My spare Century blocks are cracking.

[Horsley-Anarak]

I have just looked through my box of spare century blocks.

I thought that i had 4 good ones and one with a hairline crack .

Now I have two with hairline cracks and the cracked one is opening up like a spring flower bud.

Before the winter it showed a very tiny hairline crack now it is scrap.

Beware buying any secondhand block, I thought I had spares for the next twenty years, now I am not sure.

H-A

[electrosys]

Bad news indeed ....


Still - no worries - whack it on Ebay ... you might just get £16 for it !

(said with tongue held firmly in cheek ...)

[Niander101]

THought you would take off the heads [as you do] clean out all the crap
then fill the waterways with oil would last forever?

[Horsley-Anarak]

The heads are off Niander.

The point is that they crack around the exhaust port nearest the crankcase.

There is a void there that is impossible to get at. When the rust expands to fill that void, the pressure cracks the exhaust stub.

How ever well you clean out the waterways, you cant clean out this void, you may never stop century cylinders from failing in that spot.

QB cylinders have an open exhaust stub, that may suggest that Seagull realised there was a problem.

I will cut open the stub of one of the ones that has a hairline crack, to see if that will let me clean out the void.

Then I will make a cover plate or plug to make it water tight.

H-A

[Niander101]

Good idea mate
im sure youll do a good job

[Taspiper]

I've been gathering some seagulls and parts and had this....
I had drilled the hole before having a womans look only to discover that on this block or whats left of it, the exhaust port is only thin and not solid like my century 100 hence no cavity.

[Niander101]

I would of thought that if you store submerged in a bucket of diesel or oil
that that will stop any further corrosion from taking place whilst in storage
especially if you can get all the air out if possible.

[Taspiper]

I would of thought that if you store submerged in a bucket of diesel or oil
that that will stop any further corrosion from taking place whilst in storage
especially if you can get all the air out if possible.

+1 I would also of thought so. Excluding oxygen should work. Or maybe vacuum pack the parts so affected.

[NeilF]

Didn't I see a link for http://www.evaporust.com/ on this forum? Soak the whole head for a week in this to get the rust out of the void (does it really work?). Then, grind out a deep V in the hairline crack and fill with HTS-528 cast iron brazing rods ("The perfect rod to use for high-heat applications up to 1400 degrees, such as a cast iron manifold, or for high-stress areas, including joining cast iron ears or repairing cracks in blocks").

Would this work?

[Taspiper]

Sounds ok but I'm not farmilliar with those rods.
Most brazing rods for cast iron work by flowing over the cast iron and bonding to the grain structure. It's somewhat like using glue.
We use a Eutectic product that is basically powdered cast iron. This is applied by a special torch when the cast iron is at melting temperature. The benefits are that it is an actual fused join made of quality cast iron. The draw back is that I've found problems in fusing large areas or areas of differing thickness where on cooling cracking can occur.
It's possible than long pre and after heating/cooling may help with this.
It would be interesting to try an old seagull block but another downside is the cost of powder and while there are more old blocks out there I guess replacement is the answer for now.
Old exhaust manifolds can also be a problem where most of the iron content has been burnt away.
We also use TIG and cast iron mig wire. Both work with differing success rates depending on the job. Quality cast iron usually welds like a breeze anything else can cause problems.

[electrosys]

I've often mused on the idea of having a removable water jacket - not an easy design brief with those ports getting in the way - so that the jacket could be removed at intervals, the inner surfaces cleaned out and given a lick of anti-corrosion paint, and the jacket replaced with new sealing washers, gaskets or whatever. That way the cylinder would last until it eventually wore out.
The jacket itself could be made from pressed steel (I guess) and it wouldn't be critical if the assembly should develop a leak, as long as the lion's share of water passed through as intended.

[JERSEYMAN]

These cracked blocks seem to be fetching good money!! You could make a small fortune selling yours

http://www.ebay.co.uk/itm/British-Seagu ... 3a6e5c31ca

[Collector Inspector]

Yep

Me as well....................

B

[Taspiper]

I'm thinking of flushing my motor with soluble oil after use instead of fresh water, not sure if it would be of any benefit though.
I did buy a product called "salt off" which you spray on externals and hose off. Apparently this can also be used as a flush.
Don't know how you would ever know if any of these thing work though until your engine is stuffed!
It's also possible that some castings were porous, resulting in areas for salt to get in and attack. It's not easy getting a perfectly homogenous casting with no flaws.

[Stelios_Rjk]

Any idea if it is safe to sink in http://www.evaporust.com/ a block? I am concerned about the bore.