RandomTask

Sounds stupid, have you changed the radiator cap? System needs pressure else the coolant will start to boil and temps go up. Try throwing an 18lb cap on there?

austinseanchris

Have not tried to turn on the heat yet...will definitely try that.

austinseanchris

I havent ever changed the cap. Its been the same cap thats been on it since Ive owned it(8 years now). Its a Stant 15lb cap and looks like new inside and out.

383vett

Blown head gasket

austinseanchris

No hydrocarbons in coolant(block test kit) and no loss of fluid loss?

fparkin

you got all air out of system? must t look and see water pump running when car running that is a little strange it gets 260 is catalyst converter ok.

austinseanchris

I can honestly say I dont know. I cracked open the bleeder valve on too of the thermostat housing until fluid came out and then tightened it back down. That being said, to me, I would imagine it would be more involving than something that simple?

austinseanchris

2 brand new pumps in which both are getting power and you can hear it turning w/o the car cranked...

austinseanchris

No cats either...

ex-x-fire

Pull off a heater hose, start up, it should pour out like a garden hose. Simple flow test.

vetteLT193

I'd bet money it's a loose connection. Double the ground wire to a second spot, check all the connections, and install a small led light somewhere where you can see that the pump has power.

A buddy of mine set his up to light when it is working and turn off when the pump fails. He also added an override switch so he could run it with the car off for quicker cool downs at the track

austinseanchris

I will try a flow test sometime this weekend as well as checking for connections and will report back.

Tom400CFI

I like the "Check the heater" test. It's less messy than the "garden hose" test...and it works. If you've got HOT heat...your water pump is pumping water.

I don't "get" why the second fan is coming on either. It should hit ~230, first fan should come on, and the temp should start dropping pretty quickly....especially in 40* temps!

austinseanchris

Well when I was driving it home on the initial day of the overheating, I turned the heat on to see if itd bring the temps down. It blew out heat, then it went to cold and hot to cold.

As far as the fans go, the second fan comes on at 236. So usually under normally conditions, the first fan comes on at 226 and brings the temps down. In the event it does not, while the first fan is still on, the second fan comes on at 236.

As of the last two times I cranked it, it did fine thru the first heat cycle. It got to about 240 and the temps dropped to 218. By the time the temps were nearing 230, the puke tank was about to overflow so I shut it off.

belairbrian

I know you changed it out about 4 years ago? But it sounds like a radiator or Fan issue. The first fan should have an effect unless it's really hot out. You mentioned that when the second fan comes on it pulls down from 236 to 215.

If you aren't moving coolant the second fan would have no effect.

Could be a fan blade slipping on the shaft. Could be partial blockage on the first fan side of the radiator.

Just seems the second fan pulling the temp down, points to the fans or radiator.

Beyond that, maybe a collapsing hose, but I assume they were new 4 years ago.

Tom400CFI

That's a clue. It shouldn't be going cold. I'd re-check that now. If you're temp gauge is over ~140* or so...and you don't have HOT heat all the time, you're either low on water, or you're not moving water. One or the other. Or both.

austinseanchris

Well, over the last 2 days, I think I've possibly figured out what may be going on. I've been taking into consideration everything you guys have recommended.

Just to re-iterate things here...lets recap what is currently installed that is new(and when I saw new, I mean within 4 years and no more than 1000 miles:
-AFR 195 Super Comp heads, comp rockers, comp cam, timing chain, new delco opti, new plugs, new wires & ported intake. Car dyno tuned once all completed.
-Mezeire electric water pump(took the one from 4 years ago off and put a new one on 3-4 months ago. No miles on it yet.
-Three diff 180 degree thermostats. Checked first one when removed and put in boiling water on stove. Performed as it was supposed to. Prior to installing other 2, checked them on stove as well and worked as intended.
-New Be Cool aluminum radiator
-Two different 15lb radiator tank caps
-Tried bleeding air from bit on top of thermostat housing until fluid came out. Once trickling out, I tightened it shut.

That being said, I'm aware I'm kinda beating a dead horse here, but just kinda double checking things to be positive that I havent overlooked anything.

So I started with the hoses to make sure none were leaking, dry rotted or collapsing. Also checked the metal hoses as well leading to radiator & puke tank.
-No hose problems while off or idling. Check!

Opened bleed valve on t-stat housing until coolant came out and re-tightened it. When car was running, tried squeezing main hoses to see if that helped get air out.
-Not sure if that helped?

Checked the radiator cap for excessive wear and for pressure rating. Tried 2 different identical caps.
-Cap looks new and is a 15lb cap. Check!

