I "installed" my oil temp gauge many months ago, but never hooked it up to get readings. I didn't do so for two reasons: 1) I wasn't sure where to find a desirable spot (drain plug doesn't top the list) and 2) I thought that I might go with an aftermkt oil cooler, ideally one that would afford a tap point or two. Having not seen an oil cooler yet that I would want, and realizing that my MINI will be strictly a cool weather ride (Fall & Winter) soon, I really don't think I will be needing additional oil cooling anways...

So, I'm back to locating a tap point to get oil temps. I'm currently getting oil pressure at the factory warning light location, a la the PROMINI gauge kit. After looking at those instructions again, thoughts of having that spot also provide oil temps seems somehwhat difficult...

jlm removed the oil filter housing and tapped it, which seems like an excellent way to go. It however entails, I believe, the lowering or removal of the subframe. I'd like to avoid this, for a few reasons...

I'm open to any ideas! And if anyone has seen oil temp readings at the drain plug, and somewhere else, I'd love to know the delta. If within reason, I might go the easy way... Thanks.

 

When I got my aux gages installed from the dealer they changed the standard oil plug, with an oil sensor-plug and run the wire straight to the gage (add 12v and lighting and bingo!!!). The dealer sells the plug/sensor.

 

I love the ease of that for sure. I've just heard that readings done there, at the base of the pan are not exactly accurate. Since we have temps from others who have tap points in supposedly better places, what temps do you get at cruising speeds, normal operation? And if you track your car, what temps do you see? Thanks for chiming-in!

 

Tony: you can get the housing off without dropping the subframe. it isn't fun though. removing the header would help a lot. if you decide to do it, I can send you a tapped housing since I have one kicking around.

 

jlm, I might take you up on that! I'll look at my Bentley manual tonight to get an idea as to the extent of the work involved. Glad to hear that it doesn't involve the subframe though! I want to deal with subframe once, and only once: front sway, control arms and bushes...

Sounds like I would have adequate access with the header removed. Heck, might be a good time to swap-out the header, but I have not yet decided what to get though...

Looking more at the PROMINI instructions, their adaptor has two remaining 1/8" plugs (I now remember those). One of them could be removed, allowing for a tap point. I don't remember if that's the right size (1/8"), and if so, if there's enough space to make this happen... or if this approach is even advisable (will yield accurate readings).

jlm, thanks again. I will for sure contact you if I decide to go this route. I would still like to see some temp measurements from the drain plug... just to see how much they are "off."

 

Just found this, and had to share. GreatBear, once again, is a huge source of knowledge!

For oil teperature readings to be accurate, it is best to install the sender for the temp gauge where it will be immersed in and encounter a steady flow of oil around it. The oil does not have top be pressurized, so most people (as well as the factory) will mount the sender in the oil pan, often in place of the drain plug. You can drill and tap a spot in the pan as well.

If you mount the sender in an oil gallery (such as where the oil pressure sender is mounted) you will encounter erroneous readings in many cases. Why? Because the temp sender is a probe, albeit a short one. It needs to be in the flow of or the greatest mass of hot oil to measure the temperature. When you mount a sender via a tee from the pressure port, the flow in the area is blocked (deadheaded). While the oil in the area will conform to the pressure of the oil in the gallery (making pressure measurements accurate), there is no actual 'flow' into the tee other than what gets pushed in by oil pressure. There is no flow back out other than where it comes in. Also, since the tee will mount the temp sender a distance away from the flow, the ambient air around the tee will cool the tee, senders and the oil inside as the hot oil flows by, but not through, the area, leading to lower readings.

Think in terms of measuring the internal temperature of a roasted chicken after pulling it from the oven to know whether it's done or not. You stick the thermometer into the core part of the meat, If you stick it in the wing, especially if the chicken has been out of the heat for a moment, the temperature there will begin to be much lower than inside.

If you have no choice but to tee in a temp sender, make sure to make it the closest to the engine, and therefor the nearby flow of oil. The pressure senders can be further oil with no problems. Also, avoid using a long series of pipes or stacking of tees. Remote-mount the electrical items via a hose instead, since you end up magnifying engine vibrations the further you get from the engine due the the 'whipping effect'. THe vibrations can eventually damage senders and also strains the fittings which can actually break from fatigue. The bonus in all this is that the MINI uses a large (3/8NPT) fitting coming from the engine rather than a skinny, 1/8NPT one that a lot do. This makes any teeing arrangement much more solid, and actually can allow remote temp senders to work better (from eddy currents in the oil flow moving it around).

