Do i need to bleed the cooling system after..

[Lucky90]

Its late here on the east coast and i took off the plate on top of the throttle body ,because a little coolant was leaking. Since the plate is at almost the highest point on the motor, did i let air into the system and do i have to go thru the trouble of bleeding the system. Thanks fellas. Oh my zr1 is a 90 if it matters.

[XfireZ51]

Its late here on the east coast and i took off the plate on top of the throttle body ,because a little coolant was leaking. Since the plate is at almost the highest point on the motor, did i let air into the system and do i have to go thru the trouble of bleeding the system. Thanks fellas. Oh my zr1 is a 90 if it matters.

Let it sit overnight w cap off expansion tank.

[Dynomite]

Its late here on the east coast and i took off the plate on top of the throttle body ,because a little coolant was leaking. Since the plate is at almost the highest point on the motor, did i let air into the system and do i have to go thru the trouble of bleeding the system. Thanks fellas. Oh my zr1 is a 90 if it matters.

No you do not have to bleed the system if you only let out a bit of coolant to that level of the top of the TB. You have to get the air out if you lowered the coolant level down to the water pump (say about to center of water pump pulley).

If you do drain more coolant..... Post 8 - LT5 Radiator and Initial Coolant Fill Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp.html#post1580070559)

[Lucky90]

Thanks guys, very informative.

[tomtom72]

There are two things I notice everytime I do my cooling sys service. One is a tip from Marc Haibeck: just make the right side of the car higher than the left. You don't need much, maybe 6" at max. My discovery: if you pour the new coolant in slowly so as not to cover completely the air bleed fitting in the neck, you get most of the air out quickly even with out the right side being higher.

I think the air bleed is the top hose in the neck. I can't remember, but as you fill and get a bit of coolant over it you can see it blowing bubbles. Just don't submerge it and you will pack the system....ofcourse it takes longer to fill.:o

:cheers:
Tom

[scottfab]

Its late here on the east coast and i took off the plate on top of the throttle body ,because a little coolant was leaking. Since the plate is at almost the highest point on the motor, did i let air into the system and do i have to go thru the trouble of bleeding the system. Thanks fellas. Oh my zr1 is a 90 if it matters.

Not likely to need burping based on the above but for future reference.
Simplest burping method I've found is to simply remove the small coolant hose the goes to the TB on the driver's side. Remove it right at the TB and prop it pointing straight up. Add coolant slowly until you see a bit come out of the TB coolant connector. Reconnect. You're done. No tilting the car, no waiting a long time for the coolant to settle, no running the car up to temp and wait etc.

[Dynomite]

If you do not let coolant drain below the middle of the water pump...then NO as in your case....but if you drain below that level...then YES.

Trouble is.......no amount of "burping by gravity" will get that air out of the air locked water pump. You can blow (with your own lungs) a pressure of 5 ft of water as a comparison to lifting one side of the ZR1 or LT5 only a few inches higher. You may get lucky and the water pump spin up a little water to start flushing air but usually that is not the case.

The problem is that the Water Pump cavity is above the outlet ports (red line in photo). Air gets stalled above the water line and the pump becomes air locked spinning the air with no water movement.

http://i287.photobucket.com/albums/ll142/dynomite007/C%20Engine%20LT5/947bedc9-e7b2-4998-9234-45830bc8f7e7.jpg

As you can see in the photo, just raisng the Z or other gravity solutions may get a bit more water in the water pump because you are lifiting one port higher than the other. You may get lucky and after a couple trials get enough air out of the water pump by gravity. The Best Method is to FORCE the air out of the Water Pump.

When I blow into the Drivers Side crossover (disconnected from Drivers Side Injector Housing Manifold and CONNECTED to Passenger Side Injector Housing Manifold) I force water into the passenger side port of the Water Pump and up to the top of the water pump in that narrow path on Passenger Side of Water Pump. That forces air out of the Water Pump through the Drivers Side Port of the Water Pump.

