Cylinder pushed in case

[minirailz]

Last weekend I finally mounted my rebuild engine in the bug, to take it for a first spin.
The break-in procedure was done before, but had to wait to install it.

First 10km went great, then it started to get less peppy, which got worse and worse.
Barely got it home after 30km running on 2 cylinders.

When home I tried starting it again and (I quote Zundfolge ):
The valves where so tight, no compression at all, it was just whirring like a windmill...
Valves were set correctly the night before the ride.

After re-adjusting the valves, compression remained 0 on one side. The head was loose. Probably one or more striped threads?
Nope The jugs started sinking in the case, the first 2 rows of fins are broken, so any tightening of the head bolts, just pushing the cylinders deeper in the case.

In order to fix this I will need to order a new set of jugs & pistons.
The question on my end remains: how did this happen

I measured all precisely, case = 90mm, heads are 90mm, 69mm stroke and 77mm pistons.
Going for standard 1300cc setup (F-code engine).
Cylinders are the right size and also match the old cylinders which I removed last year.

Torqued the heads in the described sequence, first at 10nm (7.4 lbf.ft) and later on 32nm (23.59 lbf.ft).

Only thing I can think of now is that the head(s) must have been on an angle, maybe because the pushrod-tubes were a pushing the head up from below?

Any idea/advice is welcome. I don't like to keep buying piston-sets...

Regards,
Dennis
ps: current broken set is Mahle, I'm able to get Kolbenschmidt as well, any preference?
ps2: case was machined so mating surface is flat, heads were rebuild as well.
ps3: I don't consider myself an engine rebuilder, just like to learn stuff

[gwal]

the only way i can see this happening is if you had a late 1300 case but used early 1300 barrels,

post 74- 1300 used a standard 1600 case iirc

but i am probably wrong

are you positive that the bottom barrel spigot size is identical to the old barrels?

andy

[minirailz]

Hi Andy,

It's a '68 or '69 case, so 90mm it is
Thanks for the info though, I didn't knew that.

The issue is present on both sides.
Which made me sure it has to do with something I did wrong.

I added the type 3 cooling tin.
I know there a pro's and con's, but the added cooling effect appealed.

It was a pain to install, together with the other tins, but I think that is what possibly caused the issue.

What if, the cooling tin was installed too far forward. The head would 'settle' on the the tin and not on the cylinder, right?

Whatever the outcome is, I'll go back to the stock deflector plates anyway

Dennis

[gwal]

the cooling tin did not cause this

[PatJr]

my guess is that the case wash machined for larger cylinders then the ones that were matted up to it, not enough seat for them on the case
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[Dale M.]

[minirailz]

[Vanapplebomb]

Yeah, the case opening was way too large for those cylinders. Most original VW cylinders/cases I have measured fall with about 0.25mm (~10 thou) of clearance between the spigot of the cylinder and the bore of the case.

Yours obviously was several mm of clearance, which clearly indicates the wrong case/cylinder combination. The seating surface of the cylinder was probably just touching the case on its very outer perimeter…with almost no surface area in contact with the case.

It might have even been as bad as to not have the cylinder seat land on the case at all. It could have already been through, and just resting on the cooling fins.

Either scenario…

I hate to say it, but this should have been immediately obvious the second the first cylinder was dropped into the case.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[Vanapplebomb]

[modok]

The wall thickness on that cylinder looks far to thin to be for a 1300
Compare old part to new.

[minirailz]

[modok]

I think I understand. There was a stepped ledge to locate the cylinder in the 90mm case register, but this entire section had broken away.

These cylinders are not strong enough..... made in china? Flawed casting?

Maybe converting to 8mm studs might help?

Your picture is not working but here is another set of 1300 cylinders to compare with
https://www.thesamba.com/vw/classifieds/detail.php?id=2439718

[minirailz]

Please find a comparison of the old and new jugs below.

Hopefully this is convincing enough regarding right size jug vs bore

Dennis

[minirailz]

[oprn]

Oh ya! The problem is clear now! Those new cylinders are for something else, at 36 HP or a 356? I don't know but they are completely missing the step up by the start of the cooling fins that seal on the case. What is wrong with the old cylinders? Can you not hone them a bit and reuse them?

Once again the beauty of the stock parts is that they actually FIT!
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[minirailz]

True, as a last resort I could reinstall the old jugs.
But I wanted a fresh motor all together, so reusing worn jugs would kill that idea a bit.

The question now is how to proceed. I have three options:
1. buy the same set again, hoping for better (but maybe Kolbenschmidt instead of Mahle?)
2. re-use the old jugs and cylinders
3. upgrade to 1600cc jugs, as the case bore is also 90mm and my heads are already milled for 94mm. (now using rings to downgrade to 90mm...)

Thank you all for your input so far!!

Dennis

[modok]

You need to be refunded, and return the cylinders to mahle so they can understand the problem and fix it.

Simply too weak because they are too thin.
They need to be made thicker so they don't break.
The iron they are now using is weaker thus the bottom flange needs to be thicker.

It's a very simple problem.

[mikedjames]

If the base of the new cylinders has gone into the block to break off the fins, the cast iron being sheared off by the magnesium will almost certainly have broached the case and now enlarged the holes in the case in an irregular way . There may not be enough metal left for your old cylinders to go back in now. You may have to machine the case for larger diameter just to have an even shelf around the hole for the cylinders to mate with..
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[minirailz]

Both thank you for your replies.
As a beginner/learning engine builder I rarely blame bad manufacturing and will look at my own miss-use of parts/tools first.

But I had a hard time figuring out that my line-bore was not done straight either, which had nothing to do with me or my skills...

I will contact the seller, see what they say.
I'm blessed with a VW parts dealer/manufacturer in the next village.
(BBT, maybe you heard of them )

The case boring is scored but not much enlarged. Where the fins broke, the cylinder is practically smaller than what is should be.

Dennis

[oprn]