Ducati Issue

[Ducati999]

Friends,
I had an issue with a knocking sound from my 97 Ducati 748. The valves were adjusted about 800 miles ago and I dont think the noise is from the heads. I have pulled the heads, jugs, pistons, rods, clutch and both side covers on the motor and still have no idea what could have been making the "rapping"

I ran this bike last year on the track with no issues and the noise appeared when I fired her up this past spring for her first track trip this year. The noise sounds like a bad rod bearing with a solid "rap" while idling and increases with more RPM. The sound does not get much louder with higher RPM but more often (slightly louder) and I cant figure out what could be causing it. I have inspected the crank, rods and pistons, cases, bearings, water pump, oil pump, clutch, jugs and clutch and cant find any sign of damage or "too lose" tolerances which could cause this noise.

I am looking for any advice as to what else to check. Other members have heard the noise and we all thought it was a rod or main bearing but they are all in spec and the crank looks and spins fine. I have taken this motor apart multiple times and am quite familiar with its workings but this has me stumped.


Little back ground on this bike. The prior owner crashed it after purchase from original owner who took great care of her. The last owner could not afford to fix her so he parked it outside in North Carolina for 2 years. Sometime during the 2 yrs, the cover he had on the bike blew off and the motor filled with water, bugs, dirt, leaves......... then he moved to Mass. I bought the bike for 1200 with boxes of new parts, old parts and broken pieces--plus an inflatable pool lounge for some reason---. I pulled the motor apart and found a bent rod on the Horizontal cyl and tons of dirt and crap in the motor. I drained everything I could and cleaned/refilled everything. I replaced the bent rod and put in new pistons and bearings. I found a bearing with a bad spot last time i pulled the motor apart and I replaced it but the Rap is still there. She always starts right up and runs strong but the rapping noise is fairly loud and I dont want to ride it till it is corrected. I will try to answer any questions you may have if you are trying to help me solve this mystery. I like the bike and have very little money invested so I dont mind buying some parts to make her strong again.

[dcj13]

Any chance it's a wrist pin / piston slap?

[Ducati999]

Originally Posted by dcj13

Any chance it's a wrist pin / piston slap?

It does not appear to be. I had to (gently) drive out the wrist pins so they are tight but not too tight. Thank you for the response this is exactly what I am looking for, something I may have missed

[SLOWn60]

Is the motor running now? Have you listened with a stethoscope to isolate where the rap is occuring?

[Ducati999]

Originally Posted by SLOWn60

Is the motor running now? Have you listened with a stethoscope to isolate where the rap is occuring?

Did not have a Stethoscope but I did try the screwdriver to ear method with no useable results. This is why I have stripped this motor down 3 times already before today. Each time i found something minor and thought "this must be it" and threw her back together with no change except once when the noise would not start at idle but after 15-1700 rpm. All the other times the noise was present at idle (1000 RPM) I have throughly inspected the components and cant find anything that would make that loud a "RAP" when running and there is no resistance (more than normal) when turning the motor over by hand. The motor is nearly 100% apart as described in my LLOONNGGGG first post. Thank you for the reply and Happy New Year!

[dcj13]

I don't know much about desmdromic valves...

Do the desmo heads have pressed and/or staked valve seats? If so, is a valve seat loose, making noise when running, but in place when valve is closed?

[SLOWn60]

The only thing I've got and it may not be possible with this engine and perhaps only if you took it apart before you fired it up in the spring:
Is it possible something was put in backwards so an oil gallery is blocked or possibly clogged? You may be hearing a rap but it hasn't occurred long enough to have caused visible damage in the short time you've run it but without oil or inadequate oil to fill the squish zone.
That's all I've got!
I do find a cheap auto stethoscope is a fantastic assistant to isolate a problem but of course, the engine has to be assembled!
Happy New Year!

I must say; it would be ironic if it turns out to be a clogged passage!

[Ducati999]

Originally Posted by dcj13

I don't know much about desmdromic valves...

Do the desmo heads have pressed and/or staked valve seats? If so, is a valve seat loose, making noise when running, but in place when valve is closed?

I did a visual inspection on the valve seats and they look fine (solid). I have not yet checked to see if one of the coletts that hold the valve shim in place has come out or been smashed flat but the valves are still in adjustment range so this is unlikely to be the issue. I had about the same thoughts as you the first time I pulled the motor apart for this issue and I removed the cams and rechecked all tolerances but the noise was still there when i reassembled!

