Which bolts should I use?

[J Hamilton]

Going to put a new radiator core in my 42 D and replace the rusty crusty bolts that bolts the core to the tanks. Should I use regular steel bolts or stainless steel bolts? Some of the bolts thread into the cast iron tanks. Wondering if these dissimilar metals, stainless and cast, would be a bad idea together? Just thinking as stainless won't rust and corrode, but regular bolts are easier to extract if/when they break. Thoughts on this?

 

[jon f mn]

Don't use stainless, they are a disaster if you need to take them out again. Besides, will you be around long enough for regular bolts to give you trouble? The originals are 70 years old, that added to our current age makes us very old.

 

[casecollectorsc]

Put some anti-seize on the bolts if you think it may need to come apart later. I'm old enough I probably don't need it...won't be around next time it comes apart.

 

[Tramway Guy]

X2 on non-stainless. Use zinc-plated and ant-seize. No grade 8 either.

 

[John Saeli]

Jon: I'm puzzled on the stainless. What happens when you have to remove them?

 

[tomturkey]

Even with anti-seize stainless tends to gall the threads and seize. My advise, like the others, just use regular bolts with anti-seize if you like. gobble

 

[wore out]

(quoted from post at 05:03:49 04/06/23) X2 on non-stainless. Use zinc-plated and ant-seize. No grade 8 either.

''No grade 8 either.''

Why the prohibition on Grade 8 bolts, even though not required here for strength?

What is the downside, besides they cost more?

 

[Nedd]

Most factory bolts were around grade 5. Oxidation/rust
doesnt matter too much for grade. So if you ever have to
do it again and the bolts break off, its way easier to drill
out a grade 5 instead of grade 8

 

[wore out]

''So if you ever have to do it again and the bolts break off, its way easier to drill out a grade 5 instead of grade 8.''

On the other hand, it's MUCH easier to snap off a Grade 5 bolt before it breaks loose vs. a Grade 8.

As an example, it's MUCH more likely that a Grade 8 manifold bolt will come out without snapping off vs. a lesser grade.

And a good cobalt bit will usually make quick work of drilling out even a Grade 8 bolt, IF needed.

 

[jon f mn]

As said above, the threads will gall up and the bolts will twist off when trying to remove them. And that's not even over time, but will happen right away. Plus they are tough but soft, so they stretch and that could cause leakage in this use.

 

[RJKeith]

If you use stainless, be sure to use anti-seize. Stainless will gaul up with itself or just about anything else, and you will not get them apart. Anti-seize will prevent this.

 

[RJKeith]

Most grade 8 bolts I have seen are anodized to resist corrosion.

 

[Stephen Newell]

It should be good enough to use yellow coated zinc bolts. I would use a little anti seize lubricant lube what ever bolts you choose.

 

[ChillyB]

There are good stainless steel bolts. Your local store doesnt stock them (17-4PH).

Only reason to use grade 5 is because you are an industrial company with bean counters looking to shave a nickel. There is zero reason or circumstance where a grade 5 has an advantage over a grade 8. Yes, a grade 5 is easier to drill. And more likely to need drilled. Because it's an inferior fastener.