mAin centre bearing shells

[Itsblue]

I’ve been stripping down my CU 2.0L engine over the weekend , cane apart pretty easy. Once the cylinders were off I did notice it was not as easy as I thought it should be to turn the crack .

Anyway got the crank halves apart , cam looks well worn with some marks and flattening of the lobs

Now the crank the two centre shell main bearings , they are gem Vw with 021 105 531E stamped on them as well as Vw there’s a elephant pic stamped next to it

The bearings are loose in the case , by about half a mm so at this point I assumed the case is worn the other circular bearings are all a good fit in the case .

So I try the bearing on the crank the bearings have changed shape they are loose in the case and you would need considerable force to get them around the crank ( hense the hard to turn crank while stripping down .

I’ll post up some pics if anyone has any experience or comment it would be greatly appreciated




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[937carrera]

Have you measured the crank journals to see if it's standard and then the outside of the bearing.

Was the main bearing was still located correctly in the case.

Almost looks like the case has been line bored and standard bearing fitted ??

Just looked up the part number, it is standard, should be 70.00mm o.d, check the OD of the other mains

[Itsblue]

Yep at first I thought the case had been line bored , but the bearings don’t even fit the crank I Googled the part number but not much info , it’s not the same part number listed on Vw heritage , I looked up the part number on Vw classic parts , it says bearing for industrial engine 08/50 to 07/91 I’m thinking it’s the incorrect bearing
Addition info says that the crank for that bearing is fitted to the T2 up to 79 and the 411/412 up to 74

This engine came in my camper it ran just pretty slow I drove it couple of hundred miles , the guy I purchased it off said it had had a replacement engine

The crank journals measure 60.00 mm give or take a couple of tho , interestingly the centre main measures the same all across the surface , which would lead me to think it hasn’t gone very far since this bearing was installed , another thing when taking off the cylinders all the compression rings were point down and the gaps in the rings at the same place on the pistons

Maybe the muppets who did that fitted the incorrect main bearings

I could do with a bearing to check in the case perhaps

I’ll get the cam drive and dizzi drive off and check the other circular main

Thanks for the info


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[937carrera]

As the CU is basically a big bore type 4 engine I have dug out my 412 Haynes manual as I don't have the T25 one with me:

Journals 1,2,3 should measure 59.97 to 59.99mm, bore diameter 70.00 - 70.03
Journal 4 should measure 39.98 - 40.00mm, bore diameter 50.00 - 50.04

Clearances
1,3 - .04-.18mm
2 - .03 - .17
4 - .05 - .19

Muppets is a harsh word... but sounds true

There's some useful links to the bearing manufacturers in my WBX engine rebuild thread here https://club8090.co.uk/forum/viewtopic.p ... &start=105

I'm pretty comfortable you have the correct bearing there, for a Std / Std use, but not necessarily if the case has been machined, depending what has been done.

Try measuring the diameter of the "assembled" 2 piece bearing if you can.

How do the other bearings look - hopefully not as expired as the one above

[Itsblue]

I’ll put the two halves together and measure them later after further investigation on Vw classic parts the part number is correct for the middle mains , you know it seems as though it’s been put in a vice and squished !!
I’ll measure and post up some pics later

[937carrera]

... or inserted incorrectly on assembly

[silverbullet]

That engine can't have had any oil pressure with a bearing rattling around in the case like that?

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[multisi]

I have some used bearings with the same original number and marks if you need any measurements.

[Itsblue]

The pressure light went off pretty well instantly when it was running

[Itsblue]

Ok so I’ve been measuring the case and the bearing shells here’s what we found


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[Itsblue]

So the case is as it should be thank god ! The bearing is some what squished compared to what they should be

I took the crank shaft and the centre mains to the machine shop today , the general consensus is that the change in shape of the bearings due to it getting very hot

Although fortunately they think a polish on the crank should be all it needs after measuring to see if it’s still in spec

So we will see what they have to say

Another issue is the cam which looks well worn , I’m thinking of going for a better performing cam , what would you guys recommend based on your experience

Thanks again


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[multisi]

Just measured mine and they are 70mm.

[937carrera]

That looks like pretty good news overall, especially if the crank just needs a polish.

Any indication of why the bearing overheated, or do the engineers think it was simply assembled incorrectly, giving tight clearance and subsequent overheating as the top layer was removed ?

Delighted you managed to catch it in time

[Itsblue]

So the crank is back from the engineers , it was not able to just polish , so was reground 0.25 under on mains and big ends to match looks pretty good now though




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