Cooling System R&R
12-03-2010, 11:55 AM
#1
Safety Car
Thread Starter
Cooling System R&R
Hey guys,
I just finished changing all the fluids in the Z. The only thing left to do is the cooling system. For years I did that service on my old 92 LT-1 so I'm not completely unfamiliar with procedures. That said, the LT-5 is some what different according to the FSM.
Last time I had it done by the dealership. I prefer to do it my self though. That way I know it is done right. Are there any ''tips and tricks'' that I should be aware before I jump into the project? Thanks in advance.
I just finished changing all the fluids in the Z. The only thing left to do is the cooling system. For years I did that service on my old 92 LT-1 so I'm not completely unfamiliar with procedures. That said, the LT-5 is some what different according to the FSM.
Last time I had it done by the dealership. I prefer to do it my self though. That way I know it is done right. Are there any ''tips and tricks'' that I should be aware before I jump into the project? Thanks in advance.
12-03-2010, 01:01 PM
#2
The LT-5 can be finicky with air pockets. You need to be careful when doing the LT-5. I pour the coolant in very slowly and it works for me. Another trick is to have the car elevated as described in the article below by Marc.
Just go slow and take your time. If you rush and get air pockets, it can be a pain in the *** and if you are not careful and don't know you have an air pocket, you can do damage to the motor.
You want to only use the green coolant. They have it at Napa and it meets 1825M GM Spec. You also want to mix with distilled water only.
To be extra careful, you can measure the amount of coolant you took out compared to how much coolant you put in to make sure its equal.
Read this article in its entirety.
http://zr1specialist.com/HAT%20Web/a...%20Coolant.pdf
Good Luck
Just go slow and take your time. If you rush and get air pockets, it can be a pain in the *** and if you are not careful and don't know you have an air pocket, you can do damage to the motor.
You want to only use the green coolant. They have it at Napa and it meets 1825M GM Spec. You also want to mix with distilled water only.
To be extra careful, you can measure the amount of coolant you took out compared to how much coolant you put in to make sure its equal.
Read this article in its entirety.
http://zr1specialist.com/HAT%20Web/a...%20Coolant.pdf
Good Luck
12-03-2010, 02:20 PM
#3
Le Mans Master
It's really straightforward if you are just changing the coolant. Open the pressure cap, and then open the radiator drain plug on the passenger side. About 3 gallons will come out. Close the radiator, and add coolant back in.
I've never had this problem, but if you can't put in as much coolant as you drained out, check out Marc Haibeck's tip for this: http://zr1specialist.com/HAT%20Web/a...%20coolant.htm
You will also want to remove the unpressurized overflow tank by the passenger side headlight well. There are like three bolts that hold it in, plus the coolant line to it. Then you can remove it, clean it out, and reinstall it.
I've never had this problem, but if you can't put in as much coolant as you drained out, check out Marc Haibeck's tip for this: http://zr1specialist.com/HAT%20Web/a...%20coolant.htm
You will also want to remove the unpressurized overflow tank by the passenger side headlight well. There are like three bolts that hold it in, plus the coolant line to it. Then you can remove it, clean it out, and reinstall it.
12-03-2010, 04:23 PM
#4
Safety Car
Thread Starter
It's really straightforward if you are just changing the coolant. Open the pressure cap, and then open the radiator drain plug on the passenger side. About 3 gallons will come out. Close the radiator, and add coolant back in.
I've never had this problem, but if you can't put in as much coolant as you drained out, check out Marc Haibeck's tip for this: http://zr1specialist.com/HAT%20Web/a...%20coolant.htm
You will also want to remove the unpressurized overflow tank by the passenger side headlight well. There are like three bolts that hold it in, plus the coolant line to it. Then you can remove it, clean it out, and reinstall it.
I've never had this problem, but if you can't put in as much coolant as you drained out, check out Marc Haibeck's tip for this: http://zr1specialist.com/HAT%20Web/a...%20coolant.htm
You will also want to remove the unpressurized overflow tank by the passenger side headlight well. There are like three bolts that hold it in, plus the coolant line to it. Then you can remove it, clean it out, and reinstall it.
