Main bolts, Head bolts

[unklpat]

On the topic of failures, has anyone had nissan main bearing bolts, or head bolts fail? Again, not high speed/racing applications, or associated with a bearing failure from lack of lubrication. Just curious. Pat

[theunz]

I had a head bolt break on my U20. Bolts were on there third use. ARP studs now!

[Solex68]

Like "Mike M" said...I believe the rule of thumb today is use the ARP replacements in the U20.

[unklpat]

So, there has been instances of factory bolts breaking? Is that after multiple uses, or rebuilds? I'm just curious. Pat

[JT68]

Yes on the head bolts- they typically go into yield , but don't typically break unless they rust in place and break on removal.

There were large head and small head U20 headbolts, the smallhead variety are junk, the large are perfectly good and work fine.

Never with the main bolts.

We typically keep all the ARP fasteners in stock and open 24/7.

[unklpat]

Thanks for that, Jim. I'm finding that there are a lot of rumors, or heresay, about these motors. In other worlds, the main/head bolts are generally okay. Gust trying to find out what's actually happening. Pat

[JT68]

The large diameter OEM headbolts are fine. The small diameter are junk-throw them away.

The ARP head studs are great, but if you overdo the torque, the blocks can crack. That will really, really ruin your day. (obviously MUCH worse than a head gasket failure)

The OEM main cap bolts virtually never fail.

We use ARP main studs in race engines, but they are certainly overkill for street builds.