The power of your cooling system

[starliner62]

While working on a 59 Lark hardtop project, I came across this head bolt and I thought it would be interesting to pass along. Even though the engine in this car comes from a different manufacturer, the results are pretty much the same for any engine.
The head bolt pictured came out of a big block Chevy engine, rebuilt by the previous owner. All of the head bolts are exposed to the cooling system when installed. You can see that the bottom of the bolt has eroded quite a bit. Opinions may vary, but it appears to me that a poorly maintained cooling system was a big contributor to the erosion of this bolt. Needless to say, I ordered a set of new head bolts.....
Take care of your cooling system, flush and fill with fresh coolant so you don't kill your engine.

[Bamajak]

1959 Lark

While working on a 59 Lark hardtop project, I came across this head bolt and I thought it would be interesting to pass along. Even though the engine in this car comes from a different manufacturer, the results are pretty much the same for any engine.
The head bolt pictured came out of a big block Chevy engine, rebuilt by the previous owner. All of the head bolts are exposed to the cooling system when installed. You can see that the bottom of the bolt has eroded quite a bit. Opinions may vary, but it appears to me that a poorly maintained cooling system was a big contributor to the erosion of this bolt. Needless to say, I ordered a set of new head bolts.....
Take care of your cooling system, flush and fill with fresh coolant so you don't kill your engine.

Would this "Big Block" fit in my Lark?

[DEEPNHOCK]

Interesting...
Knowing dissimilar metals can react in the right environment, I wonder if the one bolt became the sacrificial anode in an electrical discharge situation?
Was the battery ground cable hooked to this bolt?
Just curious.....
Jeff

[starliner62]

Over half of the bolts were like this. All of the bolts showed some signs of corrosion. There was sealer on all of the bolts as required on big block Chevys, with the ends exposed to coolant. Talking to my Chevy guru, he stated that this is pretty much a normal thing, but he has noticed it more in recent years. Maybe a change in coolant formulas or the additive packages in the coolant.
The prices on head bolts are pretty reasonable, so it pays to replace them.
This engine had very few miles on it, so I would imagine that the damage had already been done when it was put together.
There was a good bit of money spent on this engine and it really surprises me that a couple of extra bucks was not spent on new head bolts.

[starliner62]

Yes Jack, it would..

Would this "Big Block" fit in my Lark?

[jclary]

As far as I know, all manufacturers recommend replacing all head bolts that are torqued. This is regardless of whether or not they were eroded by exposure in the water jacket. Once stretched by the forces of the torque, the strength values have changed and they are considered unreliable.

For years...I have violated this rule. The probability of me and my torque wrench being unreliable is greater than the probability that the bolt will fail.

[Skip Lackie]

The probability of me and my torque wrench being unreliable is greater than the probability that the bolt will fail.

Exactly, John. Couldn't possibly have said it better.

[Mike Van Veghten]

Jeff -
Not nearly that deep..!

John C. -
No, not always. That comment (replacing torqued fasteners) Is for "modern" engines. The older engines used fasteners that were basically...over designed. Today, the fasteners are designed just for the job that they do and designed to do it only one time. They are basically...a lesser grade fastener and when used, they are torqued to their "yeld point", which causes the plastic deformation (streatching) you mention. You "can" reuse the normal Chevy (big and first design small block) head and main cap fasteners more thAn one time.
Don't confuse the older engine fasteners with current designes.

In a proverbial nutshell, long use in an engine without antifreeze or some other corrosion inhibitor....water WILL...eat many metals..!

Mike

[Noxnabaker]

When I got my s.b. Mopar out & popped out the frost-plugs... guess how much sludge-rust I found?
Halfway up the cylinders! & even thou the cylinders are slanted & it's "only" on the outside the stuff reached that high, it still makes me think how many engines suffer from bad cooling because of greedy thoughts like "oh I never drive in cold weather so I don't need anti-frees"...
& then the corrosion...
+ Jeff thoughts; something has to act as anode thinking electric-wise.