Thank you for the reply, I need to keep checking and need ideas where to look!

[Ducati999]

Originally Posted by SLOWn60

The only thing I've got and it may not be possible with this engine and perhaps only if you took it apart before you fired it up in the spring:
Is it possible something was put in backwards so an oil gallery is blocked or possibly clogged? You may be hearing a rap but it hasn't occurred long enough to have caused visible damage in the short time you've run it but without oil or inadequate oil to fill the squish zone.
That's all I've got!
I do find a cheap auto stethoscope is a fantastic assistant to isolate a problem but of course, the engine has to be assembled!
Happy New Year!

I must say; it would be ironic if it turns out to be a clogged passage!

I dont think it is a clogged passage but anything is possible. With all the crap that was in this motor I was expecting for some missed pile of garbage to break loose and plug up something. I must have done a pretty good job when I originally cleaned everything out because there has been no significant dirt in the oil filter or on the "pre-screen" filter. there is plenty of oil getting to both heads and the crank would be quickly destroyed without constant supply of oil. This may be something stuck inside one of the valve guides or one of the cam shaft bearings (highly unlikely) but I have pulled nearly every part of the motor short of splitting the cases (up next) and every part has been clean and free spinning. I cant find any evidence of an issue but I have pulled it apart 4 times now and the three past times it still made the noise (loud enough to fail tech at the track even with a dry clutch banging away) each time! I even pulled the entire clutch basket out of the motor to make sure it was not in the tranny or clutch but it still rapped like coolio!

Tanks again for you help!

[Ducati999]

UPDATE:
Still have not found anything that could event make a noise like I am experiencing. I just pulled the flywheel and the magnet part of the Stator. I was almost hoping to find a broken tooth on a gear or something but all I found was a small aluminum washer that was trapped between the end of the crank and the little inspection cover. I had found some small (tiny flakes barely visible) shiney nonmagnetic particles in the oil. There were only a dozen or so visible and this looks like the source of the flakes. Another dead end. I almost hoped there was something broken that caused the flakes but the end of the crank just wore out the center of the washer a little and could not have caused the noise.

I have a 916 crank and pistons with matching jugs and the EPROM chip. I will be splitting the cases and putting in the 916 parts and will continue to look for the cause of the noise. After all the work I have done on the motor at this point, I an starting to believe the source of the rap must be in the heads. There is no sign of any source for the "sound" in the low end. There are only the starter gear, primary hear and the oil pump left in the motor at this point and only the oil pump cant be fully inspected while mounted. Since the pump will be rebuilt/replaced and I doubt it could even make the sound and still work, this would only leave the heads as the possible source. I would still like any ideas you may have and I will update any discoveries. I may just contnue this thread as my rebuild documentation.

[Motofool]

Originally Posted by Ducati999

........I pulled the motor apart and found a bent rod on the Horizontal cyl.........

I would focus my research on that bent rod and the other parts that could have been affected by that misalignment but were not replaced or repaired.
If one rod was bent, the other one could be deformed as well (a possible source of noise); assuming hydro-lock as the common cause of the bending.

Prior to that, I would check the possibility of the clutch as source of the noise.

This guides may help:
http://www.aa1car.com/library/engine_noise.htm

http://www.onallcylinders.com/2014/0...engine-noises/

[Ducati999]

Originally Posted by Motofool

I would focus my research on that bent rod and the other parts that could have been affected by that misalignment but were not replaced or repaired.
If one rod was bent, the other one could be deformed as well (a possible source of noise); assuming hydro-lock as the common cause of the bending.

Prior to that, I would check the possibility of the clutch as source of the noise.

This guides may help:
http://www.aa1car.com/library/engine_noise.htm

http://www.onallcylinders.com/2014/0...engine-noises/

Hernan,
Thank you for your response. I replaced the bent rod, caused by a broken belt at the time of the crash by the previous owner and I replaced both rods at that time and the head which was also damaged and we checked out the crank to be sure it was not effected. I also ran this bike on the track last season and did multiple street rides with no issues. All I did over the winter was install a Ohlins shock and an oil change. When I started it up there was this rap and its been there and the same since then. I have only put 5-7 miles on it since this started to do testing. I have also run the bike with the entire clutch, pressure plate, hub and basket removed to eliminate everything "down stream" so to speak and no change. I will read the links and see what else I can find. Thank you and hope you have a great new year!

