The thrust bearing on the cam shaft lost one of its flanges? WTF? How does this happen? Anyone seen this? Maybe some extra metal from the failure got into my main bearing?

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Some Questions

1) the thrust edge that broke, what end of the motor was it? oil pump or flywheel?
2) did you use double thrust for this build?
3) what cam? who made it?
4) what oil pump? could you have used the melling that requires trimming? did you do the extra o ring seal?
5) did you mock this motor up with the cam /crank without the gear set to make sure it spins free before final assy?
6) did you check cam end play before final assembly? (thrust clearance)
7) what tweaked you to tear the motor down?


better photos of the back side and bearing surface please.
Cheers

Mike

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In all my years of working on Type 2, 411, 412 and 914 motors for VW Canada, this is a new one to me. However if this was on my bench, this is what i'd be looking at.

1) measure the cam journals to make sure they are in spec. However im quite sure your cam is toast now. but confirm or deny the cam that was involved here is in spec or not.

2) cam line bore. is it proper and straight? if you dont have the tools for this, take it to a machine shop. Or find another block.


Other items

a) picture of the oil pump cover - gear side please

b) to check the cam thrust clearance, with the case half on a stand, install the bearings. drop the cam in, use feeler guages to check the clearance or end play. or slide it back and forth with a dial guage set up to measure the thrust clearance.

c) how do the rest of the cam and crank bearings look?


d) Cam gears. check for proper lash.


some other thoughts.

I dont like playing hide and go seek with these motors. If the cam wasnt ground oversized by accident by webcam, i'd be looking for another block. I would be looking real hard at the oil pump drive and cam gears. always install a double thrust bearing for the cam. So, cam joirnal too big, block twisted, cam gears or low oil pressure. Always mock you motor up first with no cam gears installed. Its a pain in the ass, but well worth it. this way, with the block all torqued up, you can spin both cam and crank, slide them back and forth to make sure everything is in order.

Say, is there any chance you accidentally installed that thrust bearing in the wrong side of the block? I.e. used the other standard bearing and covered the oil gallery hole for that journal? ..... Just sayin"

Cheers

Mike

I'd sure take a careful look at the condition of both the camshaft and crankshaft gears. Could be a chinger in the steel gear pushing the cam into the thrust surface. The bearing also shows signs of being dry. Why did the #1 main bearing seize?

The Cap'n

After seeing both, if this is the same motor with the seized main bearing...
You need to look at your oiling system...slumping ain't right.

Well, it was a cold start after not running for over 6 months. I did NOT pull the plugs and spin it to build pressure. Wish I would have.

And I just had a thought. When installing the pump the FIRST (well, actually second, due to having to tear it down to get out a dropped washer), I snapped the end of the cam off with the oil pump 180 out of orientation. Replaced the cam. Think I bent the gear?

Ya think that may have been hard on ...well... just about everything in that area?

Geez. That traumatic? I F-ed up the whole case maybe?

Wow. Bingo.

Yes, get another case and gear set. Did the crank survive? If it really did, flush the hell out of the oil drillings.

A whole new case? Oh god, I need a drink.

Yup a whole new case. Much better than half a case.

No fears man. what doesnt kill us makes us stronger.

Good luck with the new up and coming build.


Cheers

Mike

Say it ain't so. Any way I could verify this?

did the cam shaft come in contact with the block when the thrust end of the bearing broke off? Did it chew up the block just a tad? If so its toast.

You can measure all the cam journals, then check alignment. Again, maybe something you dont have the tools for?

must have spent 5K on measuring tools when i bought the boring bar. a local air cooled shop should be able to do such an inspection for you.

All I have are a dial indicator and calipers. I suppose I can measure the widest part on each case half to get an idea.

Wait a minute. You snapped the cam because the oil pump was 180 out? Not likely. There is no "right" way to install the OP, as long as the tab lines up with the slot in the camshaft. The tab on the shaft is centered, and will fit 2 ways. Sounds to me like you used a T1 pump to "get better oil pressure". We can see how well THAT worked, huh?

Krusty's Back!

The Cap'n

Captain, I humbly beg to to differ. The drive shaft is offset to the towards the top a bit, where it centers on the cam. Put it in upside down, and the tab hits the gear just below center. Thats how I snapped off the end of a new cam, right behind the flange that bolts to the gear.

You posted while I was typing... and answered my question, thanks.

More forensics. Oil pump cover, showing wear, and the cam geat, with a boogered tooth.

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I would imagine he means upside down.
Pound in a T4 pump upside down and you would get the same result.
I've used type one pumps for years with never an issue, but then I have have always modified and installed them correctly.

Is that a steel or AL cover?

Aluminum cover. Yeah, I did the grinding down of the tang on the pump trick. It does NOT bottom out in the cam gear.

