Thread: Why V8 bores crack,,,

Because tiny aircraft crash into the blocks or the block has been sawn up.

I'm not sure what you are pointing out, Pedro.

I think hes pointing to the uneven machining, but anyone who has machined castings would know that castings are generally irregular and its virtually impossible to get every casting perfectly machined especially in a large scale manufacturing environment, somewhere on the machining drawings there would be tolerance conditions that should make it clear what the acceptable conditions are.

I don't think that's where the 4.0/4.6 litre blocks crack.

Originally Posted by p38arover

Because tiny aircraft crash into the blocks or the block has been sawn up.

I'm not sure what you are pointing out, Pedro.

X2

More info please Pedro

Deano

Originally Posted by p38arover

I don't think that's where the 4.0/4.6 litre blocks crack.

It could be indicative that the block wasn't very well aligned with the machine and one side of the bore wall was thinner etc, but this kind of thing is expected with machined castings, and generally these kinds of miss-alignments look a lot worst than they actually are, the scallops are nicely rounded and there is little visible step on the other side.

Someone else may point out that their bore cracked at the point where it was thinnest, but of course it would, the question to be answered is what was the designed minimum wall thickness, did the failed block exceed this, and was the design thickness adequate for normal use.

yes I remember this from this mob, they explain it well , if I had one i'd be worried too

RPi Engineering - Re manufactured Rover V8 engines. Cracking blocks and Top Hat liners explained - YouTube

Like the others - not getting the pic

Originally Posted by thai_tiger

yes I remember this from this mob, they explain it well , if I had one i'd be worried too

RPi Engineering - Re manufactured Rover V8 engines. Cracking blocks and Top Hat liners explained - YouTube

Aha! That explains Pedro's pic.

When my 4.6 was reconditioned and fitted with tophat liners, I think (but can't be sure) the engine builder welded up the crack.

When I bought the car it was fitted with venturi LPG, not injected (I later fitted injected LPG). It used to boil at the drop of a hat. I pulled the radiator and found this:

p38aradtopcopy9ms.jpg

I wonder if the combination of a not well tuned LPG system and a faulty radiator caused the block to crack.