Bad Waterpump or Air in system?
Thread Starter
Staging Lane
Joined: Mar 2011
Posts: 63
Likes: 4
From: Chicago Area
Bad Waterpump or Air in system? I installed a new AC Delco water pump with upper and lower radiator hoses today on my '99 Trans Am with 80k miles. I didn't change the thermostat. It's a 180 degree hypertech unit that maybe has 2000 miles on it. Never had a problem with it.
I started the car up with the cap off and the system full to bleed the system. I squeezed the upper and lower hoses many times to try to work out any air. The temperature rose pretty quick. Right around 210 degrees, the steam vent return hose in the radiator started spitting out coolant. Before my buddy went to turn off the car at about 218 degrees, the level in the radiator rose very quickly and started to overflow. I heard a nasty gurgling/bubbling sound as well when this happened. We shut the car off and the level dropped. The lower hose to the thermostat is still cold.
I tried about a dozen times but the same thing keeps happening.
I loosened the bolts to the thermostat and coolant was there. It started leaking all around it.
I read a bunch of forums and the only new information that I didn't already do was to disconnect the TB coolant hose when filling and keep filling until water comes out of the hose. I just did this fill procedure but it's late so I'll fire it up tomorrow to see if it makes a difference.
Any help is greatly appreciated!!
I started the car up with the cap off and the system full to bleed the system. I squeezed the upper and lower hoses many times to try to work out any air. The temperature rose pretty quick. Right around 210 degrees, the steam vent return hose in the radiator started spitting out coolant. Before my buddy went to turn off the car at about 218 degrees, the level in the radiator rose very quickly and started to overflow. I heard a nasty gurgling/bubbling sound as well when this happened. We shut the car off and the level dropped. The lower hose to the thermostat is still cold.
I tried about a dozen times but the same thing keeps happening.
- Could the water pump be defective?
- It's probably unlikely the thermostat just went bad at this moment.
- Possible air in the system??
I loosened the bolts to the thermostat and coolant was there. It started leaking all around it.
I read a bunch of forums and the only new information that I didn't already do was to disconnect the TB coolant hose when filling and keep filling until water comes out of the hose. I just did this fill procedure but it's late so I'll fire it up tomorrow to see if it makes a difference.
Any help is greatly appreciated!!
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
I always fill using the top radiator hose.I hold the hose up high and fill. It takes a little longer but it always works the first time with very little to be added after warm up. I bet you have air in the system.
Thread Starter
Staging Lane
Joined: Mar 2011
Posts: 63
Likes: 4
From: Chicago Area
Thanks for the tip. I want to try that but I put new Mishimoto hoses on that are super tight and a pain in the a$$ to get on and off. I'll definitly do that on my other car when I do a antifreeze change.
Thread Starter
Staging Lane
Joined: Mar 2011
Posts: 63
Likes: 4
From: Chicago Area
I was able to fix it. It was air and a lot of air in the system after all.
I jacked the nose of the car up pretty high and I also unbolted the steam vent tube on the front of both heads. I filled up the radiator until fluid was starting to come out of the two holes in the heads. I'm thinking I just had huge air pockets in the heads and they were heating up way too fast before the rest of the system. Car holds a steady 187 now. Took 15 minutes for all the bubbles to stop in the radiator. Nice even flow of fluid from the steam vent return now.
I jacked the nose of the car up pretty high and I also unbolted the steam vent tube on the front of both heads. I filled up the radiator until fluid was starting to come out of the two holes in the heads. I'm thinking I just had huge air pockets in the heads and they were heating up way too fast before the rest of the system. Car holds a steady 187 now. Took 15 minutes for all the bubbles to stop in the radiator. Nice even flow of fluid from the steam vent return now.
Yup had the same issue. ANYONE reading this in the future, ALWAYS fill through the upper rad hose (other end attached to the water pump not the upper radiator port) so it goes to the water pump properly. Also replaced a perfectly good pump as I thought the pump was the issue until I realized the procedure is much different than with sbc. Air was in my system, checked 2 different thermostats in hot water and couldn't understand why they wouldn't work installed but worked fine when tested...well obviously coolant wasn't reaching the thermostat making it basically useless. Filled through upper rad hose and all my issues disappeared.
Last edited by foxsl; Dec 23, 2015 at 10:39 PM.
