Sump plug oil temp yes or no?
pigeondave - 21/1/21 at 02:00 PM
Hi all,
Hope the New Year is treating everyone well.
I'm looking into having a way of logging oil temp for a DL1 datalogger and was thinking about doing it via the sump plug.
On a zetec blacktop I believe to to be a M14 x 1.5 thread is this correct?
Is there a temp sensor which people recommend? Or is it a case of looking through the internet.
I'd ideally like one with a AMP Junior Power Timer connector as i believe it'll have less chance of dropping the wires and it'll be
easier to keep the wet out.
Is there a massive don't do it reason why I shouldn't replace the sump plug with a sensor?
Thanks
pigeondave - 21/1/21 at 02:15 PM
im finding things like this, but the length of the thread get me worried
https://uk.farnell.com/avx/94099-00-030/sensor-temp-40-to-150deg-c-m12/dp/2455461
procomp - 21/1/21 at 02:33 PM
Had a customers car a month back.
He had a sump plug from either Burton performance or Merlin motorsport cant remember which, but supplied a Zetec alloy sump plug that was then tapped
through middle to what ever sensor he had fitted, sure it was a single wire sensor.
Slimy38 - 21/1/21 at 03:50 PM
I can't help with the original question, but is the sump oil an indication of general temperatures? To me it seems like a lot of oil that
isn't circulated too often, in a metal tub that is exposed to wind chill. A sensor nearer the filter would make more sense to me.
pigeondave - 21/1/21 at 03:53 PM
quote:
Originally posted by Slimy38
I can't help with the original question, but is the sump oil an indication of general temperatures? To me it seems like a lot of oil that
isn't circulated too often, in a metal tub that is exposed to wind chill. A sensor nearer the filter would make more sense to me.
I see your point. I just assumed that it all flowed through there. didn't think of the chilling effects.
nick205 - 21/1/21 at 04:13 PM
quote:
Originally posted by Slimy38
I can't help with the original question, but is the sump oil an indication of general temperatures? To me it seems like a lot of oil that
isn't circulated too often, in a metal tub that is exposed to wind chill. A sensor nearer the filter would make more sense to me.
This seems sensible to me. The sump sits low and gets lots of airflow around it, which will help lower the oil temperature. I'd be inclined to
look at where the engine designers/factories fit the oil temp senders and follow their approach. Just my thoughts BTW.
big_wasa - 21/1/21 at 04:29 PM
I’ve got mine in the drain hole. can’t say if it’s an accurate indication but it’s showing what I was expecting. I believe the flow rate means it’s
cycled quickly.
snapper - 21/1/21 at 06:43 PM
I found an adaptor that fitted the M14 sump thread and the small oil temp sender in an Pinto alloy sump, been oil tight for years
gremlin1234 - 21/1/21 at 07:18 PM
I think monitoring it at the sump plug is open to all sorts of variation, the physical sump temp, air flow, oil flow and all.
since one of the functions of the sump is cooling, - many have fins just to do this-
but it should be a good repeatable metric.
my preference would be to mount the sensor on the dipstick
[Edited on 21/1/21 by gremlin1234]
Oddified - 21/1/21 at 09:20 PM
On my car i fitted the sensor in the remote oil filter housing with the tip in the oil flow, responds very quickly to changes. I'm not so sure
fitting one in the sump plug would be as responsive/accurate but that's only a hunch.
jollygreengiant - 22/1/21 at 07:45 AM
quote:
Originally posted by gremlin1234
my preference would be to mount the sensor on the dipstick
[Edited on 21/1/21 by gremlin1234]
Have you EVER had to retrieve an MOT test machine oil temperature probe from around the crankshaft of a engine that was STATIC but running?
Just asking
I HAVE.
CosKev3 - 22/1/21 at 09:10 AM
Half way up the oil level of the sump is the recommended position for taking oil temp,as this will give you the best average temps.
Hence why dry sumped cars take the temp from the oil tank,the best average and most stable place to monitor it.
Adapter in the sump plug could read slightly lower,as it's the coolest part of the sump when the car is moving.
Positioning in the engine could give you higher temp readings than average.
But I can't see any of them really being much different.
ttalps2000 - 22/1/21 at 09:11 AM
i run mine in the drain bung on my Zetec. If you want accuracy, dont bother. When you stop in traffic etc, it rapidly rises, as soon as you start
moving again at a decent speed, the wind cools the sump and it drops right back again. Its not at all accurate and im looking to move mine whilst the
engine is out this weekend.
James - 22/1/21 at 12:30 PM
What about inline/tee'd off the oil pressure sender?
Down near the ground is a fairly harsh environment of rocks/debris and I'd be worried about the sender getting damaged or ripped out somehow.
obfripper - 22/1/21 at 03:09 PM
Iirc there is an oil gallery plug to the left of the pressure sensor hole, an appropriate temp sensor in there would give a good indication of oil
feed temperature.
