Killer_Z

iTrader: (1)

ok hears the deal. a few months back my car started over heating, the water pump was bad, it was leaking, so I changed it to a new style ls2, w/ new stat. car ran fine for about 2-3 months, then out of the blue it started overheating again, i would let it sit then it worked normal. wierd.

so when it did it again, I changed the oil, and flushed the. drained it stuck a hose w/ valve open until it came out clear. put new fluid, and burped it. read a few articles. once again, car ran perfect for another month or so. then randomly over heated again. let it sit for about 30 min, didn't do anything and started running fine again.

so got home, changed the thermo, thinking it might have gotten stuck, put a 160* in there, ran perfect until the day before yesterday on my way to an interview. pulled over car off for a few minutes, like 10 or so. didnt do anything turned around and made it home ran normal.

so I changed the temp sensor and the radiator cap. ran to the store still over heating. ugh. so got home, opened the radiator. water boiling, and turned on the car after the pressure was released, and slowly ran water int he radiator with the car on, to top it off.

yesterday morning i followed a step i read a few threads down, and disconnected the coolant hose from the tb and ran water again car on, until the water was running threw the tb coolant hose.

I made it to my interview, rescheduled. made it there and back no problem. so far seems to be fine. but thought it was fine after I did all the other stuff too. I dont want to be in the middle of traffic and it happen again.

all times fan's turned on. I hooked up a actron scan tool on my way there and back to my interview maybe 50miles round trip. and the coolant temp shows a steady 210ish. peaking at 227. while gauge on the dash shows under 210. my torque pro on my phone shows 160, even w/ the 180* stat in it. so all 3 gauges are showing different readings.

am i missing something or is this sign of head gasket? I checked the oil from when i changed it. and did not see any water in the container. so i dont see it being a gasket issue, i hope.

any more suggestions. I can't shell out a few grand to get the head gasket's changed. If i'm gunna shell out that type of money i might as well go w/ a tsp stage 2.5 ls6 heads and cam kit. that is under 3k and maybe find people to help install for bear and pizza!!

Please help this guy out. i'm getting upset. my car has been insanely reliable no issues until now.

LS6427

iTrader: (2)

Sounds like a blown head gasket........

Changing head gaskets doesn't cost 3,000....it costs more like $300 in labor and $100 for new gaskets. If you can find a mechanic to do it on the side at your house. It takes 4 hours start to finish.

Put a pressure tester on and see if its leaking down pressure......if it does leak down and you do not see the leak externally....DO NOT start the engine until you remove ALL 8 spark plugs and turn the engine over to get the water/coolant out of the cylinder that it leaked into, otherwise you can lose the entire engine if you try to start it with coolant in a cylinder.
If it leaks down pressure....you have a blown head gasket.

160 tstats are not good.....go back to the 180, you will get better cooling.

.

LS6427

iTrader: (2)

Sounds like also a bad radiator cap but you said you replace it. Did you replace it with an 18psi cap...?

Maybe also top the system off WITHOUT a tstat installed so you know 100% sure that you DO NOT have an air bubble in there......put the cap on. Go for a ride until you are up to operating temp.....pull back into your driveway and drive the front end up on ramps. Wait 15 minutes.....then come back and look for external coolant leaks......

You could have a leak somewhere that's spitting coolant out.....then sucking in a lot of air after it starts to cool. That big void of air in the system will cause the coolant to boil much faster than it will if its topped off with no air bubble.....

.

LS6427

iTrader: (2)

Also...you could remove the tstat and top it off...then go for a long ride on the highway at a steady 65mph (max)......see if it boils over and overheats. If it doesn't, then the tstat is bad.
City driving without a tstat will most likely cause overheating pretty fast though.....

(bring some jugs of water with you....lol)

.

Killer_Z

iTrader: (1)

K I will try the suggested this weekend. Maybe I can find a local fbody guy to help.

scotty2000ss

iTrader: (2)

Did you get the job??

Killer_Z

iTrader: (1)

And yes the cap is 18 psi.

Killer_Z

iTrader: (1)

Lol. Not yet. Waiting to hear back for 2nd interview with the ceo.

oh and should I buy a new ls2 chain while i'm doing the gaskets? might as well pay a lil extra and get the ARP bolts.

oh and might as well do wires and plugs, since its needed anyways.

LS6427

iTrader: (2)

NO need for the chain....no need for the bolts.......factory stuff is all you need.

IF......its a blown gasket and the heads need to come off....get a valve job and have them mill the heads if needed. Make sure they are straight before putting them back on.

Re-use all factory parts......none of those kinds of upgrades make any power.

.

RPM WS6

iTrader: (3)

When you say "overheating", what do you mean?

227°F is not overheating, in fact that's the factory cut-on temp for the low speed fans. I would certainly expect to reach that temp idling in traffic on a hot day, unless your fans have been programmed to engage earlier and they are unable to cool the engine.

If you are seeing temps like that while cruising at steady speed for extended periods, only then would there be reason for concern.

FiredUpZ28

In the 80's the fans wouldn't even come on until 235*F. 227 is far from overheating. I think 250-260 is considered overheating. 230-240 is just hot, that's all. Maybe vac n fill the cooling system. You seem to have had it opened up enough. Maybe there is some air in that sucker.

