hebelracing1

Ok guys, new to the forums, but not new to the world of cars or repair them. I have a decent background in the Chevy 350's. I recently was requested to work on my uncles 96 camaro with the ls1. He had a overheating problem, got the thing darn hot. He had someone else replace the water pump, and the thermostat, and after doing so, the mechanic told him it'd be wise to replace the head gaskets. So I under took this task. Tore it all down, replaced the head gaskets , also he thought the heads may be warped, so we out a set of replacement heads on that I had acquired. I thoroughly cleaned the heads and installed them. Got the whole car together tonite. Fired it up, motor sounded great, then, it happened. The motor still overheats, it can run for about 5-8 mins and the temp gauge is pegged and the overflow starts spewing like a fire hydrant. I followed all protocol for bleeding the air outta the cooling system, and I am really stumped on this one. A few things of interest, both radiator hoses get pressurized while the motor warms up, the drivers side hose stays cold by the radiator, passenger side one warms up fairly decent during warm up. The temp gauge in the instrument cluster tops out, and the fans don't kick in for another 3 mins or so, as if the coolant is staying in the engine and not going through the water-pump? The hoses are hooked up according to what I have read from other portions of this site, also this was a Florida car, and while it was down there the heater core was leaking and it was removed and the hoses routed together. So this is what I know, my knowledge of the reverse cooling system is minimal, so any words of encouragement and tips are greatly appreciated.

LS6427

iTrader: (2)

Unless he put an LS1 in it....a 96 will have an LT1 engine.

Usually when an overflow tank starts pissing out coolant, either air is getting pushed into the cooling system or you have a line routed wrong to the overflow tank.

I would take the t-stat out, put the housing back on and see what happens. If it runs ok, you have a bad t-stat.

If it still gets coolant pissing out the overflow, you have a head gasket issue and air is getting pushed into the cooling system.

.

BOBS99SS

iTrader: (2)

^ good advice,

BOBS99SS

iTrader: (2)

op did your uncle
put in a ls1?

hebelracing1

I apologize, late night posting after a full day of working on this beast, it is a LT1, sorry for the typo, when the car heats up there are no visible bubbles in the radiator, so I don't think the head gasket is bad, I'd hope not since its brand new, I've burped and bleed the thing numerous times, I get a nice stream of coolant out the bleed valve. I'll have to check the thermostat, that seems to be the next logical step. The lines to the overflow tank appear right. The highest line under the radiator cap is routed to the overflow tank, and the next one down is routed to the t.b. So I will take another crack at it, but this is what I know.

LS1121

iTrader: (17)

When you have the cap off of the radiator can you see the coolant flow? Maybe the radiator is plugged?

hebelracing1

I hadnt really noticed, as the motor warms up I reinstall the cap as the fluid starts to expand and come out the cap opening. When I was filling the radiator after the rebuild it did take a full jug and a half of coolant, plus a jug full of water.

LS6427

iTrader: (2)

5-8 minutes is not enough time to even get to operating temp at idle.........even if the t-stat is stuck closed. Really, the only way to get the coolant thats sitting in the heads to get so damn hot, so damn fast to where its blowing it out of the overflow......is a blown head gasket.

Heat is one thing, these engines should be able to get to 260 degrees and you should have ZERO boiling over of coolant......its when air is in there that shoots the temps UP fast. Then the added coolant system pressure from a blown head gasket will push the coolant out of the overflow, pushing it past the radiator cap.

Maybe do a simple coolant system pressure test.......but make sure you remove all 8 spark plugs. Because if you do have a pressure drop during that test, coolant could be filling a cylinder and then if you start it you could hydralock it and lose the engine completely. Make sure all cylinders are clear of coolant/water by turning it over with the plugs still out to get the coolant to shoot out of the plug holes.

Air is getting in there if coolant is boiling over. My engine has seen 260 two times when I lost my serpentine belt during a highway run.....zero boiling over of coolant. Just had to let it cool down. No air = no boiling over of coolant.

Take the t-stat out and go for a drive. That will tell you something if it does not boil over in 5-8 minutes.