Checked radiator up front and behind condenser with a flashlight looking for debris(leaves, trash, etc.).
-Clean as a whistle. Check!

Checked all electrical connections for water pump and MAF sensor.
-Everything plugged in/connected. Check!

Checked to see that the fans were operating as designed.
-First fan comes on at 226 degrees. Second fan comes on at 236 degrees. Check!

Using the NAPA block test kit(purple fluid in pump), I took off radiator cap and performed the test.
-Fluid did not turn green and fluid stayed purple indicating no hydrocarbons in the coolant system. Check!

Tried 3 different 180 degree thermostats.
-After taking first one out and prior to installing other two, checked all 3 in boiling water on the stove. All began to open at 180 degrees. Check!

Took the Meziere electric water pump that I put on 4 years ago off and put on a new identical one.
-I can guarantee power is going to the pump & I can hear it turning. Check!
________________________________________ ________________________________________ _________________________
So yesterday I broke out the funnel kit with radiator tank attachments and installed it on the coolant tank near the firewall. Went ahead and filled it up with as much coolant that it would take. Once coolant was full and a little was sitting in the tank, I began squeezing hoses and bled any possible air out of t-stat housing. Pulled it down a hair but still had a little fluid in the funnel. Puke tank up front was empty. Cranked the car. Was running fine and heating up. After a couple mins, the fluid in the funnel went down a hair. After about 4 minutes, fluid began coming back up through the funnel. I was at 160 degrees. Remember I had a 180 t-stat installed. The puke tank up in the front nose began filling up rather quickly. 170 came and the funnel was about half full. 180 hit and puke tank up front was almost full and starting to smoke from the heat. At 187 I had to shut it off because the funnel was about to overflow and so was the puke tank. When I cut it off, I could hear bubbling and gurgling throughout the hoses. After a few minutes, the coolant in the funnel began to go down and eventually ran back down into the tank. That being said, I was done...

So here we are today. I got to thinking, if I take out the thermostat and do not put one back in, coolant should be able to run free throughout the entire system. Obviously I wouldnt run the car w/o a thermostat but if it still overflows, then that should tell be I have a blockage somewhere, right? More/less an idiot test for me I guess. So I remove the thermostat, hook everything back up. I siphoned out what was in the puke tank up front. Put my funnel back on and poured a half gallon of distilled water into the radiator tank near firewall. Looked in there and it was maybe a third to half way full. Cranked the car...it ran for about 5 minutes before it began coming back up thru the funnel again. At that point it was at about 165 degrees. After roughly another minute, the temp was at 188 degrees and I had to shut the car off b/c the funnel was about to overflow again with coolant. Once I shut it off, I could hear it gurgling and bubbling again. However, nothing went to the puke tank this time. After about 3 minutes of being off, the coolant that was about to overflow out of the funnel, went back down in the the radiator tank and I removed the funnel.

So...all that being said...does this not seem to sound like theres a blockage somewhere? Like maybe coolant isnt flowing completely through the entire system? So now I'm to the point of whats the next step? Do I got ahead and re-drain the radiator and then remove the shroud, and take out the radiator and try hosing it out to make sure nothing is clogged in there? And if I'm ripping that out and making a mess, probably would be a good time to go ahead and drain the block too, right? No reason to half-*** and only drain half the coolant. But the kicker is those knock sensors. I remember when I bought the car 8 years ago, I tried removing those and they played IMMORTAL HELL. Got one out and the other, the housing broke off and I had to get a shop to get it out. But I'm wondering if there could be a blockage somewhere in the engine? Hate to try to take those out and pull that crap again. But, thought it would make sense to get them out and flush the engine with water to ensure nothing is blocked. If I tried blowing compressed air through there, would that help or just "blow" the problem elsewhere? I still think two brand new water pumps being defective are slim pickings. Also, the fluid thats in the car is very clean...no trash, debris, dirty, etc...

Good news = possibly found culprit. Bad news = if I gotta remove knock sensors, I may as well start crying now.

So, that being said...not sure if I've made progress but to me, makes me think theres no circulation? At this point, whats next...?

ex-x-fire

Check for flow at heater hoses.

Tom400CFI

Removing the T-stat won't work in an LT1. The coolant won't flow correctly when the stat is removed.

When it's warmed up, run the heater and see if you have good heat.

austinseanchris

I did check the heat yesterday. Turned it on full blast. It was luke warm at best...Only ran for about 8 mins b/c coolant was about to boil out of funnel and puke tank...

And so you are saying that it will not flow continuously throught engine if t-stat is gone, correct?