LT5 Coolant Fill - ZR-1 Net Registry Forums

ralph92ZR1 · 03-29-2007

I need some advice. I have replaced my hoses and clamps after a complete drain of the coolant system. The manual states to flush, fill the system with DI water and the pressure cap on. Run for 3 minutes and drain. Continue draining and flushing until clear. For the final fill with a 50/50 mix of ethylene glycol and DI water, this is added to the neck of the surge tank. Marc's article of Oct. 2005 states watching for jetting from the hose below the pressure cap, thus I believe this is done with the cap off several times to hopefully purge the air. Is this correct??

Thanks for the help. Great to see Spring arrive early.

birddog01 · 03-29-2007

Ralph,
On your final fill you should run car with the cap removed until the thermostat opens. You will know when this happens because the level in the upper radiator tank will drop and should begin to bubble. With the engine off check levels in both the upper tank and the recovery tank. The level in the recovery tank should be at the full hot mark. If not than fill to this mark. Don't worry about air, it goes from the bottom hose below upper resevoir cap to a junction with the plenum air bleed hose and from there to the top right hand corner of the radiator. There is an air bleed access plug on top of the radiator at this location. Hope this helps.

ralph92ZR1 · 04-04-2007

Thanks for the advice. However here is what has happened and I am sort of stumped. I ran the engine with the car on jack stands and level as a flush procedure; then installed a new thermostat {Delco # 10135627 131-51}, ran the engine 3 times with the pressure cap off the surge tank and did observe the jetting of air and coolant out the hose below the neck. I never left the coolant temp read greater than 195 Deg. F. I then allowed the engine to completely cool. No leaks, etc. The next day I put on the pressure cap, and took the car around the block at slow speed until the temp came up to 195 deg F or so; I also watched the level in the recovery tank and filled it to the hot mark. Anyway, normally in the past while driving I could observe the coolant temp get to about 195 deg. F to 200 deg F or so and then drop[indicating the thermostat opening]. However now the temperature rose slow and steady and got to 215 deg, F. without ever showing a drop - indicating the thermostat likely did not open?. So I pulled the car into the garage and allowed it to cool overnight. To my surprise, today the coolant level was still at the "hot" mark in the recovery tank. I know the thermostat is in properly. I called the dealer to verify the Delco number and it is for the LT5 engine; however there was no info on the temp range. He suggested it might be sticking. I wish I had tested it first in boiling water but didn't. As you know it is a pain to drain and open the thermostat housing again but I don't feel comfortable just driving it until I can get some advice from anyone having experienced this. Does anyone know if the Delco #'s are correct?
I appreciate any and all thoughts...

birddog01 · 04-04-2007

Ralph,
Are your fans turning on? It doesn't sound like they are working. Check these before you remove the stat again.

ralph92ZR1 · 04-05-2007

Yes, the fans are working; I just took the car out and even loaned a laser heat sensor to check hose gradients. Anyway, before I left I opened the pressure cap and reseated. For whatever reason the temp rose to 195 deg. F. stayed there for awhile, then dropped to a90 deg. F. This cycle continued for 20 minutes of driving so it seems ok. Then I pulled it in the garage to simulate sitting in traffic. The temp rose to 225 Deg. F., the fans kicked on, and the temp dropped. Alll is well. Maybe the thermostat was stuck initially because it was new.
Thanks to all for the advice.

A26B · 04-05-2007

Ralph,
Sounds pretty typical to me. I think air gets trapped and takes a couple of driving/rpm/thermal cycles to work out.

jonszr1 · 04-06-2007

you might want to try a tuner to change the f an on temp.I never like the fact that the fans didn't come on till 225 i had mine reset to 190 on and am tons happier now. jmho

ralph92ZR1 · 04-06-2007

I'm going to check on a Haibeck chip.

Thanks

03-29-2007	#1
ralph92ZR1 Join Date: Dec 2005 Location: Shillington, Penna. Posts: 67	LT5 Coolant Fill I need some advice. I have replaced my hoses and clamps after a complete drain of the coolant system. The manual states to flush, fill the system with DI water and the pressure cap on. Run for 3 minutes and drain. Continue draining and flushing until clear. For the final fill with a 50/50 mix of ethylene glycol and DI water, this is added to the neck of the surge tank. Marc's article of Oct. 2005 states watching for jetting from the hose below the pressure cap, thus I believe this is done with the cap off several times to hopefully purge the air. Is this correct?? Thanks for the help. Great to see Spring arrive early.

