Ducati.ms - The Ultimate Ducati Forum banner
  • Hey Everyone! Enter your bike HERE to be a part of this months Bike of the Month Challenge!
1 - 20 of 29 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter · #1 ·
So ordered and installed the new expansion tank, which was a pain in the !^%$ - BTW, you basically have to take everything off to get to it. Took it out for a ride all was well, then once it got up to the 220 mark, the tank started spewing coolant and steam right on my throttle hand. Resulted in second degree burns (would have been worse without gloves). Let the bike cool down and limped it back home.

Couldn't figure out where it was leaking, thought for sure it was a hose. Let it run in the garage after tightening the hoses and adding fluid, and sure enough started spraying from the seams.

Someone mentioned an aluminum tank, anyone have a link or experience with them? The one i saw did not have the electronic mount on it.
 

·
Registered
Joined
·
200 Posts
I've not had coolant tank issues (knock wood). You must remember that the pressure increases with temperature and very significantly with temperature if over-filled. Run the level at the lower to mid level when the bike is at 180F/90C. Temperature here is very important. Once you have established that WATER level let the bike cool to ambient temperature then vent coolant header tank to atmosphere. Cooling system is now serviced.

Did you fill it to max when the water was cold?
 

·
Old Wizard
Joined
·
3,007 Posts
System pressure does not increase with coolant level, only with temperature. Once the pressure reaches a certain level, the pressure relief valve lifts.

The design flaw that causes cracked coolant expansion tanks first started with the 916 model and continued on subsequent variants. A leak develops at the tank's mold line (parallel to the fork tube) that appears to be caused by fatigue from thermal cycling and vibration.

The main reason that a Ducati superbike coolant tank cracks is that the tank expands as it get hot but there’s not enough clearance around it to allow free expansion in all directions. In particular, there is a rubber grommet that holds the tank in place and presses it tightly against the frame. Because the grommet is somewhat oversized, it causes the hot plastic tank to be compressed by the frame and receive vibration transmitted through the frame.

When you install the replacement tank, trim the rubber grommet to avoid a repeat of this failure condition.
 

·
Registered
Joined
·
79 Posts
System pressure does not increase with coolant level, only with temperature. Once the pressure reaches a certain level, the pressure relief valve lifts.

The design flaw that causes cracked coolant expansion tanks first started with the 916 model and continued on subsequent variants. A leak develops at the tank's mold line (parallel to the fork tube) that appears to be caused by fatigue from thermal cycling and vibration.

The main reason that a Ducati superbike coolant tank cracks is that the tank expands as it get hot but there’s not enough clearance around it to allow free expansion in all directions. In particular, there is a rubber grommet that holds the tank in place and presses it tightly against the frame. Because the grommet is somewhat oversized, it causes the hot plastic tank to be compressed by the frame and receive vibration transmitted through the frame.

When you install the replacement tank, trim the rubber grommet to avoid a repeat of this failure condition.
love my duc, but italy needs a few japanese engineers. just say'n.
 

·
Premium Member
Joined
·
1,516 Posts
Buy an ali job from komodo and be done with it.
 

·
Come in Spinner :)
Joined
·
9,092 Posts
These tanks have been known to fail first ride after replacement.. some are faulty and no amount of free play is going to fix that... it's a russian roullette thing with them.
Going the alloy tank route is a better way to go as is doing some cooling system mods & keeping the temps from becoming extreme.

.
 

·
Registered
Joined
·
31 Posts
Discussion Starter · #12 ·
Ok, installed a new tank from the dealership and guess what... split again at the seams.... :eek:

There has to be something else wrong or I am very unlucky (3 tanks in a few months)

Before I buy an aluminum tank I want to make sure it isnt something else... what else could it be?????
 

·
Old Wizard
Joined
·
3,007 Posts
Your not alone on this. The design flaw that causes cracked coolant expansion tanks first started with the 916 model and continued on subsequent variants. A leak develops at the tank's mold line (parallel to the fork tube) that appears to be caused by fatigue from thermal cycling and vibration.

