Try this, go down to Autozone, checker or harbor Freight, spend 20 - 30 bucks on an infra red temp gun, then "shoot" the oil pan and the thermostat housing that way you will verify your water and oil gages, I did it and they were real close to what the gages were indicating.

 

That must be one rare LT4. They don't come with oil coolers.
also, the "idiot light" for high oil temps won't come on until 300 F.
So you don't have high oil temps.

 

I am the 2nd owner of my 96,(my first C4) I guess the guy that got it new added it as were the Fiske FM 10 wheels on the LT4 when I got it 8 years ago. The rest of the changes I have had done.
I assumed it came that way:o I know assume. I should have looked at my two GM books.

Happy New Year
Louis

 

oil temp went to 300 while water temp stayed at 168. temp outside was 55.


i feel confident that guages are ok. oil level and pressure is fine. will not cool oil.

 

Have you tried the water drop on the dipstick test? If the oil temp is that high, dropping a bead of water on the dipstick with oil on it should cause immediate boiling or spatterng of the water.

Even touching the oil on the dipstick will be painful assuming a 300 degree temp. After 10 minutes of running, normal oil temps should be around 150-170 and that would feel hot but not to the point where it would hurt.

Also try the infra-red temp reading test. Find the local Harbor Freight store and get one of their cheap infra-red temp readers. Run the engine again until you see temps in the 280 range and point the beam at the side of the oil pan. Pull the dipstick out and check the oil on it. If the readout is anywhere close to the gauges indicated temps, then you do have a big problem in the engine somewhere.

It's also possible that the sender that was replaced could be bad too. There is only one oil temp sensor that feeds both the digital readout and the analog gauge.

There has to be an answer here and hopefully you are not looking at an engine tear-down.

 

Did your mechanic replace the oil temp sender on the side above the oil filter area. If oil temp is that high, you would have other issue happening if it just started recently. There would be metal to metal, or something to cause the oil to get that high, or a blockage.
I would say if your pressure is fine, no knocking noises going on, than you simply have a bad oil temp sensor.
An infared temp checker to see what the oil is really at is a good idea.
Also, it takes a long time for analog gage to show the same as my digital, and I have changes my temp sensor.
I wish I could see the car, that helps so much

 

the only thing that would cause 300 degree oil temps are doing 5000 rpm's for 1/2 hour straight.

 

i have read all the posts that are questioning the guages. i know for a fact that the guages are fine. today, at an idle, the oil temp went to 300 degrees while the water stayed at 168. i had to open the hood and let the motor cool down. it had an obvious smell of overheating. it was not good. it smelled like everything that was on or near the block was overheated.

as all of you, i am not sure why thisis happening. i am hoping that someone else out there had this same problem and can say xyz is the cause. if not, my only choice is to take it to the shop.

i know we have top mechanics in this group and it is strange that we havent heard from the gurus.

thanks for all the replies.

ron

 

I am no guru but this sounds like spun bearings to me.

 

HAVENT HEARD FROM THE GURUS?
I have 11 years on this car, and have done many mods, broke many things. The answer lies within you now.
Check the oil temp externally, use a thermometer of some sort.
This will eliminate the sensor, NOT the gages, then we will be past that. Verify the sensor is sending the right signal to the gages.
Then we can move on to bearings, etc etc.
Do the basics first. High oil temp is associated with improper cooling of the oil, or your sensors are telling the gages what is roght.
If you have a mechanical issue related to making high oil temps, you would have heard it by now.
Also, check that your PCV isnt clogged.

 

Did I miss it? or did you post your oil pressure when this occurs. I agree the first thing I'd do is shoot it with an infared....just to make sure there's no electrical problems with the sensor or wiring. I'm also curious about the oil viscosity you're running? There are so many possiblities i.e. bad oil pump, blocked passages, metal to metal etc. we need as much info you can share to help you.

 

If you really have 300 degree oil temps, the coolant should be going higher than an indicated 168. Assuming that the oil is circulating through the oil passages properly, really hot oil will cause some of that heat to transfer into the coolant passages. That will cause a rise in coolant temps.

If the engine is quiet (not making any unusual sounds) then I still believe the problem could be with a bad oil temp sensor. The chances of getting a new sensor that is bad is slim, but it can happen.

You mentioned that "oil pressure is fine"; What is the oil pressure at idle and at say 2000 RPM when the oil temps have reached the indicated high numbers. Please post the pressure in psi, not just "fine". High mileage motors can have fairly low idle pressure like 10psi and once the RPM's come up, 30-40psi is normal. Also post the oil pressure numbers when the engine is cold (has sat overnight, not just a few hours).

Low oil pressure can indicate a number of things; blocked oil passages in the block, the crank, the lifters and lifter bores, pickup screen, or the pump itself could be bad.

Have you tried to touch the oil on the dipstick when the temps are high? Is it extremely hot to the touch? Will you try to get an infrared temp reader and check to see what temps show up at the side of the oil pan. Then pull the diptsick with the hot temps and check the oil on the stick with the reader.

It's to the point now that you need to give us some specific data values. We are trying to help here but the next step is to verify the oil temperature from a source besides your gauges.

 

Back in post #8, he said this:

I think he has some mechanical issue, and it's serious.

 

I agree to an extent, but oil and water temps should be really close. The Oil gages take a while to register actual temp, and water is pretty quick to change.
If he has mechanical issues causing oil temps to be that high, as he states, then the water would be high by default as the oil will heat that water up pretty quick.
I think a more experienced set of eyes and ears need to be on this Vette, to verify the symptoms we have going on here.

 

with that too!

I have never seen a car's oil temp. get that hot that fast and still keep normal water temp. and normal oil pressure.

Hell, under normal conditions it takes a good 15-20 mile drive to get oil up to normal operating temps.

Something just does not add up here.

 

rebuild engine time.

 

Ron
As you said the engine makes a noise when the oil gets hot is Serious. Take it to a Chevy Dealer and have them look at it. I bet they do a compression test to check for broken piston rings etc. I would not keep starting it up and getting it Hot. Let us know what the Dealer says, sorry no one has a Sure fix that is just minor to repair.
Louis

 

The only time I have ever seen high oil temp and not coolent was when all the rod bearings were spunn.

 

and that would result in nil oil presure.

 

It is just possible the water temp gauge is screwed up. Later! Frank