oil temp sender position?

rick · 11-19-06, 09:49 AM

what is the best oil temp sender position, low in the sump or after the oil cooler before it goes back into the engine.

thanks

David Briggs · 11-19-06, 11:42 AM

I would think that low in the pan(most are that way), the temp going into the oil pick up is what is critical.

Neal · 11-19-06, 12:11 PM

I put mine in an unused port of the remote oil filter adapter.

Bill Musarra · 11-19-06, 08:21 PM

Both David and Neal are correct. You want to know the highest temp the oil is reaching. If you plumb it in after the cooler, you are seeing the coolest the oil can be. Not a number that would tell you anything. If you had a very efficient cooler, you might be scorching the oil and you would never know it until it was too late.

Bill

Scott Calabro · 11-19-06, 09:55 PM

Respectfully, I would disagree.... put the temp sender in a position after the cooler just before it enters the oil supply galleries. This way you will know the temp going to the main bearings. ( very important ) It is inconsequential what the temp is in the sump or remote reservoir. Also some type of thermostat and cooler by-pass should be used to keep oil temps between 200 - 230 deg F. Never lug the motor with cold oil !

Sandy · 11-19-06, 11:35 PM

Quote:

Originally Posted by 5150

Respectfully, I would disagree.... put the temp sender in a position after the cooler just before it enters the oil supply galleries. This way you will know the temp going to the main bearings. ( very important ) It is inconsequential what the temp is in the sump or remote reservoir. Also some type of thermostat and cooler by-pass should be used to keep oil temps between 200 - 230 deg F. Never lug the motor with cold oil !

Doesn't totally make sense IMHO, if you have a decent cooler you oil will likley be in a nice safe temp range anyway. If your oil is cooked from over heating (as said in a prev post) you likely will never see it. Most racing pans as well have the pickup in the sump that I have seen (Aviaid, Armondo, Canton, etc).

Sandy

Bob Putnam · 11-20-06, 08:04 AM

I'm voting with Sandy. The main idea of measuring the oil temperature is to ascertain the condition of the bearings, not the efficiency of the oil cooler. Bad bearings will cause an increase in oil temperature in the sump but that won't necessarily show up in the return line of the oil cooler.

Lynn · 11-20-06, 09:47 AM

Neal,

I am with you. I put mine in a very easily accessible port on the oil filter adapter as it comes out of the engine. The oil is NOT going to cool much, if any, between the sump and the filter adapter. I agree with all of those that want to know what the temp is PRIOR to the oil cooler. That's not to say that it wouldn't be valuable at some point to check how efficient the cooler is (with a base line you can also evaluate if it is getting sludged up), but as to a day-in, day-out point to monitor the oil temp, I don't think so. After all the reason for monitoring this is to get a little warning that a bearing(s) or something is starting to go bad and give you a chance to shut down before the whole engine is ruined. This will be most definitive in the pan or somewhere in the early part of the pumping/plumbing system.

Regards,
Lynn

Mark Worthington · 11-20-06, 10:25 AM

Monitoring both temperatures would be best, but I would be more interested in the temperature upstream of the cooler.

rick · 11-20-06, 03:01 PM

6 to 1 for the sump/pan but...... I still like the idea of one after the cooler too, so maybe 2 or 3 or 4 on 1 gauge with an switch in between sump/cooler/gearbox/water

thanks

Sandy · 11-20-06, 03:03 PM

How many gauges can you realistly monitor

. I have enough trouble just keeping an eye on tach/temp gauges!

Sandy

Russ Noble · 11-20-06, 03:49 PM

You're right Sandy.

OK for a road car where you've got plenty of time to talk to passengers, look at the scenery and gaze at all the gauges. But then for a road car do you really need oil temp anyway!

On my last car, I had big bright idiot lights mounted on the top of the dash set to come on at 30psi for oil and 120*C for water. Still didn't have time to check the tach at critical times, so this project is going to get a rev limitter as well. Then I won't really have to look at anything! Mind you for endurance racing it will be important to monitor a whole lot of things more closely but there's unlikely to be so much intense "do or die" driving in a long distance race, so should be able to concentrate on the gauges.

Oil temp OUT of the motor and the trans are critical. So long as temp out is OK, temp in doesn't matter. IMHO

Cheers

Dean Lampe · 11-20-06, 05:05 PM

Let me solve the arument. Use electric sending units in both places and run the wires to a switch then to the gauge. You will be able to toggle back and forth if you are curious. One gauge, 2 temp readings.

