Cracked block woes

[Fourdy]

Story of woe. -

This 276 blown block has approx. 3k miles since installed. I have had a heating problem since the very first. I of course made the radiator companies stock go up by buying more even “better” units. 3rd and last one is a Brassworks.

Driving in my NW weather upper 70’s lower 80’s I could drive 50-60 miles or so with temp slowly moving up to 190+. Getting to the destination and shutting down it would of course cool down. If i got stuck in traffic the temp would go up and then suddenly jump to over 200 degrees. Shut down, cool off and go again. I took the heads off and spent hours cleaning the inside of the block. It had a lot of scale type material that I uses a magnet to get out.

Put it all back together and had the same cyclic temp problem. Up to this time, I have checked numerous times for exhaust gases in the radiator with zero results.

Time to get serious so I removed the engine, tore it completely down and had it double hot tanked. Got it all back together and ran it in my garage for 45 minutes to check it out. Temp to about 190 and shut it off. When I checked the water level 20 minutes later (yes with a rag over the cap) there was no pressure relief at all. Just like taking the cap off a cold radiator.

The next morning my Son was to take a ride with me to check things out. Walked around the car after it had run for a couple minutes only to find water (not moisture) coming out of the driver side exhaust. Immediately checked the radiator for exhaust gases again with instant results to the positive. Blue turned bright yellow and a full stream of bubbles.

Out comes the engine, torn down and purchase the Speedway pressure tester. 60# pressure with no indicated leak using soapy water. #8 cylinder appeared to have been steam cleaned.

I have talked to a few machinists and engineers that have suggested that I have a block crack that remains tight until a certain point in heat is reached making it open more. It finally got bad enough to remain open and grab my full attention. No crack can be seen with a mag, glass anywhere in the cyl or valve pockets. May be in exhaust runner in back.

Does any of this sound logical to you guys? Anyone need a block to fill with cement and go racing? lol It is very hard for me to give it up to the junk yard.

I have a new block all ready to replace this one and hoping for the best.

I would appreciate any comment you may have.

Fourdy

[40 Deluxe]

Here is a perfect home for Tod's new block!

[flatheadmurre]

They have a bad habbit of leaking thrue the headbolt going into the middle exhaust runner.
Material crack in the middle separating upper and lower part of the threaded hole.
A loooong timesert insert in that hole solves that type of leak or even a longer thread on the stud.

[B-O-B]

You are looking at it with a magnifying glass but did you or anyone Mag the block with a electro magnet & iron shavings ?

[Fordestes]

Try to borrow a black light and a little fluorescent dye and put it under pressure. a minute trace will shine like a diamond in a goats a--, you may be scrapping a repairable block, If you were closer I would dye test and pressure it up ,I can understand your frustrations especially when it cant be detected with pressure alone.

[Mike51Merc]

Sponsored Links (Register now to hide all advertisements)

Don't forget----- it could be the HEAD.

[Fordestes]

Another hint would be to use fluorescent mag iron powder, it can line up and then be seen with a black light somewhat easier than reg. white powder mag dust.

[Fourdy]

Not the heads. Occured with 8cm heads then new Edelbrocks. Guess I could send it in and pay for a magnaflux. Can that find cracks hidden within the block?

Fourdy

[richard crow]

put it two geter get a can of zotight do as the inst. say problem solved

[Kahuna]

Fourdy
I had a similar problem with a block that I had put a lot of money & effort into.
Ultimately it was a crack in the passenger side exhaust port for cylinder #4.
There was no fix for it that I could find anywhere. I ended up starting out with a new
block that I got from Vern Tardell. Very sad

[Fourdy]

Kahuna - that is exactly what we are beginning to believe my problem is only mine is in #8. Yes - extremely dissapointing. I do have another machined block sitting in my garage and hope to be back on the road again. It is just hard to make the final decision to "toss" it.

Fourdy

[flatheadmurre]

Pressure test and a borescope should be able to find the leak ??
Magnaflux is limited to what the eye can see.
Heated pressure test tanks are used on aluminum heads just because of this reason that cracks open up when getting hot.

[rotorwrench]

A pressure test won't help you "find" a leak in an exhaust port but if it won't hold its mud then it can confirm an exhaust port leak. The usually crack through in the siamese center ports but they can crack anywhere and some just can't be seen.

[tubman]

Just curious. What type block is this? Is it an 8BA, a 59A, or one of the earlier ones (99a, etc.). I've scanned the thread twice, and I don't believe it's specified.

[flatheadmurre]

Originally Posted by rotorwrench

A pressure test won't help you "find" a leak in an exhaust port but if it won't hold its mud then it can confirm an exhaust port leak. The usually crack through in the siamese center ports but they can crack anywhere and some just can't be seen.

Why wouldn´t you find a leak in the exhaust port ?
My latest odd leak was in a casting fault in the oilfill of a 59ab...finding the bubbles in the water and locating the leak wasn´t the hard part...getting it fixed was the real pain in the rear.

[Ol' Ron]

I've used Morso stop leak with some success. How long it will last is????

[Russ/40]

Fourdy, i had the same experience as you have. I was convinced there was a crack in the roof of the intake runner that nothing would help visualize. I too purchased the pressure test kit from Speedway, and it eventually pinpointed the crack. Mine was in the bore, but the crack didnt start until 2 inches down the bore and proceeded only 1 1/2 inches. Its hard to imagine it was missed during the build, or if it occured after the build. I too tried to will the problem away, not wanting to give up on the block. A second look with a pressure test might turn something up. With mine, i could have easily missed it again, as the crack showed so little leakage, and only showed leaking in a 1/8" portion of the crack.

Added after Ron's post.
No prior attempt with block sealer resolved my problem.

[revkev6]

i ran a motor for 25 years that had the oil pan rails welded up! the last couple years I was smelling coolant in the exhaust and the transmission needed a rebuild so I pulled it to replace the gaskets (thinking head gaskets) and rebuild the transmission. well... just to be safe I made my own pressure tester and it didn't take much pressure with some dish soap sprayed into the exhaust ports to find two ports with cracks.

enter complete new block!!!

don't despair though as I plan to load the old one up with leak stop and do my damnedest to see how much a flatty can take before it blows!

this is what my cracks looked like.

[richard crow]

i will say it again i have had flat heads when running the water was coming out the exhaust pipe put zotight block saver in & never had problems even years later this stuff works what do you have to loose just the price of the zotight

[revkev6]

Originally Posted by richard crow

i will say it again i have had flat heads when running the water was coming out the exhaust pipe put zotight block saver in & never had problems even years later this stuff works what do you have to loose just the price of the zotight

in my case?? piece of mind. My roadster isn't easy to get apart and for 25 years I've not trusted it to drive more than a few towns away for a few reasons. now, i've buttoned up some issues and hope to be able to take some trips with it.

sounds like he has the block out of the car at the moment. I wouldn't chance it myself. the cracked block i have will go in another car I'm building... at some point.