Oil cooler operation???


I hooked up a low cost OBD2 BT dongle to my OBD2 (ECU) port so I can monitor many more engine parameters from my 7" Android tablet via an app like TORQUE PRO or DashCommand; I also use OBDLink because I'm using an OBD2 BT dongle sold by the same company.

I have the dongle semi-permanently connected under the seat. It is the type that has an automatic "sleep mode" so as not to inadvertently drain a 12V battery if left connected all the time. When I restart the engine the dongle "wakes up" and re-pairs automatically to the BT in my tablet. This is convenient so I don't have to ever remove the seat before a ride.

I have my tablet bungee cord strapped over my bike's instrument gauges, so I can monitor engine parameters of any interest while riding. This works well at night, but not so much during daylight due to reflected sunlight washing out the tablet's LCD display even with the brightness increased to maximum.

I have the Android OBD2 app setup to continuously monitor and display engine oil temp, in degrees F (fahrenheit) on a virtual analog gauge built-in the app.

Btw, this technique does a great job of indicating instanteous and average "MPG" while riding. Other parameters of interest are fuel rate, TPS, MAP, MAF, timing advance, calculated engine load, 12V battery voltage, and of course engine rpm and vehicle speed.

While just taking a ride within the city limits with speed limit of 35, I noticed the oil temp slowly rising to 220F. This was the high point just before I turned off the engine and parked the bike in my garage after a ride of about 15 minutes. I'm not sure if that was the "peak", or if it would of increased even higher. Of course, without any air flow thru the oil cooler, while warming up the engine and/or at a stop light, it probably would have.

It was only in the low 70 degrees F this afternoon during my ride, almost a perfect day for a leisurely ride of only a few miles.

Does anybody know what operating temperature the oil cooler thermostat kicks in? Is there internal oil flow thru the cooler at all times while the engine is operating?

From my observation, it must peak at 220F or higher, which seems a bit high to me with some amount of outside air flowing thru the cooler.

It seems to me the one "design weakness" of the 865cc Bonneville engine is that it does not have a forced air cooling fan mounted behind the oil cooler. If it did, it could be thermostatically controlled to help keep the engine oil from over heating under worse case operating conditions.

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Street Tracker
AFIK oil temperature can reach up to 270 F

oil flows thru the heat exchanger all the time, no thermostat, but best not to let the engine idle for extended periods, like over 20 minutes
see this http://www.newbonnevilleriders.com/forum/showthread.php?t=10673

but as long as you remain moving all is ok. I have ridden regularly during extreme hot days and once it reached 47 C (116 F) on my ride home from work, and no harm was done and my Bonnie has well over 100,000 Kilometers clocked up
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Whew !!

You have too much time on your hands with all this wiz bang techno stuff .

Worried about oil temp ?
Change oil , ride motorbike.

Hooking up the angle of the dangle doohickey, to a machine that is over engineered to begin with is sort of like pissing in to the wind off the back of your own boat.

Blocking the proper tachometer / speedometer with some piece of high zoot wizerdry is a slap in the face to tried and true engineering . Why bother ?

Just poking a bit of fun at you , from the old school of riders group :)


Fwiw, I think having too much time on my hands comes with being recently retired. :)

270 degrees F!!! Wow, that seems rather extreme even for an oil and air cooled engine!

But, you're right about blocking my OEM gauges, because stupid me, now I can't see the Neutral indicator! I need to come up with a better way to mount my tablet behind the windscreen without covering up my bike's speedo and tach.

Nevertheless, it is interesting to find out how many MPG my bike is capable of and a few other normally "hidden" pieces of electronically derived information.

For instance, I saw an instantaneous peak of 70 mpg the other day while cruising at very light throttle (~5%), and the engine timing advance peaked at 35 degrees while accelerating at higher revs.
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Me toooo. I have oil temp and oil pressure by my right calf. I can see both easily.This T100 is a great over built solid engine easy to work one and tune.
Press on.....


