts: 5,235
Likes: 898
From: Myrtle Beach SC
Appreciate the tips from all.
8Vette7
Checked all hoses and found none collapsed. Nice and firm and when I squeezed the top hose, the fill tank gurgled.
Interesting exercise to work thru. I haven't changed out coolant yet but went thru the list. At cold, coolant was at bottom of "cold fill" mark. Took forever but once it got to 210, coolant was at full mark and after working through the list, coolant had moved beyond the full mark.
Took it out for a drive, and tho only 52 out, stayed at 190 but the traffic conditions weren't the same that contributed to the 218 mark. I would say cleaning the filter was a significant improvement.
Again thanks!
PS: Also turned A/C on with blower motor on full. Fans came on. Turned them off and watched them spin to a standstill.
8Vette7
You could also have some air that has gotten into the system and can't work its way out. That will often happen if the pressure cap goes bad. Here is the procedure for burping the system:
Took it out for a drive, and tho only 52 out, stayed at 190 but the traffic conditions weren't the same that contributed to the 218 mark. I would say cleaning the filter was a significant improvement.
Again thanks!
PS: Also turned A/C on with blower motor on full. Fans came on. Turned them off and watched them spin to a standstill.
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Joined: Mar 2011
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From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
I agree with the others who have said that 218 is not in the worry zone yet.
But if you have driven the car under similar conditions and it has always stayed around 190 there are a couple of things to check out. When the car is cold, check the top radiator hose. Look to see if the walls of the hose are collapsed and touching one another. This can happen if the pressure cap is bad. The cap has to hold pressure as the coolant gets hot and expands but as the coolant cools it also has to allow atmospheric pressure back in. Dirt in the tiny hole in the cap that accomplishes this can result in the hose collapsing. If the hose is collapsed you need to replace the cap to prevent this from happening again.
You could also have some air that has gotten into the system and can't work its way out. That will often happen if the pressure cap goes bad. Here is the procedure for burping the system:
Start w/ a cold engine
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
But if you have driven the car under similar conditions and it has always stayed around 190 there are a couple of things to check out. When the car is cold, check the top radiator hose. Look to see if the walls of the hose are collapsed and touching one another. This can happen if the pressure cap is bad. The cap has to hold pressure as the coolant gets hot and expands but as the coolant cools it also has to allow atmospheric pressure back in. Dirt in the tiny hole in the cap that accomplishes this can result in the hose collapsing. If the hose is collapsed you need to replace the cap to prevent this from happening again.
You could also have some air that has gotten into the system and can't work its way out. That will often happen if the pressure cap goes bad. Here is the procedure for burping the system:
Start w/ a cold engine
Remove rad. cap
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Start engine
Idle for 1 minute
Install cap
Cycle RPM from idle to 3000 until coolant reaches 210F
Shut off engine
Remove cap
Top off
Thanks,Matt