Best location for oil temp sender on e30

[george graves]

but you can't really have a "mecanical" temperature reading, they're all going to use a thermistor.

Fluid in a tube, it expands, the pressure moves the gauge..

[nando]

fine, but if mechanical temperature sensors were superior, I think that nobody would use thermistors for temp readings - except they do, for everything. ;)

also the only way to do a remote oil temp reading would be from a pressure line off the engine, that would never work from the oil pan.

I was seeing oil temps of 250f on the track today. pretty hot. one good reason to stick with synthetic!

(coolant temps are sub 200 for reference)

[reelizmpro]

Because of the turbo manifold, I have a remote oil filter and aftermarket cooler on my M Technic. It works well, perhaps too well. There is no oil thermostat! I'm sure you guys know about optimum oil temperature. I have an oil temp sensor in the pan and it never reads more than 150 F on a Turbo M20. Either the cooler is overcooling the oil or the pan sensor isn't accurate, maybe both. I'm going to install another temp sensor in the oil filter housing on the block and a sandwich thermostat from Jegs. Starts opening at 160 degrees and fully opens at 180 degrees.


I originally planned to install the sandwich between the block and the filter housing, but it's a little on the thick side compared to other more expensive sandwiches. While I probably could get it to work, the hoses will be pretty close to the manifold tube.



The other way I could install it (and I'm leaning this way), is install the thermostat at the remote filter housing where the oil filter is. I have yet to try it but it shouldn't be a problem. I just have to remount the housing to accommodate the added length of the sandwich. The housing is only about a foot and a half away from the block so it should see the same oil temp.

Plan to get it all finished tomorrow.
Any thoughts?

Copied and pasted from another thread. Tomorrow I'm going to have my fabricator buddy install a 2nd temp sensor in the oil filter housing on the block. I'm interested in the oil going to the bearings so I'll be tapping in AFTER the cooler. Temp sensor 1 should be hotter than number 2. If not, can we conclude temp sensor 1 is inaccurate? This should be interesting. I will update tomorrow.

[Uber E30]

So i ordered number 13 and it seems the bolt got changed. It doesnt have the large "cylinder" on top anymore... its just a flat bolt which wont work well for this application. It seems the sensor would almost stop all oil flow being that low in the bolt.

Is it necessary to run that pressure sensor? I dont even recall seeing it when i took my oil filter housing off yesterday but maybe i was just preoccupied.

[nando]

the pressure sensor is just a switch that turns on the dummy light. if you've got a pressure gauge the sensor will usually have it's own pressure switch. in any case it's not critical, by the time the dummy light comes on your engine is usually toast anyway.

[Uber E30]

So, if my housing has that sensor i can just swap it for the temp sensor and be good?

[nando]

yes, as long as you're ok with not having the dummy light.

[Uber E30]

Its just the light in my cluster right? Yeah im ok with that

[nando]

yep

[reelizmpro]

Ok, just got finished installing my oil thermostat. With the AC compressor, turbo manifold, etc. It makes running oil lines and relocation kit sort of a pain snaking the lines around. Anyway, I installed a second oil temp sender in the housing on the block measuring inlet oil after cooler. Fully warmed up the gauge now reads a touch over 180, which was to be expected. Previously, the pan sensor (measuring HOT oil) only read 150. That's at least a 30 degree difference. The previous owner put the sensor in one of the worst possible spots, high on the drivers side of the pan. The M20 is tilted at an angle and the oil returns on the passenger side from the head. I imagine a drain bolt sensor would do a better job since it's on that side of the engine.

[george graves]

Just FYI - there are also sensor that have a pressure out for a gauge, and an output for the warning light if you want to keep the light working.

Nando - from what everyone say, you were right - the pan isn't going to give you accurate oil temps (why I didn't believe you, I don't know - it's just not what I expected)

Thanks!

[faffierwaffle]

Sorry to Reopen a VERY old thread, but times have changed, i have a new question, and servers stop hosting photos... so thanks in advance if you take still take the time.

My question references tapping the hollow bolt in the oil filter housing. Which i believe is #5 here.

the original pictures do not load any more so this is slightly an assumption. if anyone can post a picture of the bolt being tapped, thatd be amazing.

I want to measure oil temp sensors by tapping this bolt and sliding a ds18b20 temp sensor inside the bolt and then sealing it at the top. Will this work?
The bolt is hollow but sealed so there is no actual flow inside the bolt, correct? Someone mentioned they did their pressure sender through the bolt that implies oil flows through the bolt, how is that possible if its sealed. Am i also supposed to drill into the side of the hollow bolt to allow flow and then measure the temp of the oil flowing? If there is flow how hard is it to seal at the top since i cant just tap and screw because the sensor is just a wire wrapped in heat shield (the tip is not shielded obviously :D). Thanks for you time.

[vpilarrt]

The hollow bolt is used on the 325e/I, not the 318is. I used a T fitting (actually a ~2" ling bar with a port tapped into the side) screwed into the port where the OEM oil pressure sensor (#12 in your attachment) attaches.

[Panici]

Not sure if this helps.
This is my plan for pressure and temperature sensors. I have all the parts, but haven't had a chance to put them in.


Sorry for the multiple/large pictures. I had trouble with hosting and uploading making the text unreadable.

[reelizmpro]

Sorry to Reopen a VERY old thread, but times have changed, i have a new question, and servers stop hosting photos... so thanks in advance if you take still take the time.

My question references tapping the hollow bolt in the oil filter housing. Which i believe is #5 here.

the original pictures do not load any more so this is slightly an assumption. if anyone can post a picture of the bolt being tapped, thatd be amazing.

I want to measure oil temp sensors by tapping this bolt and sliding a ds18b20 temp sensor inside the bolt and then sealing it at the top. Will this work?
The bolt is hollow but sealed so there is no actual flow inside the bolt, correct? Someone mentioned they did their pressure sender through the bolt that implies oil flows through the bolt, how is that possible if its sealed. Am i also supposed to drill into the side of the hollow bolt to allow flow and then measure the temp of the oil flowing? If there is flow how hard is it to seal at the top since i cant just tap and screw because the sensor is just a wire wrapped in heat shield (the tip is not shielded obviously :D). Thanks for you time.

The hollow bolt isn't sealed. There's oil flow from the block through the middle. There's an o ring seal on the outside and there are oil holes so the oil can travel to the oil cooler. This bolt is featured on the 325i only. I did this 20 years ago. Drilled a hole in the bolt head and welded a nut on top of the bolt with the correct thread (also to space it back a bit) and used an M3 vdo oil temp sender since I had an M3 cluster in my 325.