998 Got Real Hot.. And Not Starting Now

screenshots from the 998s workshop manual I have. if you need a copy, let me know and I can sort an upload somewhere. it is 61MB, so can't go by email.

 

Just as an aside, I do sometimes worry that my 998 is running hotter than it used to. I only have a 5 min ride out/in of town before hitting the open road, but, esp returning, it still starts to roast [at which point the clutch gets unhappy, and it sometimes stalls]. How anyone rides these things through an Italian city in summer is beyond me. I guess they generally don't...

 

For the 916 and the 998 may be the same, it is possible to get higher capacity fans - that's the way I'd go.
My 999 runs too cool at open road speeds but once the speeds drop, the temperature climbs rapidly.
What temperatures are we talking about and does your fan control the temperature when it kicks in?
Are you running an open clutch cover?

 

Hi mate, no, standard closed clutch cover. I think from memory it runs at about 80-85 when on the open road, but goes up to the 100, ie past the 'noon' point, very quickly, when in traffic.

 

On my 748 which runs with just one fan I have changed my fan sensor to one that starts the fan 5 degrees earlier, I don't think you can do this with the testerstretta engines though, I think the fans are controlled by the ecu.
Steve

 

@Birdie you are correct - item 1 is the ECU, 17 & 18 are the fans. I have got hold of a simple switch to do a manual bypass for when it looks like it's getting hot.



seems to be switched on the ground side, as the common connection to 17 & 18 is from the fuse box, so I guess I am going to have to fit the switch as a short to ground from the G/G & G/W wires (or at least that's what I think they look like).

maybe I might need to fit a diode or similar to prevent shorting the ECU to ground, too??

Anybody done this mod and can confirm/correct?

edit, maybe a 2-way switch would be better with fan as common and switching between ground and ECU?

 

My 999 runs at 70 on the open road and I reckon that's too cool, in fact I suspect the ecu is enriching the mixture at that temperature, so not exactly fuel efficient if that's correct. Maybe a rad protector would restrict the flow through the non fan assisted portion of the radiator just enough to raise that a little.
If the oil is going to be water and mayonnaise free, we need the oil temp to get above 100C at least sometimes, so 100C is not such a bad thing.
My 320d oil temperature rises to 100C and just sits there, steady as a rock until you switch it off - that is the medium, normal, centre point on the gauge.
As long as the temperature is controlled by the fans when they switch on, we should be fine. It's when the fans come in and the temperature continues to rise that we need to worry, especially if the temperature creeps past 125C or so.
The combination of the pressurised cooling system and the 50/50 coolant mix mean that the coolant won't boil until getting on for 130C. Fully synthetic oil should be fine at that temperature but once the coolant starts to boil the cooling system won't be properly effective any more, so not a good thing.
Our fans are deliberately set by Ducati to come on at just over 100c and I'm sure that's no coincidence - they could set it to any temperature they want.
The main thing is that the fan/s control/s the temperature when they do switch on.

 

You can get a lower temp switch for the 998. At least you could back then. Evoluzione used to make them and I found a new one on eBay a few months ago for £20.
Haven't connected it up yet and will see what the temps are like this summer before deciding whether to fit it or not...
I might see about re flashing the ecu to get the fans on a bit quicker. Did this with my 848 and worked well.

 

If the fans only slow down the temperature rise, I can see why you'd want to do this as the earlier they come on, the more time it will take for the temperature to rise to dangerous levels.

However, if the fans do their job of controlling the temperature and prevent it from rising further, why bother? Circa 100C wont do any harm at all and will actually allow any water in the oil from condensation to boil off.
However, if the fans don't control the temperature rise properly, I'd suggest that more powerful fans would be preferable to earlier switching - if they are available...

Btw, I accept that coolant temperature and oil temperature are not necessarily the same thing.

 

Exactly! And well pointed out...
I have read all the horror stories about these engines getting stupidly hot so when I saw the switch for sale at a decent price, thought I'd get it anyway, just in case...
Another reason was that if we ever move back to Seville, Spain, I'm sure the switch will come in handy as air temperature there can sometime reach 45 to 50 degrees.
Have to admit that my engine temps don't seem bad at all. The fans seem to be doing their job well enough. Maybe has something to do with the new hoses I fitted and Motul motocool antifreeze. I don't know...

 

Trouble is, you're very well aware of the engine getting hotter when it does. When you're on the open road, the engine is running cool and what heat there is being whisked away in the slipstream.
When you slow down and stop, the engine runs hotter and the heat just radiates straight at you or is blasted at you by the fans. That and the climbing numbers on the dash leave you in no doubt that things are getting warm down there. However, as long as the fans are keeping things under control, there really is no need to panic - we should be pleased that any moisture in the oil is being well and truly purged

Do Motul make any special claims for their coolant or is it just good quality but otherwise ordinary, coolant?

 

^ sorry. Just woken up!

Don't know if the Motul real helped or not but the fact it is new, system flushed out and at only 5 squids a bottle, means job jobbed.

 

I am having a problem with my fans but that is another story. While googling about I came across a thread which I believe is on Ducati ms It relates to the 848/1098 series.
On these there is a single temp sensor and the guy found that it reads low and is very slow showing change. He tested it using a remote temperature sensor
His final analysis was that the temp sensor is shrouded inside the pipe work by the plastic it screws into. He used a dremel to remove some of the plastic. To get the tip into the water flow.
It appears to have made a big difference. False temp readings as you know will affect the fuelling

 

How about Flatairbag's original 'problem' of the overheating ? Did you find a solution for that please ?

The reason for me asking is that my 998 also runs very hot when going from the open road (80 to 100) into traffic. I live in the UK and on a warm day a couple of weeks ago it hit 120 (end of the scale).

I have checked fluid level, cleaned the radiator and checked that both of the fans cut in/out at approx 103 and 106, but as I'm off to Spain in a few weeks (where it is obviously a lot hotter), I am concerned that I may be heading into overheating problems.

I would appreciate advice whether this is something to worry about please or not ?

Thanks.