"49 Roadmaster Blues - Cracked Block

[Dan O]

Went back to work on installing the rebuilt head, manifolds, etc. on my 1949 Roadmaster 76s and discovered a crack in the block after cleaning off all the rust and grease!  I'm embarrased to say it was not noticed before but I thought/hoped it was a casting flaw.  Not my day at all. 

 

Is it possible/worth it to fix a crack?  It's under the manifolds an inch under the head but long and it can be reached easily (photo attached).  But I would hate to fix it and find another crack intermally.  I've read a bit on this forum of it being done successfully but if I have to pull the engine, I'd just as soon rebuild the whole motor.  Anyone in Houston area have a good block?  There was one here in town on eBay but it just got shipped to Connecticut last week or so as luck would have it.  The new buyer actually said he has another untested block crated and would ship to me for $400 - $500 plus $250 shipping.  It came from RPM in Minnesota (?).

 

 

Edited June 12, 2016 by Dan O (see edit history)

[JohnD1956]

I would consider torqueing the head down now, and doing a compression test and a leak down test, If it had sufficient results on both then chances are the crack is just external and then I might consider trying to have it repaired.  That area would never been seen once your manifolds are on anyway.

[Dan O]

Quote

I would consider torqueing the head down now, and doing a compression test and a leak down test, If it had sufficient results on both then chances are the crack is just external and then I might consider trying to have it repaired.

 

It's been torqued down and still leaks water readily.

[Ttotired]

Personally, out it comes.

Judging by the trickle of water in the picture, its cracked into the water jacket.

To weld cast iron, it needs to be preheated to try and bring the whole casting up to a high temperature to help with it not cracking during the weld.

You can look up "Pinning" the crack as well, but however its done, its going to be pricey, only worth it if your insisting on numbers matching.

 

[JohnD1956]

I would expect it to leak water,  I figured that a compression test would show if there was a crack into any of the cylinders.  The leak down test is how long the cylinders hold the compression.  This test can be done without water in the system.  But only do so if the engine means that much to you.  I have never performed such a repair, and the expense may not be worth the effort.  In the BCA, for judging the engine number is not looked at. If you replace the engine with another Buick engine of the same vintage that is acceptable.  I do not know about other clubs judging.

[JohnD1956]

Let me clarify the judging comment.  In BCA 400 point judging, the engine number is not looked at. Another Buick engine of the same vintage is acceptable.  In the BCA Archival judging the number is still not researched or looked for, but you would be responsible for telling the judges that you changed the engine.

[Bill Stoneberg]

If it is like Texas my car is registered using the engine number.  I dont know what would happen if I had to replace it.

 

I might try the compression / Leakdown test and if it passed that, try some JB Weld.  You only have 7 pounds of pressure in the cooling system.

 

[old-tank]

2 hours ago, Bill Stoneberg said:

If it is like Texas my car is registered using the engine number.  I dont know what would happen if I had to replace it.

 

 

 

Just don't discard the old engine until a DPS officer inspects and issues paperwork for the title change.  In the past some replacement engines were just re-stamped with the old engine number.

[Ben Bruce aka First Born]

I am thinking like Bill. One could even use a 4lb cap. Coolant would just boil at a lower temp.  And if one is thinking about replacing, nothing lost but labor if it fails. Might even drill each end of the crack and braze it up. Nothing too lose, assuming the crack is in just the outer water jacket.

 

  Ben