oil temp

[ACHiPo]

Originally Posted by patrickt

I saw your post over on the FordFE forum. When you pull your sensor out and stick it in a pot of boiling water, if the needle on the gauge goes right up to 100 degrees Celsius, then it pretty much has to be a goofy result of the placement of the sensor in the pan. We've seen that happen from time to time on oil temp sensors. But you've pretty much got to do that test -- you can't just live with a gauge that gives you the wrong readings.

See no evil?

[patrickt]

Originally Posted by ACHiPo

See no evil?

Yes, it's kind of like that TV commercial where the woman puts the sticker over her Check Engine light.

[ACHiPo]

Update:
Took the car out for about an hour today after wrapping the oil cooler in metallized 3/8" ceramic wool thermal barrier. The air temp was in the low 60s. The water gauge read between 80C and 85C. The oil temp gauge read a tad above 40C. When I got home I put an instant read thermocouple on the remote oil filter mount and it read 180F (82C). That makes me feel better that everything (except the oil temp gauge) is working the way it should. I'm guessing either it's just a calibration issue with the bourdon tube, or the tube is cooling the liquid inside and messing up the reading. I can live with it being low, as long as the oil is not too cold.

I did hear back from Nissonger and they recommended checking calibration by pulling the bourdon tube bulb from the engine and submersing in boiling water. I may try this next time the car's on the lift. Or just live with it.

[eschaider]

You guys could save a lot of time. and experimentation by installing a quality oil thermostat. Pick your target temperature, buy a T-Stat for it and be done.

Here is a very nice, small high flow billet unit, click here => Improved Racing

Ed

[bobcowan]

Unless you're racing, you really don't need to know your oil temps. Did any of your other cars come with an oil temp gauge? Does it worry you that they didn't?

If the oil temp in your Cobra gets to 200*F, do you do anything about it? Or do you just say, "Hey, look at that".

I changed mine to a transmission temp gauge. Much more valuable info for me.

[DanEC]

I like oil temp gages and have them in most of my cars including my newer Shelby GT350. They are a more useful indicator for me of when I can stop babying the motor/car during warm up, than an oil pressure gage or an engine coolant gage.

[patrickt]

And for those of us with solid lifters, and aluminum heads on an iron block, your lash will start out less than your spec'd amount, then grow to be more than your spec'd amount, and then shrink back to the spec'd amount for hot lashing, all based on the thermal expansion rates of the different metals. It took me years to figure out that simple, obvious fact.

[jetblue69]

If you stated it, I apologize... But by any chance do you have an oil thermostat? I installed a Canton thermostat on my Cobra before I even drove it for the first time. I homemade an aluminum bracket for it and mounted it to the forward cross-member and plumbed it in with the usual AN braided line. I think ERA has a "rough drawing" of the plumbing schematic in their "additional tech" portion of the website. And in regards to the oil viscosity, which I know I'm gonna start a holy war here but... it depends on the clearances of your rod and main bearings and environment your driving your car. I personally built my engine for my car and can tell you that I run straight 40W but that can be another thread.

[ACHiPo]

Originally Posted by jetblue69

If you stated it, I apologize... But by any chance do you have an oil thermostat? I installed a Canton thermostat on my Cobra before I even drove it for the first time. I homemade an aluminum bracket for it and mounted it to the forward cross-member and plumbed it in with the usual AN braided line. I think ERA has a "rough drawing" of the plumbing schematic in their "additional tech" portion of the website. And in regards to the oil viscosity, which I know I'm gonna start a holy war here but... it depends on the clearances of your rod and main bearings and environment your driving your car. I personally built my engine for my car and can tell you that I run straight 40W but that can be another thread.

I don't have an oil thermostat. I thought about adding one, but Peter recommended against it--just one more thing to malfunction. Whether that was out of true reliability consideration or just the PITA factor of installing one I'm not sure, but the oil seems to come up to temp in 5-10 min which is plenty quick for me. It gives the tires a chance to warm up a bit as well, which keeps me from ending up someplace I don't want to be.

[davids2toys]

FWIW, just a few thoughts on weird oil temps:

1) The builder of my car actually had the water temp gauge sender screwed into the oil pan and the oil sender screwed into the hole for the water sensor. He actually drove it like this for ten years! Those gauges and senders are identical except one is labeled water and one is labeled oil. I thought I had a faulty water gauge because it was actually reading oil temp at the pan which is nothing close to the water temp at the top of the engine. It would also behave funny. The water temp would read about 180, but when you started driving above 3000 RPM for any reason, the water temp gauge temp would start rising very quickly and the only way to make the temp come down would be to drive easier to keep the RPM under 3000. When I asked the previous owner he said it had always done that and he had just gotten used to it.