My concern is tackling the thermostat housing itself...getting it back together without leaks. Seeing some of the responses here and at the ''other'' forum, some of you guys don't mess with it doing the radiator and over flow bottle.
Just how bad is it to crack open the T. housing and avoid leaks ie: seal, hoses????
Thoughts?????
12-03-2010, 04:55 PM
#5
Burning Brakes
Member Since: Oct 2002
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refill per Mac website.
Filling the LT5 With Coolant
Marc Haibeck
Sometimes even a simple thing like refilling the engine with coolant can become a huge problem. I have found that about half of the time, there can be some difficulty refilling the engine if over three quarts of coolant are removed for service. This is a serious situation because the engine can become very hot although the temperature gauge shows that the engine is somewhat cool. This is because the coolant sensor cannot measure the overall temperature of the engine if coolant does not flow past the sensor.
The engine holds about 15 quarts of coolant. This includes the heater and the black surge tank. It does not include the overflow reservoir under the right headlamp. In general it is a good practice to collect and measure the coolant that is removed from the engine. This way the refilling can be monitored and one will know if there is a going to be difficulty before the engine is started. As the coolant is poured in, the air vent tube located just below the filler cap should bubble with air as the engine fills. Install the cap, start the engine, and within a few seconds remove the cap and add coolant until the surge tank is full. The air vent should be streaming coolant. A complete refill is about 14 quarts. The remaining quart is then added to the overflow reservoir and then the engine will draw in the final amount that it needs on the next cool-down cycle. If this happens, you should be thankful for having a lucky day.
If the engine accepts only 12 quarts or less, this is usually the first sign of a refilling problem. If the air vent tube does not bubble as the coolant is added, this is another sign that you are heading for trouble. Install the cap, start the engine, and within a few seconds remove the cap and add coolant until the surge tank is full. If the air vent tube is not steaming coolant when the engine is running, the system is air locked. This can be very stressful for the engine. At the same time, one can observe that the temperature gauge is not moving. It can also be observed that the left camshaft cover is becoming very hot, often over 125 degrees, too hot to touch, but the left water manifold tube going to the radiator is nearly cold. This is why the temperature gauge is reading low, there is no coolant flow. The engine block is building heat quickly, and there is no coolant flow. The engine should not be allowed to run for over three minutes with this condition present.
In this situation, it will often be found that the engine is filled to the top of the injector housings. This can be verified by removing a throttle body coolant hose and coolant will be found at the fitting. How can the engine be filled to the top, but two or more quarts of coolant are missing from the fill? The problem is that there is an air bubble in the engine. Where? The tip-off is the fact that coolant is not flowing from the vent tube. The problem is that the water pump is air locked. Then the pump cannot move the coolant.
In the past, I have used a procedure that I wrote about in the October ’05 issue of the newsletter. I have found that it sometimes helps, but some engine still won’t completely fill with my previous procedure.
I have found a new method that has never failed to fill an engine. The solution is simple; lift the right side of the car to allow the air to rise up to and flow out of the right side of the engine.
When the height of the right side of the car reaches the critical point, the air vent tube will begin to bubble and the engine will accept more coolant. Place the car back in the level position. Install the cap, start the engine, and within a few seconds remove the cap You will be glad to see that the vent tube is streaming coolant. This means that the pump is circulating the coolant. Add coolant until the surge tank is full. Install the cap. Fill the overflow reservoir about three-quarters full. On the next cool down, the last quart will be drawn into the engine.
Filling the LT5 With Coolant
Marc Haibeck
Sometimes even a simple thing like refilling the engine with coolant can become a huge problem. I have found that about half of the time, there can be some difficulty refilling the engine if over three quarts of coolant are removed for service. This is a serious situation because the engine can become very hot although the temperature gauge shows that the engine is somewhat cool. This is because the coolant sensor cannot measure the overall temperature of the engine if coolant does not flow past the sensor.