The main reason that a Ducati superbike coolant tank cracks is that the tank expands as it get hot but there’s not enough clearance around it to allow free expansion in all directions. In particular, there is a rubber grommet that holds the tank in place and presses it tightly against the frame. Because the grommet is somewhat oversized, it causes the hot plastic tank to be compressed by the frame and receive vibration transmitted through the frame.

When you install the replacement tank, trim the rubber grommet to avoid a repeat of this failure condition.
 

·
Registered
Joined
·
31 Posts
Discussion Starter · #14 ·
Your not alone on this. The design flaw that causes cracked coolant expansion tanks first started with the 916 model and continued on subsequent variants. A leak develops at the tank's mold line (parallel to the fork tube) that appears to be caused by fatigue from thermal cycling and vibration.

The main reason that a Ducati superbike coolant tank cracks is that the tank expands as it get hot but there’s not enough clearance around it to allow free expansion in all directions. In particular, there is a rubber grommet that holds the tank in place and presses it tightly against the frame. Because the grommet is somewhat oversized, it causes the hot plastic tank to be compressed by the frame and receive vibration transmitted through the frame.

When you install the replacement tank, trim the rubber grommet to avoid a repeat of this failure condition.
I did shave the rubber grommet when I replaced it, the tanks I have installed are brand new OEM, what are the odds? Is this symptomatic of some other problem in the cooling system?
:mad:
 

·
Old Wizard
Joined
·
3,007 Posts
I did shave the rubber grommet when I replaced it, the tanks I have installed are brand new OEM, what are the odds? Is this symptomatic of some other problem in the cooling system?
:mad:
The pressure relief valve is in the reservoir cap. If it's defective and doesn't lift until the pressure is too high it could result in excessive coolant system pressure that damages the tank.
 

·
Registered
Joined
·
200 Posts
The pressure will increase much more rapidly with temperature in the event that higher water levels are run. It is likely that the cap is a blowoff valve, that should not actuate during normal intended operation.

Bottom line, want lower operating pressures?

Run less water volume in the system (i.e. lower level in header tank).
 

·
Registered
Joined
·
5,202 Posts
There has to be something else wrong or I am very unlucky (3 tanks in a few months)
Might be worth checking/replacing the cap incase it's allowing too much pressure to build up?

But I too had 3 tanks fail within a few months, one of them after the first 10 miles of use.

In all I got through around 6 tanks (can't remember the exact number) until I got one of Ken's ally tanks which has been perfect - bike even runs a couple of degrees cooler.

Odd thing was my first tank lasted around 7-8 years and then the rest all went bad over a 3 year period, although the last one was taken off whilst it was still good.
 

·
Old Wizard
Joined
·
3,007 Posts
The pressure will increase much more rapidly with temperature in the event that higher water levels are run. It is likely that the cap is a blowoff valve, that should not actuate during normal intended operation.

Bottom line, want lower operating pressures?

Run less water volume in the system (i.e. lower level in header tank).
The pressure in the cooling system is a function of the coolant temperature only and is independent of the fluid volume in the header tank. The maximum pressure allowed is determined by the set point of the pressure relief valve.
 

·
Registered
Joined
·
5,202 Posts
The pressure in the cooling system is a function of the coolant temperature only and is independent of the fluid volume in the header tank. The maximum pressure allowed is determined by the set point of the pressure relief valve.
Indeed and any excess coolant runs into the catch tank between the cylinders so causes no problem.
 

·
Registered
Joined
·
200 Posts
"The pressure in the cooling system is a function of the coolant temperature only and is independent of the fluid volume in the header tank."

wrong, Wrong, WRONG.

The expansion of water compresses the air in the header tank which pressure of is governed by polytropic compression. When the total volume of the system is known, the volume of water can be established from a system pressure vs. temperature curve.

Now, it is true that the maximum possible pressure is governed by the pressure relief valve (in this case header tank cap). But that is set such that the cap pops off before a cooling system component bursts.

In the case of the popping tanks, the cap popoff pressure is too high-- i.e. the tank popoff pressure is lower!
That said, typically the popoff pressure of the pressure relief valve is typically significantly higher than intended operating pressure.

I recommend to people running the coolant at the lower level in the tank to keep pressure low.

Worst case scenario would be to fill the cooling system to the high mark with the system cold.
 
1 - 20 of 29 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top