Dave
coyoteboy - 22/1/21 at 03:51 PM
quote:
Originally posted by ttalps2000
i run mine in the drain bung on my Zetec. If you want accuracy, dont bother. When you stop in traffic etc, it rapidly rises, as soon as you start
moving again at a decent speed, the wind cools the sump and it drops right back again. Its not at all accurate and im looking to move mine whilst the
engine is out this weekend.
To be honest that may well be accurate. Variation isn't inaccuracy if the oil is actually varying with airflow and oil flow speed!
You're trying to get an indication of oil temp at the hottest point in its cycle through the engine. And it can take many paths around the
engine, some hotter than others. The only common place is the sump, or maybe the pump input. The hottest point could be anywhere. Is it that exactly
the hottest spot? No. But if you mount your sensor in the head, how do you know that the crank oil isn't hotter? OR vice-versa? Have a turbo? The
oil output from that is probably hottest.
For practicality reasons, and for the sake of +/-5 degrees, the sump plug is going to give you a good answer, and account for its inherent air
cooling. ALL the oil goes through the sump, and the pickup is at the deepest point. Why not put it there? IF you're running a system that is so
critically on the edge that you need the precise highest temp point, get financing some head and oil gallery drillings and do some investigation to
figure out which location is correct, rather than guessing 
If I were doing it, I'd go head or sump and ensure my cooling was sufficient to
give margin. My 370 has the OEM probe in the sump, this is used to pull performance if it goes over 130, so they thought it good enough to base
automatic engine protection on it.
[Edited on 22/1/21 by coyoteboy]
pigeondave - 22/1/21 at 04:02 PM
quote:
Originally posted by coyoteboy
To be honest that may well be accurate. Variation isn't inaccuracy if the oil is actually varying with airflow and oil flow speed!
You're trying to get an indication of oil temp at the hottest point in its cycle through the engine. And it can take many paths around the
engine, some hotter than others. The only common place is the sump, or maybe the pump input. The hottest point could be anywhere. Is it that exactly
the hottest spot? No. But if you mount your sensor in the head, how do you know that the crank oil isn't hotter? OR vice-versa? Have a turbo? The
oil output from that is probably hottest.
For practicality reasons, and for the sake of +/-5 degrees, the sump plug is going to give you a good answer, and account for its inherent air
cooling. ALL the oil goes through the sump, and the pickup is at the deepest point. Why not put it there? IF you're running a system that is so
critically on the edge that you need the precise highest temp point, get financing some head and oil gallery drillings and do some investigation to
figure out which location is correct, rather than guessing If I were doing it, I'd go head or sump and ensure my cooling was sufficient to
give margin. My 370 has the OEM probe in the sump, this is used to pull performance if it goes over 130, so they thought it good enough to base
automatic engine protection on it.
[Edited on 22/1/21 by coyoteboy]
Yep I was thinking along similar lines of, all mixed in the big reservoir at the bottom gives a good average. Putting something in the gallery could
potentially restrict the flow.
And finally, the sump plug is the path of least resistance for me, as its the easiest to do when I change the oil later next month.
Seems as though only one person has echoed my thoughts of stones and crap bouncing about underneath causing havoc, so it's probably me being
overly cautious.
Thanks for all the help guys
I'll let you know how it turns out.
procomp - 23/1/21 at 03:50 PM
As a general rule of thumb, the oil temperature in the engine galleries will be running around 15Deg hotter than the temperature seen in the sump.
THATS assuming the water temperature is running at a sensible 85Deg.
Like most things it is a balancing act as either a high water or oil temperature will affect the reading of both.
Basically a typical engine wants,
water, 75 - 90 Deg before the Rad
Oil, 90 - 115 Deg in the sump,
Other considerations. Air to oil coolers are hit and miss regarding airflow V speed V damage. Water to oil coolers are much more consistent at
maintaining oil temp and can be mounted in a non airflow dependent position. BUT will raise the water temperature due to the obvious transfer of heat
but this method does help warm the oil from cold far quicker.
My 2p worth.
snapper - 23/1/21 at 10:31 PM
Oil temp is only relevant when it’s to hot or cold, you want a steady average, oil temp sender in the oil gallery is only one step up from the
sump.
Sump - pump - oil gallery then after this does it start to take on heat so IMHO sump temp is the major volume of oil and should be perfectly ok
steve m - 23/1/21 at 11:54 PM
How many tin tops have an oil temp sensor ? not many, if the cooling is right, and works, then the Oil temps will follow,
To my knowledge no car on this forum, is pushing mega Bhp, that needs any form of oil temps to be even marginally worried about
Possibly some track cars, but never a road car if driven within the law
steve
Slimy38 - 24/1/21 at 08:43 AM
quote:
Originally posted by steve m
How many tin tops have an oil temp sensor ? not many, if the cooling is right, and works, then the Oil temps will follow,
To my knowledge no car on this forum, is pushing mega Bhp, that needs any form of oil temps to be even marginally worried about
Possibly some track cars, but never a road car if driven within the law
steve
Hmm, my superb has an oil temp reading, I wonder if it's actually an oil temp sensor or just a more accurate version of the temperature gauge.