03-29-2007	#2
birddog01 Join Date: Feb 2007 Location: central NYS Posts: 26	Re: LT5 Coolant Fill Ralph, On your final fill you should run car with the cap removed until the thermostat opens. You will know when this happens because the level in the upper radiator tank will drop and should begin to bubble. With the engine off check levels in both the upper tank and the recovery tank. The level in the recovery tank should be at the full hot mark. If not than fill to this mark. Don't worry about air, it goes from the bottom hose below upper resevoir cap to a junction with the plenum air bleed hose and from there to the top right hand corner of the radiator. There is an air bleed access plug on top of the radiator at this location. Hope this helps.

04-04-2007	#3
ralph92ZR1 Join Date: Dec 2005 Location: Shillington, Penna. Posts: 67	Re: LT5 Coolant Fill Thanks for the advice. However here is what has happened and I am sort of stumped. I ran the engine with the car on jack stands and level as a flush procedure; then installed a new thermostat {Delco # 10135627 131-51}, ran the engine 3 times with the pressure cap off the surge tank and did observe the jetting of air and coolant out the hose below the neck. I never left the coolant temp read greater than 195 Deg. F. I then allowed the engine to completely cool. No leaks, etc. The next day I put on the pressure cap, and took the car around the block at slow speed until the temp came up to 195 deg F or so; I also watched the level in the recovery tank and filled it to the hot mark. Anyway, normally in the past while driving I could observe the coolant temp get to about 195 deg. F to 200 deg F or so and then drop[indicating the thermostat opening]. However now the temperature rose slow and steady and got to 215 deg, F. without ever showing a drop - indicating the thermostat likely did not open?. So I pulled the car into the garage and allowed it to cool overnight. To my surprise, today the coolant level was still at the "hot" mark in the recovery tank. I know the thermostat is in properly. I called the dealer to verify the Delco number and it is for the LT5 engine; however there was no info on the temp range. He suggested it might be sticking. I wish I had tested it first in boiling water but didn't. As you know it is a pain to drain and open the thermostat housing again but I don't feel comfortable just driving it until I can get some advice from anyone having experienced this. Does anyone know if the Delco #'s are correct? I appreciate any and all thoughts...

04-04-2007	#4
birddog01 Join Date: Feb 2007 Location: central NYS Posts: 26	Re: LT5 Coolant Fill Ralph, Are your fans turning on? It doesn't sound like they are working. Check these before you remove the stat again.

04-05-2007	#5
ralph92ZR1 Join Date: Dec 2005 Location: Shillington, Penna. Posts: 67	Re: LT5 Coolant Fill Yes, the fans are working; I just took the car out and even loaned a laser heat sensor to check hose gradients. Anyway, before I left I opened the pressure cap and reseated. For whatever reason the temp rose to 195 deg. F. stayed there for awhile, then dropped to a90 deg. F. This cycle continued for 20 minutes of driving so it seems ok. Then I pulled it in the garage to simulate sitting in traffic. The temp rose to 225 Deg. F., the fans kicked on, and the temp dropped. Alll is well. Maybe the thermostat was stuck initially because it was new. Thanks to all for the advice.

04-05-2007	#6
A26B Join Date: Dec 2003 Location: Arcadia, OK Posts: 3,392	Re: LT5 Coolant Fill Ralph, Sounds pretty typical to me. I think air gets trapped and takes a couple of driving/rpm/thermal cycles to work out. __________________ Jerry Downey JERRYS LT5 GASKETS & PARTS http://www.jerrysgaskets.com 1994 *ZR-1*, Black/Black, Lingenfelter Aerobody, 416cu in, 3.91 gears, coil-over susp, Brembo brakes, etc. 2016 Black-Red, 3LT-Z51 Auto 8-speed.

04-06-2007	#7
jonszr1 Join Date: Sep 2006 Location: lone pine and mammoth lakes Posts: 1,406	Re: LT5 Coolant Fill you might want to try a tuner to change the f an on temp.I never like the fact that the fans didn't come on till 225 i had mine reset to 190 on and am tons happier now. jmho

04-06-2007	#8
ralph92ZR1 Join Date: Dec 2005 Location: Shillington, Penna. Posts: 67	Re: LT5 Coolant Fill I'm going to check on a Haibeck chip. Thanks