The "NewBonneville" oil temp gauge has a "redline" at 250F (or 120C). Does that imply the max oil temp should not be allowed to go over that limit? Would it ever really get that high with normal air flow thru the oil cooler?


this article makes sense to me. And my oil temp runs about 230... a bit hotter on hot Summer days.


As an aside, Brother Dear worked with a gal who had a nice harley she rode rode to work, but she lived less than five miles away and didn't ride the bike very much outside of work. They guys in service went to change her oil and it was a glob of goo in the crank. She never got it up to temperature to burn off the sludge.
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Here's a decent solution for TWO analog gauges, one for oil temp and another for oil pressure.



Street Tracker
It seems to me the one "design weakness" of the 865cc Bonneville engine is that it does not have a forced air cooling fan mounted behind the oil cooler. If it did, it could be thermostatically controlled to help keep the engine oil from over heating under worse case operating conditions.


I binned the oil cooler after rodburner (Steve) gifted me his frame rails...the oil now runs through the frame and back to the pan. Runs as cool as before - so no worries.




I decided to get the British Customs oil pressure gauge kit for my bike. It's one of the more expensive gauges at $155 list, plus CA tax and shipping, but appears to have good overall quality. The kit comes with a SS braided hose about 12" long, a chrome plated banjo bolt adapter and a mounting bracket. The gauge itself is liquid filled for dampening purposes and can be ordered with either a black or white dial face (rest of the gauge is black), incremented from 0 to 100 psi. I ordered the black dail face, because I think it is nice looking and will blend in better with the rest of the black surfaces on the engine.

I suspect it can be mounted on either side, but I'll probably put it on the right side as shown in the photo posted earlier. In that position, it should be easy to see while riding with a quick downward glance. Mounting it on the left side might be better because I'm usually on that side when first starting and warming up the engine before going for a ride.

I almost decided against this gauge due to the difficulty getting a wrench on the stock banjo bolt head on top of the tranny case. This bolt must be replaced with a longer one for a double banjo coupling with the lower end of the oil pressure hose connected there. Fortunately, a 5/8" open wrench just fits and the OEM bolt loosens quite easily. The rest of the gauge mounting procedure should be a piece of cake.

On a tight budget, given a choice between an oil temperature or pressure gauge (although both can be purchased and mounted separately), I think the latter is more important. The low oil pressure red indicating light on the tachometer could burn out or the oil pressure sensor potentially malfunction. Like any high performance engine, I think it is better to have independent feedback of oil pressure (as well as an indirect indication of adequate oil capacity), then solely relying on an idiot light!

Here's a BC YouTube video of the installation of this kit.

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I completed installation of the BC Oil Pressure Gauge today. It took about 2 hours taking my time. The hardest part was finding dropped copper crush washers. Another troublesome thing was getting the gauge to mount to the right side TB manifold upper RH bolt.

I deviated from the way BC did it in the video (above) by adding a couple of spacer washers to the mounting bracket. This positioned the pre-formed mounting plate a little further away for a bit more clearance, thus prevented gouging the side of the manifold and to make sure the gauge is mounted perpendicular to the center line of the bike.

Lastly, with the oil line coupler tightened to the fitting on the bottom of the gauge, and the banjo bolt on the other end connected to the top of the engine, the dial face was naturally positioned to be facing upside down, i.e. rotated 180 degrees appearing to be backwards. However, this makes the first half of the dial facing on the outermost side and easier to see while seated on the bike. Nevertheless, I twisted the gauge on the hose fitting slightly counterclockwise, so the mid band of the dial face is facing outboard.

I started the bike and the reading immediately jumped up to nearly full scale (~80 psi). It settled back down as the engine warmed up to about 60 psi and continued slowing dropping at the engine heated up. With engine fully warmed to its hot idle speed, such as after a ride on a warm day, the reading drops all the way down just above ~10 psi.