See Details for forcing the Air out of the Water Pump Area in this thread :thumbsup:

Post 93 - Filling With Coolant and the Air Locked Water Pump (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-5.html#post1581827089)

[tomtom72]

Okay, I know I want to ask this Q: how come all of us don't blow head gaskets after we do a cooling sys flush & refill?

I get what the visual about the pump impeller housing vs the ports' location. What I can't square is that how then can you fill the system with all the hoses connected and just the top tank open?

:o
:cheers:
Tom

[tomtom72]

:o sorry Lucky90 for the hi-jack! My bad.

Hi Cliff!:)

:cheers:
Tom

[Dynomite]

Okay, I know I want to ask this Q: how come all of us don't blow head gaskets after we do a cooling sys flush & refill?
I get what the visual about the pump impeller housing vs the ports' location. What I can't square is that how then can you fill the system with all the hoses connected and just the top tank open?
:cheers:
Tom

You CANT fill the system with all the hoses connected completely with water....you WILL have air in the Water Pump Area. The Water Pump Impeller will catch a little water at the bottom of the water pump and start throwing it around sucking in a bit of fresh water and then throwing that around and pretty soon you have all the air out of the water pump. But not all the time and that is with TB Coolant path NOT blocked.

It is a bit less risky.......Because in your case you have not blocked TB coolant which is an air path back to the coolant tank for air. You still have the issue but with that TB path open and lifting the car a bit you can usually get some water in the water pump area enough to get the water flushing out air on first start.

But as you know.....Marc has his special method for a reason as many of you have run into the air locked water pump but catch it on first start up BEFORE blowing the Head Gasket :D

ALL of you do not Blow Head Gaskets because you do not let the situation get that far ;)

As an aside...You know Marc makes a TB Heat Bypass Line TB Heat Bypass Line (http://www.zr1specialist.com/HAT%20Web/products/throttle%20body%20heat%20bypass.htm) and he installs that rather than totally Blocking TB Coolant like I do. I talked with Marc and he does not Totally Block TB Coolant for a specific reason. Guys will drop coolant and then end up blowing his installed Head Gaskets because of the difficulty of solving the Air Locked Water Pump without that TB coolant path in place.

BUT NOT Cliff as he came up with a fool proof solution to the Air Locked Water Pump (with TB Coolant TOTALLY Capped off) on both a 90' and 91' :D

Filling With Coolant and the Air Locked Water Pump (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-5.html#post1581827089)

As you can see in the photo, just raisng the Z or other gravity solutions may get a bit more water in the water pump because you are lifiting one port higher than the other. You may get lucky and after a couple trials get enough air out of the water pump by gravity. The Best Method is to FORCE the air out of the Water Pump.

http://i287.photobucket.com/albums/ll142/dynomite007/C%20Engine%20LT5/947bedc9-e7b2-4998-9234-45830bc8f7e7.jpg

Once you get the air out of the Water Pump, Water Flow Dynamics flushes out any remaining air at high spots in the Injector Housing Coolant Manifolds even with TB Coolant Totally BLOCKED.

[scottfab]

Its late here on the east coast and i took off the plate on top of the throttle body ,because a little coolant was leaking. Since the plate is at almost the highest point on the motor, did i let air into the system and do i have to go thru the trouble of bleeding the system. Thanks fellas. Oh my zr1 is a 90 if it matters.

Not likely to need burping based on the above but for future reference.
Simplest burping method I've found is to simply remove the small coolant hose that goes to the TB on the driver's side. Remove it right at the TB and prop it pointing straight up. Add coolant slowly until you see a bit come out of the TB coolant connector. Reconnect. You're done. No tilting the car, no waiting a long time for the coolant to settle, no running the car up to temp and wait etc.