Murray Cowley · 11-20-06, 05:35 PM

Dean,
proper job !!
You got it.

Bernard · 11-20-06, 05:41 PM

Quote:

Originally Posted by 5150

Respectfully, I would disagree.... put the temp sender in a position after the cooler just before it enters the oil supply galleries. This way you will know the temp going to the main bearings. ( very important ) It is inconsequential what the temp is in the sump or remote reservoir. Also some type of thermostat and cooler by-pass should be used to keep oil temps between 200 - 230 deg F. Never lug the motor with cold oil !

Scott, I agree with you.... But only for your last sentence

As you say, the best way is to use a thermostatic 4 ways valve to have a constant working oil temperature. Oil radiator as well the oil sump volume should be sized to keep the oil temperature at a constant value what ever the external weather and the road (or race) traffic. It means that if you install the oil temperature sender at the engine oil input, you will record only a constant value (the regulated oil radiator ouput temperature value). For my view point, it is preferable to read the oil bearing output temperature value. Only this temperature will reflect the engine load. To reinforce my argument I would like to show to you some pictures of my last oil temperature problem.
Picture one: oil (and water) temperature are very high (normal is not above 260°F)
Picture 2: After investigation the rod bearing number 8 was at the begining to be destroyed (to be compared with an other rod bearing)
Picture 3: here is the oil sender location on the return oil filter (at this point, oil is back from the bearings to the tank).
To conclude, I understand that it could be easy to fix the oil temperature sender on the remote oil filter that is located on the input circuit but it is preferable to weld a socket on the sump or if you use a dry sump to connect it on the oil return line. In a similar way, the water temperature sender is connected at the water output going to the radiator.
Is is my only 2 cents comment in this friendly forum

Scott Calabro · 11-20-06, 06:50 PM

Hi all !
Great dicussion and you all have good thoughts and points. the reason I think it should be right before the bearings is so you will know what the bearings are seeing. That is why its in the pan on wet sump engines, from there it goes to the pickup, pump, fiter and or bypass and straight to the......bearings ! Effectively measuring oil temp just before it gets supplied to the crankshaft. As far as oil temp used as an indication of bearing condition that is not the best way either. Cut open the filter and inspect it or better yet send the filter and an oil sample out to a lab for anaylsis on a regular basis, so you can trend engine wear. What I don't understand is why any ROAD driven, liquid cooled car engine would need an oil cooler in the first place. The engines are never really stressed, or operated at constant high power settings for more than a few seconds at best. Especially a car like a 40... maybe if your towing a boat ?

Respectfully,
Scott

Sandy · 11-20-06, 07:32 PM

Quote:

Originally Posted by 5150

Hi all !
Great dicussion and you all have good thoughts and points. the reason I think it should be right before the bearings is so you will know what the bearings are seeing. That is why its in the pan on wet sump engines, from there it goes to the pickup, pump, fiter and or bypass and straight to the......bearings ! Effectively measuring oil temp just before it gets supplied to the crankshaft.

Scott

Scott - This would be a fine argument for a car with no oil cooler as the oil temp is the same coming out as it is going in

But for a car with a cooler still want to see what the temp of the oil is before the cooler where it is meaningful. BTW, I don't use a temp gauge on the oil or a thermostat on the cooler on the Mustang (Large Fluidyne), no more holes for new gauges

I'm also not so keen on putting an oil thermostat on my car, but for not for anything other then less plumbing the better, and I live on the west coast where cold is not usually a problem. I also run synthetic oil and also wonder if that helps with the not needing it. About the only thing that I can think would be to keep the oil at some reasonable operating temp when cold temps exist, but not sure how this is even affected anymore by synthetic oils extended temp capacity (Would be a good place for some discussion too). I know many of Beemers (M3, etc) have limitations on RPM until things are hot, but not sure if that is strictly oil related.

Yes a good thread indeed!

Sandy

Scott Calabro · 11-20-06, 07:59 PM

Hi Sandy,
Your right this is a good thread. I'm just speaking from my 24 years as a jet mechanic. I have NO GT40 wrench time. What I can say is that almost all racing technology and design has its current or past roots in the aviation industry, From AN fittings to carbon fiber, to turbos and nitrous oxide.
The GT40 is no exception. Its tub is directly rooted in WWII tech. So when I say something in response to a post I'm trying to give the forum the benefit of my experience. I would just warm up the oil to at least 160 deg before any fun, and the way to do that is measure it before it gets pumped to a bearing. Its just my humble opinion, I hope I have not been impolite.
Regards,
Scott