Non-BMW Stuff on a BMW Forum
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Clutch-type LSDs, in my experience, will always be a little noisy and clunky. Older diffs can have some excessive backlash in the gearing , but even a healthy new/rebuilt clutch type LSD is going to be a little clunky as the pin moves back and forth between the opening in the carrier halves.
Loose u-joints can sometimes cause it.
slop in the CV axles is most certainly a thing.
A bad center support bearing will most definitely clunk as well.
There is also quite a lot of backlash in the transmission too.
I was able to get my E30 drivetrain to an acceptable level of driveline clunkiness to where as long as I was driving smooth there was no noise. Pausing a fraction of a second longer than normal to let the engine slow down to match the speed of the next gear also helps.
The CSB was the last link in my search for a quiet driveline though.
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For the ticking: rocker arm coming out of adjustment or perhaps a manifold leak. I have had a rocker lose adjustment before. An injector could also be extra noisy so dont rule that out.
I find that running Lucas Fuel Additive really quiets the M20 down a bit and im not sure how or why but It seems to be a product that actually helps.
The clunking has gotten worse so I don't believe it is just natural play in the system.
I will check the rockers tonight. I have a video but I cannot get it to load on here. I can definitely check to see if it has an exhaust leak, but this sounds internal to the engine.
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A clunk like your describing has typically been worn U-joints in the driveshaft (for me).
Easy to check if it's in the air. -
Are those easy to replace?
Also, got a mechanics stethoscope at lunch and listened around. There was not an injector that was louder than the other, they were all the same. So I think I'll rule that out. The sound was almost non-existent in the block, so I'm going to hope a couple valves are out of adjustment.
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BMW u-joints are non-servicable. In the event that there is a non-OE driveshaft in there, there may be grease fittings (probably too late even if thats the case).
For a reman driveshaft, I have had great luck with these guys and they still seem to be the cheapest around
https://www.wholesaleimportparts.com/.
While the valve cover is off, just check to make sure the rocker arm retainers are all seated securely. if any seem a bit loose you can remove them and bend them a bit for a better fit.
What oil are you using?
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BMW u-joints are non-servicable. In the event that there is a non-OE driveshaft in there, there may be grease fittings (probably too late even if thats the case).
For a reman driveshaft, I have had great luck with these guys and they still seem to be the cheapest around
https://www.wholesaleimportparts.com/.
While the valve cover is off, just check to make sure the rocker arm retainers are all seated securely. if any seem a bit loose you can remove them and bend them a bit for a better fit.
What oil are you using?
I popped the valve cover off at lunch. Visually nothing looked out of order. I went through and checked all the eccentric nuts and I did find two nuts that weren't extremely loose, but I got probably a quarter turn out of. I'll go through and check clearances tonight.
I'm using what the book says - Castrol GTX 20w50
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A clunk like your describing has typically been worn U-joints in the driveshaft (for me).
Easy to check if it's in the air.How do I check this?
Also, found a rocker that was way out of adjustment. Will fix that and hope that cures my problem. And then move on to driveline.
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How do I check this?
Also, found a rocker that was way out of adjustment. Will fix that and hope that cures my problem. And then move on to driveline.
With the driveshaft removed you just physically move the yoke in both directions on each axis. As long as it moves freely the U-joints are fine. The Center Support Bearing (CSB) will cause drive line vibrations before the u-joints. The csb can be checked without removal. As long as there isn't any cracks in the rubber bushing around the bearing and no significant play its good.
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With the driveshaft removed you just physically move the yoke in both directions on each axis. As long as it moves freely the U-joints are fine. The Center Support Bearing (CSB) will cause drive line vibrations before the u-joints. The csb can be checked without removal. As long as there isn't any cracks in the rubber bushing around the bearing and no significant play its good.
I don't necessarily have vibrations, it's a clunk after shifting and engaging the next the gear. Unless I shift delicately then there is no clunk.
Picture of it sitting in the garage. Did a short drive today and it was good. Minus the shift clunk.
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Noisy lifter all better?
I always wanted to try some shockproof gear oil in the trans and diff to see how it helps cushion the lash noise
in the E46 world, that drivetrain noise is referred to as the “M Clunk”. The LSDs really can be that noisy
https://www.zpost.com/forums/showthread.php?t=166867
https://www.6speedonline.com/forums/bmw-m/173049-e46-m3-driveline-clunk-what.html
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Noisy lifter all better?
Yup. Found one that was probably all the way out of adjustment.
I forget you did replace subframe bushings?
I have not touched the driveline at all - including rear subframe bushings. I'm treating everything in this car as if it's never been replaced.
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Reason I asked is that if these are shot it can also cause the clunk.
Differential bolts to the subframe are all tight?
They should be. My hope is to pull the driveline out and do new guibo, CSB, diff mount bushing, and rear subframe bushings.
Or when the subframe is tearing the floor out of the car
Ew
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I am probably going to take this block in to get honed, but in order to do so I need to remove these things. I believe one drives the oil pump and the other is the oil pressure sending unit. I know the gear for the oil pump can not just be remover and reinstalled, but can this little piece pop out? And how do I remove the oil pressure unit?
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That aluminum bit is an oil pressure relief valve. You can remove it, no problem, with a 22 or 24 mm wrench or whatever it is. Theres just a loose spring on the other side.
the oil pump drive shaft can be removed via the recessed cap with the bmw logo on it. Make sure you do not forget to put that part in! Ive read a couple threads of people anxiously firing up the engine and quickly realizing they forgot a part. You should also use a drill and a 6/8mm socket on the other end of the shaft (the end under the bmw cap) to prime the oil pump and preoil the engine before startup
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Do NOT remove the intermediate shaft bearings unless there is something wrong with them. Replacement is not an easy task. They need to be honed to size after installation.
I'm not removing that. I just need to know if it's okay to remove this rod without doing anything crazy to reinstall it.
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I'm not removing that. I just need to know if it's okay to remove this rod without doing anything crazy to reinstall it.
It should just pull out. But it's been a while since I built an M20.
You can take the intermediate shaft out for cleaning and stuff just the bearings should stay in place.
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