Is my SBC 400 block cracked???'s

[dickeymoore]

I have a sbc 400 engine that ran fine on the engine stand I did a compression test and leak down test and everything looked good but today i looked at the sieds of the block and it looks like cracks on both outsides of the blockone on each side see pictures, is my block cracked?Thanks

 

[Built6spdMCSS]

Looks like just how the casting was done. If it was cracked you'd have water coming out, if you have had water in it already.

 

[dickeymoore]

haven't ran it with water

 

[Ribbedroof]

Looks to me like water has been seeping out, judging from the stains/rust. I have seen a few cracked there...BUT have also seen some with funky casting there as mentioned by 6speed

 

[ck80]

Looks to me like water has been seeping out, judging from the stains/rust. I have seen a few cracked there...BUT have also seen some with funky casting there as mentioned by 6speed

I was about to write the same thing. If you're able to run it on a stand just get her full of water, run her up to temp so the tstat opens and burps the system, and see what happens. It's a lot less work to pull a radiator and hook up the hoses while sitting on something to run on the test stand than put in and out of a car.

That rust stain makes me question, but, it could be nothing.

 

[ELCAM]

If you have a shop vacuum where the hose can be placed in the output, tape up all but one radiator hose connection with duct tape and tape the vacuum hose to the last water inlet/outlet. Should be able to feel the air coming out of the crack.

 

[Built6spdMCSS]

Looks to me like water has been seeping out, judging from the stains/rust.

Same I was thinking also given the discoloration, or it was brushed off/wiped with a rag to get a closer look. Especially in the second pic. Only one way to find out.

 

[Built6spdMCSS]

If you have a shop vacuum where the hose can be placed in the output, tape up all but one radiator hose connection with duct tape and tape the vacuum hose to the last water inlet/outlet. Should be able to feel the air coming out of the crack.

Yup, bolt up the water pump and plug it all off but one port. Vacuum or compressed air, see what it does. Throw some soapy water on it like a tire to see bubbles.

 

[dickeymoore]

So help me out hook tge shop vac up to the thermostat housing with the radiator and radiator hose hooked up to waterpump and run shop vac or what?Thanks

 

[Built6spdMCSS]

Bolt up water pump, block off all hose ports with tape except the one wide open one to the radiator. Shop vac hose to that, tape it good to seal it. If you have the setting where it will blow air out turn it to that and see if you can feel air around the suspected crack spot.