13 replies to this topic

[tomsbluemini]

Hi all...

I used to have an MPi, and no matter what I did to it, no matter how hard I drove it, in town, country lanes or motorways, the oil temperature gauge hardly moved(it did move a tiny bit so it definately worked!)

now on my second MPi, the oil seems to run much hotter. It seems to be about 85 degrees around town (where most of my driving is done,) and just done a decent 140 mile motorway run andthe temperature has gone up to 120 degrees.

I've given the car a recent oil change and used that Halfords classic oil (2ow40) I think but don't quote me...

What should the oil temperatue be? presumably, the cooler the better as that would give it better cooling properties if it was cooler to start with? Is it something that an oil cooler would help with?

I know that every mini is different, but it just seems odd that my old MPi's oil ran really cool and this one's oil seems to run much hotter...

Ideas on a postcard please

Cheers

Tom

[jamesmpi]

I'll ask the obvious question, do you have a sump guard on your current mpi as that would reduce cooling of the oil via the fins on the sump.

Also you don't want "cool" oil, but you do want it to operate at its intended operating temperatures. This varies depending upon the type and grade of oil I think......but fluctuating oil temps like you describe is odd

[jaydee]

85-95 deg does not sound bad.. 120° sounds quite hot!

[tomsbluemini]

Yes I have a sump giard. Now you've said that, it makes perfect sense!

I live in London, home of many, many speed bumps. I'd like to keep the sump guard as i'd rather damage the guard thwn the sump.

I understand about the oil not being too cool, but clearly dont want it to run too hot. It's 20w50 oil i'm running.

Would an oil cooler be effective or would it make the oil too cool to work effectively?

Thanks in advance

Tom

[jaydee]

Fit the small type cooler, 10 rows, with a 74° deg thermostat.

[jamesmpi]

Fitting a 10 row oil cooler is probably a good idea but as said above make you you fit a sandwich plate with a built in thermostat.

For an mpi your best bet is to buy a short / small oil cooler and mount it on the right inner wing below the expansion tank. You will notice there is a gap between the edge of the radiator and the inner wing. This allows a good amount of air to pass through but it is very tricky especially when mounting the sandwich plate.

If you need move advice then let me know

[nev_payne]

Before rebuild Sir D hit 120C regularly. Since then, and a regrade in oil, he barely hits 100. On the trip to France he pushed above 100.

The only real factors affecting oil temperature are how often the engine is firing. Do the fluctuations occur with more driving up hills or in lower gears, than in drives with downhill or flat open road?

Edited by nev_payne, 31 May 2012 - 03:44 PM.

[jamesmpi]

Also you could drill some more holes or slots into the sump guard to allow more air flow over the sump......

[tomsbluemini]

Thanks for all your help guys.

The Minisport kit doesn't come with a thermostat so that will take some finding.

As regards mounting, would there be enough room to mount it behind the grille just next to the radiator? I'm trying to think about best airflow whilst also keeping the job simple...

Cheers

Tom

[jamesmpi]

I don't think so because of your oil filter.
I brought all the parts last year but haven't got round to fitting it.

You can get the sandwich plate here
http://www.merlinmot...=Sandwich plate

Merlins will sell all the parts you need but can get oil cooler off eBay for about £60

There is one very important consideration point and that is the thread of you block for the oil filter. For some very late mpis they changed the thread size to 13/16 unf I think but trying to find a short stubby oil filter with that thread is impossible (you can no longer fit the standard length filter or it will foul on the radiator).
To fit the filter you need to buy an extension piece (again from merlin) because of the added thickness of the sandwich plate. But you will need to get the bolt machined it down to 3/4 unf so that you can screw on filter.
Below is an extract from a friend who had to do the same....
No. It's 3/4. I couldn't find a filter easily either. I got the 13/16 bolt and had the male thread reduced. In the unf system the pitch (threads per inch ) is the same for 3/4 and 13/16 so it's a 15 min job on a lathe to cut it down.

It's a balls ache to get it done but does work very well.

Finally I would highly recommend buying some anti vibration mounts from merlin for mounting the cooler to the inner wing. They work a treat
http://www.merlinmot...=Anti vibration

James

Edited by jamesmpi, 01 June 2012 - 12:21 PM.

[jamesmpi]

There is a little more info on our club website. Pages 10 to 12 of this build thread
http://www.abingdon-...rt=60&Itemid=60

I forgot to say that you might need buy a longer drive belt for this setup and modify your coil bracket to give clearence for the sandwich plate

[bluedragon]

I'd pause for a moment before going to an oil cooler.

Is the water temperature rising? If the water temps are not excessive, and there's no sign of overheating (boiling overflow tank, etc.) then I would think it unlikely that oil temperatures would be soaring. I can't imagine a cause that would make oil temps climb and yet water temps remain reasonable. There should be some relation between the two values.

So, if water temps are reasonable, perhaps the oil temp sensor is inaccurate. I will say, it takes some heavy loads to get oil temps to move into the upper ranges - I had to see 35°C+ temps climbing a steep rise @high altitudes (1200+ meters) to see oil temps push into the high range (but safe for a synthetic 20/50 oil.) It would be hard to imagine such conditions in London, even in the summer.

If you can measure oil temps with an alternate method, that might give better guidance. Not sure what's possible other than plumbing in a known, accurate oil temp gauge - perhaps an infra-red thermometer gun aimed at the sump after the oil temps register high?

Of course, perhaps the car is overheating and the water temp gauge is reading too low. But I imagine there would be engine symptoms of that, since the ECU depends on the water temp sensor to properly function.

[jamesmpi]

I agree with the above. My info above I'd just guidance if you choose to go that route....

I would advise having a read of Keith Calvers technical section of this months mini mag. He talks about the common misunderstandings for needing an oil cooler......it in he says that identifying the oil temp in the sump is the key reading that you need. Maybe it's worth putting so time into that, rather then fitting a cooler now?!?!

[jaydee]

Fit a mech oil pressure gauge, i'd expect a pressure of about 60 psi cold, when warm drops around 40 psi at idle and 50-65 psi at revs.
Now when the oil temp gauge shows high, if the oil pressure drops below 50 psi while driving at revs, you need the oil cooler.