LS6427

iTrader: (2)

227*F is a sign of a problem with an aluminum LSx engine. I have never seen temps like that with the 3 LSx engines Ive owned.....including my new iron 390ci.
227 is not overheating....but its hotter than it should be for an FBody. Vettes run hotter than FBodies.........

A healthy cooling system should keep any LSx engine (N/A set-up) no more than 220*F in city driving. 185-190 highway.

He said the coolant was boiling.....that means air is in the system. Where its coming from is the question.

That's why he needs to remove the tstat and go for a ride (highway only) and see if it still boils over or gets pushed into the overflow tank......

.

Killer_Z

iTrader: (1)

227* was the last temp after I changed the sensor and cap. B4 the needle would get burried. Didn't have the gage but the cel would trigger enuf to where it retarded the timing. Happened one time driving home and I was around the corner from my home and car cel came Cuz needle burried when I pulled up into the driveway. So that's what 280+ I believe.

Aren't the head bolts tty?

Killer_Z

iTrader: (1)

Steady driving at 60 it maintained a 200-205* but around town 227 was tops with new cap and sensor. Wonder if i should get it completely flushed. Might be the best bet. Hasn't noticed any odd noises no water in oil from the oil change. And no performance loss.

LS6427

iTrader: (2)

Flushing doesn't fix overheating problems. If the coolant is clean its something else.

Next time the engine is dead cold.....take the radiator cap off and top it off with water. Then start it up and let it idle until the temp starts to come up.
Wait until the tstat opens.......**Keep checking the temp of course while you wait***
As soon as the tstat starts to creep open you will also start to see the coolant squirt from the hose coming from the cross-over hose. Then when the tstat fully opens you should see the coolant drop down and/or start to flow fast. Top it off immediately......do not wait.
Then......when the tstat closes the flow will stop. WAIT again till it opens and you see the same flow begin. Top it off again if needed. You can do that a third time if you want....but after two times of topping it off it should be free of all air.
Note***while you are waiting for the tstat to open if you grab the throttle and rev it, if the coolant level drops down during the rev.....you have air in there waiting to be bled out. So do that process 2-3 times and you will get it all out.

Note 2**** If you are standing there waiting for the tstat to open and it keeps getting hotter and hotter and you never get flow....you have an air bubble on the engine side of the tstat. The only way to get it past the tstat is to rapidly squeeze the upper and lower radiator hoses while the engine is running. Just keep trying......the bubble will pass.

If you do that, then go drive and you still overheat and/or get boiling coolant......you have a blown head gasket.

.

Killer_Z

iTrader: (1)

K. I'll give that a shot. Now upper and lower hoses. Got a pic of exactly which they are? I'm assuming it's the 2 thin ones that are together. Not the one coming off the stat to the radiator. Also do we not have a valve to bleed it? Didn't see em on n e of the hoses.

Thanks for the help btw. Greatly appreciated. Just been scratching my head Cuz it works fine then out of no where it over heats. Needle burries.

LS6427

iTrader: (2)

Upper hose is the big one that runs across the fan shroud and connects to the water pump. The lower hose is the same size hose that has the tstat attached and runs to the bottom passengers side of the back of the radiator.

There is no bleed valve.

If its running cool, then all of a sudden gets hot.....that usually means a sticking tstat.

.

Killer_Z

iTrader: (1)

K. I'll do that for good measure. That's what I thought. Sticking thermo. But happened again after changing it.

RPM WS6

iTrader: (3)

Sounds like everything is fine then. Those previous spikes to 280°+ were in fact a problem and way too much heat. Perhaps your last round of repairs has fixed it.

You will continue to see a peak of 227°F in traffic/idling situations on hot days so long as you have stock fan settings. 200ish at cruise in mild weather is to be expected with the stock 187°F t-stat. On cool/cold days, you should see the steady speed cruising temps drop to the mid-low 190s with the stock t-stat.

If that's the case, then every stock LS1 engine ever built and driven in hot weather has a problem.

All four of mine have reached these temps in hot summer weather, while idling in traffic with stock fan settings. Low speed fans engage at 227°F and turn off at 218°F. This is normal behavior on hot days in traffic. You can easily change this with fan tuning, but that's how they are when stock.

I agree that if you are seeing 227°F as a continuous reading while cruising at steady speed in mild weather, then there is cause for concern. The stock t-stat is a 187°F unit, so the engine should be much cooler than 227° during sustained, steady speed cruising or in very cool outside temps.

Did any of them have the factory stock fan settings? Even here in Chicago, which isn't nearly as hot as FL, I would reach 227°F on hot days during extended idling in traffic, then the fans would kick on (low speed), and temp would come down - exactly how GM designed it. And that was even when these cars were brand new.

Killer_Z

iTrader: (1)

Yeah I figure 227 is normal for in town and traffic. But it's so random when it happened. I think I discovered the problem. I went to the store yesterday and noticed a significant puddle under the car. I think that could be letting air in at times. That leak n e ways. B4 I dismissed it as ac because the puddles were small. So I think that leak is letting air in. Or am I way off in thinking that?