11mm vs. 12mm Head Bolts

[Gecko]

I have done a bunch of reading here and in other forums regarding the 11mm and 12mm diameter head bolts issues and was hoping for some clarification.

If I understand this correctly, the blocks that use the 11mm head bolts have a greater likelihood of cracking. This is also likely to occur after the 1000 mile re-torquing of the head bolts. The cracks that occur typically end up splitting the block in areas which cause oil leaks into the coolant passages. Although I didn't read it explicitly, I would also think that the cracks reduce the strength of the joint which in turn could cause reduced clamping pressure on the head gasket. This would also lead to leaks and oil getting into the coolant system via bypassing the gasket.

Do the blocks using the 12mm diameter head bolts have more material around the bolt holes? If they do, this would mean that one couldn't just drill out a block from 11mm to 12mm and change head bolts, correct?

Thanks

[coke]

Yeah. The blocks are beefed up around the bolt holes in the 12mm block.
The 12mm blocks generally don't have any of the problems the 11mm did, unless they are severely overheated.

You can help a 11mm block by using cylinder head studs vs the bolts.

[vwtyp133]

... Do the blocks using the 12mm diameter head bolts have more material around the bolt holes? ...

Yes, and they are drilled/threaded deeper, for more gripping power.

[Gecko]

Just bought an '81 with oil in coolant. It has socket head cap screw hex head bolts so I assume they are the 11mm. Haven't gone any further on the diagnosis/dismantle but options to look for sound like a cracked block or warped head.

Trying to determine if I should replace the motor with another 1.6L N/A but with the 12mm bolts or not? New/rebuilt or used? If I get used, new bearings and pistons or not?

Decisions, decisions...

If I do go with the block that has 12mm head bolts can I assume that all my other components will bolt right up?

One other question, what is the difference between the short block and long block? Are those the 1.5L vs. 1.6L or is that something else?

Thx

[coke]

I'd use a 12mm block over a 11mm block anyday. In fact, I'd go out of my way to find one before I put an 11mm block back together.

Accessories and all that will bolt up. Your cylinder head would have to be drilled out to accept 12mm bolts if you wanted to use the same cylinder head. But the 12mm blocks and heads are still fairly easy to get for the most part.

[82vdub]

I'd shoot for the 12mm 1.6L block as well. More than likely, you'll get a 12mm block as the 11mm 1.6L motors were around for a short time. A shortblock typically doesn't have a head on it, and a longblock includes a head.

[Ira B]

I have an 11mm motor and have had nothing but joy with it.
When I got it, it needed a head gasket and I was very, very careful about procedures when re-installing the new one.
Top quality gasket.
Super, super clean bolts and mating surfaces.
Super clean block threads, threads chased, then cleaned again with carb cleaner and vacumed clean.
Two drops of clean motor oil applied to each bolt thread and careful torquing/re-torquing.
I also drive like an old man.

That said, the 12mm motors are probably better but I suspect a lot of the bad rap the 11mm ones get is due to sloppy workmanship and overheating. They are both nice little motors.

[coke]

My vw mechanic friend who owned and operated a VW Shop for 25 years had someone roll in with 60k miles on a new 11mm motor, cracked block.

[datsunwildman2]

Hello
I am looking for a 11mm head the one I have is cracked and my rest of engine is in good shape

[82vdub]

Where is your head cracked?