[Ducati999]

Apologies to @Motofool,
Hernan,
No disrespect intended. I was interrupted when writing the reply and did not correctly remember how to spell your name.

Update on the bike: The 748\916 series motors (AKA Desomo Quattro) had an update in the crank after several charging issues caused by the 2 wire charging system. Earlier versions had just 2 wires from the stator to the voltage regulator and the later bikes came with a 3 wire charging system. There is a variation in the crank to accomodate the upgraded charging system. I had to verify that the crank I purchased was the older 2 wire system same as my current piece. I have not yet removed the crank but the calipers tell me there is no visible difference between the 2! I have the jugs, rods, pistons, EPROM chip and crank to do this job. I am ordering the gasket/seal kit for the motor this week and I am spraying all the bolts to remove the motor this weekend. There is still one possible hurdle to this job. In order to remove the motor and split the cases, I have to remove the Single Sided Swing Arm. This is a notoriously difficult job. The steel bolt (nearly 26" long) runs thru the rear of the motor case and tends to bind on the bearings. I am hoping this come apart as easily as the rest of the bike but it can be a real show stopper! I will know better on Saturday if this is going to be a B!t@& of a job or not! Wish me luck!

Should all this work out as planned I will have 15-20 additional HP along with the included torque and a nearly new bike! I am going to replace the bearings in the swing arm, wheels and steering head and lube and replace everything else that needs attention while I have the bike torn apart. I am also adding the 27-30 MM offset triple clamps which are said to transform the handling of these bikes! I have already rebuilt the forks and may add a gold valve kit and I installed a fully rebuilt Ohlins shock which I have not even had the chance to try out yet! This bike should be incredibly fun on the track once I am finished with the rebuild

[Motofool]

No appologies needed, Ant

If both connecting rods are straight and the noise persists with no clutch, I would inspect the valve train next, including the clearances between valve's stem and guides.

As one the above links explains, you may be able to change the intensity of the noise by removing the spark from one cylinder at a time, determining which one has the problem.

[greg737]

Posted via Mobile Device

[greg737]

Just a quick thought for your ongoing search for the source of the knocking noise: Remember that the bike's valvetrain rotates at 1/2 of the crankshaft speed. In the past I've been able to determine where a weird engine noise was coming from by listening closely (using an automotive/mechanic's stethoscope) at idle speed with a focus whether the noise matches the idle RPM or the lower (1/2 speed) of the valvetrain.
Posted via Mobile Device

[Ducati999]

Originally Posted by Motofool

No appologies needed, Ant

If both connecting rods are straight and the noise persists with no clutch, I would inspect the valve train next, including the clearances between valve's stem and guides.

As one the above links explains, you may be able to change the intensity of the noise by removing the spark from one cylinder at a time, determining which one has the problem.

Rods are straight and I have checked the shim clearances but I have not disassembled the shims to see if one of the little wire colletts they use as retainers have come out of place and been crushed. @greg737 mentioned that the noise would be at half the RPM if it were valve train related and I would say it definitely sounds like it is half. There is not a constant RAP, RAP, RAP but a RAP--RAP--RAP so I believe I have a new direction to focus my search! I will not have any time to look into the heads but I will update when I get to take a look.

Thanks again @Motofool and @greg737

Ant

[adouglas]

[SLOWn60]

Originally Posted by SLOWn60

I must say; it would be ironic if it turns out to be a clogged passage!

This made no sense at all!!! Sorry Ant; I always think Gordon (Ducatiman) whenever I see "Ducati..." is the poster! My bad!

[Motofool]

Originally Posted by Ducati999

Rods are straight and I have checked the shim clearances but I have not disassembled the shims to see if one of the little wire colletts they use as retainers have come out of place and been crushed......

I had a similar situation with an air cooled Honda engine once.
The guide of one valve was so worn out that made a noise, but there was no smoke in the exhaust because the guide-stem seal was still working well.
A cam can exert enough dragging force on the end of a valve as to create a lateral force and wear on the guide.

[Ducati999]

Originally Posted by Motofool

I had a similar situation with an air cooled Honda engine once.
The guide of one valve was so worn out that made a noise, but there was no smoke in the exhaust because the guide-stem seal was still working well.
A cam can exert enough dragging force on the end of a valve as to create a lateral force and wear on the guide.