Cruising on a hot engine, up to about 75 mph on the freeway, in high gear, the pressure reading goes up to about 70 psi, which seems about right for proper lubrication and cooling of the engine. The oil temperature reaches equilibrium between 225 to 230F under this relatively high speed cruising condition with plenty of forced air flow thru the oil cooler.

Bottom line, this is a good quality product and works well on a late model Bonnie.
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Oil pressure gauge installation

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Oil cooler fan installation

As a follow up to this thread, I just completed another related project to add a suitable 12V DC. 4.5"D cooling fan behind the stock oil cooler on my Bonnie. The fan is an all metal, puller type, that fits fine and puts out a decent amount of air flow. I'd estimate the fan's flow rate is ~200 CFM +/-10%, although I could not find any definitive specs for the actual rating other than fan's maximum current of 2.4A. I actually measured closer to 2.0A at 13.5V. The more airflow the better, but this size fan may be all that will fit behind the cooler, and I certainly prefer a fan with a motor and mounting shroud of all metal construction.

NOTE, I found one other promising, but slightly larger fan (5.2"D), made by SPAL Automotive, with a higher current rating and therefore a more powerful electric motor with a maximum flow rating of 313 CFM. If it fits okay, I may try out this alternate, but I'm concerned about the higher - less desirable - load on my 12V battery.

Surprisingly, it is almost like Triumph intended for the OEM cooler to have a fan mounted in the "free" space behind the cooler and front of the engine nestled in between the header pipes. They must have decided against it to save weight, money and improve the looks of a naturally air cooled engine.

To best of my knowledge, in the entire history of the Bonnie, none were ever designed to have an oil cooler fan. Not to mention this is a totally neglected area in terms of Triumph accessories for the old air cooled Bonnies. Triumph's engineers are smarter than me, however I use to be a Product Assurance Test Engineer and know full well how excessive heat is the enemy of reliability.

Why do this you ask? Because I'm retired, have plenty of free time and think it would be a worthwhile thermal management enhancement to my Bonnie. I plan to make no permanent mods in doing so. If the fan proves to be of little added value, I'll just remove it and go back to stock. Hopefully, I've seen the last of 270F plus oil temp excursions in slow speed traffic, especially on hot Summer days! :nono:

Here are a couple of photos from both right and left sides of the bike showing the completed installation of the new fan. As can be seen, it was a really tight fit. At first I didn't think the fan had enough clearance, but it did even without unbolting anything to slip it in there. I'm certainly glad it is of all metal construction in such close proximity to the header pipes; no more than 1/4" worse case. Also, look carefully and you'll see a small On/Off PB switch velcro'd to the frame just under DOM/VIN sticker in the upper right of the first photo. This is just temporary as I plan to mount a proper On/Off rocker switch to control the fan from the center section of my handlebars.


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I'm surprised nobody replied to ask the results, which I forgot to mention in my previous post.

To say the least I am quite pleased! With respect to similar before and after test conditions, the net drop in maximum oil temp was -31F (or -17.2C) relative to an OAT of 72F, assuming any measurement error should have cancelled out.

With my newly installed oil cooler fan running continuously, after a 30 mins of engine warm up in my shaded garage, then going for a short ride of 25 miles at speeds between 0 to 35 mph on city streets to 50 to 65 mph on the freeway, with a few stop signs in route, the highest oil cooler temperature reached was 219F (~104C). Freeway riding seemed to produce generally higher temps compared to riding on city streets. The OAT during the ride was 72F under mostly clear sky in the late afternoon. There was a light breeze, but matter I did the route twice in both directions so that should not be a factor.

I believe at certain higher speeds, the fan's effectiveness is mitigated by how much natural air stream is pushing air into the front of the cooler. At higher bike speeds, the fan may actually act as a partial air flow restriction. It seems to me that the main benefit of the fan occurs at slower riding speed especially under 35 mph, which is the nature of stop and go. At higher speeds the fan is seemingly much less effective and can simply be switched off, letting the natural air stream convection heat transfer do all the work.