The engine holds about 15 quarts of coolant. This includes the heater and the black surge tank. It does not include the overflow reservoir under the right headlamp. In general it is a good practice to collect and measure the coolant that is removed from the engine. This way the refilling can be monitored and one will know if there is a going to be difficulty before the engine is started. As the coolant is poured in, the air vent tube located just below the filler cap should bubble with air as the engine fills. Install the cap, start the engine, and within a few seconds remove the cap and add coolant until the surge tank is full. The air vent should be streaming coolant. A complete refill is about 14 quarts. The remaining quart is then added to the overflow reservoir and then the engine will draw in the final amount that it needs on the next cool-down cycle. If this happens, you should be thankful for having a lucky day.
If the engine accepts only 12 quarts or less, this is usually the first sign of a refilling problem. If the air vent tube does not bubble as the coolant is added, this is another sign that you are heading for trouble. Install the cap, start the engine, and within a few seconds remove the cap and add coolant until the surge tank is full. If the air vent tube is not steaming coolant when the engine is running, the system is air locked. This can be very stressful for the engine. At the same time, one can observe that the temperature gauge is not moving. It can also be observed that the left camshaft cover is becoming very hot, often over 125 degrees, too hot to touch, but the left water manifold tube going to the radiator is nearly cold. This is why the temperature gauge is reading low, there is no coolant flow. The engine block is building heat quickly, and there is no coolant flow. The engine should not be allowed to run for over three minutes with this condition present.
In this situation, it will often be found that the engine is filled to the top of the injector housings. This can be verified by removing a throttle body coolant hose and coolant will be found at the fitting. How can the engine be filled to the top, but two or more quarts of coolant are missing from the fill? The problem is that there is an air bubble in the engine. Where? The tip-off is the fact that coolant is not flowing from the vent tube. The problem is that the water pump is air locked. Then the pump cannot move the coolant.
In the past, I have used a procedure that I wrote about in the October ’05 issue of the newsletter. I have found that it sometimes helps, but some engine still won’t completely fill with my previous procedure.
I have found a new method that has never failed to fill an engine. The solution is simple; lift the right side of the car to allow the air to rise up to and flow out of the right side of the engine.
When the height of the right side of the car reaches the critical point, the air vent tube will begin to bubble and the engine will accept more coolant. Place the car back in the level position. Install the cap, start the engine, and within a few seconds remove the cap You will be glad to see that the vent tube is streaming coolant. This means that the pump is circulating the coolant. Add coolant until the surge tank is full. Install the cap. Fill the overflow reservoir about three-quarters full. On the next cool down, the last quart will be drawn into the engine.
12-03-2010, 05:00 PM
#6
Burning Brakes
Member Since: Oct 2002
Location: pa
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If you leave the rad cap in place when draining (hot)it will suck the overflow dry. for such a low milage car with a change with in the past few years you should be ok....
(you should just sell it
)
(you should just sell it
)
Last edited by Zproud; 12-03-2010 at 05:09 PM.
12-03-2010, 08:16 PM
#7
Le Mans Master
I get the idea here about draining the radiator at the petcock and emptying the overflow tank. In talking with Marc a few years ago *I recall* he mentioned that one needs to open up the thermostat housing to drain the block. Only draining the radiator will not empty the block so a lot of the old antifreeze is still in place. (like the LT-1, you have to remove the 2 knock sensors from the bottom of the block in order to get a complete drain)...just draining the radiator won't get all the antifreeze out.
My concern is tackling the thermostat housing itself...getting it back together without leaks. Seeing some of the responses here and at the ''other'' forum, some of you guys don't mess with it doing the radiator and over flow bottle.
Just how bad is it to crack open the T. housing and avoid leaks ie: seal, hoses????
Thoughts?????
My concern is tackling the thermostat housing itself...getting it back together without leaks. Seeing some of the responses here and at the ''other'' forum, some of you guys don't mess with it doing the radiator and over flow bottle.
Just how bad is it to crack open the T. housing and avoid leaks ie: seal, hoses????
