i've half had an(electrical) oil temp gauge fitted to my car, but have had mixed opinions on where the sender should be placed. i first had the wrong size adapter and purchased a larger one. what i over looked was that the adapter was for a ready made bung hole above cylinder 3, but the subaru garage had been trying to fit it as a sump plug adapter(so the adapter i had was still too small). subaru have argued that the sump is the best place to get an accurate reading because thats where the oil sits at all time. the supplier who sold me the gauge and 'cylinder 3' adapter says that i'll get a truer reading from the cylinder bung hole as it is the hottest area???
to be fair, the supplier is going out of his way to enable me to have a sump plug modified (if i want it placed there), but this will take time to organise, but will be hopefully free of charge.

opinions on this would really be appreciated. i'm having the car tek3 mapped in a couple of weeks and realise the importance of an accurate oil temp reading so i want it all sorted by then.

 

I say above No3 cylinder, thats where mine is.

For an adaptor try http://www.lma-group.com/motorsport/...ing_parts.html Think part No is LMA067

 

cheers m8. yep, i've got that adapter already and subaru dealer is willing to fit it there no probs....... but, they insist that placing the sender on the sump plug will give a more accurate reading??

 

true reading from the no3 plug as it sits the sender in the oil gallery on the hottest running cylinder due to the location of the turbo..... the sump plug is not ideal as it will show a lower reading due to the fact that some cooling of the oil will occure because of the airflow around the sump

 

no 3 is the best as its the hottest part usually 10-15 degrees more than rest of engine due to header tank.

 

The proper way to do it is to get a boss welded into the sump for the temperature sender to get an acurate reading. It's the true sump temperatures that are of any use to know.

 

I'm sorry, I'd have to disagree with the above, and my reason would be:

Surely, you need to know the HOTTEST temperature your oil is getting to, not an average?

Alcazar

 

thanks for the replies. the more pepole i ask the more i'm hearing above the r3d cylinder, as it will give a max temp of oil being used rather than the temp of oil sitting in the bottom, kind of makes sense. it is strange the main mechanic and service manager at my subaru local dealers are insistant that a sump plug adapter is the better option?

 

they don't always know best some do some don't. when i asked for adapter for my oil temp sender they said for sump and when i said no number 3 they didn't even know what i was on about which i told them then they said they only fit subaru gauges and the sump is where there sender goes but they said they very rarely fit them at all so have little experience in them.

 

cheers m8. sounds like a similar story.

 

from what has been said above does anyone on here have their oil temp read from the sump. the most popular view i get is that the hottest temp from the oil gallery is needed, but i don't i want to know whether the oil is being cooled properly? hence get the reading from the sump.

 

checking the cooling ability of the oil is not the main function of the gauge...... you need to know how hot the oil gets during hard use because oil is rated at specific temperatures..... should the oil exceed the upermost temp reccomended then it begins to loose its lubricating qualities...... not much point it being there after that and then engine failiure occures .....part of its function is to take heat away from the hot bits as it circulates through the system...... it will cool well by the time the sender in the sump reads it,but you wont know the highest temp it has reached.... this is vitally important and should not be overlooked

 

thanks for the reassuring words rigga. but i am getting many conflicting arguments over this(not just from this forum, but elsewhere). the reason i'm setting up an oil temp gauge is due to having a MY99 tek3 remapped in a couple of weeks. so just want to make sure the gauge will read useful temperatures that i can watch to ensure that a hotter running engine/turbo is working safely and the oil in the car is sufficently doing its job. the car is for road use, i've been told that you need to watch the temp espeically on hot days when booting it.

 

I run mine in the sump as I have a pressure gauge in No.3.
I get a steady 85 degree's with normal driving.
However if you have an earlier car without the plastic undertray, you will see lower values due to airflow cooling under the car. With the undertray in place the sump seems fairly protected, as I found out when I ran for a while without the undertray.

 

so in your opinion, do you feel that the sump location may be a better option than above the 3rd cylinder.
p.s my car has an undertray.

 

I have mine in the sump also, for the same reason as Scott; oil pressure for the oil light and the pressure gauge are both taken from the top of no.3

 

you can do both as i have temp and pressure above no.3. the reason for temp been above no.3 is so you know the max temp at all times as to me there is no point knowing average temp as the whole point of having an oil temp is knowing when to back off when it gets too hot.

so say for example my back off point is 100 and yours with sump temp is a 100 now my engine will be a max of 100 were as yours will be 115 max temp at your 100 reading. this is why most pick no.3 as its much safer to know your max temp as the average serves no purpose!

 

On track I've been seeing 130oC with the Defi sender above No.3, I back off at this point If the sender were in the sump, that high temp would be masked.

It's a lot easier to fit the sender to the sump plug than to No3, maybe why it's a favourite location for some?

Anyone know what an excessive oil temp is? I use Motul 15/50

 

anyone got a pic of where the sender should go..cheers

 

On 98-00 models its here. think its the same for earlier cars also, but not sure about the bug-eye onwards cars??

Remove this plug, fit your gauge probe to your adapter, then fit the adapter into this hole. (it's easier that way )

 

this is where it is and how i have mine apart from pressure on side of connector and temp on top





hope this helps

 

thanks for all the informed replies to this thread, been really helpful.

 

Same on a newage, loads of swearing and skinless knuckles to get thet ***** out and replaced with the temp sender. Pressure sender replaces the original and T pice not used. Original is useless and even discoonected does not throw a CEL.
Boost tapped off dump valve with a t piece and short piece of silicone tubing to prevent cutting the pipe

 

True that #3 is where it's hottest (where my temp sender is too), but the sump temp is the temp of the oil that is supplied to the bearings.

Either would be fine by me. My main concern would be viscosity lowering due over temperature of oil that is getting supplied to the bearings.

 

Where in the circuit is the gallery above No.3?

 

As far as I remember it feeds the cams before draining to the sump. I saw a diagram a long time back, but no idea where that was..