Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Oil Cooler for 3.0 Roadster

Hello All,

Just purchased a 2005 Roadster (USA) and I'd like to add a proper oil cooler. Has anyone done this along with the removal and bypass of the sandwich plate from the water pump?

Thanks, Brian

Hi there,

Saw this on GoMoG recently. Make no comment if it is correct but worth considering.

R.

What is engine temperature? My roadster, along with most other cars I've owned, has a water temperature gauge. After a few, usually less than 2 miles the dial shows 80 or 90 degrees. The fan cuts in now and then to keep the needle below 100.

But does this measure engine temperature or just water temperature?

My 2013 BMW has only an oil temperature gauge.This takes 5 to 10 miles to reach normal; long before the oil is warm the heater works well.

So, my conclusion: for the first 10 to 15 miles the water temperature gauge is fairly meaningless as it simply shows how hot the water is, nor how hot the engine is. Once the engine and oil have reached a steady temperature state the water gauge is probably enough. But how do you know the motor has reached steady state? Also without an oil temperature gauge it is not possible to know what is happening, and more importantly if an oil cooler is ever needed. Over-cooling oil isn't a good idea, like the rest of the engine it needs to be at a constant 80 to 90C.

So why does the industry (other than BMW) fit water temperature gauges?

Interestingly on the MOG it is possible to use the oil pressure gauge as a proxy oil temp gauge. Cold the oil pressure is about 5 bar. It stabilises at 1 bar at idle, 2 bar at 5000 rpm, but as with the BMW it takes 10 miles or so to get there, long after the water is hot.

Good question Peter. I agree that water temperature is not ideal for deciding when the engine is up to temperature. As you say the gauges often reach their normal range within a couple of miles, especially if the sensor is positioned up stream of the thermostat (i.e between the cylinder head and the thermostat). If that is the case you are only seeing the rate of temperature rise in the cylinder head area. Thereafter, the temperature is controlled by the thermostat itself. I don't know, but I guess that the obsession with water temperature gauges is rooted in history when boiling coolant was a major source of breakdowns and so you needed to keep an eye on it.

As you say, oil temperature is by far a better indication of the engines overall operating temperature. I've got a dashboard with the 4x round Smiths gauges and I've been considering a modification to install a Smiths combination water temperature and oil pressure gauge (the 2x half moon type) and then add an oil temperature gauge in the spare position left by this. I'm also considering fitting an oil pressure light, there is pressure switch at the oil pressure sensor, so I'm going to investigate this. Probably both projects for over the winter months.

I can't see the need for a cooler as the engine runs under 100c as Peter states. THe Roadster is not like the plus 8 where the fan seems to be no all the time.

Are you in the UK Brian, or somewhere much hotter?

He's in the US I believe.

Whether it's colder or hotter is another question

Welcome to TM Brian, I'm sure you'll find this forum extremely helpful with many interesting topics.
Where in The U.S. are you located?
How about a few pictures.

Death valley?

I can't comment directly on Oil Coolers on the Mog, but the 370Z is known for having horrible oil overheating issues. In the summer my OEM oil temp gauge will get up to about 250F and on the track the car quickly overheats and goes into limp mode after a few laps. After installing a thermostatically controlled oil pressure hookup plate and a 25 row setrab oil cooler by car won't get above 220 in the summer in daily driving and I've never had a problem at the track with it either. Just means I have to put an extra quart of oil in when I change oil.

Where I live it's very humid and average temps range anywhere from 24 to 103F (-6 to 39C)