cylinder head bolt hole oil leak

[mhubbard]

So I had my 360 rebuilt by a local shop and have my mechanic doing all the button-up work... today they started it and this is what happened:

On the driver's side, on the rear of the cylinder head, there is a bolt hole underneath a freeze plug that when running, oil streams out of it. My mechanic (and he has been around awhile so theoretically, he should've seen it all by now) has never seen anything like it. This hole's purpose, it seems, is to brace a transmission bracket although, it is threaded as if it is the intention is to have an actual bolt in it.

Any thoughts as to what may be going on here?

Thanks!
Mike

[tedlovesjeeps71]

Got a pic??


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[REDONE]

The heads are interchangeable between left and right, so the driver's side has the same accessory bolt holes in the rear that the passenger side has on the front for the power steering and such.

My only guess is that someone has drilled that hole before (either to remove a broken bolt or to rethread it) and went to far.

I don't know off hand which of those holes would drill into an oil passage though.

[tedlovesjeeps71]

^^ so probably ok to coat a bolt and plug the hole.


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[REDONE]

Oops, I said that backwards! But I also went and looked and that hole would be for the alternator mount if the head was on the passenger side, so on the driver's side it's unused. Just stick a bolt in there with some RTV.

[derf]

The heads are interchangeable between left and right, so the driver's side has the same accessory bolt holes in the rear that the passenger side has on the front for the power steering and such.

My only guess is that someone has drilled that hole before (either to remove a broken bolt or to rethread it) and went to far.

I don't know off hand which of those holes would drill into an oil passage though.

There are no oil passages in the head. Oil is fed through the pushrods and then ends up sloshing around, giving everything a good coating.

There are drain holes from the head down to the block. It's possible that the hole got punched through to this drain hole and that's what's causing the leak. In that case, a bolt with some thread sealant would stop the leak. That oil is under zero pressure so you don't have to worry too much about anything more than just plugging the hole with anything.

[Tanker]

There is a head bolt that needs sealant due to water port. Drivers side under the exasht I think?

[mhubbard]

Okay, so I talked to the mechanic this morning and this is the plan of attack! Thanks, gentlemen. I'll let you know how it goes. I think I'll be getting it back in my driveway either tonight or tomorrow (with luck!!!!)

[mhubbard]

...... the rebuilder had the same seal+bolt plan. Do I need to worry any about the fact that a transmission brace "locator" is partially inserted into the hole tho?

[derf]

...... the rebuilder had the same seal+bolt plan. Do I need to worry any about the fact that a transmission brace "locator" is partially inserted into the hole tho?

From the factory, the bracket that held the transmission lines was attached at the bellhousing. Not sure why there would be a "brace" on the head.

[mhubbard]

From the factory, the bracket that held the transmission lines was attached at the bellhousing. Not sure why there would be a "brace" on the head.

It is more of a locator - what it is coming off of I am not precisely sure since I wasn't around when it was being reconstructed and dropped in.

Talked to the mechanic this AM - leak is gone and she runs like a champ! Barring any unforeseen disaster or mechanical mayhem, I plan on picking it up after lunch today!!!

[TeaBag]

I just finished a rebuild on my 91. Those bolt holes are indeed to mount the metal vacuum lines bracket that serves the transfer case. They shouldn't go all the way through. It sounds as though someone might have run a tap in there a little to far or possibly too long of a bolt or broke a bolt off, drilled it out and went too far. Either way, totally ok with putting a bolt with sealant in it.