1835 Bus build Rattle.

[early]

I have a rattle coming from the front crank snout. it is audible and continues until it warms up a bit.

it seems like it is camshaft backlash and goes away as the gear warms up, sounds weird i know.

wondering if anyone has had a similar situation.

this is my 1835 Bus engine i built last year.
Camshaft is a Webcam 86 dash 5 with CB lightweight lifters, CB aluminum pushrods and AA slipper foot rocker arms that come out to about 1.34 .

i thought the sound was valve train and took the rockers off and re-shimmed them to a loose zero and adjustment is .006.

the Cam gear is -2 Magnesium VW gear drilled and spot faced for new cam use that i got from Berg. and when i first set it up the backlash felt good as gold.

when i took this engine apart the first time it had a -2 Gear in it so that is why i used the -2 but after reading about the codes under the distributor my block is stamped WD which equates to a -4 cam gear ( according to the chart i have seen on here) so that would put me off .02mm on gear size, so that makes sense.

now this engine did not make this noise until about a month ago and it has less than 1000 miles on it since last years build.

here's a couple youtube videos of it running and one of the borescope i sent down to look at the crank gear, gear shows a little bit of scratching on it.

if you local gurus could have a look and a listen and give me your opinions i would be thankful. my next step would be to pull the oil pump and inspect the gear itself.

thanks in advance guys

https://youtu.be/lDsvS_6MtHQ

https://youtu.be/DwQzIJkgUBk

borescope

https://youtu.be/OFU2pfKU46Y

edit added this cam stamp post:
https://www.thesamba.com/vw/gallery/pix/2532111.png

[Dave Becker]

I had a similar thing happed to an engine I built, pulled it down and found the cam thrust was way off and rattling, AA dual thrust cam bearings Engle 100 cam, thrust clearance was set correctly when the engine was built.

I have noticed AA cam bearing "settle in" so now clearance them after assembling the case with the cam and bearings in place and giving both ends of the cam a couple of taps with a copper drift, no problems since.
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[early]

[SGKent]

the issue with the cam thrust is that sometimes it changes if the bearings are a bit spread. Have you checked the end play on the crankshaft?
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[early]

[veedubcrazy]

Cam sliding back and forth in its bearings? Could be gear wore down the thrust... Check that oil to see if it looks like graphite...
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[Brian_e]

I had one start doing this, and mine ended up being the cam gear.

Without stripping it, I pulled the oil pump cover off, and pulled the top gear out. Then I stuck a big screwdriver in the hole, and turned the cam back and forth to see if there was excessive backlash in the cam gears. I think i also rolled the engine over to TDC when I did it. Maybe I took the rockers off to relieve spring pressure? That was a really long time ago.

Brian
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[early]

[74 Thing]

I think you can see the cam gear teeth through the fuel pump block off area.

As Brian E indicated above, maybe pull the rockers then the oil pump cover and remove the upper oil pump gear and see if the cam gear backlash is excessive using a screw driver (may sure you do this to maybe 4-6 spots while rotating since it can be loose on one side and just right on the other).

[veedubcrazy]

[scrivyscriv]

That first video sounds almost like the fan rattling. Did the noise change any with the fan belt off?
It could also be a loose crank pulley.
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[early]

[74 Thing]

You can test for sure by removing the fan belt for a min at idle.

[modok]

Don't want to jinx it, but maybe the gear is loose on the cam.

I always bathe those bolts in 640 green sleeve retainer like Berg, and IMO never use star lockwashers on magnesium, and probably not on aluminum either.
Maybe I'm paranoid.....or maybe I'm not. I don't know.

Also now and then you can get abnormal wear on the cam gear if the crank gear is distorted, and that can happen if the key is too tight in the gear.

Loose pulley or flywheel or fan or generator pulley also possible.
Or the cam ate the thrust bearing.....tho I doubt it with a WEB cam, but some of the other companies forget to mask off the thrust faces when they parkerize the cam and that sure doesn't help things.

I didn't watch the vid, just covering all the usual suspects.

[74 Thing]

Remove the fan belt to eliminate a loose belt/alt pulley or fan.

Also do what Modok suggested and check the crankshaft pulley bolt and maybe pull the pulley off and inspect the snout area.

If those don't work then pull the oil pump cover. The teeth on the cam gear look ok in your borescope, but you should check it on 4 spots 90 degrees apart in case it is worn in one area and not consistently worn throughout.