Oil Cooler

I have coolers on all my bikes fitted between the filter and tank return with a bypass valve:

Oil Cooler
 
Madnorton said:
From random sampling on various bikes even a day when it was 32 C, the oil tank temperature was not even near the working temperature of the oil.
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What is the working temperature of oil in a Norton twin? Exceeding 212 'F/100 'C is not good for any oil, but does it matter much if the temperature is 80-90 degrees C (176-194 'F)?

Measuring temperature in the oil tank doesn't tell you how hot oil can become within the engine. Because of the limited flow of supply, oil draining from the cylinder head is considerably hotter, and this should be our parameter of concern. So, I suggest putting a temperature gauge in the crankcase rather than in the oil tank (the indicated temperature will still be too low because it mixes with oil thrown off the crankshaft).

I think any measure helping to cool oil to the cylinder head is worth a consideration, at least for those doing extended trips.

- Knut
 
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Madnorton said:
Unless you live in Death Valley or the hottest parts of Oz, then you certainly will not need one. In the UK, not even if you ride full throttle everywhere. From random sampling on various bikes even a day when it was 32 C, the oil tank temperature was not even near the working temperature of the oil. If you ride in traffic congested areas, an oil cooler is not much help in which case you need a decent oil.
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I race a Rickman.....I have burnt my inner thighs on the frame/oil cooler/oil tank!

(solution was to get more padding in the seat to get my legs further from the frame rails! ;))
 
MichaelD said:
I put an oil cooler on my Commando when I was taking lengthy holidays in the South of France, a combination of a very hot sun and very slow traffic along the coast roads did concern me, my oil pressure dropped to almost nothing at times. I ran the oil return from engine to a cooler mounted high on the front of the frame, then back to the oil tank (1970 bike, no oil filter). It all worked really well, keeping the oil temperature down and oil pressure up.

Now when I ride the bike its in the UK and generally North of Preston, so traffic is generally fairly light, giving plenty of airflow over the engine, and the ambient temperatures aren't high 30s, so I've just removed the oil cooler, it wasn't doing any good, and was probably just keeping the oil at a less than optimum temperature.
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You had me at "lengthy holidays in the South of France"
 
The cooler in post #1 is unlikely to be very efficient.
There are no fins inside the tank to extract heat from the oil, so it can only cool the surface of the tank.
Oil temperature is more a function of the load on the engine than ambient temperature.
Maybe a heavy bike traveling at speed, 2 up, loaded with luggage on a warm summer day can benefit from a cooler, but otherwise not.
I did extensive road tests with different temp. probes in hot weather with my Commando ( light, solo, alu oil tank, alloy barrel..) and oil temp. in the tank had trouble reaching 70 °C. ( = too cool)
When not traveling, I keep the oil level at a minimum.
 
ludwig said:
I did extensive road tests with different temp. probes in hot weather with my Commando ( light, solo, alu oil tank, alloy barrel..) and oil temp. in the tank had trouble reaching 70 °C. ( = too cool)
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Please explain why 70 °C is too cool ?
Oil temperature in an air-cooled engine is not to be considered the same way as oil temperature in a water-cooled IC engine, which (at least in cars) often has an integral oil-to-water heat exchanger, which provides an approx. temperature balance between the two.

In our Nortons there is no direct coupling between coolant medium (=air) and oil. Engine temperature (which varies according to location) is affected only partially by the engine oil.

- Knut
 
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mdt-son said:
I think any measure helping to cool oil to the cylinder head is worth a consideration, at least for those doing extended trips.

- Knut
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Right.
If you look at a Norton cylinder head, the 3 lower front fins form a deep V between the exhaust ports.
Because of the tilt of the engine, it is a trap for hot air, especially at slow speed.
That is why you can ( should..) drill a hole through the 3 lower fins here:

Oil Cooler


It will create an upwards airflow at what is probably the hottest part of the engine.
There are a few other things one can do to keep the cyl. head cooler, but drilling that hole is the easiest.
Also, if possible, restrict the oil flow to the cyl. head.
Some think that extra oil to the head will help cooling, but it is the other way around: the head will heat up the oil, and that (over) heated oil will run down on the camshaft and followers.
Because of the inclination of the engine, there is too much oil in the timing case, and the spinning gears and cam chain heats the oil. Drill a drain oil below the oil pump.
(Credit to Jim Comstock, do a search..)
In short : it is better to prevent overheating of the oil in the engine, than cooling it afterwards.
( putting burnt toast in the freezer won't make it edible..)
 
