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toms57
08-04-2014, 10:29 AM
I am just completing installing a 2000 model LS1 in my 57 Chevy.
The radiator that I already had did not have a port for the steam tube to attach to. I have seen that you can drill and tap into the top of the water pump and pipe the steam tube in there. That is what I have done.
Is there still a possibility that I have air trapped in the heads?
The car runs really cool (180) on the highway, but sitting at an idle it acts like there maybe air around the temp sensor because the fans cycle off and on rapidly, as well as the mechanical gage temps go up rapidly. If I keep the RPMS at 1500 or so, then the temps stay down.
Is there something that I should do to be sure that there is no air trapped in the engine somewhere?

Also, are most people still running the warmed water thru the intake air inlet ( can't think of the proper name), or are they bypassing it too?

Thanks, Tom

Rick_L
08-04-2014, 11:35 AM
Sounds like trapped air to me. How much run time on the installation? It should be self bleeding to some degree. Does you engine/cooling system have any air bleed fittings, like on the top of the thermostat housing?

On your second question, it's pretty common to bypass the coolant flow through the throttle body.

toms57
08-04-2014, 12:00 PM
It seems possible to be trapped air. I have run about 75 highway miles so far and it still acts a little better, but mostly the same. My thought was that it should work the air out, but in some ways the LS engines are a different animal.
There is no bleed valve that I am aware of, so I may have to just take the hose off and see if it releases any air. While doing that I may bypass the throttle body at the same time. Possibly the throttle body could be contributing to the trap.

Bluegrass Trifive
08-04-2014, 05:40 PM
I am just completing installing a 2000 model LS1 in my 57 Chevy.
The radiator that I already had did not have a port for the steam tube to attach to. I have seen that you can drill and tap into the top of the water pump and pipe the steam tube in there. That is what I have done.
Is there still a possibility that I have air trapped in the heads?
The car runs really cool (180) on the highway, but sitting at an idle it acts like there maybe air around the temp sensor because the fans cycle off and on rapidly, as well as the mechanical gage temps go up rapidly. If I keep the RPMS at 1500 or so, then the temps stay down.
Is there something that I should do to be sure that there is no air trapped in the engine somewhere?

Also, are most people still running the warmed water thru the intake air inlet ( can't think of the proper name), or are they bypassing it too?

Thanks, Tom I know lots of people running set ups similar to yours with no problem. I assume your radiator fill is higher than the high point of the water level in your heads? Are your fans controlled by your engine ECM or their own sensor and relay set up? If ECM the programmed parameters could be an issue. If it has an aluminum radiator it would probably run on the freeway with very little need for fans at all. The stock ECM program doesn't kick the first fan on till about 208 to 210. Maybe this is what you're seeing? It's pretty easy to change the set points if you have access, some handhelds can do or software such as HP Tuners or EFI Live. Hope this info helps figure it out.

toms57
08-04-2014, 07:06 PM
The radiator top hose if well above the engine. it goes over the radiator support on a radiator in the six cyl position. It is an aluminum Griffin original down flow style. The fans are controlled by the ECM and that seems to be functioning OK except that they kick on and off erratically, and too quickly to be an actual water temp change in the engine. I may want to change the set points, but I don't believe that this is the current problem. I think that The first one kicks in at 190 and the second at 200.
It acts to me like it is a water flow issue because when you rev the engine to around 1500 the temperature will begin to drop back.
I don't believe that the engine is as hot as the sensor or the mechanical gage indicate that it is. When the gages are indicating 230+ an infrared temp gun is saying that the head beside the sender unit is more in the 190 range. then you rev it up and the gages get more in sync with each other.

Rick_L
08-04-2014, 07:19 PM
Again from your detailed description it sounds like air.

As long as the programming for the fans gives you a 10 degree or more difference between "on" and "off", you shouldn't see rapid cycling of the fans unless there's air. And I'll bet the s/w won't allow you to program a smaller difference between on and off anyway.

Bluegrass Trifive
08-04-2014, 08:19 PM
I'm sorry I missed your comment about the gauge fluctuation at the same time as the fan cycle. Do you have both a temp sensor and a separate mechanical gauge or a single sensor that drives the gauge as well ? Just curious. Could be just air I've just never had an issue other than on a Vette or two with the water fill being lower to the engine.

toms57
08-04-2014, 08:46 PM
I have a factory sensor in the front of the drivers side head and a capillary tube gage in the rear of the passenger side head. I think that I am getting false readings from the mechanical gage. the heat gun does not agree with the mechanical gage except when the engine is held at a fast idle for a while. The first thing that I tried was to try to bleed air by loosening the nut on the fitting at the head, but did not observe any air escaping.

Tonight I unhooked the hose from the steam tube and ran a hose from there to the open radiator cap hole. To my surprise, there was no water flow out of the tube until the engine was revved up, then flow began with some but very little air bubbles observed. while this was going on, the gage inside was going up.
I am also wondering if it could be a pump issue. I would have expected a constant flow out of this tube even at an idle. It had to be at a fast idle to get any flow, and a real fast idle to get a full stream flow.

I don't understand the thermostat being on the cold water inlet on these engines, but I am wondering if something could be going on down there.

Just thought of this, maybe I need to remove the sending unit from the head and see if I can release air from there. May try that tomorrow.