748 oil problem? - TwoWheelForum: Motorcycle and Sportbike forums
 
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post #1 of 16 (permalink) Old 08-28-2005, 05:39 PM Thread Starter
 
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748 oil problem?

Hi all,

I have a 1999 748. I just bought it last week, it has ~10000 miles on. Sounds and runs very well.

I noticed that when i rev it over 7000 rpm (while idle or driving in 1st or 2nd..) the oil pressure light starts flickering. I change the gear up, revs drop lower, no more oil light, till i rev it again over 7000.

What could be the problem?

Thanks and regards
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post #2 of 16 (permalink) Old 08-28-2005, 05:57 PM
 
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Have you checked your oil level in the crank caseing?
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post #3 of 16 (permalink) Old 08-28-2005, 08:32 PM
 
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Might need a filter, or sending unit, or is low on oil. Or even the oil viscosity has broke down not letting the oil register any pressure due to it being water thin. Or the oil pump its self. Not sure but I would start with something in the lubrication system.
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post #4 of 16 (permalink) Old 08-29-2005, 11:45 AM
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Quote:
Originally Posted by Earlzach
Might need a filter, or sending unit, or is low on oil. Or even the oil viscosity has broke down not letting the oil register any pressure due to it being water thin. Or the oil pump its self. Not sure but I would start with something in the lubrication system.

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post #5 of 16 (permalink) Old 08-29-2005, 12:01 PM
 
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I would start by changing the oil and filter...then start eliminating possibles until culprit is found.
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post #6 of 16 (permalink) Old 09-07-2005, 07:19 AM Thread Starter
 
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Thanks guys for the answer.

I changed the filter / oil and it still does it.

One other strange thing is that i filled the coolant liquid at max and in a few days it went bellow minimum. Temperature often went at ~100 degrees while driving in traffic (town).

I checked for water patches under the bike but i could find none, i also checked for steam on the exhaust or coolant liquid boiling but it seems ok.

What could be? Water pump????
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post #7 of 16 (permalink) Old 09-07-2005, 08:21 PM
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If it's not leaking it's not the water pump. It might be a head gasket...




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post #8 of 16 (permalink) Old 09-08-2005, 12:30 AM
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The water tank will empty once or twice if it was low. I don't know why but, it does. When I flushed my 998. I had to fill it three times before the water level stayed up.

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post #9 of 16 (permalink) Old 09-09-2005, 07:54 AM Thread Starter
 
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I refilled the water tank and in the last 2 days stayed at ~maximum. I will still check.

My other issue is the oil pressure light coming at high rev.

While idle or in any gear (1,2 mostly) when i rev hard over 7000 rpm, the oil warning light starts flickering.

I replaced the pressure sensor and it does the same, so it must be a lost of pressure in the system. My first guess would be the oil pump or the bypass valve.

Ducati also suggested the worst failure could be the bearings.

Did anybody ever had this issue???

Last edited by CipiVTS; 09-09-2005 at 08:06 AM.
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post #10 of 16 (permalink) Old 09-09-2005, 04:50 PM Thread Starter
 
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LAST NEWS:

After a short run this evening, oil pressure light came up continuously at idle. I switched the engine immediately off, waited for a few minutes then, when i started the engine again, no more light. I drove for 5 more minutes on the way home and it came up again and stayed. I had to stop a few more times till i got home.

I haven't noticed any unusual noise at the engine. Can somebody explain me what this could be???

HELP
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post #11 of 16 (permalink) Old 09-09-2005, 07:33 PM
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Could it be something as simple as a bad oil press sensor or a short in that wiring?




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post #12 of 16 (permalink) Old 09-10-2005, 01:36 AM Thread Starter
 
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I changed the oil pressure sensor wit a new one and it does the same.

What is the symptom of engine damage (bearings or more)?
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post #13 of 16 (permalink) Old 09-10-2005, 04:11 AM
 
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Once a Ducati breaks. It breaks down hard...

Its almost time for maintenance. i think at 12k
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post #14 of 16 (permalink) Old 09-11-2005, 12:08 AM
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This doesn't sound good. I would defiantly check the wiring to the sensor. Hopefully that is your problem. Other wise, I would tare it down for inspection before it causes more damage.

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post #15 of 16 (permalink) Old 09-11-2005, 12:10 AM
 
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Quote:
Originally Posted by jeeps84
This doesn't sound good. I would defiantly check the wiring to the sensor. Hopefully that is your problem. Other wise, I would tare it down for inspection before it causes more damage.
Hey I know all about tear down!!!!!
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post #16 of 16 (permalink) Old 09-13-2005, 06:51 AM Thread Starter
 
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I discussed with Ducati about the issue and they suspect it's the oil pump bypass valve, so they have to order a new pump....

Anyway they will have to actually check it (measure oil pressure etc).

About the water disapearing thing, i noticed that after a 30 minutes ride, the water which was at max is now at minimum...

I read on another forum about 748s that had a water expansion (upper one) cracking issue

Has anybody heard of this thing?
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