Drive with a cracked head?

[Bonnewagon]

Hypothetically: If you had a cracked head, needed to move a vehicle that otherwise ran well, and towing was not an option, could you drive a vehicle a short distance with a cracked head? The drive would be less than 100 miles. The crack is at the top of a straight six head, between two exhaust valves, not affecting compression in any cylinder. Coolant is leaking up out of the crack and into the valve cover area, draining down and mixing with crankcase oil. The crack is small, and the leak is small, taking a long time to ruin the oil. You could remove the radiator cap which would stop the coolant from building up pressure. You could remove the thermostat too which would help relieve pressure. And finally you could drop the coolant level down to below the crack. Theoretically that would keep the coolant from leaking up into the valve cover area since that is the highest point of the cooling system. Without saying just tow it, do you think this would work?

 

[airboatgreg]

Bearing cannot side much coolant, if you are replacing the engine loosen the cap, put some KW block seal in it, drain coolant and fill with water, drive easy, go for it

 

[pontiacgp]

I would drain all the coolant and use plain water and like airboatgreg suggested use a block sealer And how come it cannot be towed?

 

[yourownself]

I would say go for it, but think about how bad it will be to get stuck after 5 miles. If you feel confident that you can limp that motor 100 miles, go for it. Especially if you’re replacing the motor anyway.


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[Bonnewagon]

Block sealer was another great option I considered. I just hate to add that stuff to an otherwise tight system and cause a clogged radiator. The engine should not need replacing but the head must be. Doesn't adding sealer require a pressurized system? I was afraid the time it took to build pressure, and the sealer to seal the leak, the oil would get contaminated again. What I did was to drain the coolant, drain the butterscotch-looking oil, refill with used oil, and ran the motor to check for good oil pressure and no expensive noises. It passed. I guess I could add sealer, run it until it sealed, then change the oil again right away. Leave it to Steve to ask about towing when I said NOT TO!

 

[lilbowtie]

I would go for it watching temp. I would also try a sealant - I used Moroso ceramic block sealant for a crack in #2 cylinder and made the last 2 races that way.

 

[pontiacgp]

I also suggested using plain water which is easier on the bearing if it gets mixed with the oil

and what about cleaniing the crack and sealing it with JB Weld

 

[Gonzo1970]

JB Weld the crack, then get it to where it needs to be once the JB Weld has cured completely.

-Gonz

 

[Bonnewagon]

Yes, plain water would be best. JB weld sounds good too, I won't know if it's feasible until I get the valve cover off. Right now I can barely see the crack through the oil filler hole. Thanks for all the advice and suggestions. I think I can pull this off. It's a charity job for an elderly person still living in pre-war economy land.

 

[pontiacgp]

If I could use my CAA to help you out I would....