For me I just use it as an indication not to be too harsh on the gas pedal when it's still cold, even though the temp gauge and the cabin heaters
show things are warm.
coyoteboy - 25/1/21 at 11:04 AM
quote:
Originally posted by steve m
How many tin tops have an oil temp sensor ? not many, if the cooling is right, and works, then the Oil temps will follow,
To my knowledge no car on this forum, is pushing mega Bhp, that needs any form of oil temps to be even marginally worried about
Possibly some track cars, but never a road car if driven within the law
steve
I'd say any tracked car would need it for sure, but most others probably not. That said, I'd rather know than not know. It takes a LOT
longer to get the heat up in the oil than it does in the water, for example. 1 mile into a trip my coolant is at open-stat point, it can be 5 miles
plus before oil even moves the needle.
My 370 sees the oil hit 110C if I'm sat in traffic after using lots of heavy acceleration, high speed alone doesn't really upset iit. Over
in the US they have lots of problems with the same exact setup overheating in their higher ambient temps.
[Edited on 25/1/21 by coyoteboy]
pigeondave - 25/1/21 at 01:15 PM
quote:
Originally posted by steve m
How many tin tops have an oil temp sensor ? not many, if the cooling is right, and works, then the Oil temps will follow,
To my knowledge no car on this forum, is pushing mega Bhp, that needs any form of oil temps to be even marginally worried about
Possibly some track cars, but never a road car if driven within the law
steve
It's just something to do really. I have dusted off an old DL1 which I bought years ago. I'd like to get it running with the car and thought
what can I measure with it. I bought the lead which hooks it up to the Canems ECU so I have got that side logging. Oil seemed a good idea.
I think after a bit if a radiator mod I might be running too cold. (I have a bigger Rad than the polo one).
coyoteboy - 25/1/21 at 04:19 PM
You can't over-cool if you have a stat? OK that's a slight simplification, but for anything close in size you can't. The stat will open
when it's the right temp, and close when it's cooled below it, averaging out at the right flow through to give the right temp. If your rad
over-cooled, the stat would shut to let it heat back up. There's a bit of hysteresis of course.
[Edited on 25/1/21 by coyoteboy]
Angel Acevedo - 25/1/21 at 07:05 PM
My Ford 5.0 has what looks like a temperatura probe mid sump, so i´d be inclined that is a good location.
As you want to log the Oil Temperature, it is also safe to assume that you will be logging other parameters, and as mid race you may not be able to be
checling it every few minutes, it may help after a few runs to set an alarm. If prone to do so, even if the bottom of the sump is not the best place
for reasons stated above, it may set off an alarm early enough if the oil is getting hot even if you are losing oil.
I´m just rambling, I hope this makes sense.
pigeondave - 26/1/21 at 10:24 AM
quote:
Originally posted by coyoteboy
You can't over-cool if you have a stat? OK that's a slight simplification, but for anything close in size you can't. The stat will open
when it's the right temp, and close when it's cooled below it, averaging out at the right flow through to give the right temp. If your rad
over-cooled, the stat would shut to let it heat back up. There's a bit of hysteresis of course.
[Edited on 25/1/21 by coyoteboy]
Maybe over cool was the wrong word.
What I mean is, if the stat takes ages open as the cold water in the rad and the stat bypass pipe takes a long time to warm up. This makes the oil
take a long time to heat up, or get to temp too. So I have to wait a lot longer before I can really depress the loud pedal.
I paid for ARP bolts and damn it! I'm going to use them
But I'm not so crazy that I'm going to rev above 3k with cold oil.
coyoteboy - 26/1/21 at 11:44 AM
You could go electric water pump and pull the stat entirely and free up some engine hp - fastest possible warm-up. Or just reduce the volume and
cooling of your bypass circuitry. Or do what Peugeot do and lob in a coolant heater (weighs about 200g) on a switched ECU output/stat switch.
[Edited on 26/1/21 by coyoteboy]
pigeondave - 26/1/21 at 12:01 PM
quote:
Originally posted by coyoteboy
Or do what Peugeot do and lob in a coolant heater (weighs about 200g) on a switched ECU output/stat switch.
[Edited on 26/1/21 by coyoteboy]
I have been looking at block heaters if truth be told. The type which go into the freeze plug.
I dunno, I'll get the oil drained and changed and install the sump plug for temp and play it from there.
I'm thinking I'll be able to go with a smaller rad in the end. Trouble is when you stop, the water temps creep up quick. I should really be
running the fan off the ECU and not the switch in the rad, but that's a whole different thread.