Type 4 Engine Knocking Noise at Idle - PROBABLY SOLVED

[raygreenwood]

The one size fits all....."0" number cam gears...are not in themselves a problem....as long as the lash is not excessive and the bolt flange area is milled flat.

I have used numerous or them with 0 issues. However....you need to measure lash at a teetb to make sure they are concentric.....and you need to measure runnout...and you need to rotate the gear on a cam with the crank in the case to check for tight spots.

If all of that checks out and your cam thrust face is polished smooth....there is no way it will wear out the thrust flange on the cam bearing. But again.....using a double thrust cam bearing set....is good insurance. Ray

[hazetguy]

have a read through this thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=692236
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[69BahamaYellow]

Split the case and got the cam and bearings out. Clearance on the thrust face is .024", way out of spec, but I can't see that there is any unusual wear on the bearing or the cam, so either I got a bearing that was too small, or the cam was ground too wide on the thrust surfaces. Does anybody have measurements for a new set of cam bearings. My current cam bearing is 1.080" at the thrust faces, the width on the cam is 1.104", giving the .024" clearance. I'd like to put this thing back together with double thrust bearings (it currently has a single), can cam bearings be ordered in oversized widths?

Thanks for sharing that post with the Jake Raby comments, Hazetguy. He described the knocking at idle sound, from axial cam movement as if he'd seen it a hundred times Well, I'm going to confirm he's right.

[69BahamaYellow]

[Amskeptic]

[Hoody]

It amazes me that people think the Brazilian aluminum cam gears cause issues. Raby used these in every type 4 motor that he built and never had issues with them. Reusing a magnesium cam gear to build a new engine is just a recipe for disaster.

[69BahamaYellow]

I can see why the aftermarket cam gears cause problems if you don't bolt them to the shaft properly (with the correct low profile bolts and cutting lock washers) and they loosen up over time.

Aftermarket quality control of the gears is always a concern, but the aluminum one I got from Webcam seems to be pretty good. backlash is less than .001" all the way around, and same goes for run out. The gear looks almost brand new after 50,000 miles of running.

Since I was mating an aftermarket cam gear to the OEM crankshaft gear, I didn't have a choice on pitchline variance. At the time, "Standard" is all they offered, and I got lucky the fit was right with my engine case, giving the proper backlash between 0 to .002".

What makes me feel like an idiot is trying to figure out if I put the cam in my engine and forgot to check for excessive clearance at the thrust bearing, or if it just wore itself down the the .024" clearance I have now. I can't find any dimensions for either cam or bearings anywhere (not in the Bently manual, Haynes manual, or web), so there's no way to know if the aftermarket cam I purchased from Webcam is too wide at the thrust surfaces, or if the cam bearings are too thin. I ended up posting a separate thread to see if anybody knows the dim's on cam bearings, since none of my local suppliers stock them, and none of the web vendors can physically put their hands on them to measure; all they know is the dim's on the shipping box

[Wildthings]

[scubaseas]

[Hoody]

My advice would be to locate some nos steel backed KS and double thrust the cam bearing. If you can not locate them which isn’t easy supposedly Glyco still steel backs their cam bearings.

[SGKent]

You know, I come here to help and get flamed. It was the Brazilian gear. I could measure the deviation in it and the replacement. Like an idiot I used it anyway because it seemed the thing to do. The bearing was within the correct lash. What happens is that the runout moves the cam back and forth which ruins the thrust surfaces on the bearing. The problem went away with a stock aluminum gear. I bought up every junk cam the came up for sale here for a couple years el cheapo, collected a full set of like new aluminum German gears in almost each number.

But I am glad the OP argued with me because when I asked him what the number it was to send him a factory ALUMINUM gear to help the situation, which is no longer going to be offered. Geeeez.

Bob - WTF mentioned magnesium? I didn't. All mine are aluminum ones in outstanding shape and they have already been milled and threaded for a new cam. No they aren't for sale.

And everyone else, including Colin. When the gear has any runout it runs the cam back and forth hammering the thrust bearing. Road Warrior did it to you Colin - want me to find the thread you posted about it?

Maybe I measured the lash and endplay wrong? Used the wrong tools? failed to bolt the gear on right? What do you think?

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[raygreenwood]

[lil-jinx]

[airschooled]

[69BahamaYellow]

[Hoody]

Steve I was not saying that YOU used magnesium cam gears. But since the Brazilian aluminum one is the one available and that’s what has been available for a long time that is what everyone uses. Many people however try to reuse their magnesium cam gear which is a disaster waiting to happen. I was not flaming you and simply stating facts.

[lil-jinx]

It may be just the picture,but that looks like a poor fillet on that cam,don't know if I would reuse it.
What did you find with the oil pump shaft?
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[Hoody]

Why don’t you just return the cam and lifters and get a new one? They should stand behind it if it left the factory subpar.

[mike77777]

Good discussion, I will be re camming a 77 2.0 liter soon. Has anyone had good results with the straight cut cam/crank gears? Seems like the lack of thrust of the gears would eliminate one possible difficulty.
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[mike77777]

I have heard of using two sets of bearings to "double thrust' the one journal. Does any modification of the thrust bearings need to be done if attempting this? Thinking of oil getting all the way around both of the thrust faces. Thanks, mike
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