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-   -   Cooling system leaks (/showthread.php?t=78220)

keith888 13-Jan-2009 05:03 PM

Cooling system leaks
I was losing a small amount of coolant from the 888 at the DSC trackday and occasionally on hot days (ie about once last year). I've finally got around to having a good look and I don't seem to be overheating as there is no sign of it blowing out the expansion tank. Its difficult to see for certain but I do have signs of a bit of seepage past a couple of clips on the water hoses and a clear drip from the bleed screw on the vertical cylinder (which is certainly tight).

To play safe, I've got a set of Samco hoses and clips on order (Racebikebitz.com are still giving a 10% discount and free SS clips to DSC members). I also want to add a radiator sealant while I am at it so can anyone recommend something for Ducati engines?



nelly 13-Jan-2009 05:14 PM

Personally, i don't like the sealants Keith. there's lots of small water passages that can block and the mechanical seal on the back of the pump impellor could be compromised.....
A safer bet would be to have the system pressure checked, either in situ or have the rad checked off the bike.
The expansion tanks can cause problems. They are getting old now and the plastic can harden and crack. Can be quite obscure when cold but opens up when hot and under pressure.
On the bleed screw, try a new copper washer and/or a dap of sealant on the threads.

keith888 13-Jan-2009 06:34 PM

Thanks Neil. I assumed that the bleed screw would have a copper washer of some sort that could do with a change. I'm pretty sure the tank and rad are OK as there were no incriminating dried blobs of antifreeze around them. Based on the deposits the bleed screw or leaking hoses/clips look most likely. Radiator sealants always seem to provoke controversy even though many manufacturers use them from new! I take your point about the small coolant passages though so I'll try without and see now I get on.


phil911 17-Jan-2009 12:04 AM


Avoid to fill up the tank above the MINIMA line.
Don't be scared to fill it 1 cm. below the line !!!
Check if the tank cap isn't obstructed . There's a hole on top for air pressure !!!
Check the rad cap as well, the internal spring must be free ...

Regarding the tank cracks, they often are located around the single nut incorporated into the plastic ...


Douglas851 17-Jan-2009 11:57 PM

I have never put any water in the white plastic tank, and water has never appeared in it. The rad is always full when checked. This applies to two 851/888s i have owned over a number of years and many thousands of miles and several track days.
The rad cap seals the rad, so I cannot see what the tank is for except to catch any overflow.
Am I missing something?


phil911 18-Jan-2009 12:18 PM

First few minutes after have started the engine, the thermostat is still close and about half of the coolant quantity becomes warm, reason why the rad coolant level is full.
Next step after few minutes when the thermostat is open, the coolant circulates all around the engine and the coolant level is going down.
In order to avoid a too high coolant temperature and air entries into the circuit through the tank, (air entries supposed to create knockings !!), it's necessary to fill in the tank to compensate for coolant variation ...

I wouldn't take the risk to disregard this detail ...
Our babes are considered as "oldies" now, let's pay attention to the smallest detail !!!


keith888 18-Jan-2009 06:22 PM

1 Attachment(s)
The first stage is now complete with the Samco hoses fitted (pic attached). They certainly tart the old girl up nicely! The old hoses were certainly past their best and starting to craze at the ends. The copper washer on the rear vertical cylinder bleed screw appears to be the wrong size (too big) so is a likely culprit for a leak. I just now need to make sure the overflow pipe is OK and refill.


duc daz 29-Jan-2009 10:00 PM

i had a leakage on my 999 bip found out it was coming out of the hoses so i nipped up the clip and been fine since

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