Another Renix overheating thread
 

When I bought my 90 Waggy it was running hot, no prob I thought, I'll just do some cooling system maintenance. Replaced the water pump, thermostat, housing, upper and lower hoses, fan clutch, pressure bottle and cap, had the radiator flushed and pressure tested, flushed the cooling system. Filled the system back up, tried to burp it, still getting hot, pulled the temp sensor on the back of the block, no air, pulled the top hose it was empty, aha I thought, filled it up, put it back on, ran it again, still hot. Used a thermal gun and the back of the engine was about 230*, front was about 170*. Took out the new Stant Super Stat (195*) and boiled it, it didn't start to open until about 205. I'm going to call the dealer tomorrow and see if they have one in stock (it's 45 min. away), if not I'll buy a Carquest one and boil it. If that works it's going in. We'll see if that takes care of it.

Good job and good plan. When yo uget a chance, use your thermal gun and make sure you have good flow through the radiator. Who flushed the rad?

When u say "had the radiator flushed", does that mean that a rad shop separated the tanks from the core and "rodded out" the tubes in the core? If not, I'd suspect the rad as it is the main component in the cooling system.

T-stats react very slowly and a t-stat is not suddenly exposed to sudden boiling water inside a motor. I doubt u will get a accurate "open temp" on any t-stat, regardless of brand, if u expose it suddenly to boiling water from room temp. U do have the coolant bypass/flow loop open/functioning? Since the t-stat is at the front of the motor and the front of the motor was about 170, I wouldn't think a 195 t-stat would be even close to opening in 170 coolant.

a local shop, he charged me $25 for my last one, this time he charged me $65. If I had known it was going to be that much I would've put it towards a new radiator.

I doubt he did that, he just told me he flushed it and pressure tested it.

The coolant bypass/flow loop is open and it was at 210 or so

Presuming all the new cooling system components are working, including the stat since it was open at 205, it sounds like the rad is the only old component and that could be the problem. No amount of flushing can remove heavy scale build-up inside a rad.....rodding out the core is the only way to remove heavy scale. Again, if the rad is the only old component........:dunno:

Is it the dash gauge that is indicating overheating?

the gage does read hot, it actually matches the reading I got on the IR gun when I pointed it at the sensor.

The dealership is closed today, carquest (the only parts dealer in town) has the same Stant tstat I had in, is the Mr. Gasket tstat better?

Re-check the t-stat.....a 195 stat should be wide open in boiling water. Wide open is open about 1/4"-3/8". Again, If it's in boiling water for several minutes, it should be wide open. Remember, t-stats open/close very slowly. If the t-stat is wide open after several minutes in boiling water, it's not causing your overheat.....something else is. Here's a pic of a wide open t-stat. It's a 180 and is wide open at 195.

I bought another stant, it was all they had, drilled a small hole in the flange and installed it. Prior to that I tested both of them again, the new one definitely opened sooner and faster than the one I took out. Got it all put back together (filled the upper hose until fluid came out the tstat housing), started it up and it seemed to take longer to get hot but it did get hot again. I'm thinking the upper hose is full of air but don't know how to bleed it off. I'm seriously considering a new open radiator but I'll put it through a few more heat cycles first.

Ordered new open radiator, will be looking to reuse my existing bottle as my overflow.

Way to go.

The existing bottle will need to be modified a little with the "open" cooling system......no longer pressurized (hot motor), it must be internally at atmospheric pressure constantly.

This is what I was thinking, I'll use the bottom connection to go to the fill neck overflow, either leave the top connection open or if I cap it I'll drill a small hole through the cap.

What about grabbing an HO reservoir at the JY?