High Oil Temp Problem 1994 vette
Thread Starter
Cruising
Joined: Aug 2006
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High Oil Temp Problem 1994 vette
1994 vette. Oil temp exceeds safe operating temp. Mechanic stated he replaced a sensor or something that was supposed to fix the problem. needless to say, the reason I post now is because it didnt. is there a common problem that would only make the oil temp rise. the water temp is fine. Seems to be a difinite oil circulation problem or something. I look to the experts to help me here.
Thanks!!
Thanks!!
Race Director
Joined: Oct 2005
Posts: 11,771
Likes: 177
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Ok, what is the oil temp?
How do you know it's high?
Maybe the actual oil temp. is just fine, and the gauge is not working right.
In any case post what temp readings your seeing. Both the analog gauge and the digital gauge.
How do you know it's high?
Maybe the actual oil temp. is just fine, and the gauge is not working right.
In any case post what temp readings your seeing. Both the analog gauge and the digital gauge.
Thread Starter
Cruising
Joined: Aug 2006
Posts: 10
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answers
the car is stock. milage is about 114k. analog gauges. visible smoke from dip tube when it gets hot. how hot? pegs the gauge. water temp stays at 180. takes only a few mins at idle for this to happen.
thanks again.
thanks again.
Race Director
Joined: Oct 2005
Posts: 11,771
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
In the center cluster, with the speedometer. You have a "gauges" button on the dash. Push the button and cycle through all the readings (water temp, oil temp, volts).
I find it extremely hard to believe your oil temp could get that hot in just few minutes. Something is wrong with your analog gauge.
Typically, oil temp will run 10-20 degrees hotter than your water temp.
As for the smoke you see coming out of the dip stick. That does not mean the oil temp is overheating. At normal operating temps., it's very possible to see that if you take the dip stick out.
Burning Brakes
Joined: Dec 2001
Posts: 777
Likes: 1
From: Fort Worth Texas
With 114K you are seeing what the PVC valve is not venting( smoke from dip stick). Do a compression check( wet and dry test) and see how bad your piston rings are worn or valve guide seal leaking by the valve stems.
I bet you have a sending unit that is shorting out. Or a bad wire in the harness that goes to the dash. What is the digital gauge reading???
Is the oil pressure OK when the dash shows the oil is Hot? Digital reading. Is the engine making a nocking noise when the oil shows Hot?
I have built and torn up a lot of SBC in the last 35 years and I have never seen a engine get the oil that Hot that Fast and the water temp OK.
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Race Director
Joined: Oct 2005
Posts: 11,771
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Thread Starter
Cruising
Joined: Aug 2006
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oil temp
i will watch the guages and shut the car off when it climbs over 250 degrees. by then, there is an obvious smell of hot oil coming from the car. it will continue to climb if i dont shut it down.
Burning Brakes
Joined: Dec 2001
Posts: 777
Likes: 1
From: Fort Worth Texas
What is the oil pressure when the oil is 250?
What is the oil pressure when the oil is 220? Your oil needs to be about 220 to burn off mositure etc. But if it keeps going higher than 250 when you are driving at 30 MPH and you have good pressure there must be a Serious engine part that is about to fail. A broken piston ring that has turned or jammed in the piston that is creating the friction to heat the oil Too high. I assume you have clean Mobil 1 oil and a good filter. My 96 LT4 has a oil cooler from the factory that I clean every oil change. But I do not think that is your problem.
Do a compression test and leak down test. Does the engine idle smooth and run smooth when the oil is Hot?? I will talk to the shop that just balanced and blueprinted and bored my LT4. He has been building Race engines for years. You got me on this problem. But do a compression test and post what the reading on each cylinder is.
Burning Brakes
Joined: Dec 2001
Posts: 777
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From: Fort Worth Texas
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Just out of curisoty, what is the oil pressure cold? What is the pressure when you see the oil temp at 250?
It could be that some oil passage is clogged up and oil is not flowing through a bearing, either crank, rod or camshaft bearing. There should be no real reason for oil temps to climb that high so quickly. The fact that you say this only takes a few minutes from startup to get high oil temps means that something is wrong internally.
If you hear some sort of knocking sound, I would bet that the oil pump is bad or that the pickup is clogged. Very little oil flow will cause a rapid rise in oil temps. You don't see the coolant temp rising as the cooling system is working properly.
Also, the C4 analog gauges are for the most part not as accurate as the digital gauge display. Does the digital oil temp display 250 when you shut the engine down?
