oil temp sender position?

[Jim Cowden]

If it is of any interest The rule of thumb I have always used if the engine is efficient it will see similar oil and water temps.
I always expect between 80-90deg c.

My oil supplier has told me most mineral oils are good to about 170deg c.
That was some time ago so it may have changed.

Sandy
Synthetic oils
One thing I have noticed is I had an engine that I raced for some time and had a few issues with,I ran it on mineral and synthetic.
On mineral when it ran a bearing it looked like it.
On synthetic it had substantialy less damage no discoloration and the journal looked brand new.
It wasnt but it needed a mic to conferm.

Other than that I still think minerals do a good job.
I have 2 customer cars ,2lt turbo engines that see 400hp at the rear wheels and are both on mineral both run 90-100deg c and would see a lot more loads on the bottom end than a N/A V8 I would think.

Jim

 

[Scott Calabro]

Hi Russ,
Good questions. I don't know if you can see actual "bearing operating temps". To me they wouldn't matter as long as the cooler can manage to provide the desired inlet temp. I don't think its the O/T gauges job to monitor bearing condition. That would be a job better suited for regular oil and filter analysis by a lab. Or at least at every filter change cut open the filter and inspect it. (filtercutter.com) Immediate problems would be for the O/P gauge to indicate. An O/T gauge at the inlet WOULD give indications of excessive temps, i.e.ambient air temp is excessivly high, cooler air flow blocked, cooler clogged, cooler by pass inoperative etc.
If you have bad bearings generating high heat its because they are probably wrecked anyway and this would have been indicated long before the high oil temps, either on the O/P gauge or by regular filter inspection.
If I had a cooler on my car I would set it up to keep inlet O/T at 200-215 deg while running Mobil 1 15w50, after the engine was broken in, straight 30w mineral before that with GM's moly oil additive.
Why do 40's have coolers any way? Is it to replicate the original look? Or is it because the H20 sys. is marginal at best and really needs the additional cooling capacity of an oil cooler?

 

[Ron Earp]

Hi Russ,
Why do 40's have coolers any way? Is it to replicate the original look? Or is it because the H20 sys. is marginal at best and really needs the additional cooling capacity of an oil cooler?

Because some users track their cars and they'll need an oil cooler as the oil gets plenty hot. There are lots of examples of performance cars being on track and oil temps being simply too hot in my opinion. I was in a SCCA T1 C5 Z06 Vette, which I think has a stock cooler, and watched temps hit 270F in about five laps. Too much I think for oil life, although the car did okay with it and runs in the 250F range regularly.

Ron

 

[Scott Calabro]

Hey Ron,
I meant for all around street use. Once you pull out on the track and race competitively its a different story. I bet for the vast majority of 40 owners its unnecessary. I know with my ride I have problems getting enough oil temperature blasting around New Enland roads in the summer. That's with a 205 deg. thermostat !

470 HP 383 SBC
71 high nickel content block with canted 4 bolt main caps
AFR 195 cc heads
Comp 270 hyd roller & rockers, with rev kit
10 to 1 C/R
Mahle pistons
6 inch rods
Lightweight 4340 crank
Moroso road race pan with windage tray & moroso high press pump
Wide ratio muncie
3:23 rear

 

[John Fitzpatrick]

Is discharge temp really a reliable indicator of proper lubrication at the bearings? If a rise in discharge temp occurred, how could you isolate the cause or distinguish it from anything else downstream?

 

[Ross Nicol]

I have a habit of checking my gauges after a race and just before I switch off. I have an oil cooler before the tank and oil temp sender in dry sump tank.Oil temp is generally 110 degrees 'c' when I check after a race.I use Castrol edge mineral oil and Chemists from Castrol confirm this temp is fine. Incidentally I have been warned off synthetics by V8 supercar engine guru who experienced
advanced and early engine wear after using synthetic oils. That was good enough for me I want long engine life.
Ross

 

[Sandy]

Incidentally I have been warned off synthetics by V8 supercar engine guru who experienced
advanced and early engine wear after using synthetic oils. That was good enough for me I want long engine life.
Ross

What was the main problems he encountered? I can't say that I have seen much bad play about synthetics, other then the cost. I have been running (well abusing) it in the mustang and have not had any issues as yet. Will see what it all looks like after it blows up or I get the itch to do some more work on it. Would be interesting, would this be a good new topic? I know it has been talked about for gear boxes, but have we beaten it to death on the topic of engine oil yet?

Sandy

 

[Ross Nicol]

Hi Sandy
I think the wear was in the valve gear. The reason he was so adamant was that the oil was the only thing that was changed.The Supercar motors are stripped regularly and when confronted with the evidence the Castrol hotshots (who were out from America at the time) were scratching their heads and could not come up with an answer. I had the expensive synthetic in my car but pulled it straight out based on this. I tend to take the word of this guy who has no vested interest and is a very competent Ford engine man.I think the wear ruined parts after about 4000 km distance, sorry you'll have to convert to miles, but suffice to say it wasn't a lot. W'eve drifted off topic so a new oil one could be good.
Ross

 

[BruceA]

Well how about this for an idea. Instead of using 2 gauges for and 'in and out' temperature, why not get a single gauge but with 2 displays on it. Smiths used to make a 'dual' gauge years ago, water temp and oil pressure I think, so perhaps one could remake the gauge with 2 temperature gauge units inside it. One half would display 'sump' temperature, the other half 'post cooler' temperature

In fact Im thinking about doing this very thing for my car right now. I have limited room on the dashboard. Except in this case, the gauge would be for engine oil temperature and 'gearbox' oil temperature

 

[Russ Noble]

Is discharge temp really a reliable indicator of proper lubrication at the bearings? If a rise in discharge temp occurred, how could you isolate the cause or distinguish it from anything else downstream?