Another good area to mount the oil temperature sender is in the end of the oil filter canister. The outer portion of the sender itself is not very big, and tucks nicely inside the recess in the hex end on the canister. It does not interfere with putting a socket over the hex with the wiring removed, and it's low mass compared to a pressure sender will not strain the housing with vibrations. The biggest plus is that it is in the strongest area of hot oil flow, and due to it's size, does not impede the flow.
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I will either tap the top of the filter, or just get the MINI oil temp drain plug...

 

the ideal way to use oil temp readings is to try and measure how hot pistons and bearings are getting, best done by measuring oil temp right after it leaves those items. since the oil splahes out of tthem and collects next in the pan, the pan would be the next best opportunity, assuming you are getting at a freshly deposited and moving load of oil, (probably not). the next opportunity is after the sump pickup-oil pump-filter-gallery circuit. the top of the filter (filter exterior) is closest to the incoming oil path and still in the active flow, as you pointed out. sounds like a good place. The spot I was using is in the stream going back into the block after the filter, not in the oil pressure sensor dead end.


Same idea when measuirng water temp. right at the heat producer, the head, is where mini has the sensor and is the best place.

 

jlm, thanks for the rationale explained. I'm going to my local MINI dealership today to get either another oil filter canister, or that drain plug. It seems that the top of the cannister is somewhat thin, from what I recall reading. And, the low profile 36mm socket I use for oil changes would contact the sender, unfortunately. Once tapped, and snugged, the sender would stick-out about .5"...jlm, about how much meat would you say there is on top of the oil filter housing? Thanks again.

 

I believe you can get a cannister from PROMINI that is already tapped for a sender if I remember right. I think the post is well over a year old.. Call PROMINI and ask them . They may have what you need.

 

the actual canister wall thickness, in the hollow of the nut, is less than 1/8". you don't want to be installing and re-installing senseors there very often or put any hanging weight there.

 

So the drain plug sender would probably be the safest solution? How much does MINI charge for one of these?

 

jlm, thanks for the thickness info. While it seem that the top of the cannister is the best place to take such a reading, it's not ideal given that there's not much material there. Your location is very sound also, but involves a fair amount more work. Trade-offs and compromises, as usual. I've made my decision... the easy way, for once

Just got back from my nearest MINI dealership. The guy said that he doesn't have any... special order item After asking me if I wanted him to call of local dealerships, I said sure... He then comes-out with one in a baggie that he took out of a kit. 60 bucks!

Well, with a 10% discount, it did help a little, but still... I like how long the thermocouple (hope that's the right word) is though. It's a good 1" long. I of course got 5 quarts and oil, and a filter also...

FWIW, the part # that's written on the bag is: 82940 004 581.

 

MINI Madness has a remote Oil Cooler kit. It replaces the factory oil cooler with a remotely mounted cooler [in front of the radiator]. The plate that covers the factory location has holes for both oil temp sensors and oil pressuer sensors. A very good idea!

 

Well aware of that one... A few of us were not so keen on the idea of it not having a thermostat though. Pilo is or was doing one also, and with what he shared a little over a year ago, there was no t-stat as well. I'll hook it up on Sunday....

 

Tony if you didn’t see my reply in another thread regarding the temps I’m seeing with by drain plug temp sensor here it is again-

During normal driving where the outside temps are around 70-75 F I see temps around 100C (the needle is right on 100 or just a shade above. At night during normal driving I typically see the needle just under 100 C (I estimate 98 C or so).

On the last MINI run it was a somewhat hot day 80 + and after some spirited driving up a hill for several miles I was seeing about 112C.

I would assume that as you say these temps would be lower as they are being measured at the bottom of the oil pan where the most cooling would occur. I would be interested in hearing the temps. others are seeing from sensors mounted in the oil filter housing (another typical sensor point) or some other place more towards the innards of the engine. This would be just as a point of interest. As long as you know what the normal and aggressive driving temps are no, matter where they are being measured at you can monitor if the ranges are being exceeded and hopefully prevent a problem. That would be the main purpose of any measuring device wouldn’t it?

IMO I think the oil drain plug is the best way to go for the ease of installation and the reliably and ease of servicing you get from this test point.

 

SCMCS, thank you for posting here as well... I had not seen your reply in that other thread. Just met some deadlines at work ( ) and now have some time to catch-up...

There are temps in other threads for comparison purposes. I'll go dig those up... While common sense seems to dictate that readings from below, at the plug might be lower, I'm not sure..., or if so, it might be only minimal.

Contrary logic though has me thinking that if some of this oil is not get circulated as effectively, then it's not going through the cooler as much also... maybe balancing-out things pretty well, providing good data. Rationalizing my decision I guess

I believe the really important thing is to have solid baselines for reference purposes. Sounds like you have some already, so if you see deviations going-forward, you'll have reason for concern. Thanks again.

