conrod nuts

[hirstydg]

Hi All

Engine of my 3.8 FHC was recently rebuild and reassembled using the original big end bolts and castellated nuts with new split pins. The sump is off again (don't ask) and so I have the opportunity to replace bolts and/or nuts with upgrades. I spoke to Rob Beere (extremely helpful) about this and following his advice I am inclined to reuse the original bolts, but replace the nuts with the later XJ 6 type from SNG. These have no split pin so no risk of broken pieces ending up in the oil pump, however, should I use Locklite during assembly. Any opinions on all this most welcome.

Many thanks

David

[Quattrofrank]

I dont see the reason in doing this, just use some torque grease and torque them to correct tourqe and thay will be fine.

Its is not common practice to use locktite on internal engine parts.

[abowie]

I'm quite surprised at Rob Beere's advice.

These bolts are subjected to a great deal of force, are cheap to buy and destroy your engine if they fail.

In a situation where there was no choice but to reuse them checking them with a stretch gauge would be mandatory but personally I can see no good argument for reusing them ever.

The modern nuts are set and forget and do not require Locktite.

I stripped an engine once where Locktite had been used on the main cap (not big end) bolts. It took a 4ft bar and every ounce of strength I could muster to undo them.

[Durango2k]

The problem imho that the Bolt part where the hole For the Pin Is maybe thinner, so the "clamping" area of the nut won't clamp as we'll as it Would on a solid Bolt.

I did go the same way Rob Beere suggested, after Talking to a Horch Specialist. He said use a toothbrush and brake cleaner, then Blue Loctite and torque to spec.

Carsten

[hirstydg]

Thanks everyone. Mixed opinions so still undecided.

David

[Moeregaard]

When I did the first rebuild of my very early 4.2, back in 1983, I reused the original rod bolts with the castellated nuts. I was in college at the time, didn't have a pot to pi** in or a window to throw it out of, so I cut costs where I could. I had no failures over the next eight years, but every time I changed the oil I would find bits of cotter pin inside the canister. Chris Harvey mentions this in his book "E-Type: End of an Era."

In 1991, when I had the funds to do a proper home restoration, I pulled the engine down and found more cotter pin bits in the sump, and the oil-pump lobes were seriously knackered. I spoke with a well known Jaguar restorer here in the U.S., and he recommended replacing the castellated nuts with the later items. I asked what, if any, thread-locker he recommended and the answer was blue Loctite. I did this and had no problems. Things may have changed over the last 20 years, so I would do some asking around, but I can highly recommend NOT using the castellated big-end nuts.

[hirstydg]

Thanks for that Moe. I have heard of similar experiences from other XK owners. I'm going for the later type of nut and will add Locktite on the basis that it can't do any harm.

David