Oil temp sender location?

[NickW]

G'day,

 

Where is the best place to locate an oil temp sender?

 

I have a dry sump xflow with a Mocal remote filter (not currently with a sender hole, but I could drill and tap one). However, that would put the temp sender in the feed from the oil tank to the engine, so the oil would be fairly cool? Is it not better to have the oil temp sender on the output from the oil pump back to the tank, so that you get a reading of the oil temp as it would be in the engine?

 

Help and suggestions greatfully received. (as long as the second word isn't off)

 

 

Thanks,

 

Nick.

[Jason Plato]

As you have already pointed out , you can either measure the temp going to the bearings or the temp coming from the engine .

I would prefer to measure the temp of the oil going to the bearings , as this will tell you if you need aditional oil cooling in the system .

 

Hence also the use of a temp sender in the K belltank . I have checked the temp of my sender ( bottom of belltank near return pickup ) vs the temp of the oil coming out of the engine and its reached a maximum difference of 25 degrees - this was whilst blatting round Donnington .

 

Hope my 2p worth helps ? . You may also wish to talk to the guys at Think Automotive for their suggestions ?? .

 

Dave

[NickW]

Dave,

 

I hadn't thought of it that way, I guess it is more important to know the temp of the oil going into the engine.

 

Thanks,

 

 

Nick.

[elie boone]

Nick, if the sender is in the oilreservoir you know when all of the oil is up to temp.

[Roger King]

Ideally, you want to measure the oil temperature at the bearings, but for people with normal budgets this is impractical.

 

The best compromise is to measure it in the sump. We often fit a sender unit into the sump filter plug by drilling and tapping the correct thread. This is about the hottest place to measure from in practice.

 

It is important that oil is not run beyond it's specified temperature. If you measure in the tank after the oil cooler you are getting a false impression. A really efficient oil cooler could bring even superheated oil down to an acceptable temperature before returning it to the tank.

 

Having said that, a tank reading is usually a reasonable indication of the situation so long as you allow for the fact that is lower than the peak figure.

[Paul McKenzie]

Slight thread hijack.

 

Roger,

What's the optimum oil temp. for a 2.0XE? and what's the highest temp. you'd want to see before fitting a cooler.

Thanks,

Paul

[NickW]

Roger,

 

Thanks for the info, hadn't thought of putting the sender in the sump plug!

 

Following on from the previous post, I've had a look around at spec's for various oils and they mention vicosity at 100 C, but no maximum recommended temp.

 

Is 100 C a resonable level to keep below when measuring in the sump? Or wouldn't the oil normally get that hot?

 

Thanks,

 

Nick.

[Roger King]

Max oil temp varies according to the type of oil, so I can't specify a max figure for an XE. Synthetic oils are often specified as being OK to around 140 degrees C, but there is never any mention of whether or not this applies to tank temperature or peak temperature.

 

We try to run most engines with a maximum figure of 110 degrees C with synthetic or 100 degrees C with mineral. Minimum would be around 75 degrees C.

 

If temperatures try to exceed this under the hottest possible ambient conditions, an oil cooler is needed in my opinion.

 

We have found that very hot oil in engines with hydraulic cam followers can cause rattling valve gear even though the oil is below it's specified maximum figure. It appears that the oil may still be good as a lubricant, but is no longer functioning as a hydralic fluid under these conditions.

 

We have also seen a Crossflow with narrow journal big ends run on track on the hottest day of the year without an oil cooler (driver wanted to save weight, throw a rod due to bearing failure caused by oil temperature, so be warned.

[Paul McKenzie]

Roger,

Good info..many thanks

Paul

[NickW]

Roger,

 

The sender I've got is a 3/8 BSP thread, it has just occured to me that this would be a rather big hole to drill into a sump plug.

 

Do you use this size sender or something smaller?

 

Any problems with the sump plug breaking, I assume you fit the sender to the sump plug then the plug to the sump.

 

 

Thanks,

 

 

Nick.

[Roger King]

The sender we use has a 1/8" NPT thread. This is the same as the one for the water temperature sender that fits in the cylinder head (same sender in fact). Some people then use the same gauge with a switch to swap between water and oil temperature.

 

Is yours a mechanical gauge with that size of thread?

 

Yes, we machine the plug off the car, fit the sender and then fit the plug to the sump.

[stevefoster]

I had a RKE tapped sump plug VX XE. The hottest I saw last year racing was ~95 degrees with this set up. Both those meetings were not that hot amb temp

I went DS and now see ~95 degrees as hottest (Brands last yr amb temp of 32 degrees) measuring the oil temp in the bottom of the tank.

 

 

 

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[NickW]

Roger,

 

Yes, it's mechanical capillary.

 

So I guess it won't be such a good idea to tap a 3/8 hole in my sump plug.

 

I'll have a look for another location as close to the sump as I can.

 

Thanks,

 

Nick.