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Discussion Starter #1
So my 2002 748 keeps going through coolant reservoirs! The first one cracked on the weld... This second one is a pinhole leaks the sprays coolant. The bike runs normal temps... So what gives! Is there some pressure relief valve that is stuck?
 

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Cracked Coolant Expansion Tank

Classic symptoms of a cracked coolant expansion tank that first started with the 916's and continues today. A leak develops at the tank's mold line (parallel to the fork tube) and 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.
 

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Discussion Starter #4
I trimmed the grommet when I installed this last coolant tank so eliminate the stress put on the tank. The weird part in this coolant tank failure is the pinhole leak is not on the weld line but right in the middle of the plastic near where the tube to the lower reservoir connects...
 

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When you say it keeps on going through reservoirs do you mean that you blow one every ride?

Had the same problem. I went thru 4 in a month. Try not filling the reservoir too much. Put just enough fluid that you can see some in the bottom but don't make it reach the minimum level.

If you still blow another reservoir because of over heating, check your cylinder head gaskets... you may have a leak there causing you to overheat and blow coolant reservoirs.

I hope that it is just a case of too much fluid in the reservoir.
 

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I trimmed the grommet when I installed this last coolant tank so eliminate the stress put on the tank. The weird part in this coolant tank failure is the pinhole leak is not on the weld line but right in the middle of the plastic near where the tube to the lower reservoir connects...
That is weird because I changed my tank last week and it was leaking from a pinhole leak near to the overflow pipe outlet, in the middle of the plastic and not on a join - maybe there was a bad batch?

Leak is in the red circle below and was squirting a fine jet of coolant directly sideways out of the tank;



My first tank lasted 8yrs, 2nd lasted 15 mins as it leaked at the first fuel stop on a rideout, the 3rd lasted 3yrs and was the one with a pinhole leak, fitted # 4 last Tuesday and I'm hoping it lasts as long as #1 did.
 

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Discussion Starter #8
DukeDesmo, that's EXACTLY where my coolant tank is leaking from!!! Pinhole right where you described... so it's gotta be some defect in the plastic.

As far as filling it up less. Seeing as how the system is pressurized, wouldn't filling it up less not make much of a difference as when the bike heats up, coolant expands, thus putting more pressure on the reservoir... so any expansion of the coolant would put pressure on the reservoir be it low level or regular level of coolant?
 

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Seems to me that it would be a common rubbing point...I don't know how a pinhole would just form without something rubbing that area. (see Shazam's post)
 

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Discussion Starter #10
Well I cut down the rubber grommet that causes stress on the coolant tank so it's not that... as for the pinhole, it's on the left side and there is nothing that can rub it... so the only thing I can guess is that this is manufacture defect?
 

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Well I cut down the rubber grommet that causes stress on the coolant tank so it's not that... as for the pinhole, it's on the left side and there is nothing that can rub it... so the only thing I can guess is that this is manufacture defect?
Likewise with the grommet and nothing has rubbed on that point on mine, in fact I can't even see the hole never mind any wear at that point.

I was surprised because both my other failures were on the seam, the only possible reason I can think is that when I cut the grommet, I cut a little too much so that there is a little up/down play in the tank and maybe if it was 'bouncing' there could be some strain from the hose pulling at that area whilst the tank moved and hose didn't?

I have now fitted some thin sticky-backed foam to the frame rails around the tank so that it is held (but not too firmly) in position whilst (hopefully) able to expand as necessary.
 

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Discussion Starter #12
FYI... I talked to my ducati dealer about the pinhole in the coolant reservoir and they are sending me a free reservoir as I just got this one a month and a half ago... so it seems that this is a defect as my pinhole is EXACTLY where DESMODUKE's was in the picture you posted and not on a weld seam... not sure if your dealer will do the same.

FYI DESMODUKE.... tried to PM you, your inbox is full and rejecting PMs
 

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FYI... I talked to my ducati dealer about the pinhole in the coolant reservoir and they are sending me a free reservoir as I just got this one a month and a half ago... so it seems that this is a defect as my pinhole is EXACTLY where DESMODUKE's was in the picture you posted and not on a weld seam... not sure if your dealer will do the same.

FYI DESMODUKE.... tried to PM you, your inbox is full and rejecting PMs
My tank is 3 years old so I doubt they'll change it, it was already a swap as the first one I bought leaked from new.

Have cleared the PM box now.
 

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To update this thread, the new tank I fitted in June started leaking again on Saturday - same place on the flat near the hose outlet to the rear cylinder.

I got a new one today, dealer told me there is no warranty on them?? :mad:

So it lasted 95 days and probably around 1000 miles. I'm really hoping this one does better... :(
 

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I popped 2 in a 3 month period about a year ago. I found 2 things that may have contributed to these failures: I had sludge in my coolant and had it changed out during the 1st failure. After the 2nd I blew through the expansion tank and sludge came out of my overflow bottle u tube outlet. The other issue I found the U tube outlet from the overflow bottle pinched between the throttle body and frame.

Since then I fitted the Moto metal hi-flow cooling fan and I am running consistently 10 degrees cooler in all conditions, so this is definitely helping by relieving the workload on the expansion tank.
 

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i'm glad i'm not the only one having this issue. my brother's 998 got a pin hole on the weld/seam of the coolant reservoir a couple of months ago and had to replace it. he hasn't had any issues since but he also doesn't ride that much. now i've got the same issue on my 998. does anyone know of a good fix other than purchasing a new coolant reservoir and hoping for the best?

it seems to me that this is a flaw in the design that has not been corrected.
 

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The pin hole's probably due to a poor mould design, I know we had some problems at work with a similar thing - the material flows into the mould at gates situated around the mold. The pin hole is probably where two material fronts come together, just a weak point in the moulding.
We solved it with another gate in the mould......but not much that can be done if Ducati don't seem interested! Probably just try to keep pressure down i.e. less collant in the reservior as said might help.
 

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Time for a fan switch. I never let my bike get to hot anymore. Dont like coolant spraying at me.
 
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