Oil coolers...

Bob Z. · May 27, 2012

How many run an oil cooler on their Norton?
I had one on long ago, but have not reinstalled on my current daily rider.
An issue is that the alloy finned cooler was placed just above the front isolastic mount between the frame tubes.
The oil lines had to be run from the return line at the back of the timing case, over the gearbox and under along the bottom right frame tube, then into the
cooler, then exiting the cooler back along the bottom frame tube and up into the oil tank connection. Probably close to 6-feet of hose?
Never had a problem but wonder if the length of the required hose was a potential problem?

I recall the Triumph Tridents had their cooler up above the cylinder head, so the return line may have been above the oil tank oil fill level.

Any thoughts?

john robert bould · May 27, 2012

The oil as to pass through the engine,so a few feet of tube aint going to make a lot of differance. on the plus side the system as more cooler oil.down side un-tidy pipes and possible chaff /rub holes if not positioned right...remember vibes and pipe chaffs on frame members.

goo · May 27, 2012

maybe you should stick a temp gage somewhere first. then if you install a cooler you have before and after data that you can share here.

concours · May 27, 2012

I have the oil pressure gage, no cooler. (yet) Riding 125 miles in the cool rain with the spray from the wheel on the crankcase confirmed what I had suspected. Oil pressure was improved 25%, 20-50 racing oil being used. I am planning an oil cooler as soon as I figure out a tidy location/mount.

ILLF8ED · May 27, 2012

My '72 750 has over 50,000 miles without the benefit of an oil cooler. Summer gets over 100 degrees in the Sacramento valley. Change the oil often and stop stressing.

Dances with Shrapnel · May 27, 2012

illf8ed said:
My '72 750 has over 50,000 miles without the benefit of an oil cooler. Summer gets over 100 degrees in the Sacramento valley. Change the oil often and stop stressing.

You may do more damage by installing an oil cooler by creating an excessive oil warm up time. In my opinion, lubricity and feed are probably less of an issue with colder oil when using the modern multigrades but driving off moisture is important and that does not happen until the oil is sustained at a toasty warm temperature. If you are finding oil/water emulsion in your oil tank or dip stick, in my opinion, this is not a good thing.

A lot has to do with your ride style; whether it is dominated by short jaunts or long high speed hauls in high ambient temperatures.

I would do an oil temp check now and then to see what you are working with.

With oil coolers I pondered sourcing a thermostatically controlled valve that would bypass the cooler until oil temperature indicates it could use some cooling.

From a technical standpoint I personaly take a problem definition approach to these types of concerns. I ask "is there a problem"? Do I really understand the whole picture? What "all" will happen when I make the change?

mikie3117 · May 27, 2012

Got one. Probably do not need it. I have actually seen oil pressure too high while riding in the mountains in rain/hail. I have checked oil tank temps at various times and my Norton rarely gets over 160 degrees. My twin cam 2006 Harley tops 220 degrees under same conditions. Interestingly though, there are temp gradients from the top to the bottom of oil tanks.
Mike

marinecommando · May 27, 2012

What do you call too "High" oil pressure?

kraakevik · May 27, 2012

There is in fact oil-temperature stratification from top to bottom in the oil tank--the same principle at work in a domestic hot-water heater.

I have a Hyde cooler mounted on the front downtubes; a thermostat actuates the circuit when oil temperature rises above 165 degrees Fahrenheit. Even on days in the 60's the cooler comes on after a run on the tollway; it also actuates during traffic tie-ups in the summer.

I wouldn't run one without a thermostat--riding as I do all winter keeps the oil temperature down enough as it is--but it's surprising how much thermal overhead there seems to be when you come off an 80-mile-an-hour run and sit for three or four minutes waiting for the off-ramp light to change. The thermostat opens the circuit briefly--then closes again a mile or so down the road. That oil gets hot.

The 850 has a huge oil cooler mounted just under the coils with no thermostat--it probably holds a quart and a half of oil. I bypass it in non-summer months--but it too gets plenty hot after a hard run.

Tim Kraakevik
'72 Combat, '74 RH10 850
kraakevik@voyager.net

marinecommando · May 27, 2012

Did any of the Manx race bikes run coolers?

marinecommando · May 27, 2012

I would have thought that just by fitting an oil filter would help dissipate the heat generated. So on that train of thought increasing the length of the hoses would have the same effect?

Dances with Shrapnel · May 27, 2012

marinecommando said:
What do you call too "High" oil pressure?

I suggest taking a look at a few oil manufacturers recommendations. With a quick search on line I come up with 250 degrees F for one oil in a ROTAX application but this is a general number with some assumptions imbedded in it. I am not sure if they are distinguishing between an air cooled and liquid cooled engine.

Some critical thinking here is that you are reading temperature at the oil tank and it has already had some cooling residence time dribbling down the crankcase shell. With an air cooled engine there are considerable swings in the temperature of various components of the engine due to a variety of reasons whereas a liquid cooled motor generally has a more steady state temperature. I have scanned a warm/hot Commando engine with an indirect thermometer and it is interesting to see the span of temperatures across the motor.

In my race bikes I get a little concerned when oil temperature in the tank rises above 235 degrees F and that is a somewhat arbitrary threshold. It is usually an indication that something is wrong.

marinecommando · May 27, 2012

I understand the temperature part, it was the "high pressure" part that I didn't understand.

Bob Z. · May 27, 2012

Here is a photo of the type of cooler I used to run.
If mounted any higher, the front fender will come close to it during full compression.

Dances with Shrapnel · May 27, 2012

marinecommando said:
I understand the temperature part, it was the "high pressure" part that I didn't understand.

Ooops

My reading comprehension went a bit off there.

I don't have a specific number, maybe someone on this list can give you a specific number. I think what we are concerned with is excessive oil pressure.

I know we bumped pressure up on one of the Commandos and the lip seal between the timing cover and crankshaft end blew out. What I mean by blew out the seal is that the lip of the seal folded over. Fortunately it remained in place and provided adequate feed and some pressure to prevent the motor from being damaged.

marinecommando · May 27, 2012

Surely with it mounted in front of the engine all you are doing is disrupting the cooling air flow over the barrel and head at speed. Air cooled bikes were developed when there was a lot less traffic/ congestion on our roads, hence no need for extra cooling. One of the only reasons we don't use water as a lubricant is because of its low boiling/evaporation point.

marinecommando · May 27, 2012

Perhaps if you set the pressure relief valve lower this wouldn't happen with the seals. That's what it's there for.

Dances with Shrapnel · May 27, 2012

marinecommando said:
set the pressure relief valve lower

Already done and lessons learned. The engine build had plenty of input from plenty of people. It was a learning experience. The pressure relief valve was set much high in order to chase after a perceived problem.

We skipped over that part about "problem definition".

mikie3117 · May 27, 2012

Hello to all. Too much pressure for me was when my Old Britts oil pressure gage topped 90 psig at speed. It was a miserable mountain ride and the temps dropped to @35 degrees. Wet, cold and I did not want to bust an internal seal. I bypass the air flow for the cooler when ambient is less than 60 degrees here in Colorado.
Mike

pelican · May 27, 2012

many threads about this already if you use the search feature

Oil coolers...

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