Cracked block?

[audimd]

Hey was wondering if you guys think my block is cracked. In the middle of a head gasket change. Overheated m54 engine.

https://photos.app.goo.gl/HA18E5xgQS5JiBkn7

https://photos.app.goo.gl/DdDYzEzDYfVYDfUW7

[E39 Newbie]

Unless you can actually see a crack I think you'll have to have the block sent out to a machine shop for crack checking. I'm not sure how common that is. If the block got that hot then it's probably also warped and that you can check.

Take a mechanic's straightedge and check from front to back along the middle, then front to back diagonally both directions. Then side to side across each cylinder. Use a feeler gauge to measure warpage. I think the max warpage is something like .0025" in any direction. If it's more that that you'll need a new block. Do the same with the head. PO overheated my E39 and both block and head were severely warped.

[audimd]

In the pics I attached there is a little indentation in between the cylinder walls in the bridge the thinnest part of the block. I can feel it with my finger nail.

[E39 Newbie]

In the pics I attached there is a little indentation in between the cylinder walls in the bridge the thinnest part of the block. I can feel it with my finger nail.

ahh, OK. When I replied the links weren't there. It doesn't look good to me. Did you check for warpage yet?

[audimd]

I measured the block it is straight. The head is warped 0.011". Not sure if this can me machined out?

[E39 Newbie]

Somebody with more machining experience than I should chime in here. I *think* the head can be machined up to .011 if you use the 1mm head gasket. But that "crack" thing in the block would have me worried.

[audimd]

I looked at the block and the head gasket again. The head gasket broke in all the areas between the cylinder bridges where those lines appear. I think they are scratches from the broken gasket. Measures the block again it's straight. The head I remeasured at 0.020" 0.5mm so it's beyond resurfacing limits.

[E39 Newbie]

I looked at the block and the head gasket again. The head gasket broke in all the areas between the cylinder bridges where those lines appear. I think they are scratches from the broken gasket. Measures the block again it's straight. The head I remeasured at 0.020" 0.5mm so it's beyond resurfacing limits.

Sounds like it is. The head warping is the most common thing. Often the head bolts pull out of the block, too. If you're going to replace the head you might as well Time-Sert the block and never worry about that problem again. Of course, by the time you pay to get another head rebuilt, and the Time-Sert kit, you can probably just get a complete engine from LKQ or someplace.

[benica]

Coolant and oil mixing? Might see signs of Mileage? Prior overheating issues? Usually...warning signs...and....if you're that far into a teardown...and mileage is above average...might has well replace...