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ludwig said:
I would prefer it to be over 70 to get all the water out.
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For every gallon of petrol you burn you create approx 1 gal of water, most goes out the exhaust and is seen as steam coming out of the exhaust pipes on cold mornings. Blowby past the rings down into the crankcase brings some of this water into the oil. Best way to get rid of this water is out the oil tank breather pipe which requires the oil to be hot enough in the tank to release the water. Fit an oil cooler that works all the time and you end up with a lot of water in the oil.
 
kommando said:
For every gallon of petrol you burn you create approx 1 gal of water, most goes out the exhaust and is seen as steam coming out of the exhaust pipes on cold mornings. Blowby past the rings down into the crankcase brings some of this water into the oil. Best way to get rid of this water is out the oil tank breather pipe which requires the oil to be hot enough in the tank to release the water. Fit an oil cooler that works all the time and you end up with a lot of water in the oil.
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Never had no signs of water in my oil from been running an oil cooler all year round, but so many have a lot of opinions about running an oil cooler, but it works for me and my Norton runs so much better with what I have been doing with it, its reliable and I gotten long life out of my motor, my motor gets up to temp when out and the hot oil is getting cooled down a bit before going back through a hot motor and with a smaller capacity oil tank it's very important, I have never topped up my oil between oil changes.
Even my Land Rover Defender runs an oil cooler (TD5 engine) from the factory and it holds 7.2 ltr of oil.

Ashley
 
kommando said:
Fit an oil cooler that works all the time and you end up with a lot of water in the oil.
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Ha! "A lot of water" is like asking how long is a rubber band. The rather short intervals of oil changes, combustion of oil (yes, some oil goes the opposite way past the piston rings), evaporation of water past the venting system due to the engine's internal heat (we all have fabulous reed valves by now, don't we?), and lastly ongoing evaporation from the oil tank vent along with other light hydrocarbons should minimize potential problems of having water accumulation in the oil, I think.

Cooler oil also reduces evapration of light substituents and reduces breakdown of the long molecular chains with excessive heat, thus reducing the loss of lubrication properties, which results in lesser engine wear.

Counting it all, I think the benefits outweigh the possible downsides by far.

- Knut
 
It always boils down to how you ride, where you ride, the conditions, if you ride hard all the time or if you pussy your bike, if your in a hurry or what, my Norton as well all my old AC British bikes have never had any problem running an oil cooler in all these conditions, from running around the suburbs/city, to out on the highway/open roads, on long haul travel to fast runs up in the tight twisties/ranges, it doesn't miss a beat no matter what rev range I sit on and as I say works for me and the Norton runs so well all year round, the motor has never let me down no matter how hard I push it and as I say everyone has their own opinion on the matter, that's what a good forum is about everyone can have their say, do what you think is best for your own bike and enjoy.
After 48+ years on my Norton I think I have a good understanding of it by now and what's best I can do for its long life, it seems to be happy and has only broken things when I done some thing stupid, lucky that is very rare, fingers crossed/touch wood lol.

Ashley
 
Yes, once the engine has been first run after an oil change water enters the oil, there is an equilibrium between the water coming in via ring blowby and the heat evaporating the water and then exiting via the breather. The colder the oil the higher the water content as less water is driven off. High water content ages the oil via oxidation and reduces the oils potential oil film thickness.
 
kommando said:
Yes, once the engine has been first run after an oil change water enters the oil, there is an equilibrium between the water coming in via ring blowby and the heat evaporating the water and then exiting via the breather. The colder the oil the higher the water content as less water is driven off. High water content ages the oil via oxidation and reduces the oils potential oil film thickness.
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I just ride and enjoy my bike time, hasn't killed it yet, in fact haven't killed any bikes in the 50+ years of riding, blew up two car motors from loss of oil pressure, first one got me home with a lot of noise the other I was 100 miles from home and it just locked up and died on the side of the road lol, I had to shoot it to put it out of its misery lol.
 
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