I think what I was trying to say, but didn't express myself too well, was that the oil has a maximum safe operating temp and that is the reading that I personally would like to see monitored. Sure that is controlled by the inlet temperature but if you experience a rise in inlet temp, how do you know whether the oil is still at a 'safe' temp after it has heated up and is working inside the motor? Unless you know the relationship of temp in to temp out you have no idea. How do you find this relationship? And what's the point when you can easily directly measure the outlet temp instead.

In aviation possibly they know this relationship for each type of motor installation and have strategies to cope with abnormal readings long before they become critical.

In a racing application, it is reassuring if you see a temp increase to have an indication of whether you are most likely to still be OK keeping your boot into it and also to be able to decide at what stage it would become advisable to start short shifting to attempt to control the rise. I prefer the (percieved to me) relative certainty of the direct outlet temp measurement to best monitor this.

For a road application maybe excessively low oil temps could be a problem and it may be better to know the oil temp at it's lowest point, that is at the inlet.

So we are talking about a 'safe operating range' maybe the answer is for racing measure the outlet, for road measure the inlet.

Maybe Dlampe was right when he said two senders and a toggle switch !

Cheers

 

[Jac Mac]

Fit the oil temp sender in the pan if wet sump or in the line from scavenge pump (prior to any cooler if fitted) to dry sump tank. You want to know your peak temp so that you can call it quits before the oil quality starts to go away.

Then using an infra red pyro take some readings @, cooler before and after, filter, pan , front & rear scavenge lines and compare them. Lets say for example you suspect a spun bearing on a dry sump setup, the oil in the affected area will be fried. Same thing applies to left/right cylinder heads with regard to valve train oiling. Get familiar with what your engine/gearbox etc is trying to tell you and you will save youself a lot of guesswork if/when a problem does occur.

Jac Mac

 

[Steve C]

Former Navy Nuc Sub engineer here...On the boats main turbine, turbine generators and reduction gear bearings were/are ALL (each and every one of them) directly monitored at the bearing shell as it is the bearing temp that is of concern. Obviously we don't have this ability so the next best indicator IS sump temp (and a pretty good indicator esp if a dry sump with a small volume and small cross section to the airstream) but, as we all know sump temp is always lower than bearing temp and depending on ambient AND speed of movement of the sump through the airstream the temp differential will increase (monitored sump temp will get lowered)...Bad enough the airstream affect on pan alone but, if the temp sender is located on the front of the pan (as most are) now the airstream is cooling the sensor fitting as well as the pan itself.......My input based on engine design limitations (can't get to the bearings directly); it is best to monitor sump but good idea to insulate front of sump, if in airstream, and sensor bung if in front of engine....Steve

 

[Sandy]

BTW I started a synthetic oil discussion thread so this one can stay focused.

Synthetic Oil

Sandy

 

[Howard Jones]

Let me ask this. On SBF's you have a oil pressure port up along side the cam gear cover near No. 1 cylinder. This is a oil galley coming right from the pump and by extension right out of the bottom of the pan. How about using this port for a oil temp gauge and put the pressure sender elsewhere.

 

[Paul]

I have both the pressure and temp sensor at that point but because the temp sensor is not directly in the block I do not think that I am getting the correct oil temp readings. Just another little mod to do. You never quite finish a GT40 do you.

Regards

 

[Lynn Larsen]

Paul,

Good point. One must also be careful about adapter bushings, etc. no matter where the sensor is placed: if the sensor is out of the flow and shielded from direct contact with the stream, the readings can be significantly impacted, especially the ability to measure short term changes.

Steve, unless one has sensors/gauges that are precisely calibrated and/or nuclear melt down is a possible outcome, I think that what most of us are getting from the instrumentation is comparison to "known good" conditions and trends. While there is no doubt that airflow over parts does have an effect, I wouldn't consider it significant because of the entropies of the materials involved and lack of precsion in the measuring mechanisms. None of your statements are wrong, IMHO, but I am just not sure how applicable they are to systems under discussion, excepting the statement on the impact of airflow on dry sump lines with low flow and small cross section.

Regards,
Lynn

 

[John Fitzpatrick]

Let me ask this. On SBF's you have a oil pressure port up along side the cam gear cover near No. 1 cylinder. This is a oil galley coming right from the pump and by extension right out of the bottom of the pan. How about using this port for a oil temp gauge and put the pressure sender elsewhere.

That would seem like a good idea- but do you think the block's thermal
"inertia" (don't remember the thermodynamic term) would stabilize the sensor temp through the fitting and prevent oil temp fluctuations from being registered?

 

[Howard Jones]

John, I think you might have a point. Having slept on it I think that this port is after the filter and I my system the cooler also. Probably not the best place after all. I think I will move it to the pan drain hole. I will need to make another plug that I can adapt to fit the sensor.