Thoughts?????
However, I'd suggest you drain via the radiator petcock and decide for yourself. 3 gallons at least will come out. The system only holds about 3.5 gallons total.
That's nothing like an LT1 where about a gallon comes out the radiator, then another gallon each comes out of each knock sensor hole.
12-03-2010, 09:30 PM
#8
Safety Car
Thread Starter
I'd change the thermostat if I bothered to open the housing. It's not hard to do. There is of course some risk of breaking a hose fitting from the small plastic-clipped hoses that connect to the top. And there's some risk of cross threading it or damaging it some other way. Anything is possible, though it's not like some risky procedure. It's pretty easy to do it right and have no problems.
However, I'd suggest you drain via the radiator petcock and decide for yourself. 3 gallons at least will come out. The system only holds about 3.5 gallons total.
That's nothing like an LT1 where about a gallon comes out the radiator, then another gallon each comes out of each knock sensor hole.
However, I'd suggest you drain via the radiator petcock and decide for yourself. 3 gallons at least will come out. The system only holds about 3.5 gallons total.
That's nothing like an LT1 where about a gallon comes out the radiator, then another gallon each comes out of each knock sensor hole.
I was not aware that you could get 3 gallons out of the system via the radiator. That's good enough for me. I won't bother with the T housing at all.
12-03-2010, 10:27 PM
#9
If you remove the overflow tank, you want to make sure you get the hose on tight. If not, it can drip and overtime, you can lose a lot of coolant. Drips are hard to see because they run inside the front bumper assembly and then eventually drip on pavement. My coolant reservoir is always like new so I leave it alone. On my lt-1, I've had it dirty before and yanked it out for a thorough cleaning.
12-11-2010, 08:12 PM
#10
Safety Car
Thread Starter
Hey Guys...Here's an update.....I finally got a ''few minutes to myself'' to change out the antifreeze. In draining the radiator I only got approx 6 measured quarts. and....just over 2 quarts out of the overflow bottle.
Since the system holds about 15 quarts, I left about 1/2 behind in the block??. By not opening the T-stat housing I*assume* that made the difference. I don't understand why I didn't get more out via the radiator??
I guess that it will be fine since the coolant is changed out every year. (done in previous years by the dealer).
I did however use the coolant sold at Napa auto supply that meets GM 1825-M mixed 50/50 with distilled water. Maybe next year I'll be brave enough to crack the T-stat housing and get most of the coolant flushed out.
BTW..no problems on the refill with air blocks. I did do the filling real SLOW though.
Since the system holds about 15 quarts, I left about 1/2 behind in the block??. By not opening the T-stat housing I*assume* that made the difference. I don't understand why I didn't get more out via the radiator??
I guess that it will be fine since the coolant is changed out every year. (done in previous years by the dealer). I did however use the coolant sold at Napa auto supply that meets GM 1825-M mixed 50/50 with distilled water. Maybe next year I'll be brave enough to crack the T-stat housing and get most of the coolant flushed out.
BTW..no problems on the refill with air blocks. I did do the filling real SLOW though.
12-12-2010, 08:04 AM
#11
Le Mans Master
Weird. A lot more comes out of my radiator when I drain it. Maybe mine is the exception. That said, the factory recommendation is 2 years/30,000 miles with just draining what comes out of the radiator. So I personally would not be concerned about it.
If you've never changed the thermostat, I'd probably want to do that sometime as it would be 15-20 years old.
If you've never changed the thermostat, I'd probably want to do that sometime as it would be 15-20 years old.
12-12-2010, 09:35 AM
#12
Safety Car
Thread Starter
Weird. A lot more comes out of my radiator when I drain it. Maybe mine is the exception. That said, the factory recommendation is 2 years/30,000 miles with just draining what comes out of the radiator. So I personally would not be concerned about it.
If you've never changed the thermostat, I'd probably want to do that sometime as it would be 15-20 years old.
If you've never changed the thermostat, I'd probably want to do that sometime as it would be 15-20 years old.