Previously, before installing the fan, under very similar test conditions, while monitoring the oil temperature using exactly the same method, I saw a high of 250F before shutting down the engine to let 'er cool off. Engine idle duration time was not measured, but I'd estimate it was considerably less than 30 minutes.

Based on higher OAT riding conditions, in the high 70s, I believe the maximum temperature would increased even higher. For example, when I took a ride a few weeks ago and was cruising up a long up hill grade, I saw a whooping 280F on warmer day. Maybe this is just the nature of the beast, but such high engine temps, when sustained over longer periods of time, eventually will be detrimental to reliability, so I want to have better thermal management control over the oil cooler; hence the idea for the fan.

When I got home I continued to let the engine idle for an additional 10 minutes to see if the oil temp would stabilize. It eventually leveled off at 205F. Compared to before without the fan, that was a significant drop of at least -65F (-36.1C). In both cases I had an 18" circular room ventilation fan on the ground in front of the bike blowing air toward the open garage door to the rear, so no toxic fumes accumulated in my test area. Before this mod, the idling in the garage test resulted in a continuously rising oil temp of about 270F at its highest before I turned off the engine. The oil never reached a stabilized temperature without the aid of the fan mounted behind the cooler!

On cooler or warmer days, from a minimum of 65F to a maximum of 75F respectively, which is normally the range of my personal "sweet spot" for riding in my area, if the peak engine oil temp remains below 230F, with cooling fan running, that would be acceptable. This helps prevent water condensation from forming in the crankcase, but is still well before the breakdown temperature of a good quality, fully synthetic oil.

For the cost of a $30 fan, a simple on/off switch, some hookup wire, electrical tape and corrugated tubing, plus several hours of my time, I'd say this was a very worthwhile mod!
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Today, I received an alternative 12V fan from an Italian company by the name of "SPAL". It is a low profile, "puller" fan that should fit better behind the cooler. For comparison, here are the basic specs for both the original and this latest SPAL fan:

2FastMoto 130mm fan ($33):

5.875" OD x 3.0" depth metal frame
??? CFM (Unspecify by OEM, but I'd guess at most ~250CFM)
Puller, with five paddle blades
2.4A current rating (I measured 2.0A)

SPAL 130mm Fan ($53):

5.51" OD x 2.3" depth plastic frame
342 CFM puller with five paddle blades
4.8A at zero static pressure (measured 4.5A)

Obviously, the SPAL fan is a bit more compact overall with better specs.

I have one other fan in mind, also made by SPAL, with even better specs. Plus, it has a finger guard that neither of the others come with. I found it on ebay for only $29 (new) with free shipping. I should receive it sometime next week. Here are the specs:

SPAL 140mm Fan ($29):

5.91" OD x 2.3" depth plastic frame
363 CFM puller with five paddle blades
5.5A at zero static pressure (measured 5.15A)

Obviously, this last fan alternative listed above has the most bang for the buck and produces the most airflow. However, it has the biggest OD and may barely fit between the headers. I'll have to mount it biased toward the bottom of the cooler to get the maximum clearance between the pipes. Even then, there still might not be enough free air space to avoid melting the plastic cowling of the fan. After I get it, I'll just have to see how well it fits, then go with the most compatible size fan to avoid potential issues. The other SPAL fan has the advantage of drawing ~1A less current from the battery and still outputs a fairly high airflow. I don't want to overload my battery with a fan capable of drawing 5.5A (66W), so I will install an on/off switch in series with the ground return to the Hi/Lo headlight bulbs. With the headlight off, fan on, the increased load on the battery will remain close to nill to alleviate this concern. Obviously, operating the fan is for day time use only, although the 5W bulb in the headlight remains on all the time to keep the bike "legal".

I should make the final fan selection by sometime next week. Stay tuned . . .
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And the winner is . . .

I finally received the last fan today and was able to successfully install it behind the oil cooler. This is the biggest and highest possible air flow fan that will fit in there, and quite fortunately, the cheapest (only $29 shipped).

