Main and Camshaft Bearings - Can they be reused?

[VWLover77]

If an engine case is split open, does it automatically mean that the main and cam bearings must be replaced? Or is there some "mileage limit" under which the bearings can be reused?

I'm considering the possible disassembly of my 2.0L Type IV that was rebuilt with an align-bored case and all new bearings 3,000 miles ago.

Thanks!
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Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[Glenn]

Can they be reused... sure. Should you... only if they are VERY low mileage.

Ask yourself this: Is it worth the $100 saving to reuse them and risk having to replace them in the near future.
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[aeromech]

Why are you splitting the case?
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[VWLover77]

I'm not sure I am splitting the case, but it may come to that. The engine has a noise that I can't figure out.

Glenn, would you consider 3,000 miles "very low"?
_________________
Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[VWLover77]

I know it's very difficult to diagnose engine noises from iPhone videos, but here you go....

Hear all that "clacking"? This engine has hydraulic lifters. Inside the Bus with all the windows up, it's quite noticeable at idle. It gets lost in the other noise as engine revs increase. Pulling plug wires makes no difference. Engine temperature makes no difference.


Link

_________________
Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[SGKent]

unless they are scored or damaged I'd reuse main, cam and rod bearings if they only have 3,000 miles on them, unless you have deep pockets and lots of new old stock items lying around. If they had 40,000 miles on them in a T4 I'd say probably toss a coin if they looked good, 50,000 miles yes. I raced, worked in a shop that did high end racing machine work, and rebuilt engines for a living at one time. That is what I base my suggestion on. They MUST go back in the same spots you take them from.

Try to use a stethoscope or long screwdriver to pinpoint where the sound is loudest. Use a small (1/4" etcT) diameter hose to your ear to listen for exhaust leaks. You can also put a rag over the exhaust to listen for hissing and if the sound gets louder. Last, it it is an automatic, did you inspect the flex plate for cracks? They will make all sorts of weird noises.
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[aeromech]

Does the sound go away when you increase rpm’s up over 2000? Loose cam gears can act that way.

Edit: have you inspected your sump screen for metal?
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[SGKent]

[VWLover77]

I will check the noise level at 2000 rpm and above.... (I do find it hard to believe the cam gear is loose - I used both star washers and loctite on the bolts.)

An oil change will be done soon, and will include checking the sump screen as well as checking the oil itself for swirls.

Yes! I'm well aware of the need to carefully torque the sump cover nut.
_________________
Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[aeromech]

Did the sound exist a the beginning or did it develop after some mileage?
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[raygreenwood]

[Abscate]

If you are a typical Bay window driver of 5-6k A year, a used set can last 5-10 years. No need to replace on a “ while you are in there” basis

Cost of a DIY engine pull amd tear down is about 20 hours at $25, so $500
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[TrollFromDownBelow]

[airschooled]

I hear uneven induction/exhaust pulses and a deeper grumbling from heavy parts, not the “snap” of an exhaust leak. Can we have a 20-second video from one vantage point with the deck lid open?

Robbie
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[SGKent]

I hear a light pffffst sound in the back ground like an small exhaust leak. I do not hear the uneven pulses Robbie is hearing. My ears are 71 years old so I don't have as good of hearing as someone younger generally does. I also heard a light clickity which sounds a bit like an uneven valve adjustment.

use the methods I suggested earlier to pinpoint the noise that concerns you. Those are the only methods I know to isolate noises.
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[raygreenwood]

[telford dorr]

Considering that the lifters can be removed for inspection without splitting the case, I'd avoid splitting...
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[Starbucket]

For the original question, the only time the Main and cam bearings are ever touched by their shafts is the last rev.s of the motor and the first rev.s of start-up So the bearings are fine Unless you see wiping from poor assembly. They still sell plasti gage so if in doubt measure.

[VWLover77]

In an attempt to respond to most of the comments and questions....

- It's a manual trans, so no flex plate to crack
- The noise has been there from the start of this engine build
- The noise is there at 2K rpm and higher, but gets lost in all the other noise as the revs increase
- I double-checked the cam bolt clearance when assembling the engine and there was no concern. The cam gear is an original VW that was machined to provide bolt clearance (See photo at the bottom of this post)
- The lifters are all set to 2 turns after contacting the valve stem
- Solid spacers are on all rocker arm shafts

To try to get away from any exhaust leak noise, I shot this video from the driver's seat with the windows up. You'll probably need to use headphones. (The changes in volume are not real and due to the iPhone reacting to something other than the engine)


Link


Cam bolt clearance

_________________
Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[airschooled]

There's deep resonant "thudding" around 400 cycles per second. It has an overtone in the higher "clacky" register, which may be more prevalent in person. That speed means once every other rotation, which corresponds with the four-stroke cycle for one cylinder.

If you bunt the cat with your wrist do you hear rattling sounds?

As always, take the belt off and listen. Try it for 10-20 seconds with the fan off too, if you want a different perspective. Oil cap off at idle may also give you a different earshot, though a blown PCV diaphragm will allow that to serve as a giant vacuum leak and stall the engine.

Robbie
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