I am looking forward to tearing into the heads Saturday (wife willing!) The Horizontal head had the most water in it while the bike sat and one of the valves was nearly frozen when I got the bike. I replaced the valve but not the guide and I would guess that either some crap got in there or the rust/oxidation has worn off and opened the clearances enough to cause the noise. This would allow the valve shim clearance to stay in spec yet still allow enough movement (in the wrong plain) for the noise I am hearing. I hate to do it at this point but I may need to reassemble the entire motor again (5th time) and see if the noise is gone after I check the heads again!

By the way,
Should anyone need assistance with their 748/916/996 or 999 series Ducati, I know a guy who takes them apart all the time!!

[Ducati999]

I managed to do a little work this weekend but not as much as I had hoped. I need to get the cases out of the frame. The Single Sided Swing arm bolt goes thru the rear of the cases and the frame and the bolt needs to be removed to fully remove the motor. I have picked up most of the required parts for the rebuild.
So far I have:

Pistons, rings and Jugs
Balanced crank and rods with new rod bearings

New crank bearings and seals
New Output shaft Bearing and seal

New Oil pump
New water pump

I have to go back thru the heads still. I may have to do a full rebuild on them.
Not sure where the noise was coming from but with all the new/upgraded parts there should be nothing left to make noise.

The tranny will be checked and anything bad will be replaced along with anything else I find during the rebuild. I only paid $1200 for the bike and I think this rebuild will cost less than $1000. $2200 for a Ducati 916 with a solid motor will still be a great buy!

[Bigballsofpaint]

If the old saying "time is money" is used, your farther in the hole than my 848! Good luck man!

[adouglas]

Originally Posted by Ducati999

Not sure where the noise was coming from but with all the new/upgraded parts there should be nothing left to make noise.

O ye of little faith....

It's a Ducati. OF COURSE there's something left to make noise.

[Ducati999]

Originally Posted by adouglas

O ye of little faith....

It's a Ducati. OF COURSE there's something left to make noise.

This ^^ reminds me of a little story I read on the Ducati forums. Guy had the low end in his low mile bike self destruct. The dealer asked him why he had not brought the bike in sooner as it must have been rattling for some time before failure---his reply--- With the dry clutch and Desmo valve system it has never NOT rattled!

[Ducati999]

Sorry I have not had time to get on here and update this thread. I have now managed to get the motor out of the frame (after 4 hours removing the swing arm bolt!) and I managed to get the cases all cleaned up and ready to split. I broke the left (stator) cover removing it and I bought a replacement but I got the wrong one. I will purchase another today and we (my father and I) will split the cases this Saturday. Cant wait to see what the 916 can do compared to the 748 motor

[Ducati999]

SO--This past weekend did not happen. Padre was sick and did not come over and the wife jumped in and had a "list" for me to occupy my time. I just had some major positive changes at work so I have decided to send the crank, pistons and rods out to Mr. Ben Fox to have them balanced. I am not looking to get any more power than a stock 916 out of this motor so I will not be doing anything special while Mr Fox has the parts. Balancing the crank will smooth out the motor and take some of the stress off of the main bearings. I am building this motor for reliability (as reliable as a Ducati can be) not high HP. I have the 999 if I need or want more power, I just want a bike that is fun to ride on the street and an occasional track trip. The 999 will be track only and this bike will be my daily ride. I have a few small improvements planned but nothing more than some polish and squish setup. I will post up the cost and some pics after I get the parts sent out to FOX.

[Ducati999]

My last update to this thread was a non start on any work--what a difference one week can make! My dad is feeling better and we got down to business.

First off: We went thru the heads again and everything is within spec. Actually the valve clearances are right where they were set at the last valve adjust. No too surprised at this since I only put 4-500 miles on the bike since the last service. Cams, bearings, valves and seats and rockers are all OK. Some of the rockers are showing the pre wear but are not failing yet, there is just visible wear on the chrome. This is to e expected in a 20,000 mile motor and they look great for having been under water for some time!

Second: We checked the main bearings for the crank and there is the slightest movement, not enough to cause the rapping I heard but definitely need to be replaced. We did find a bearing that had more than acceptable play but no sign of the cause of the Knocking sound I had heard. I will replace all the bearings and seals in the low end before she gets buttoned back up. Still cant tell where the noise would have come from but more on that below.

