Id first try burping it again. If you dont have one of these, I highly recommend:
But I'm a big fan of 160 stats and fans on in the 180s. With the iron block you may want to try it too...

EDIT- 04 LM4 alum block.

 

Ahh that makes sense. For some reason I thought he went with a Aluminum 5.3. Yea I would do a 160 T stat and set the fans to come on in the 180's.

 

Ah! I just went back and found that its an 04, LM4, so it's AL. Good catch! Shouldn't be having an issue being alum, but Im still a fan of the cooler stat and lower fans and that overflow funnel tool.

 

Possible air or pump rpm not sufficient. Where do you have the cyl head vents plumbed to? Highest point in system? Whose water pump do you use? I prefer AC Delco OE, part number 251-xxx. Side note - for vehicles that don't have a cooling system vent or air bleed valve at the top of the system, this is the best way to fill system - Airlift 550000 Even with a vent, this is the fastest way to fill any cooling system. Lastly, a 180F stat is fine. GM spec'd 195F primarily for emissions purposes.

 

probably got air in. I’m gonna work at that first.
I have the factory 2004 gto water pump. 104k miles. Worked fine on the other engine. I’m gonna drive it up on ramps and keep burping it. Iirc I had this happen once before. When the air pocket finally came out, it was a big ole air bubble in my funnel that connects to the cap fitting.
I have the factory cylinder head crossover in the front and I added one to the rear and tapped it into the hose that goes to the front.

 

Good call. Big fan of getting rear port coolant lines instead of blocking them off.

 

its aluminum.

 

I fill mine through the upper tad hose into the pump. I leave the steam vent connections loose st the heads. As the coolant reaches the rear vents and dribbles out, tighten and keep filling until the fronts leak.

Put the radiator hose hose back on and fill the radiator to full.

I have the factory 4 corner steam tubing connected to the radiator just below the fill cap but above the coolant level. With the cap off I can see the flow.

The radiator cap is the highest point in the system. But just filling it w/o doing what I described always results in an air pocket somewhere.

Those vacuum fill things are good and necessary for lots of modern cars.

 

I think it’s better now. I put it on ramps and let it idle for a while. Pulled the fan relays and let it get up to 210 ish. It got a good bit of bubbles out. I think I’m gonna flush the system. It’s got some trash in it from the other motor when I changed head gaskets. I tried my best to not get that graphite **** in the cooling jackets but it was impossible. I may flush it Saturday and put the lowest mix of coolant I need to keep it from freezing up. I’m drill a couple holes in the thermostat too. That should help burp it better.

 

So I rode around till about 1am Friday night. Ride around Saturday and Sunday trying to put some miles on it and tweaking my tune. I didn’t want to say anything just yet, but I was disappointed in the car at first. As you guys know, while it was apart I put the medium hardness polyurethane motor mounts in. Man it was harsh as ****. I was stressing. It was also transmitting more noise along with the vibration. For a few days I could hear the pistons slapping it rattling until the engine gets up to temp. I know, forged pistons and a .005 piston to cylinder wall clearance, it’s bound to make some noise. Being that my car is quieter than the norm, I could hear every noise very well. I was honestly considering changing the motor mounts first. Then I was gonna pull the engine out and have the skirts coated. Add this along with my higher coolant temps and my damn ac not working. I was very disappointed. So......

I worked out the air bubbles as the coolant temp is more stable now.
I drove the car to work yesterday and sucked the system down and found it didn’t have much Freon in it. Crap. Must have a leak. Put some dye in and traced it to the schrader valve. Whew. Easy fix. Ac blowing cold now.

so at first, when I’d leave my house, it low key sounded like a diesel at low rpm. And it had lots of vibrations I could feel. This isn’t what I want in a street car. I want quiet and smooth. I asked around and a few friends told me the poly mounts need a little breaking in before things smooth and quiet out. Well they are right. I put about 300 miles on it this weekend and it sounds much quieter and smoother. Like it was when I had the stock motor in it. So I feel better now. I think the pistons still make just a little noise till the coolant temp is 100. It seemed it worse when I cranked it in the 30ish degree outside temps. Now it’s warmed up over the weekend and I don’t hear anything. I went by my buddy’s house and told him about the slight noise. He asked what my piston to wall clearance was. I told him it was .005. He said well if I wasn’t boosted I’d want it a little tighter but he said he likes to see .005 on a boosted application and he said it’s going to make a little noise till it warms up. He said he’d rather it be .005 and have a little noise when cold than to be tighter and no noise but be pushing 15+ psi to it. Now when it’s warmed, it’s quieter than my stock motor.

I didn’t hear anything today or yesterday. So maybe it’s only in freezing temps.

I ended up putting some Fosgate separates in the doors last night. That’s a sign I’m happy now. I really enjoyed driving it this weekend. Now I gotta install all the other crap I have for it. Amps, remote start, 2 step, meth injection etc. I’ve been collecting stuff for quite a while.

 

Glad to see the car is "settling down". Finally got my meth kit sorted, I think you'll be a fan. If you want some real fail-safes for it let me know and I can share.

 

Well that’s some progress then and sounds like you fixed any bugs. Must feel great to drive it now for sure. One day when mine is built I know I will be stressing haha.

 

i'm all ears!

yep, i drove it to work today. Finally go the DFCO to work properly. I gotta work on the tune to get better fuel mileage....it got like 14mpg this morning lol.

I get paid in the next day or so, i'm gonna hit up summit and order my Map sensor so i can do my boost timing retard.

 

I don't have a progressive (got screwed buying a used kit, long story) so I went with an adjustable boost switch for turn on (1-15 psi adjustable). So my fail-safes are as follows and you can adapter them to your kit as you see fit. It may be overkill to some but I've seen to many horror stories where either the pump got stuck on with the car off and hydrolocked the motor or the kit didn't work when it should have and blew the motor.

• Boost switch sets minimum pressure to provide ground to the relay that activates the pump.
• Power to the relay is a switched ignition source which prevents a short in the boost switch or if I pressure test the cold side with the car off from accidentally turning the pump on and dumping meth into the car with it off. With the car running if the meth turns on you know immediately because itll bog the car at idle and the LED indicator will turn on (2 bullets down).
• I run a solenoid on the output of the pump which must also be activated in order for meth to flow. Others use a check valve. Ensures no siphoning of meth when the kit is off.
• I run an LED indicator to show when meth if flowing, but this is powered from a 50 psi hobbs switch that is placed POST solenoid in the meth feed line. This guarantees that if that LED is on I have at least 50 psi of meth flow in the feed line. Other kits just "assume" that it's on because the pump is drawing current.

 

So I had planned on switched power. And using my iat sensor to pick up the drop in temp to add a little timing. The meth will only be used as supplemental to higher boost levels. I don’t plan on tuning for it to be dependent on it....if possible. My boost controller will be used to activate it at a predetermined level.

where did you get the pressure switch?

 

hobbs switches are all of the place and relatively cheap. McMaster Carr or Amazon etc. Some are adjustable. I happen to have 1 left over in the parts drawer and measured it with a compressor and it tripped at 50 psi.

 

I never thought about the pump running while the car was sitting then your engine is wasted that would suck! Sounds like you have a good fail safe system good job man.

 

Thnx!

 

I have a Hobbs switch I got in my Fore kit that I will sell. Has the harness and a barb fitting already installed. Worked perfectly. $25 shipped.

 

Glad to hear you got to log some good miles on the car Kfxguy. Get with us when you're ready to order the MAP sensor and we'll get that going for you.