Low coolant temp issue
 

My wifes 97 silverado with the 5.7 is having an issue getting to and staying at operating temp. Here's the scenario to date. The truck has 260 K on it, the second engine has 122K on it. Last winter it showed hot on the gage, (220 F), so I checked the fan clutch and then replaced it because it had failed. It still was acting strange, hot to cold and back at times, so,I put a new water pump and t-stat in, followed by a new heater core. Then last summer I installed both new sending units, the one on the lower drivers side head for the gage, and the one at the t-stat housing as well, thinking it was time due to years and wear. So all in all it has all new parts on the cooling system, right?
Here's the kicker, it won't get up the operating range and stay there,(195-200). It sits about half way to the 210 on the gage. I used my infared gun on it and at the t-stat housing it reads 165-175. On both heater hoses it reads 150 ish. Upper radiator hose vaires between 150 to 185, lower anywhere from 90 up depending on how long it's been running. It just won't stay at the t-stat number ever..... (195F). Anyone have any ideas? I've read somewhere about the by-pass having something to do with under cooling, anybody want to comment on that? It's coming on to winter here in Northern Nevada, and the wife is complaining about the low hear in the cab. I don't blame her, I get a bit cold and I'm done too.

What temp is the new thermostat rated for?

195 f

tested it on the stove, opening at 195-198, closes at 190 ish.

Could it be that the thermostat is not seating properly in the housing and letting coolant flow when it should not be flowing?

The restrictors in the intake manifold gaskets are blown out.


Allan

Are you talking about the exhaust restrictor plates installed in the intake gasket ??

no.... checked it, it wouldn't' let the housing seat, you'd know by the angle when trying to tighten the bolts....