Third: Split cases! I did not think we would have got this far already as there are a few specialized tools required to remove castle nuts and gears, which I have ordered but have not yet arrived. We got the dreaded flywheel nut and flywheel off (many on line horror stories about removal) and the primary drive gears out with a little Italian ingenuity! The clutch side has all the castle nuts and a drive gear that requires a special puller but it turns out that you don't have to do much to the clutch side to get the cases apart. We pulled all the bolts and they came apart with a 2x4 and hammer. Looks to me like this motor may have been apart before as there was not a single gasket in the motor! All the cases were sealed with Ducati Tri Bond sealant.

Summary: We mic'ed the new crank and rods and checked the tranny. The oil pump looks really good inside-it will be replaced but it does not look like anything bad was sucked through it. Everything in spec so once new bearings and seals arrive I can begin reassembly. There is a single gear still on the shaft that drives the oil pump and I am trying to remove that so I can replace the bearings it rides on, its stuck good so I have a puller on it and have been heating it and hitting with a deadblow hammer but has not budged yet. The nut holding the gear is off but the shaft is tapered with a woodruff key and she is stuck. After the gear is off, I will post pictures of the cases and other parts. Since we could not find any sing thing that even could have caused the rapping noise I was hearing, we think it may have been a combination of several loose tolerances causing the sound. When this is all back together there is no way the sound (should it return) could possibly come from the bottom end and I will have to focus my search to the top end. I really hope this eliminates the rap but since we did not find the source, all I can do is replace the parts and hope its corrected!

[Ducati999]

Since we have had such a mild winter so far, Mother Nature wanted to even things out with 2 FT of snow the day after we got 1/2" of ICE! Well silver lining is that I got 2 days off and had some time to work on the motor.

My last update said that there was a single gear, stuck on the clutch side of the crank, which would not come off. I have tried heating along with a "gear Puller" and have been spraying penetrating oil daily and shocking it by banging on the puller with a hammer. Yesterday I got out my 4ft persuader bar and added a few dozen FT/LBS of torque to the gear puller bolt---BANG and the gear is off! I was able to remove and inspect the 748 crank along with the right/clutch side main bearing.

There is a wealth of knowledge on other forums about these motors and there seems to be a consensus about which bearings go bad and why. There also is a huge debate/opinion that Ducati got/used a bad batch of main bearings! Well they predicted that the (slightly) smaller left/alternator side bearing had more play than the right/clutch side bearing. I will replace both but this leads to my next problem. There are 2 types of main bearings: Old/new style and the bad style. I have seen multiple pictures showing the difference between them but they did not say which one was which and I cant tell which one to buy since they share the same part number. This means I could order new bearings and could end up with the bad style! Anyone with Knowledge of this please let me know if you can help. I can just get them from Ben Fox or Gotham Cycle ($74 ea) and make sure they are the right ones but there are many on e-bay for less than half price I just want to be sure I am getting the better style bearing. I may just pay the extra to be sure I am getting the proper part but would prefer to save the $$ for other parts if someone can help me identify the correct style.

I pulled out the transmission and it looks great -especially since the motor was full of water and has 20,000 miles on it, no visible wear and no chips, or rounded dogs. This tells me that someone loved this bike before it was crashed and stored outside leading to water entering the motor! All the bearings for the tranny, starter/water pump and the shaft that drives the cams all look good and are within spec! I will replace the crank alternator bearing along with the output shaft bearing and one of the tranny bearings but the rest will stay. The bearings I am replacing are still good but they receive lots of torque and now is a good time to replace them.

I had stated earlier that I thought the motor might have been rebuilt before but I have since read that Ducati stopped using case gaskets after 1995-1996 and so the lack of a case gasket on this motor does not mean it was opened up before. I prefer to use case gaskets rather than trust the Ducati tri-bond sealant but this could effect the crank pre load. Also you have to be really careful using sealant on motors as the extra that gets pressed out from between the cases on reassembly can break free and cause issues with oil delivery to critical parts of your motor. This motor has 20,000 miles and I still find bits of the sealant every oil change!

That is all I have for now, I am ordering bearings and Tri-Bond, plastigauge and waiting for my crank to be balanced. Please speak up if you have any info on the difference in the main bearings as I am still trying to figure this part out. I wont wait too long before I just buy the right ones at the higher price but I still would like to get them from E-Bay for cheaper if possible.

I promise I will get some pictures up soon. I get so busy working and checking that I forget to snap any. I will try to get some tonight!