88blackiroc

iTrader: (3)

So after going through 3 thermostats. Each time the the car got really hot, close to the red indicator on the temp. gauge, and they all got stuck and finally said f*ck it and removed it. This isnt really revelent as the problem occured with the 160 tstat to.
Anyways what what happens is while cruising to work the car will warm up fine, get to about 190ish and stay there for a while and then start to increase to 220 to 230 then drop back down to 190 for a bit. Then after 5 minutes or so itll repeat. This really is starting to irritate me as its been a problem for a long time. I put in a new radiator and fluid in about a month ago and it hasnt changed anything. If i turn the car off then restart it itll idle a tad low(600 or so) and be fine after i start driving . I thought that their may be air in the system but i thought that these systems bleed themselves? And im not sure if it matters but i also have the heater core byppassed as it broke a while ago and didnt feel like ripping the dash apart to redo it.
sorry for the novel but the more descriptive the better, right? anyways hopefully there is some insight on this !

2win_SS

iTrader: (1)

I kind of had the same prob. U need to bleed air. Jack up car and remove hose from stem line on heads and wait til full stream of coolant comes out. Also you can remove cap and squeeze the upper and lower hose to try and get out air bubble... Try a thread search next time... This is a common issue that has many threads. Goodluck buddy! DNT BLOW THAT LS! or we will find you! Lol

88blackiroc

iTrader: (3)

I have searched.. plenty of times! Never could find the same problem though. I suck at searching. Lol Some similar threads said they self bleed which i guess its true to a extend and Ive tried to do squeeze the lines before with no avail. Tmr ima try to take off the steam hose and wait for coolant to come out. Thanks bud! And if it does blow, well its a good excuse for a upgrade

crainholio

iTrader: (2)

What on/off temps are your cooling fans configured with?

edit: from the factory, my '01 LS1 was configured with the following temps:

Fan 1: 229 on, 222 off (no AC); 215 on, 190 off (with AC)
Fan 2: 237 on, 230 off (no AC); 248 on, 208 off (with AC)

The PCM disables fan 1 at 35mph vehicle speed, fan 2 at 30 mph. At speeds above 30-35mph you're cooling with airflow, not the fans.

So if you're seeing these temps sitting still or at speeds below ~30mph, and you haven't changed the fan settings in software, you're seeing normal operation.

2win_SS

iTrader: (1)

^^^ lol very true! Great excuse for upgrade... And check your fan op. Temps. I forgot to mention that. I didn't reliaze you had a LS in ur 3rdgen.

88blackiroc

iTrader: (3)

Stock tune for the fans. And ive seen both fans on before, yesterday actually. I parked the car when i got home from work and had to go back out right after and i went to start it the temp gauge went up to to 235ish and then back down quickly to 190 after a couple seconds. Popped the hood and both fans were running

88blackiroc

iTrader: (3)

Nope. It will even happen at speeds 50mph and up(not trying to disinclude speeds lower than that as it also happens then to). Im gonna bleed the system to day and see what happens and let you all know.

joecar

Where is the hose from the steam crossover tube plumbed to...?

Pix of your engine bay...

88blackiroc

iTrader: (3)

The very top heater hose fitting. If you want a pic of the whole engine bay, please let me know

2win_SS

iTrader: (1)

Just bleed system of air and get back to us. I'll bet you that's what it is...

djfury05

iTrader: (30)

Yep.. if the overflow tube is ran correctly which it appears as though it is, and the fans are indeed coming on, and there are no leaks.. then that leads me to believe there is air in the system somewhere or not enough coolant.

Get a 180 t-stat and put it back in.

crainholio

iTrader: (2)

There's a black plastic air dam under the car bolted to the lower radiator housing sheetmetal that is critical to cooling while the car is moving. If it's gone, or weakened to the point that it deflects rearward, you'll build heat. Check yours and let us know what you find.

LS6427

iTrader: (2)

The only way temps can move QUICKLY and not a slow gradual climb or drop...

Sticking t-stat that all of sudden opens quickly allowing cool coolant into the heads. ((quick temp drop))

You lose a serpentine while doing a hard highway run........((quick temp spike))

Bad or failing "coolant temp sensor".........((quick temp drops and spikes))

An air pocket in there will cause you to overheat, period. If the air pocket is in there on the engine side of the t-stat, that t-stat will never open, or it will take so long to open from the heat transferring through that air pocket to the t-stat that your temp needle will be in the red before it opens.

I would check the temp at the drivers side head when you see the temp gauge at 200, then pull over and check the same spot when you see the temp at 230. See if it really did rise. If not......"coolant temp sensor" is bad.