Al covers are junk.
Did you also check the clearance on the drive part of the pump body and for cam bolt clearance?

Cam bolt to pump drive was fine. I stand corrected. I can see wear on the bolts, and on the pump. WTF? Grind the bolts?

What other cover options do I have?

A lot of folks say to use the stock Type 1 steel cover instead of aluminum. It's the one Jake Raby shows
in his rebuild video.

I have a steel cover around here. I guess I could use it instead of the AL one.

Type one isn't as easy as sticking in a pump
The cam gear needs to be clearanced.
The cam bolts needs to be clearanced.
The pump body needs to be clearanced.
If you are using the stock filter console you need to match port the outlet.
Then you have double check everything again.

The cover needs to be steel.

Supposedly this pump is specifically for type 4, but obviously, the bolts and or body did indeed need clearancing. When you say clearance the gear, you mean so the bolts sit lower in relation to the gear facing?

Yes ....and then you still have to check/clearance the bolts and do all the clearance checks.

No such thing as "pump is specifically for type 4",unless it is a T4 pump. It's a modified T1 pump and you still have to do all the checks.
This goes without saying for any modified or not original part.

take a picture of the end of the camshaft...the bolt heads.

and a picture of the back of the oil pump .

please

rich

Slightly shows on the bolts, the pump took the worst of it.


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Gene Berg manufactures Cast Iron oil pump covers.

Yeah, the one laying around here is cast.

When you use a type 1 pump not only will the tang be an issue, the body of the pump will need some means of spacing so the outlet and inlet holes line up with the galleries in the case. Like a spacer between the case and pump. I think I made one at 0.080 thick, but it might have been more. The cam bolts hitting the pump are an issue as well. I still am having trouble understanding the 180 degree bit affecting the tang clearance. From what I am seeing it seems like interference with the cam stressed and broke the thrust bearing and ruined the soft aluminum gear teeth, and alignment issues starved the rest of the motor for oil. Sound like a reasonable scenario?

I agree that having a qualified air cooled machinist looking at the case is worth the trouble.

I guess I wasn't clear, coupled with misunderstanding your statement. Sorry for the confusion. I meant the drive tang, not the whole pump. I can't even imagine installing the whole pump upside down. There's more than just a slight offset in the location of the pump drive shaft ....................... IIRC, the pump won't even go all the way in if it's 180 out.

The Cap'n

We's can make anything fit bro'

Can't touch this.

Your pump and your cam gear need modification/clearancing. Your case is not ruined.

in looking at both your cam thrust bearing and your main crank bearings, I would not assume the case is not harmed.

See if you can take some pictures of the ends of the case at the bearing locations for both ends of the crank and camshaft.

Also, the bearing saddles.

rich

Failed cam bearings in this manner are somewhat normal. This is the reason why double thrust bearings are necessary. That said; properly seating the thrust bearings during assembly, prior to measurement and fitting is generally what causes this.

It's quite possible that the wrong oil pump hitting the camshaft, along with the crankshaft dowel pins being mis aligned may have also contributed to the camshaft bearings.

Rich

When the first cam got damaged by the oil pump, did you reuse the thrust bearing?
I would think it sustained some damage in that incident and perhaps that led to it's shearing off or helped it along....

Well, I got offered a 1.7 case for 50 bucks. Got it from a local guy that does a lot of 914 work. He is telling me its standard mains, does not need line boring. So I think I am going to go with that case, and not chance my old one. Maybe I will have it checked out at a later date (when I get the urge to build a big 4!).

And now to order a bunch of parts......

Cap'n - You are right. It does not go in 180 out. And if you put the nuts on the pump cover and start to tighten, you have yourself a very effective way of breaking off the end of the cam.

Cap'n - You are right. It does not go in 180 out. And if you put the nuts on the pump cover and start to tighten, you have yourself a very effective way of breaking off the end of the cam.

Hell, that's just a scratch! The PO of this engine was very determined that it would run.

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Are you having a machinist check your case before you start throwing parts at her?

Man, thats a bad one.

Well, its allegedly been checked. I measured the journals, and they do indeed measure standard. And I know my crank to be 10 under. Still think I need to get it checked?

Let me be the first to suggest using JB Weld here ........................

The Cap'n

Or a complete and total lack of camshaft longitudinal thrust control (due to the thrust deck bearing failure) led to the contact of the cam bolts to the oil pump.

That would be my hypothesis; based on direct experience.

Jake- The end of the thrust bearing that failed was towards the gear. Wouldn't that stop it from coming forward, and only allow rearward movement?

Also, Why did they design the thrust bearing to only have flanges on half the bearing? Any reason to try and source another flanged bearing half and run two?

Yes, I did keep the same bearings.

Any loss of thrust control can lead to this. The factory only installed one thrust bearing to save money.

Guys like us install a second one on the other side and some of us even use some from another engine that are stronger, too.