proper way to replace coolant
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,107
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From: RI
proper way to replace coolant
Can someone instruct me on how to fill the cooling system on my lt1? I don't want to turn it over without the right amount of antifreeze.
Also, anyone know if teflon tape on the sensor located at the pump is going to uphold?
Also, anyone know if teflon tape on the sensor located at the pump is going to uphold?
Last edited by sonomacrew01; Feb 13, 2006 at 07:10 PM.
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,107
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From: RI
I filled it to the top once. I let it sit overnight and noticed a leak out of the sensor at the waterpump so I disconnected the hose at the bottom of the radiator and no antifreeze came out. I did this to remove the sensor and add teflon tape. Is this supposed to happen?
Pro
Joined: Feb 2006
Posts: 688
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From: Concord NC
The only sensor ive dealed with is the top one(maybe the same one as you) and when mine came out it poured out. Do you have a clogged hose/outlet?? Maybe thats normal. I doubt its anything major. Not much can go wrong with a radiator and not be known. Im sure a more experienced member will chime in. Goodluck 
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
First use a 50/50 mix of distilled water and antifreeze. If you can raise the front end a little, that will help. Open both (I think your yr has 2) bleeders. Be sure to put rags, shop towels etc under them as you don't want the antifreeze pouring onto your opti. Fill @ the surge tank until you get a steady stream of antifreeze from the bleeders. Close them and countinue to top off the surge tank. When full, fire it up and monitor the surge tank filling as necessary. Fill recovery tank to proper mark. Thats about it...no hard driving for 3 complete hot / cold cycles. Check your fluid level after each cycle.
I don't know about the teflon tape tho. some sensors are self grounding. The tape may interfere with that. I'd pull the tape off and use some sealent.
Hope this helps
I don't know about the teflon tape tho. some sensors are self grounding. The tape may interfere with that. I'd pull the tape off and use some sealent.
Hope this helps
Last edited by ittlfly; Feb 13, 2006 at 07:31 PM.
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Pro
Joined: Feb 2006
Posts: 688
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From: Concord NC
BTW its more expensive also. If your tight on cash or just wanna save up for better stuff just go to napa and get the basic antifreeze and its alot cheaper. Its all the same glycerol in the end. Whats a name when its in your radiator. 4-7 dollars more just to say you have that brand? Waste
Safety Car
Joined: Feb 2002
Posts: 4,212
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From: Sun City West Az
Originally Posted by sonomacrew01
is prestone 50/50 ok to use isntead?
Pro
Joined: Feb 2006
Posts: 688
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From: Concord NC
Like I said its better to mix it yourself. The companys are lookng for the cheapest way to premix it and jack up the price. Maybe I just got a bad dose but since you do drive a corvette; naturally you would want the best. Just get bottled drinking distilled water from your grocery store and mix it with the antifreeze. 
Id advise you to flush it out real good to remove any sediments and check your hoses,clamps cap ect. Also may be a good time to replace your thermostat. I reccomend a 160 degree one. My vette runs 150 most of the time. Runs alot better
Pro
Joined: Feb 2006
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From: Concord NC
Likewise with what ittl said about the teflon tape. Id advise against that. It could interfere with your sensors and mess your cooling system up. Your local autopart store sells a jelly like substance to put around the sensors dries instantly. Good stuff 
Team Owner
Joined: Oct 2000
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From: Fort Knox, KY
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NO GO on the coolant sensor tape. The orange coating that comes on them OEM is all you need.
Ditto for the knock sensors. You don't want to alter the sensitivity of the sensors and tape can do that.
When I change the coolant on my LT1, I open the radiator petcock and the cap on the black resovoir tank. Then, I use the reverse thrust feature on my Shop Vac to BLOW all the coolant out of the system.
Once it's empty, I close the petcock, refill it with water and repeat the process until it runs clear (no coolant at all.)
Then, I refill it with the proper mix of coolant, open the bleed screws on the thermo housing and throttle body and monitor the levels for a couple of days to make sure there are no air pockets in the system.
Ditto for the knock sensors. You don't want to alter the sensitivity of the sensors and tape can do that.
When I change the coolant on my LT1, I open the radiator petcock and the cap on the black resovoir tank. Then, I use the reverse thrust feature on my Shop Vac to BLOW all the coolant out of the system.
Once it's empty, I close the petcock, refill it with water and repeat the process until it runs clear (no coolant at all.)
Then, I refill it with the proper mix of coolant, open the bleed screws on the thermo housing and throttle body and monitor the levels for a couple of days to make sure there are no air pockets in the system.