It is a 5.5" fan made by SPAL in Italy, constructed of hard (black) plastic, and comes with an integrated finger guard. It draws a minimum of ~4.25 amps of running current from the 12V battery with the ignition off. With the engine running (and charging the battery to a higher voltage), the running current is more like 5.0 to 5.5 amps. I fused the fan directly off the battery at 7.5A, with a SPST on/off switch wired in series, so I can manually control the fan.

There will be times when a fan is not needed, especially when starting a cold engine, riding at freeway speeds, or when the OAT is relatively cold for an early morning ride. I mounted the manual on/off control switch to the handlebars, which comes in handy for all those occasions.

Although this fan is relatively compact, it is quite POWERFUL with a 360 CFM rating. You can easily hear it running behind the oil cooler as it draws air thru the fins of the cooler, and then blows air over the front of the engine, partially around the sides and up both sides of the fuel tank!

It is easy to install. I used four heavy duty black tie wraps, diagonal pliers, wire stripper, a couple of crimp on wire terminals and some hook up wire. Installation, including electrical connections and initial testing, took about 2 hours.

The best fitment is with it directly up against the back side and bottom 2/3rd of the oil cooler with a small section of the front of the fan visible just beneath the bottom of the oil cooler. Do NOT unevenly or over tighten the tie wraps or they may warp the fan casing causing the blade to bind. This fan has four round mounting bosses, two on each side, perfectly positioned to align with outermost vertical columns of the oil cooler. This is the strongest and most secure location to use tie wraps to attach the fan directly behind the cooler.

With the fan mounted lower down the back side, there will be at least a half an inch of clearance from the exhaust header pipes on either side. I made sure I could fit two fingers between the sides of the fan and the headers. The more clearance the better to avoid exposing the (PLASTIC) fan to excessive heat from the exhaust pipes. This is an important fire safety consideration, helps to protect the fan from overheating and/or possibly warping the plastic casing. For this reason, I plan on running the fan as soon as my engine warms up regardless of OAT riding conditions.

To prevent overloading my 12V battery, with an additional continuous 5A load, I also installed a headlight DRL cutout switch. This will nullify the extra load on the battery.

I just finished the installation, so I have not yet evaluated the beneficial affects of this particular fan. However, I am certain, this will be as good as it gets, simplest and least costly way to enhance the Bonnie's engine cooling efficiency.

Any comments or questions please let me know.
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Okay, good news, this oil cooler fan mod really works!!!

Just completed static bike, operational testing under the following closely monitored conditions:

Bike parked, engine continuously idling (950 rpm) in shaded garage, OAT=70F, highest IAT=93F, external air circulation 18" fan positioned directly in front of bike to simulate slow moving air like in stop & go traffic while lane splitting (legal in CA), headlight turned off, battery voltage ~14.4V, 5.5"D Fan turned and continuously running after EOT of ~150F reached. Total engine warm up duration of ~45 minutes. EOT equilibrium reached after ~25 minutes. Fan can be heard running over noise from the engine idle, but not objectionable.

Test results were as follows:

Highest EOT: 175F (w/ext fan not running); 165F (ext fan running)

Min/Max oil cooler Delta-T: ~15F / ~30F (based on IR gun readings)

Lowest engine oil pressure: ~32psi (based on mech gauge readings)

These results are all significant improvements compared to the old, much lower speed, Chinese made fan under almost identical test conditions. The only advantage of that fan is that has all metal construction, and therefore "should" be able to withstand higher operating temperatures. The far superior 5.5"D SPAL fan did not seem adversely affected by close proximity exposure to the hot exhaust header pipes (measured ~250F at exh port collectors). While seated on the bike, I noticed some, but insignificant residual heating of my lower legs. There was no adverse affect on the 12V battery during this test.

NOTE: The higher cost, but better fitting (small diameter) 5.2"D Spal fan will likely work just as well.

Imo, what we have here is proof positive that this $29 simple D-I-Y fan mod really works!
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