On my new to me g20 van, the temp gauge always reads cold. I replaced the coolant temp sensor near the thermostat. Is there a second sensor on the driver's side cylinder head?

Now I noticed the oil pressure reading low on coasting or acceleration but stabilizes in the middle at a steady speed. The engine feels perfectly OK

There is another temp sensor.... its on the pass side. 1 for the coolant going into the block & 1 on the way out, comp reads them both. 2 different sensors 1 with a little brass butt & the other has a big brass butt.


Your oil gauge .... change your oil & filter. The oil is either sluggie or the oil filter is clogged.

Thanks, do you have a part no. for that sensor?

Also regarding the oil, I checked the dipstick, there was the initial residue, I cleaned it and inserted it in, pulled it out, and there is no oil registering.

I did an oil change 2000 miles ago, there are no oil leaks. No idea where the oil went.

I just went through this on my 90. The temp SENSOR is by the thermostat, it will affect your idle. The temp SENDER is the other one and is for your gauge. I had a fast and hunting idle and the sensor cured it.

Ahh I see, thank you.

I managed to fill 2.5 quarts of oil to get back to the top of the hash marks. Correction to earlier, I did the oil change about 4000 miles ago, but it should not be burning oil. I watched the exhaust as I drove and I could not see any smoke.

My 454's dont smoke either but I go thru 1 qt in a 1000 miles.

Low oil creates heat & the oil gets thinner & blows by the rings.

Might want to check your radiator fluid level.

The lower the oil the more heat, the more heat the faster the coolant evaps.

Well everyone I top the coolant to the fill line on the expansion tank, not long after driving it the coolant will go down and rest at the top of the radiator and stays like that. I do not see any coolant leaks.

Well being 2 1/2 qts low the extra heat evaporated it.

The only other thing I can think of is your heater core is leaking..


After you topped off the oil & coolant does it still want more coolant ? If so, with no other signof a leak I would say its your heater core.

Check the carpet under the dash on the passenger side. Is it wet or sticky ?

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The area below the heater core is dry. When I fill the coolant to the fill line on the expansion tank and drive around for a bit, the coolant drops to the top of the radiator.

The only place I have noticed a small amount of coolant was on the intake manifold.

I had to replace the intake gaskets on our '94 because of an external coolant leak at the rear on the manifold. Didn't leak inside the engine but seeped coolant at the rear where it mated to the right hand cylinder head. When I removed the manifold the old gaskets were like powder and were completely disintegrated.

OK , I just topped up the coolant and did a 10 mile drive, once it has cooled down I will check the level. Before filling the coolant came to the top of the main body of the radiator.

How long does it take to change the intake gasket?

Also the temperature sender, can I swap it out from underneath on ramps?

This weekend I replaced the water temp sender and it did not make a difference.

Hey OG2,

So, a few things come to mind. I'd check for:
The presence of a thermostat, it may be stuck open, or missing. That would make your gauge read cold.

You could block your radiator, run the motor, you should be able to feel the upper radiator hose get warm when the thermostat opens. Mine didn't, it was missing the thermostat. My gauge would barely register warm.

Also, on the water leak gasket issue; I had a blown head gasket on a 327 that was loosing coolant into the exhaust, and leaking exhaust into the coolant. Still ran good. You can check for that by observing the coolant flow with the cap off as well. If you have steamy bubbles in the coolant, uh oh... Even if not, time for a compression check. A low cylinder, or two low cylinders together indicates a problem.

With your description of the low oil, and loosing coolant, I can tell you from experience that if you get a motor too hot, it will begin to fail. Hopefully yours didn't overheat. If you have to do the intake anyway, I'd make sure your heads are still on tight. Again, compression check.


I didn't think mine got hot, but I knew who rebuilt the motor, so I just bit the bullet and pulled the heads anyway, since obviously there was a problem.

If you have no visible leak, and you continue to lose coolant, you need to go Sherlock Holmes on that Puppy.
Good Wrenching!