 

my vote would also be for the oil drain plug. I have my WRX setup this way and you can definitely see the deltas between your baseline operating temperature and oil temps after a 60 second autocross run. You can also see how quickly the temps drop if you hop on the freeway and cruise.

As was mentioned earlier in this thread, I don't believe you should measure temperature under pressure.

Matt

 

I am placing mine in the canister top. The canister top can be reinforced on the inside with an aluminum patch to increase the thickness. This can soldered in with aluminum solder composed of 91% Zink and 9% Tin. Soldering aluminum is simple but at the same time tricky because you have to heat the parts to reach the point of solder flow without the aid of a color change in the parts. There is a powder flux available you can use that will turn to liquid at the temp. point the solder will flow. It's also real easy to melt your part into a puddle. I wouldn't recommend this to any first time solders unless you want to learn how and practice alot on junk before you try.
***Another method would be to use JB weld epoxy. This is amazing stuff. It is designed for reliable, permanent repairs in engine compartments and heated environments up to 500° F. It's impervious to water, gasoline, chemicals, and acids. I could write a testimonials about the things I've used this stuff for.

 

norm, you were reading my mind on the J-B Weld! I put it out last night in case I bought another oil canister. That stuff is incredible. Although I won't be using it on this project, I'll be using it on another GRS IC mod later this weekend...

Well, my MCS is dripping its last few drops of oil... and I'll let it do so all night. I lossened the oil temp gauge from its cup-holder, pulled it out, and its ready to go. I then, with a stretched-out coat hanger, fed yet another wire through the firewall, down, and and behind the toggles as this is where I have my oil temp gauge, as well as voltmeter. The gauge already was connected so it lit, so I just need this last wire to get the readings...

As far as the other end of the wire, well, I ran it downward, in the front of the ECU. Again, the coat hanger helped fish in through. I'll use zip ties tomorrow when there is more light to make sure it's secure, and not touching anything that gets hot or moves...

 

in one of my incarnations, I bored out the hollow of the hex and therefore was able tap securely into the thicker hex wall, using a threaded bushing as an adapter to the 1/8-NPT for the sensor.

 

Tony, I went to my dealer this morning to pickup some parts, The canister is about $40.00+ tax, they didn't have one in stock. I probably would have bought one if they did. Don't Know what I'd do without coat hangers either.
Ive got a pretty good solution for adding water temp. sensor over on Beneth the Bonnet
jlm, that must have been a very large bushing. Did you bore all of that area out inside the Hex? All my sensors oil/water are 1/8 27 NTP too.

 

1/2 NPT, a piggy, needed some machining to tidy it up. another problem was that if the bushing/whatever is too long and you hang an electic version gauge pressure sensor, it can hit the firewall. Had the dealer refuse to change my filter at 10k when I had mine on there. eventually used a -4 AN hose and remote mounted the sensor, then the present version was to Tee off of the stock pressure sensor location and went back to the stock canister lid.

 

jlm, i'm only doing a oil temp. sensor in the canister. I have been looking for one of those electrical connectors like they used to use on Ford pickup solenoids mounted on the fender well that plug on. Kind of like a spark plug boot. I remember they were yellow. Wait a min. maybe that was on the coil. Anyway, that would provide and easy quick disconnect for oil changes. If I can't find one ( junk yard ) I'll use a brass wing nut.
How long of a nipple did you use at the stock pressure sensor location to the T? I guess I'll just pick up the shortest- 2" That location is 3/8 NTP?

 

Ok, something is not right with my oil temp gauge and/or set-up. And if not, then I have some serious issues with high oil temps!

The toughest part of finsishing-up the install was completing the oil fricken oil change. I had to spend like 20 minutes to get the dang canister threaded properly. I recall that I had this issue last time, and then I remembered what I needed to do to get it square-up properly...

I ran 16 gauge wire from the new drain plug to my AutoMeter oil temp gauge, reconnected the battery, double-checked the engine bay, then fired her up. Every looked and sounded good, and after a couple minutes I began to see the needle creep upward. I was happy, and powered it down, knowing that I would go for a drive later...

Well, with ambient temps mostly in the low to mid 60's, I saw temps mostly around 260 to 270F!!!! We are talking partial throttle, nothing beyond 3500 RPM. Heck, I had my wife with me, so you get the idea... nothing remotely spirited...

Must I use the sender that came with the AutoMeter gauge? I never questioned using the MINI one, but maybe I should have. Oil pressure seems fine, and I see no signs of oil loss, although it is late (dark) now...

SCMS was getting right around 100C or 212F in such driving conditions, so I am concerned. I appreciate any help. Thanks.

 

Tony, " Must I use the sender that came with the AutoMeter gauge? "

Yes, use the AutoMeter sender the AutoMeter gauge is calibrated to the output of that sender.