Melting Slicks
Joined: Nov 2002
Posts: 2,471
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From: 1993 Quasar Blue 'vert Scottsdale AZ
I remove the bottom radiator hose from the radiator, let it drain, re-connect, then put in a couple of gallons of distilled water. I run it a couple of days, drain it again and put in proper amt. of water, coolant and a bottle of water wetter. Don't forget to burp the system.
Melting Slicks
Joined: Apr 2003
Posts: 2,150
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From: NS
The correct way to replace your antifreeze, according to the GM Service Manual, is:
1. Drain the system. This gets about 1/2 the antifreeze out.
2. Remove both knock sensors from the block (left and right). Gets the rest of the coolant out. Re-install knock sensors.
3. Refill with straight water.
4. Run until thermo opens, full temperature. Then allow it to cool.
5. Repeat steps #1 - #4 a few times - until the water you drain is clean and clear.
6. Fill with 50/50 mixture of antifreeze. Recheck after a few heat cycles.
I did it to mine last spring. It's easier than it sounds.
1. Drain the system. This gets about 1/2 the antifreeze out.
2. Remove both knock sensors from the block (left and right). Gets the rest of the coolant out. Re-install knock sensors.
3. Refill with straight water.
4. Run until thermo opens, full temperature. Then allow it to cool.
5. Repeat steps #1 - #4 a few times - until the water you drain is clean and clear.
6. Fill with 50/50 mixture of antifreeze. Recheck after a few heat cycles.
I did it to mine last spring. It's easier than it sounds.
Team Owner
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From: Fort Knox, KY
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Originally Posted by Atok
The correct way to replace your antifreeze, according to the GM Service Manual, is:
1. Drain the system. This gets about 1/2 the antifreeze out.
2. Remove both knock sensors from the block (left and right). Gets the rest of the coolant out. Re-install knock sensors.
3. Refill with straight water.
4. Run until thermo opens, full temperature. Then allow it to cool.
5. Repeat steps #1 - #4 a few times - until the water you drain is clean and clear.
6. Fill with 50/50 mixture of antifreeze. Recheck after a few heat cycles.
I did it to mine last spring. It's easier than it sounds.
1. Drain the system. This gets about 1/2 the antifreeze out.
2. Remove both knock sensors from the block (left and right). Gets the rest of the coolant out. Re-install knock sensors.
3. Refill with straight water.
4. Run until thermo opens, full temperature. Then allow it to cool.
5. Repeat steps #1 - #4 a few times - until the water you drain is clean and clear.
6. Fill with 50/50 mixture of antifreeze. Recheck after a few heat cycles.
I did it to mine last spring. It's easier than it sounds.
Believe me, using forced air to drive the coolant out is faster than the procedure in the GM service manual.
Work smarter, not harder, I always say...
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
with the LT1, and reverse flow cooling system, you have no choice but to run the engine with inadequate coolant level at first. 'onedef92' was the only one to mention opening up the bleeder screw on your therostat housing, and this is a critical step to 'burping' or relieving the trapped air pressure from the engine forward. With the engine running, open up the bleed screw(put a rag under the bleed screw to catch the coolant once it reaches the thermo), then tighten it back up once you see coolant coming out.
Le Mans Master
Joined: May 2005
Posts: 7,354
Likes: 2,278
From: Central Maryland
Originally Posted by MikeC4
with the LT1, and reverse flow cooling system, you have no choice but to run the engine with inadequate coolant level at first. 'onedef92' was the only one to mention opening up the bleeder screw on your therostat housing, and this is a critical step to 'burping' or relieving the trapped air pressure from the engine forward. With the engine running, open up the bleed screw(put a rag under the bleed screw to catch the coolant once it reaches the thermo), then tighten it back up once you see coolant coming out.
Also be aware that some LT1s (perhaps all of them) have two air bleed screws. My '94 has one on the thermostat housing, as noted above, and one on the throttle body. Be sure to use both.
Be well,
SJW
Le Mans Master
Joined: May 2005
Posts: 7,354
Likes: 2,278
From: Central Maryland
Originally Posted by onedef92
I did it by the book the first time, too, until I got hung up on the knock sensors.
Believe me, using forced air to drive the coolant out is faster than the procedure in the GM service manual.
Work smarter, not harder, I always say...
Believe me, using forced air to drive the coolant out is faster than the procedure in the GM service manual.
Work smarter, not harder, I always say...
But, I do wonder how much coolant remains in the lower reaches of the block's water jackets using the shop-vac blow-it-out method. Have you tried this, and then yanked the knock sensors to see how thoroughly the block was purged?
I like the idea, but I can't help but suspect that a significant amount of coolant is left behind...
Be well,
SJW