Crack in heads?

[Hog54]

I know ive seen them on alot of heads,but how critical is the cracks around the spark hole to valve seats?Can you run them like that safely?

[Cotten]

Hog54!

If they blow soap bubbles on the outside under pressure, I would say they are a problem for certain.

....Cotten

[Hauula Pan]

It really depends on the severity of the crack. One shallow crack usually isn't a problem but multiple cracks or one deep one can ruin your day for sure. I have one crack that's been there for years & I've not had any problems.

[Hog54]

Hog54!

If they blow soap bubbles on the outside under pressure, I would say they are a problem for certain.

....Cotten

How do I go about checking it like that?

[jdpan]

Hog54!

If they blow soap bubbles on the outside under pressure, I would say they are a problem for certain.

....Cotten

How do I go about checking it like that?

Mix some liquid dishwashing detergent and water together, spray it around the suspected area and kick the motor over a few times, if you see bubbles coming from said area, you have a leak.

[steve_wood]

You can also try dabbing the soapy water with a small brush around the area of the crack. That way, you get less of a mess - that soapy water is corrosive. The dabbing action makes it foam up and stay in place - makes it supper easy to spot bubbles.

[Hog54]

Yeah but the heads are off and the cracks are on the inside.

[Cotten]

Yeah but the heads are off and the cracks are on the inside.

Hog54!

The point is that you should determine if they go to the outside.

Either you get resourceful and bolt up a plate to pressurize the chamber so that you can inspect not only around the plug, but through the port to the seat,...
or you just take your chances.

...Cotten

[58flh]

Hog54---clean them up good, in the ports both of them & combustion chamber. Follow what (COTTON) said make a makeshift clear lexan plate to bolt-up to (use half-inch lexan for rigidity) & presureize them!---watch for leaks everywhere, the ones you suspect that might go through first!.Look into the ports & look for the valveseats leaking.---take your time & do it rite, do it 3times if your not sure the firstime. My 2cents worth would be to fix the cracks anyway--because the envirement that they operate in it will only get worse!!(FACT). Fix-em the rightway, by somebody who knows what they are doing!--You will have piece of mind & a Good running motor!----58flh

[steve_wood]

Hog54:

Are the valves still in place? If so, another test you can try is the gas test. Install the spark plugs and invert the head and support it so it doesn't wobble. Pour gas or alcohol into the bowl. Check for leaks below. Leave it overnight and check again.

Note that this test is not as good as the bubble test. But... if it doesn't leak, you can feel just a little bit safer about putting the heads back on. You should definitely follow-up with a bubble test when the heads are installed.

[Huck]

Mine were pretty ugly, I posted some pics a while back. Anyway, I followed the advice here... Went with over sized valves, the guy that cut them fitted them nice and they passed the vacuum check. I have a solid lifter motor, so following Cottons advice set the valve train up tight. Then did a leak down test, all was good, soaped it for giggles still good! Time will tell. Anyway what I,m getting at it they will run wounded!!

[Huck]

Only happen to me..
My day.
So I’m looking for an oil leak, must need to pull the back rocker cover down a bit because on first look that’s were it coming from. Negative, it’s coming from a crack in the head to the right of the spark plug under the fin. WTH? I checked all this before,,, no leaks! As I sit their watching it leak ever so slightly as it runs,,, bad words more beer. Shut it down get TDC flop it gear pump it up to 90 psi NO bubbles WTF?? Homie says pull the timing plug and bump it with the air hose. Bubbles! Now if that don’t ruin your day you got a hole pile of heads somewhere,, I don’t, dam it!! I'm done, these heads get no more money, the test is now complete. The test reveled that dummies should leave cracked heads alone. I suck…

[steve_wood]

Huck,

Sounds like the leak is coming from the oil passage that goes from the top of the head to the bottom of the head where it then feeds into the cylinder.

Pain in the ass to tear the head off, but the repair might not be all that expensive.... You might even be able to fix it with something like Loctite Steel Putty (99913).

[Huck]

never heard of it, I'll look it up thanks.

[58flh]

Huck----as Steve said It could be a fix!---Just remember it wont be for long!--But will give you some saddle-time for-sure,-enough time to start looking for a rear head or a set of heads. Hell I have seen this stuff last for 2yrs!--But given to where its location is on your sled-I would say lay-off the loudhandle-I know its hard but the less stress you put on her the better!-just my 2----Richie