By January 22, 20074 Comments Read More →

1992 Chevy Step Van P-30 5.7L

Reader Question: My 1992 Chevy Step Van P-30 5.7L Auto Trans AC engine will not reach operating temperature. I have already changed thermostat. 195 Stant Superstat. Coolant condition is ok. I have checked fan clutch turned freely engine cold and warm. No codes stored, only 12 displays.

I think gauge is accurate. Too many other symptoms – excessive fuel consumption, heater not as hot as used to be, and more exhaust smoke, does not run as well.

Recently, it passed the state emissions. I know it would not now. It just started problems recently.

Is it knock sensor-retarding time or distributor worn? The truck has 120k new plugs wires cap rotor and air filter within last 25k.

Hey there,

I would start with the basics first. When the engine is or should be at normal operating temperature after driving awhile, feel the upper and lower radiator hoses. They both should be very hot to the touch and you really should not be able to keep your hands on them for very long.

If the lower hose is much cooler than the upper hose, I would suspect you might have a restriction in the radiator, or a lack of circulation problem like from a water pump that the impeller has been completely rusted away…..rare, but I have seen it a few times.

Place your hand at the top of the radiator and slowly move down the center, if the radiator has a cold spot in it, you are going to need a new radiator.

Feel the intake manifold as well, you are trying to find a restriction….if you have a laser heat gun that works best, but you can just start feeling everything with your hands, starting at the radiator and moving towards the engine looking for the hot to cold line. Both heater hoses should also be very hot as well.

Do not get fooled by a faulty gauge or a bad temperature sending unit giving the dash gauge faulty info. If you do not have access to a laser heat gun, put a thermometer in the radiator and check the accuracy of the dash gauge.

When in doubt, replace the cheap and easy to replace temperature sending unit just to rule it out.

Austin Davis

4 Comments on "1992 Chevy Step Van P-30 5.7L"

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  1. ernesto says:

    why my chevy 1500 is running cold after repalcing T-stat and sensor and gouge ?

  2. jay says:

    i have the same problem with my van. low heat and low temperature. have changed radiator, water pump and new thermostat 2 times but still same problem. lower rad hose is cool and top rad hose is hot. any ideas?

    • Austin says:

      First thing that comes to mind here is what temperature of thermostat are you using, you should be using a 195 degree stat. Second thing that comes to mind is a restriction in the heater core, at normal operating temperature the two heater hoses should be HOT, (if one is hot and the other is warm or cool) sometimes you can remove the two heater hoses and take a water hose and flush out the heater core (attach hose to one of the metal pipes of the heater core) ….it can be messy. If you get a lot of rusty water coming out, you will probably need to replace the heater core. Since you mentioned the lower rad hose is cool, I wonder if you have an air pocket in the cooling system and are not completely topped off with coolant. Sometimes you have to raise the engine RPM with the radiator cap off (engine cold, coolant cold so you dont burn yourself) then see if you can see coolant circulating in the radiator….if you have an air pocket, you will not see coolant circulating. Hope that helps.

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