E46 M3 Hot Oil

[Nhaden 0]

I am having an over-heat problem with my race car and am looking for suggestions...

I am seeing a significant increase in oil temperature when going through corners on the track. This shows up on the dash display and the datalogger reports from the ECU. Running along the straights it cools down again, but often not enough by the time I get to the next corner. The worst case is Higgins at Manfeild where I gain 25 degC through the corner. I back off when I see numbers over 140 degC, so don't know how high it could go.

Water temperature stays in the normal range (about 85 degC).

I am running the stock oil cooler with air cond and front fan removed. I fitted an oil diverter valve, but that doesn't seem to have made any difference. Oil is 10W60 Castrol.

Has any heard of this? Possibilities that occur to me are:

Sensor problem that is affected by lateral G's (seems unlikely)

Partial blockage in oil cooler meaning it stops working under lateral load

Something in the engine that causes it to heat under load

TIA

[turbolizard 38]

I think it is pretty unlikely the bulk of the oil is actually heating and cooling that quickly.

I would guess it is the sensor being exposed to different sources of oil in corners. Is the sensor in the sump or in some part of the pressurised oil flow path? Does the bulk of the oil flow away from the sensor in turns leaving hotter oil flowing back to the sump running directly over it?

[hybrid 1044]

Sensor should be pre oil filter as it is a true representation of the temprature coming out of the sump.

Can you send us the data log from your car ? you can tell a lot from the data.

The sensor will be working just fine unless its been wired incorrectly. EG grounded to the chassis instead of being grounded to the datalogger (dash) ground. This can cause sensors to read in correctly as it is effected by natural resistances and/or stray voltage.

There is a potential for oil pickup starvation which can be cured with gating of the sump or running an accusump system. Dry sumping would obviously be the perminant fix but its expensive _STILL_ *rolls eyes*

The grade of oil is another thing, the thinner it gets the hotter it will run and so forth.

You can also look at the position and ducting of your oil cooler it is also entirely possible at slower speeds the aero on the car is going into negative pressure around the oil cooler at slower speeds. You can put a gopro and some woolies on / around your cooler to see whats happening.

Also lastly in a race application I would look to getting a bigger cooler. Im running a large earls (holly) cooler for mine. But I would awnser the above questions first.

lots of things to think about

[M3_Power 636]

140 is really high for a s54 ...

I am gathering you are reading those temps on an aftermarket dash with stock sensors?? Or are you reading them off the car's stock dash? Because the stock dash oil temp sensor is notoriously inaccurate (apparently by as much as 30 degrees in the higher ranges).

Few things I would do with race application:

- cut a hole in the bottom plastic tray to divert air out of the bottom and back of the oil cooler (ala E92 M3) - the airflow goes no where in the E46 M3 oil cooler .. basically just back up into the engine bay, there's no escape route for it.

(this is off an E92 M3, but you get the gist)

- Get a bigger cooler ... the factory item is tiny.

For comparison with aftermarket units:

- Are you running a stock bumper? If so, get a splitter to split the air at the low pressure zone back up into the cooler hole.

- Check your constant pressure valve (CPV)

- Check your ignition timing (if data logged, check it against the oil temp) ... faulty Vanos solenoid have been known to cause retardation in ignition and causing the engine to run hot.

Ideally you want this setup to solve it all - tried and proven : )

[hybrid 1044]

If you run a stock ECU, I can log the timing / fueling easy enough.

[Nhaden 0]

Thanks very much for all of the responses.

The measurement setup is the stock sensor, which I now understand is also the oil level sensor in the sump. This sends data to the ECU and I am logging data out of the ECU which is the same as the information sent to the dash.

Looking further at the logs, the temperature goes up when turning right and down, but not by as much, when turning left. A guy at work suggested the solution was to just race NASCAR!

oil temp.pdf

The attached file is one lap (not the worst case) showing lateral G and oil temp. Red is right turn, blue left turn and green straights.

Other advice is that it isn't really possible for oil to heat up as quickly as 25 degrees in one corner so there must be a measurement problem. So I need to replace the oil level sender and then check if the problems are still there.

It does seem likely that I will need more cooling, but I will get a better read on the numbers first.

M3_Power's suggestion of trying to duct a bit more air from behind the cooler seems sensible. The aftermarket coolers that fit in the stock position (e.g. BimmerWorld) seem pretty expensive, so if I do need a new cooler, I will probably go with a more standard aftermarket one as I have plenty of room in front of the radiator.

[hybrid 1044]

What is the temprature reading from dead cold?

Is the data logging OBDII or BMWs DS2 protocol from the ECU?

Look at holly cooler .. theyre very well made ... no chinese junk here.

https://www.holley.com/products/plumbing/cooling_systems/oil_coolers/

here is mine its a tad on the large side and goes up past the bumper line

[Nhaden 0]

The data logger is an AIM Solo DL. It is spliced into the CAN Bus as the OBD port apparently isn't updated fast enough on the E46 model. I don't know the protocol, but it sounds like it would be DS2.

Oil temperature reading at dead cold is the ambient temperature, so that seems right. It increases matching the dash read-out (when it gets over 50).

How big a cooler did you need for an S50?

[hybrid 1044]

If its only updated every now and again it will be OBDII. DS2 on the MSS54 is capabile of around 10hz.

Usually youll be looking at 10 degrees above water temp for ambient on stock sensor locations. On S5X motors its on the oil filter housing bosses.

I went with a over sized one its about 200x300mm, however I still have a external oil thermostat as its still (kind of) a road car, so while it stays cool it doesnt cheat the warm up cycle to 80 degrees.

Another side of hot oil is a drop in pressure nothing dangerous, but expect levels around 25psi. You will also have more chance for cavetation in the sump and air bubble build up as the oil is a lot thinner.

[Moorsey 0]

Did you ever find the cause of the problem or a cure? My e46 M3 seems to be doing exactly the same.

cheers

Ben