Ducati Monster Forum

The following describes the cooling system as fitted to a 04 S4R (Desmoquattro) the same system is also used on other S4* models.

(http://i295.photobucket.com/albums/mm143/Tarugo996/P1000309.jpg)

The coolant is circulated round the system by a engine driven pump driven mounted on the left hand engine cover. The coolant flows by separate circuits to each cylinder barrel, and exits from the cylinder head from where it flows to the radiator where the heat is removed and returns to the pump suction completing the circuit. A thermostat provides a means of rapid warm up by restricting the flow to the radiator when the temperature of the coolant is below 65°C / 149°F.

(http://i295.photobucket.com/albums/mm143/Tarugo996/cooling.jpg)

Two electrically driven cooling fans mounted on the rear of the radiator draw cooling air through the radiator when the coolant temperature exceeds 101°C / 218°F

The system is pressurized to increase the boiling point of the coolant, this achieved by means a spring loaded pressure relief cap with a rating of 1.2bar. A tank is provided to contain coolant displaced from the system due to thermal expansion. A vacuum valve built into the cap allows this displaced coolant to return to the circuit as it cools and the pressure drops to a negative value. The cap secures to the radiator in a cam type bayonet arrangement, the pressure spring forces the sealing flange against the inner neck diameter while a second gasket under cap seals the top of the fill neck.

(http://i295.photobucket.com/albums/mm143/Tarugo996/P1000758.jpg)

(http://i295.photobucket.com/albums/mm143/Tarugo996/P1000761.jpg)

Vents are provided  in the manifolds and the pump to aid the removal of air when refilling the system.

The centrifugal circulating pump is subject to the law of infinity which means that the pumped volume is proportional to the rotation speed as is the discharge pressure and consumed power. The pump is driven at 1/2 engine speed from the timing shaft by means of a slot and tongue arrangement. A spring loaded mechanical seal is mounted on the shaft. Unusually, the pump volute has two discharge outlets, one for each cylinder. The pump takes suction from the lower radiator connection.

The wax type thermostat opening is given at 65°C / 149°F +- 2°C / 4°F The thermostat does not fully close a minimum flow is maintained to provide flow over the control sensor and to protect the pump from operating against a closed head.

(http://i295.photobucket.com/albums/mm143/Tarugo996/P1000759.jpg)

The radiator is a two pass arrangement, a baffle in the left hand header tank separates it into flow and return chambers Coolant enters though the top connection, flows from left to right through the top half of the radiator and then flows from right to left through the bottom half of the radiator to the lower outlet connection. The radiator is flexibly mounted.

(http://i295.photobucket.com/albums/mm143/Tarugo996/P1000763.jpg)

Temperature sensors are mounted in the outlet manifolds on each cylinder the sensor on the horizontal head provides temperature data to the ECU, while the sensor on the vertical cylinder controls the cooling fans.

The cooling fans operate sequentially according to the following:
With the temperature increasing, the first fan is energized at 101°C / 213.8°F, the second fan in energized at 102°C / 215.6°F.
With the temperature falling, the second fan is de-energised at 101°C / 213.8°F and the first fan is de-energised at 100°C / 212°F

Operating issues.

The radiator appears to adequately sized for the application. During tests conducted to establish the feasibility of reducing the size of the radiator, strips of tape 50mm wide were applied to the front face the full height of the radiator adjacent to the header tanks. No signs of overheating were observed in an ambient temperature of 37°C / 98°F. The smaller radiator produced as a result of these test has performed satisfactorily under both track day and city commuting conditions.

The radiator is subject to impact damage from road debris, aftermarket guards are available for protection. When fitting guards, there should be a clearance of at least 3mm between the guard and the radiator to prevent fretting between the components and to allow for some deformation of the guard should it be struck by an object.

If the pump shaft seal leaks, coolant will enter into the engine and will be evidenced by emulsified oil.

The coolant is a inhibited water/glycol mixture and will protect the coolant from freezing. Capacity of the system is 2.7 litres.

If the expansion tank does not return coolant to engine, the cause is usually traced to a vacuum leak in the hose connecting it to the radiator, or that the system was opened (radiator cap removed while coolant was hot and not closed again during “cool down”). Since vacuum draw on the coolant in the expansion tank is the only way coolant is drawn back into the system, any air leak, no matter how small, will cause the engine to draw back in air rather than coolant and the coolant to remain in the expansion tank. If you find a need to add coolant to the radiator after each “cool down” and the expansion tank level keeps rising, then a leak exists and must be found. Check all clamps and tighten as necessary. Or apply a vacuum tester to the vent line where it attaches to the tank to locate the leak.

Nice write-up! [thumbsup]

Water pump is driven at 1/2 of crankshaft speed.

Other than that, awesome!  [thumbsup]

Thanks.
Fixed, I even counted the teeth on the gears to determine the reduction. Can't understand why I put 1/4.
Can I send you the next one (S*R rear suspension) for proof reading?  ;D

Hey, I've done the same kind of thing.  :P

I'll look it over if you like.

You're assuming us flounders can read.   ;D

You're doing a great job.

Thanks.

I love reading these.

Thank you.

Thank you, I have one more almost complete and a couple in the early stages.
S*R Rear Suspension
Engine Lubrication System
Sprockets & Chains

I hope that these are benificial to the folks here.

Excellent write up!

I'm looking forward to the engine lube one,  whilst staring at the bike the other day i was thinking of rotating the oil cooler 90 degrees to make it stand vertical (air-cooled 2V), but was wondering about any cooling loss.  After this write-up on the rad. system, i doubt there would be any.  So you added 50mm tape on both sides of the rad, against the tanks, right? total 100mm of covered radiator face?

Yes 50mm each side.

This is the rad that was fabricated as a result, 100mm shorter that the std item.

(http://i295.photobucket.com/albums/mm143/Tarugo996/s4r08_10.jpg)

(http://i295.photobucket.com/albums/mm143/Tarugo996/s4r08_11.jpg)

(http://i295.photobucket.com/albums/mm143/Tarugo996/rad-side.jpg)

What can I say more han THX 11ty billion f sharing! [thumbsup] :)

You had to show your fancy hoses.  :P
I have them too! Nice write up!

don't suppose anyone has those images that are now deleted thanks to photobucket??   :'(

My questions to you gents is capacity and other data inconsistencies. A 2001 S4 service manual has 3.5 liter as the capacity and has 2 sets of numbers for when the fans turn on. I looked for an electrical diagram and found a crude colored one but without settings.
Also, the 2.7 liter capacity is including the volume in the expansion tank correct?

Might also be fun to add how much a radiator costs to replace. The oil coolers are less of a problem, as new ones are only around $560 and it appears used ones can be found for much less. But the radiators- at least for the S4RS there are exactly zero available used, and a new one from Ducati costs a whopping $2300.

So in closing I would recommend fitting a guard for each, and padding it at all contact points with some anti rubbing material to prevent damage since the bike vibrates. These are not parts you ever want to have to replace.

Brand new Chinese radiator on eBay for ~$200US.  Not affiliated, haven’t ever seen one, don’t know anyone who has one.  But, someone somewhere is making an option so I thought I’d mention it here