need help please!

[tyronehunter]

hi guys hope you all had a geeat christmas.

i own a d40 stx and have had it for a half a year now. after a few offroad adventures the clutch ended up needing to be replaced. i got it done through the dealership. dual mass to a single mass blah blah blah. they also did a normal service...oil....filter....etc

after 800km i took the ute back into the dealership and asked to speak with the service manager. i told him i had a really violent shrudder that occured between 1500 -2000 rpm particularly going up a hill. he test drove it and said there was definately something wrong. he got the service technician to test drive it but when he got back he said it was normal vibrations due to the single mass flywheels not having the ability to absorb vibration blah blah blah. i have had a chat with a few nav owners (who have had replaced clutches) and they reckon what i have is definately not right. plus i have a few clinks and clonks driving around town. for example.....when the vehicle is stationary and in neutral....there is a consistant clunk. but when i depress the clutch pedal it goes away (and so forth). what are your opinions??

i have also noticed a rise in fuel consumption (was averaging 12L before clutch and engine service). its roughly 14 to 15L per 100km now. could there be a reason for this? the exhaust gas has a really strong diesel smell (wasnt there before service).

other than these problems she goes great. am very happy with my ute

thanks for the help guys

 

[Saitek]

Sounds like timing is out. Do these have a crank angle sensor that runs off the flywheel? Also they shouldn't really be much difference from a dual mass to a single the torsional vibration springs just change from being in the fly wheel to being in the clutch plate like normal clutches. If you have a really bad vibration the clutch plate , pressure plate or flywheel could be out of balance but sounds like timing.

 

[sparra04]

Not surprised nissan mech said nothing wrong
take it to a real mechanic, my guess is flywheel oob or clutch not fitted properly(apprentice)

 

[Old.Tony]

There are a couple of things that need to be identified first.

What kind of timing does the clunking have? Does it increase with road speed, or with engine speed?

Is the clutch travel smooth, or do you feel like it's not disengaging until your foot is near the floor?

If it's related to engine speed, I'd be looking at the engine (flywheel) or clutch. The flywheel/pressure plate combo are supposed to be bolted together and balanced prior to fitting.

If they used the original pressure plate, there may have been some heat damage done to the springs. This might prevent the clutch from fully engaging. Try this: in FIRST gear, gently move off and change into second gear, bring the RPM up to about 1400-1500 and hold it there for a moment. Then plant your foot hard. Does the engine RPM rise faster than it should? This is a sign that the clutch isn't fully engaging and it will be responsible for not only increased fuel consumption, but vastly premature wear of the new clutch.

Did they replace the clutch or just the flywheel?

Vibration from a SMF that has been properly balanced and installed is noticeable as a buzzing that varies in frequency with the engine RPM and it is NEVER extreme - if the DMF was dampening that vibration, it can't have been severe. For you to have severe vibration now it means something else is wrong.

If the vibration is in time with the vehicle speed, it's likely that they stuffed up something with the front drive shaft when reassembling. That's no big surprise either - there have been a couple of recent reports of this happening. If you drop out your front drive shaft and the vibration goes away, there's your problem.

 

[Tappet]

There will be slightly more vibration vibration with the single mass flywheel compared to the DMF's. After all the point of the DMF's is to reduce torsional vibrations from the engine, they are much better at this than a conventional clutch setup or why would of they fitted them. My model Nav does have the the SMF from factory and I can say that there is slightly more vibration over a D40 I have driven with a DMF. However it sounds nowhere near as bad as what you have stated. I do experience a few vibes around the the 1700~1800 rpm mark, before or after that, all good. It does give me the shits tho as a steady cruise in 5th. @ 60K's is right on that so 4th. it is. You could expect slightly more rollover noise in the gearbox whilst in neutral, I do but there is no clucking or anything like that.

As for the higher fuel consumption. Unrelated to the clutch but I would say not to the them poking around under the bonnet and underneath. Go thru all the sensors one by one unplug- clean with contact cleaner and replug. Pay particular attention to the connectors on the Gearbox they would of been unplugged to do the job. Check the earths. Even look for stupid things like a rag left in the airbox or similar. Funnier or should I say not so funnier things have happened.

Good luck and Happy New Year.

 

[tyronehunter]

thanks for the help guys. muchly appreciated

i will check all sensors and connections. the clunking noise in neutral is a consistant clunk....half a second intervals (only way i can explain). it goes away when you apply slight pressure to the gas pedal....so it does go away with an increase in rpm.

i tried out your trick old tony and the rpm doesnt shoot up straight away. it gradually builds up with vehicle speed. the clutch travel is smooth. how do i remove the front drive shaft and test to see if that was the problem? (sorry im a engine machinist not a mechanic so this is unfamiliar territory)

to my understanding, they replaced the clutch asesembly and the flywheel.

could a slight timing issue cause the strong diesel smell and increased fuel consumption? if not what else could cause this. before the service it didnt have this problem.

thanks again guys

 

[Old.Tony]

If there's a strong diesel smell, it's time to look UNDER the car for leaking fuel.

The consistent increase in RPM means your clutch isn't slipping, so you can assume that the pressure plate is okay and that's NOT the source of your extra fuel consumption. Sounds like the leak might be it, but finding it might be an interesting exercise.

Check the oil level. There have been a couple of cases where an injector seal has failed and caused diesel to be squirted into the crankcase. With the PCV pumping back into the air intake, this could cause run-on and that's NOT something you want to see (new motor will be required - run-on continues until the engine blows itself apart or you run out of crank oil which is almost the same thing!). Find the leak before you drive it too much more.

 

[tyronehunter]

sorry old tony i think i explained the problem incorrectly. i cant smell the diesel when the vehicle is off. when i turned the ute on i can smell it from the muffler but not actually in the engine bay or underneath the ute.

sorry

 

[vool104]

The crank angel sensor plugs into the gearbox on them, you have to remove it to pull the gearbox out or you will snap it. Easily done. The problem sound harmonic mate, certain area in the rev range she's out of whack,

 

[Old.Tony]

Ahh ok, in your original post you DID say that, so I should have gone back and read more carefully.

Okay, so it's either overfuelling or it's excessively priming the CAT (very, very unlikely). Two different things here.

Mild overfuelling will show as a lot of black smoke because the fuel does get partly combusted, but runs out of oxygen, can't finish the job but gets expelled at the end of the combustion cycle regardless. Because you're not getting the full power from each power stroke, you tend to use more fuel to do the same amount of work you're used to doing. This is often caused by dirty air filters, dirty/faulty MAFS sensors, failing turbocharger actuator or a chip that's set too high.

Massive overfuelling will result in white smoke - there's way too little air present in the combustion chamber and much of the fuel is not burned at all. Fuel consumption figures are way up. Either the turbocharger isn't spooling up at all, or an injector (or two) isn't closing properly. Yours isn't an auto so I'm not suspecting a DPF regen cycle which does the same thing if your DPF has been hollowed out or removed.

It could be as simple as a vacuum line on the turbocharger actuator. It's been suggested before and people have checked, reported that the hoses look fine but the problem persists and then on second more close examination the hoses were found to be faulty. Look for a hardening around the connectors, cracks in the hosing, or broken plastic joiners.