On my '95, all the analog gauges show higher readings than the digital ones. I know the digital are supposed to be more accurate, but the analog coolant is way off; shows 260 when digital indicates 225. The oil temp and even the voltage readings are off.

Could this be a ground problem or is this just typical operation???

 

Common problem. Ignore them unless they are pegged. I always keep my digital coolant dialed up when driving.

 

I do the same. My analog coolant gauge actually reads lower than what my digital is telling me.

 

 

Also, the analog temp sensor is in the head where the coolant will be hotter than the water pump where the digital sensor is located.

 

Well....that was what I thought...typical operation.....good to hear.

My fuel gauge also is way, way off. Probably just need to take out the fuel level sender and clean off the wires that the arm rubs against. Something to do over the holidays.

Thanks again.

 

Also somewhat normal especially as it gets close to zero. I never let mine get below 1/4.

 

Analog temp reads higher due to placement, but never to that extreme. Mine are within ~5 or 10 degrees of each other. I'd do a little more investigation versus risking screwing up the passenger side cylinder head or head gasket due to overheating.

 

Any suggestions as to where to begin other than replacing the analog temp sensor?

 

unhook the wire from the sender and connect a resistor-to-ground of proper value to simulate 220*F...observe gauge reading to determine if sender or gauge is faulty...resistance vs temp tables can be found in your Service Manual.

 

If you have an old potentiometer type sensor they are excellent for these kinds of tests. I used to have a TPS marked out for resistance just for this type of thing. I just glued a piece of wood dowel to it to make it easier to operate.

 

with one of the later posters -- the difference between the two gauges should NOT be that great (on our 94, it is almost identical or at most 5 degrees difference).

How old is the anti-freeze, what type/chemical composition and how old is the thermostat and what brand/model.

Experience suggests that older anti-freeze (2 yrs plus) tends to not cool evenly throughout the engine.

Further, as thermostats age (older than 2 yrs) they tend to either not open as much, or close and open more slowly. Either can cause the LT1 coolant flow to be slowed-down or restricted and cause the back of the engine to be much hotter than the front.

Additionally, if the thermostat is not the correct one, or is a low-quality brand, or has experienced a mechanical failure (happened to me, the extra cap/plate of the thermostat seperated from the main plunger, increasing the thermostat's overall depth and resulting in lower water flow and much higher temperatures).

The LT1 unique coolant system design (reverse flow) has the digital dash sensor (ECT) mounted in the water-pump post the mixing of cooler radiator water with internal engine coolant --and-- the analog dash gauge sensor mounted in the passenger side block/head.

So, either the thermostat or the coolant could cause your increased temperature on the analog gauge and should be corrected.

Additional thought regarding your wondering about it being a bad ground -- check the grounds in the driver side outer kick-panel and on the driver side of the bell-housing...