Cooling system flush, etc. on an LT4
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
Cooling system flush, etc. on an LT4
Any good write ups on doing a cooling system flush and fill on a '96 LT4? I've only had gen 1 stuff up until this point, so reverse cooling, bleeder valves, etc, are all new to me. Thanks!
Advanced
Joined: Mar 2018
Posts: 60
Likes: 8
From: Tulsa OK
I would really suggest you find a BG dealer in your neck of the woods that has the coolant flush machine. It is a ton better than what you can do yourself or at least what I have been able to do in the past by myself. It also lubricates and cleans the rust out of your complete cooling system IE Block, water pump, heater core, radiator ect. It cost a bit, but it is well worth it, especially on a Vette.
Bobo
Bobo
Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
When car is cool drain radiator passenger side Then pull two knock sensors ( watch for coolant on body where full mask throw away paper suit etc coolant is a hazard to man and paint. Then buy distilled water at walmart two gallons is enough pour in passengers side black tank. Then start and run car for 4 minutes. Then shut car off and wait till cool Then start again and add coolant as it reaches temperture the stat will open then release above stat bleed screw and wait for full stream and no bubbles.Take car for ride and watch for warning lites and temperture rise. Shut car off and when cool top off with coolant G20 i believe is the one
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
In the procedure above^....when did you flush/drain??
Dear lord....that is massive over kill.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Supporting Vendor
Joined: Oct 2004
Posts: 761
Likes: 68
In the procedure above^....when did you flush/drain??
Dear lord....that is massive over kill.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Dear lord....that is massive over kill.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
I guess I am curious how bad your system is. If you pull the KS and find a bunch of oily gunk, you might have to get the oil out. IIRC, MB uses a procedure to de-oil and then decalcify any crud there. Now if you are having coolant for 20 years and just topped off every so often, I'd probably go that route to be sure. OTOH, if you have been cleaning regularly, I'd probably be ok going to some place where I can watch them flush the coolant if you don't want to risk it going all over the place or let it flow into the storm sewer some dark night and hope nobody calls it in to the cops. Your call.
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
NO !!! The C4 cooling system capacity is not 8 quarts - it's 16 quarts. Draining the radiator and pulling the block drains - then pouring in only two gallons of distilled water only is a good way to warp the heads !!!
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Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
In the procedure above^....when did you flush/drain??
Dear lord....that is massive over kill.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Dear lord....that is massive over kill.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
2 gallons of distilled water plus 2 gallons of coolant makes 4 total gallons ot 16 quarts since it is 4 quarts to a gallon, isn't it?
Race Director
Joined: Sep 2001
Posts: 14,680
Likes: 752
From: NEwhere Ohio
Only way to do it right is remove both knock sensors.
in fact, i believe a speed shop (before i knew how to do the work myself) didnt do this during a head/cam swap and the brake parts cleaner they sprayed to clean the deck got into my cooling jacket around the block.
a year or two later the upper radiator hose blew at a race from dry rot - likely weakened from the inside out by solvents.
in fact, i believe a speed shop (before i knew how to do the work myself) didnt do this during a head/cam swap and the brake parts cleaner they sprayed to clean the deck got into my cooling jacket around the block.
a year or two later the upper radiator hose blew at a race from dry rot - likely weakened from the inside out by solvents.
Last edited by dizwiz24; Apr 21, 2018 at 04:23 PM.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
Only way to do it right is remove both knock sensors.
in fact, i believe a speed shop (before i knew how to do the work myself) didnt do this during a head/cam swap and the brake parts cleaner they sprayed to clean the deck got into my cooling jacket around the block.
a year or two later the upper radiator hose blew at a race from dry rot - likely weakened from the inside out by solvents.
in fact, i believe a speed shop (before i knew how to do the work myself) didnt do this during a head/cam swap and the brake parts cleaner they sprayed to clean the deck got into my cooling jacket around the block.
a year or two later the upper radiator hose blew at a race from dry rot - likely weakened from the inside out by solvents.
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
When car is cool drain radiator passenger side Then pull two knock sensors ( watch for coolant on body where full mask throw away paper suit etc coolant is a hazard to man and paint. Then buy distilled water at walmart two gallons is enough pour in passengers side black tank. Then start and run car for 4 minutes. Then shut car off and wait till cool Then start again and add coolant as it reaches temperture the stat will open then release above stat bleed screw and wait for full stream and no bubbles.Take car for ride and watch for warning lites and temperture rise. Shut car off and when cool top off with coolant G20 i believe is the one
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
In the procedure above^....when did you flush/drain??
Dear lord....that is massive over kill.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Dear lord....that is massive over kill.
Fastest, best way to do it on an LT1:
1. Drain radiator and block as described above with the radiator drain and knock sensors (both sides).
2. Remove the upper radiator hose from the t-stat housing, then use that hose as a flush port, to flush out the radiator using a garden hose. Flush 'till drain water runs clean from the radiator, shouldn't take long. Re-connect rad hose to t-stat housing.
3. Remove the heater core hose from the water pump, connect to a garden hose and now you're "reverse" flushing the heater core and flushing the heads and block all at the same time, water will come out the block drains (knock sensor holes). Flush until clean -shouldn't take long.
4. Re install knock sensors, hear core hose, fill system with premixed coolant or mix your own with distilled water, top off, open bleeders until coolant comes out, close bleeders and top surge and over flow tanks...you're done.
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
I guess I am curious how bad your system is. If you pull the KS and find a bunch of oily gunk, you might have to get the oil out. IIRC, MB uses a procedure to de-oil and then decalcify any crud there. Now if you are having coolant for 20 years and just topped off every so often, I'd probably go that route to be sure. OTOH, if you have been cleaning regularly, I'd probably be ok going to some place where I can watch them flush the coolant if you don't want to risk it going all over the place or let it flow into the storm sewer some dark night and hope nobody calls it in to the cops. Your call.
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
Thanks for the word of caution. I'll make sure it's full!
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
Thanks for the vote. Feeling confident about it, and yea...I have two big jugs of the full strength, and will get some distilled water.
Thread Starter
Burning Brakes
Joined: Apr 2007
Posts: 1,003
Likes: 13
Only way to do it right is remove both knock sensors.
in fact, i believe a speed shop (before i knew how to do the work myself) didnt do this during a head/cam swap and the brake parts cleaner they sprayed to clean the deck got into my cooling jacket around the block.
a year or two later the upper radiator hose blew at a race from dry rot - likely weakened from the inside out by solvents.
in fact, i believe a speed shop (before i knew how to do the work myself) didnt do this during a head/cam swap and the brake parts cleaner they sprayed to clean the deck got into my cooling jacket around the block.
a year or two later the upper radiator hose blew at a race from dry rot - likely weakened from the inside out by solvents.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
Have the shop pull the sensors and see what comes out. If some rusty stuff comes out, I'd have them backflush it with a hose. If not, constant maintenance will work. I just keep my cars on the same pattern as the 3 MBs. So every 3, drain and replace coolant, every 2, flush brakes. Truck has long life coolant so every 100K