With everything running fine, it can take a good 10 to 15 minutes for oil temps to hit a normal range which is typically 10-20 degrees above coolant temp. When I run my 87 on track days, I hardly ever see oil temps above 260 even in 100 degree ambient air temps. I run 5W-30 Mobil-1 and the factory oil "cooler".
It could be that some oil passage is clogged up and oil is not flowing through a bearing, either crank, rod or camshaft bearing. There should be no real reason for oil temps to climb that high so quickly. The fact that you say this only takes a few minutes from startup to get high oil temps means that something is wrong internally.
If you hear some sort of knocking sound, I would bet that the oil pump is bad or that the pickup is clogged. Very little oil flow will cause a rapid rise in oil temps. You don't see the coolant temp rising as the cooling system is working properly.
Also, the C4 analog gauges are for the most part not as accurate as the digital gauge display. Does the digital oil temp display 250 when you shut the engine down?
With everything running fine, it can take a good 10 to 15 minutes for oil temps to hit a normal range which is typically 10-20 degrees above coolant temp. When I run my 87 on track days, I hardly ever see oil temps above 260 even in 100 degree ambient air temps. I run 5W-30 Mobil-1 and the factory oil "cooler".
Thread Starter
Cruising
Joined: Aug 2006
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i appreciate all the replies
i will post the oil pressure tomorrow. i will also do a compression check on the cylinders as well. this is all new to me. this is my first vette. i bought this one sept 06 and bought my second, a 2005 c6 in dec 06. i love them both but they are like two different children.
thanks again
thanks again
Le Mans Master
Joined: Feb 1999
Posts: 9,931
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From: South Carolina
St. Jude Donor '03 & '05
I understand that. But factory water temps are up to 230-245.
If they are that high, and the fans are on but not cooling enough, the oil temp will rise.
There are many things to check, I just think it is simple.
Heck, there could be a piece of newspaper up in the radiator shroud, causing the oil temp to rise due to water being high, yet not enough cooling throughout.
I had an oil temp problem once on the highway, and water temp was about 230, yet I had a 160 Hypercrap stat. Oil was over 250.
The synthetic oil can take high temps, over 250 for a while, so dont be too alarmed.
Start with the simple things, water, correct amount, and oil correct amount. Then check airflow to radiator.
If they are that high, and the fans are on but not cooling enough, the oil temp will rise.
There are many things to check, I just think it is simple.
Heck, there could be a piece of newspaper up in the radiator shroud, causing the oil temp to rise due to water being high, yet not enough cooling throughout.
I had an oil temp problem once on the highway, and water temp was about 230, yet I had a 160 Hypercrap stat. Oil was over 250.
The synthetic oil can take high temps, over 250 for a while, so dont be too alarmed.
Start with the simple things, water, correct amount, and oil correct amount. Then check airflow to radiator.
Thread Starter
Cruising
Joined: Aug 2006
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new info
when i refer to smoke out of the dip tube, it is smoke that one would expect to see from very hot oil. the car does not smoke out of the exhuast. again, h20 temp is fine. only high oil temp. guages are accurate.
i am pretty good in noticing obvious problems, this one is a mystery.
i am pretty good in noticing obvious problems, this one is a mystery.
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
This is obviously an exceptional challenge. I join the group that questions the gauge readings. There just seems to be no way that the oil could be heated so significantly without heating the coolant.
I think that you should try to verify the readings of both coolant and oil temperature. Maybe it is your coolant temp that is false. The next time you run the car, try this. When the oil temp hits 230, pull the dipstick and measure the temperature at the endpoint by using a drop of water or a secondary thermometer. Likewise, put a drop on the thermostat housing to access whether it will boil.
I know that it takes about 10 minutes in 30/40 degree weather for my oil temp to reach even 150.
I suppose that the rationalization to try the test would be sour grapes. If something is causing this much friction/heat, then your engine will have to be rebuilt or replaced anyway so you might as well do another test.
I think that you should try to verify the readings of both coolant and oil temperature. Maybe it is your coolant temp that is false. The next time you run the car, try this. When the oil temp hits 230, pull the dipstick and measure the temperature at the endpoint by using a drop of water or a secondary thermometer. Likewise, put a drop on the thermostat housing to access whether it will boil.
I know that it takes about 10 minutes in 30/40 degree weather for my oil temp to reach even 150.
I suppose that the rationalization to try the test would be sour grapes. If something is causing this much friction/heat, then your engine will have to be rebuilt or replaced anyway so you might as well do another test.
