I just finished an opti and radiator replacement on my '93 LT1 and am finding some odd happenings:

Replaced:

Thermo - 180
Heater and rad hoses
Radiator - Proliant
Opti

What I'm finding odd is that the ts never seems to open. The lower rad hose is always limp and cold while the coolant temps will reach just below 190 (I even drove it on the highway with no rise above 190). I then purchased yet another thermostat, again 180 and replaced it with the same results. Next, I took both thermos and tested them in a pot of water. Both slowly opened when my laser thermometer read approximately 195??? I'm very confused.

Any observations/thoughts from the group?

Thanks

 

I am not an LT1 expert but I would say that if you had it out and it stayed at the right temp it is working.

This is a boring test but if you let it idle up to temp and watch your temp closely you should see your gauge rise and then at around the thermo opening temp a quick drop as it opens.

I don't know enough about the LT1 to comment on the lower hose issue, on every car I ever owned the lower was the feed and the upper the return.

 

On the LT1, the lower hose feeds from the radiator up to the thermostat housing. The upper hose feeds from the wp to the radiator. What I find odd is the lower hose remains cold and limp (no pressure). I'm considering removing the thermostat temporarily to see if I get pressure at the lower hose.

 

Are you sure you are buying LT1 specific stats?

 

Unless I'm getting the wrong parts in the right box, yes.

All I can guess is that with the new rad, having flushed the system now several times and the cool (40's) weather here, she's just not getting up to temp which my gauges say.

I'll do a final fill with 50/50 and watch the temps and hope all is well.

 

Things that make ya go Hmmm

 

From one perspective, it sounds like you have accomplished exactly what everyone is trying to accomplish -- a cool engine . shame its not good or as desired... so, onwards...

Which gauge are you referencing, digital or analog? what is the temp on the other gauge (presume analog)?

Oddly, if you have air pockets, the gauges may register no temp or cooler temps, but meanwhile the engine is really hot. Does the engine seem like it is hot or cool?

Have you used your Laser temp gauge to confirm the gauge temps?

What brand radiator if not OEM and is it a double-core?

What brand thermostats and part number?

Presume the coolant level is not dropping, and that your passenger side foot well is not soaked (heater core gave up the ghost).

Have you tested the radiator cap? Have you tried pressure testing the system to see if it is retaining pressure? Lack of pressure would explain the soft lower radiator hose.

Do you have coolant flow through the engine (i.e. are the heater hoses to the heater core about the same temp (with heat turned on)?

Do you see coolant flow into the pressure tank (by windshield) from at least one of the two small hoses just below the radiator cap area? If not, maybe the water pump shaft has slipped?

After a drive, is the radiator at least warm to indicate some coolant flow?

Any chance the lower hose is old and has collapsed internally and is preventing coolant flow through the radiator (since it is on the 'suction' side - so to speak)?