.

hebelracing1

I say 5 to 8 mins, but the first time it really took 10 to 15 mins, the 5 to 8 was after letting it cool down for 30 mins or so, I do have a cooling system test kit, and I will do as you suggest. Like I said ,I don't have a working knowledge of these reverse cool systems , what I wonder, as I have read from other topics, is if the water pump is turning the coolant at all. The radiator hoses pressurize but do not get hot when the temp gauge pegs out. Also I wonder if this is the case since the cooling fans do not turn on even after the temp spikes. If the heads are boiling hot but there is no coolant flow, then the water-pump is not hot, hence why the fans don't turn on, cuz correct me if I'm wrong but the fans are controlled by the sensor in the water pump. The only time the fans did turn on was the initial engine run after the rebuild which was after about 10 to 15 mins.

LS6427

iTrader: (2)

I'm not an LT1 expert about the temp sensor location.....but the water pump always moves water, no matter what. Unless you're one in a million that has a sheared shaft, its so ridiculously rare.......but it happened to someone here this year actually.
If its sheared, yes, there's your whole problem.

Taking out the t-stat like I mentioned above, is also the only way to see if the water pump is really moving the coolant.......take it out, put the housing back on, top off the coolant/water, start the engine with the radiator cap still off....coolant will immediately start to move. If its not, the water pump shaft is sheared.

So you need to do this NEXT.....let us know what happens after you do that.......

.

hebelracing1

UPDATE!!! Alright, so after pondering your advice, I went straight for the kill, and took of the inspection cover of the water-pump. The turbine spins freely by hand so my guess is the shaft is stripped? I also had a friend turn the motor over and the turbine did not spin as well. Like I said, my uncle had the water-pump put on by another mechanic after he overheated the motor, so I'm guessing that mechanic put it on wrong and ruined the shaft. The motor has not been started since the water-pump was originally replaced, so we did not know if it was good or bad til after I rebuilt the top end.

LS6427

iTrader: (2)

The bell housing on the water pump should spin freely with the belt taken off or loosened.

Only way to see if its really sheared is to start the engine, with the t-stat OUT and see if the coolant immediately starts to flow in the radiator.

.

hebelracing1

Isn't a reverse cooled lt1 direct drive off the motor, no belt right? And when I said I had a friend turn over the motor, I meant got in the car and turned it over as if trying to start, with no impeller movement

LS6427

iTrader: (2)

Oh ok....if thats how the LT1 water pump works.......well if you know that impeller isn't moving then you found the problem. I can't believe we had 2 in one year on this site....wow.

A sheared shaft and/or a stuck closed t-stat causes your issues.....

Its just wierd that the coolant spews out so soon. If it does it with the radiator cap off when started cold, and you let it idle and heat up....thats wierd.

.

hebelracing1

Yea I have read that misalignment of the splines can result in catastrophic damage. I didn't really care for the mechanic who put the pump on, and I'm guessing he did it wrong..

chrysler kid

iTrader: (14)

Your t-stat is bad.

But I'm sure you'll figure that out after you replace the water pump

hebelracing1

Well my thought of the coolant spewing out is that if there's no flow in the heads that once the motor warms up the steam vent line would be pumping hot coolant into the radiator, once radiator is full, wheres the excess going to go if the thermostat is closed?? The overflow container?? Like I said, I'm trying to figure the premise behind reverse cooling, and how everything flows, also the thermostat is brand new with the water pump replacement, not saying that it is or isn't bad, but if there's no coolant flow, the thermostat is really a mute point.

chrysler kid

iTrader: (14)

The t-stat blocks flow so the engine can warm up, and opens when the engine reaches operating temperature.

I had a similar problem when my water pump locked up, we burped it several times but it was still back washing coolant till we replaced the t stat. ( you can pull out the T stat which is just a spring and see if that changes anything.

hebelracing1

That's something I can try after the water-pump drive problem is figured out, like I said when cranking the motor as if trying to start it, the impeller does not move, so that's my man issue right now.

hebelracing1

Ok, so I got the water-pump out, now, I see a problem I didn't see before, the impeller just slides off the shaft, and if I put it back on, it just slides as I turn the shaft?? What give's, this pump is brand new?