Or, try yet another t-stat and bleed it properly.
Proper way and easiest way to bleed:

**Bleeding the system of air:
Take the radiator cap off when its COLD, top it off, start it up and let it idle, and let it warm up till the t-stat opens. I rapidly squeeze the upper and lower radiator hose like 20 times each while its warming up to help move any air bubbles through the system and by the t-stat on the engine side. When the t-stat opens you’ll see the level drop as you squeeze the hoses, its sucking the coolant through the system. You will also see the coolant start to flow in the radiator fill neck, once it starts to flow the level should drop down a lot, IMMEDIATELY top it off with coolant/water. Then the flow will stop when the t-stat closes. Wait one more time for the t-stat to open again and start to flow, if it drops down again top it off again. Do it a 3rd time if you want to make sure. When the level does NOT drop down when the t-stat opens and coolant is flowing....you're system is free of air bubbles. I always squeeze the upper hose during the whole process to keep any air bubbles moving through. Always works like a charm. Just keep checking your temp gauge until the t-stat opens for the first time to make sure it’s not sitting there overheating from a trapped bubble. May take 10-15 minutes for the t-stat to open the first time.
If you do start to get hot while sitting there and the t-stat will not open…..you have a good sized air bubble on the engine side of the t-stat. Shut the engine off and rapidly squeeze the upper and lower radiator hoses again. Then start the engine again and see if the t-stat will open. Sometimes you just have to work those hoses to move the air through. Even after it seems topped off after a couple cycles…check it the next time you have a cold engine…top off if needed.

.

88blackiroc

iTrader: (3)

There is NO tstat. I thought i mentioned that in my first post.(not trying to be a dick)
I did attempt to bleed it though. I got home from work today and me and my dad unhooked the steam tube(warm engine) and started the car and it took a good 3 minutes to develop a solid 'stream'. So hopefully it bled out whatever was in it. Will watch the gauge closely tomorrow for sure!
And the coolant temp. sensor was replaced about 6 months ago when i accidently broke it off. If i have no avail, i shall try your method. Thanks for the infor btw!

wildcamaro

iTrader: (15)

I know it sounds crazy but check your rad cap...could be an easy fix...good luck man

88blackiroc

iTrader: (3)

Replaced last coolant flush a month or so ago

LS6427

iTrader: (2)

Oops, missed that.

Hmmm....with no t-stat you cannot get an air bubble caught in their. Check the temps at the head with a laser temp gauge. When it goes up to 220-230, check it again. I'm thinking maybe the temp sensor is bad....new or not. A lot of new temp sensors are duds.

Running without a t-stat........Usually engines keep getting hotter and hotter, very gradually. But to have a drop of 30-40 degrees without a t-stat......I say its impossible.
Without a t-stat, the engine is nothing but a water heater continuously heating the water/coolant. T-stat regulates temps....

You should put a t-stat in it.....the system will never work properly without it, especially in the hot *** summer.

.

88blackiroc

iTrader: (3)

Out of curiousity, how will the tstat help the engine stay cooler? I thought that without it, not only can the water flow better, but it always will circulate to the radiator. I understand how it helps reach operating temp. but not cool it.
also i just got to work and i saw the gauge yet again go up, then down. So im going to see if i can find a laser temp. Gauge and measure it

joecar

The LSx thermostat has 2 functions:
- open/close/regulate flow from radiator to engine (this is the TS function);
- close/open/regulate flow thru the bypass port (this is the BP function);

BP valve is spring loaded and as TS opens it increases the pressure on the BP valve making it harder to open; BP valve is opened by differential pressure across it: on engine side is pressure from pump pushing coolant thru block/heads, on pump side is low pressure (sucking) from pump inlet;

when TS is closed, the BP opens easily (~5 psi differential pressure), it is effectively open;
when TS is open, the BP is harder to open (10+ psi differential pressure), it is effectively closed;

when TS is closed, BP is effectively open and allows coolant to flow from block to pump (and thru pump and back into block);
when TS is open, BP is effectively closed and blocks coolant flow from block to pump, this forces coolant to flow out to the radiator (goes thru radiator, and returns thru open TS and into pump);

(and here's the point of it) with thermostat removed, the BP is always open, this allows two coolant paths:
1. from block to pump (and pump circulates coolant back into block),
2. from block to radiator (thru radiator and back into pump);

#1 is a low resistance path and #2 is a high resistance path...

so most of the coolant chooses #1 (circulates back into block rather than radiator).

joecar

Heater flow requires a pressure differential across the heater core, this is what the BP valve provides...

the BP valve is directly between the heater core ports on the pump.