When I replaced my water pump I did do some burping. Here is something I found on the subject of burping if you really really really worried about it:
"You might notice some bubbling of coolant out of the open radiator (or reservoir) during warm up. This bubbling is normal if you have air trapped in your system, and is caused by the air escaping as it reaches the area of the open radiator cap. Unless the bubbling is excessive, continue to let the engine run at idle for a few minutes once it reaches normal operating temperature, then shut it down. Allow the engine and cooling system to cool off, preferably overnight. Then check your coolant level again. If it dropped, that means you've displaced some of the air in your system. Refill to proper levels, and repeat the process. Do this until the level doesn't drop any longer, then replace your radiator cap and check your coolant levels at least monthly, or weekly during hot weather."

[Lucky90]

Good tip, thanks.

[Dynomite]

Okay, I know I want to ask this Q: how come all of us don't blow head gaskets after we do a cooling sys flush & refill?

I get what the visual about the pump impeller housing vs the ports' location. What I can't square is that how then can you fill the system with all the hoses connected and just the top tank open?

:o
:cheers:
Tom

By getting lucky...

An anology might help explain. Take an empty quart jar and tip it upside down and lower it into a bucket of water. The jar remains full of air even though the water surrounding the jar is much higher. Now tip the jar a bit and see some bubbles rise from the bottom end. You will now see the water level in the jar has come up a bit but there is still a lot of air inside the jar. Your water pump empeller is in that jar :D

The Air Bleed Hose Junction is nothing more than a "T" that connectes radiator top vent, TB coolant vent and passenger side coolant reservoir. With TB coolant eliminated that is reduced to a line from the top of the radiator to the passenger side coolant reservoir.

Filling With Coolant and the Air Locked Water Pump (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-5.html#post1581827089)
You do not have to wait over night Hoping you heated the water pump area up enough to draw coolant into the area of the water pump impeller by running without coolant flow the night before.

[scottfab]

Nope we don't blow head gaskets. It's like magic. The car will pull in coolant without jacking, loosening, joggling or nothing!!! wow. Read for the the way the FSM says to burp the system !!

I check my oil regularly. And opening the reservoir cap is
just right there. Imagine that? There is no panic, no quandary, no drama, just topping the coolant. It's magic. :dancing

Okay, I know I want to ask this Q: how come all of us don't blow head gaskets after we do a cooling sys flush & refill?

I get what the visual about the pump impeller housing vs the ports' location. What I can't square is that how then can you fill the system with all the hoses connected and just the top tank open?

:o
:cheers:
Tom

We don't blow head gaskets because of magic.
Back when I first got my car I had to replace the water pump.
I filled it. Ran the engine for a bit with the cop off just like the FSM
says. Once it got to temp I topped off the reservoir,, again
just like the FSM says. Let her cool. Refilled.
Ran it again. Cooled over night then topped it off one more time.
The system burps itself. It's like magic or something. Even with
all the impossible air pockets and everything. It's almost like the
the LT5 was designed that way or something. It would seem that
when the engine cools down a partial vacuum is created thereby
pulling coolant in, wow. This is all assisted by this wonderful
device called the "Air Bleed Hose Junction".
Here is a pic of the "Air Bleed Hose Junction". Sorry it's blurry
but you can still see the good stuff.
http://zr1.net/forum/picture.php?albumid=199&pictureid=2341

[Dynomite]

I check my AMSOIL 10W-40 engine oil regularly also :handshak:
And Carter makes a very nice Billet Aluminum Cover for my Radiator Overflow Reservoir Cap........
and other Billet Aluminum covers....his best so far being the Oil Filter Cover :thumbsup:

Before I forget...any of you guys/gals ever use a 9mm Wireless Inspection Camera?
I been having a lot of fun looking at the tops of my pistons and cylinder walls lately :D
And for you that want to look under the Plenum, look for oil leaks or coolant leaks in tight places......just asking ;)

1991 LT5
http://i287.photobucket.com/albums/ll142/dynomite007/D%20Engine%20LT5/f6da30fd-c4c0-4c81-9e31-f7510aaf14f2.jpg

1990 LT5
http://i287.photobucket.com/albums/ll142/dynomite007/A%20Corvette%20LT5%2090/f1e67ee1-dca6-4b7e-b799-feb1ba5026d5.jpg