2) I bought a new pan from Canton about 5 years ago, still not installed...LOL I had them weld in a new bung much lower so I could be sure the bulb was submerged in oil at all times. I did not like the stock canton higher location for the obvious reasons. To me it was barely in the oil at full, so if you were not at full oil level or driving aggressively you had a very good chance of reading the air temp in the oil pan. They liked my idea and told me they would consider a design change. I don't know if they ever did this going forward

[Whodeeny]

Originally Posted by davids2toys

FWIW, just a few thoughts on weird oil temps:

1) The builder of my car actually had the water temp gauge sender screwed into the oil pan and the oil sender screwed into the hole for the water sensor. He actually drove it like this for ten years! Those gauges and senders are identical except one is labeled water and one is labeled oil. I thought I had a faulty water gauge because it was actually reading oil temp at the pan which is nothing close to the water temp at the top of the engine. It would also behave funny. The water temp would read about 180, but when you started driving above 3000 RPM for any reason, the water temp gauge temp would start rising very quickly and the only way to make the temp come down would be to drive easier to keep the RPM under 3000. When I asked the previous owner he said it had always done that and he had just gotten used to it.

2) I bought a new pan from Canton about 5 years ago, still not installed...LOL I had them weld in a new bung much lower so I could be sure the bulb was submerged in oil at all times. I did not like the stock canton higher location for the obvious reasons. To me it was barely in the oil at full, so if you were not at full oil level or driving aggressively you had a very good chance of reading the air temp in the oil pan. They liked my idea and told me they would consider a design change. I don't know if they ever did this going forward

So does the oil temperature in the pan differ depending on where the oil temperature is measured? I have an Aviad oil pan and the sensor is placed very low in the pan at about the same elevation as the drain plug. The oil temperature just barely gets to a point that I would call acceptable. I have an oil cooler installed and I blocked off air flow to the heat exchanger trying to bring the oil temperature up. It didn't come up very much. Plus the pan hangs down a little bit so that the lower 20% or so of the pan is probably in the air stream passing under the car. My hope is that the oil that is being pumped to the bearings is actually hotter than that which is at the sensor and what I am seeing on the gauge. Is this just wishful thinking?
BD

[davids2toys]

I would say your thinking is pretty accurate. Also I think taking the reading at the pan is cooler than it would be at the head, but I could be wrong on this. I blocked mine off with see thru plexiglass because I like the way the oil cooler looks

[Gaz64]

Originally Posted by Whodeeny

So does the oil temperature in the pan differ depending on where the oil temperature is measured? I have an Aviad oil pan and the sensor is placed very low in the pan at about the same elevation as the drain plug. The oil temperature just barely gets to a point that I would call acceptable. I have an oil cooler installed and I blocked off air flow to the heat exchanger trying to bring the oil temperature up. It didn't come up very much. Plus the pan hangs down a little bit so that the lower 20% or so of the pan is probably in the air stream passing under the car. My hope is that the oil that is being pumped to the bearings is actually hotter than that which is at the sensor and what I am seeing on the gauge. Is this just wishful thinking?
BD

That's how all oil pans work.
Airflow around the pan is part of the oil cooling design.

You should move your oil temp sender to the oil filter housing. That will be a better average of oil temp within the engine.

Another way would be to have the sender in a constant fall of oil from the crankshaft, or within an oil drainback within one cylinder head.

[patrickt]

This has done me good for 15 years. That cap tube is running to an old Smiths mechanical oil temp gauge.

[Gaz64]

Patricks car above is a good example.

The sender gets doused with hot oil leaving the crank,cam,heads draining etc BEFORE the oil gets a chance to be cooled off in the pan.

Reading near the bottom of the pan is as cool as the oil could get prior to the oil being picked up again by the oil pump.

Just like a coolant temp sender is fitted at the hottest part of the engine prior to the coolant going to the radiator, the oil temp sender is best located as like Patricks or my case as above.

[6TNCRZY]

The question is, do you want to know the temperature of the oil in the pan after it has gone through the engine or after it has gone through the cooler and before it goes into the engine? I think a pan measurement is best. Oil takes much longer to rise than the coolant and a street engine with a 7 or 8 quart pan probably doesn't need a cooler. The engine likes the oil temp to be around 200+ degrees, if it's not getting there, running a cooler is a determent.

[davids2toys]

that makes good sense. I vote for the pan

[DanEC]

That could explain the bit of lag in the oil temp reading on my 67 GTX. I hollowed out an oil pan drain plug and mounted the sender in it for the electrical gage (bottom of pan). It does take a bit of driving to get the oil up to temp but after awhile it's up to 180 - 195 thereabouts which should be close to water temp from gage and IR gun readings. But it's only 6 quarts capacity compared to the Cobra's 8 quarts so they seem to warm up at about the same rate overall.